*Edited by Sevgi Akarsu*

"Multiple chronic conditions," also known as multimorbidity, is a special situation frequently encountered by global healthcare professionals, especially internists/ primary care physicians, neurologists, respiratory/pulmonologists, pain specialists, and oncologists, who spend more than three-quarters of their time in the treatment of chronic diseases and direct patient care. Thus, the increasing need for multidisciplinary approaches in the management of multiple chronic medical problems, rather than focusing on individual diseases, should be borne in mind by global healthcare professionals, public health professionals, healthcare providers, health policymakers, and pharmaceutical industries. This book is an up-to-date source of information for physicians, residents, and advanced medical students seeking a broader understanding of managing chronic disease clusters.

Published in London, UK © 2020 IntechOpen © thomasmales / iStock

An Overview and Management of Multiple Chronic Conditions

An Overview and

Management of Multiple

Chronic Conditions

*Edited by Sevgi Akarsu*


**3.1. Donor‐acceptor method**

( ) ( ) (( ) ) ( )

a r

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+Ñ× - +Ñ = - + +

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=× +- × 1 2 ( ) 1 (9)

=× +- × 1 2 ( ) 1 (10)

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(7)

1 1

where indices 1 and 2 show first and second fluids properties, and *α* is a scalar phase indica‐

1 Control volume is filled only with phase 1 0 Control volume is filled only with phase 2

This phase indicator function is the fluid property or volume fraction, which moves with it

0 *i i U t x* ¶ ¶ a

This function can be used to calculate the fluid properties in each phase as a weight function. In order to use a set of governing equations using the weight function, each fluid property should be calculated based on the volume occupied by this fluid in the surface cell as ex‐

> a r

 a m

Free surfaces considered here are those on which discontinuities exist in one or more varia‐ bles. This has been the challenge for researchers to omit or reduce this problem as much as possible. The transient state as well as phenomena such as surface tension, changing of fluid phase and Kelvin‐Helmholtz instability makes numerical simulation of such problems cumbersome. It is expected that methods used to simulate interface of fluids have a number of characteristics. These include mass conservation, simulating the interface as thin as possible,

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368 Numerical Simulation - From Brain Imaging to Turbulent Flows

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tor function which is defined as follows:

ì ï = í ï î < <

a

and can be derived as follows:

pressed in Eqs. (9) and (10) [2]:

The main idea of donor‐acceptor approach is that the value of volume fraction in downwind cell, the acceptor cell, is used for anticipation of transferring fluid in each time step. The problem in this approach is that using downwind cell in calculations may lead to unreal situations which are values out of zero and unity domain in surface cells. **Figure 3a** shows this method with the first fluid with gray color and volume of fluid equals to unity. It could be seen that using donor‐acceptor approach with downwind differencing scheme results in values greater than unity in donor cell. It is because the second fluid in the acceptor cell is greater than the value needed in the donor cell. Similarly in **Figure 3b**, using downwind differencing scheme leads to negative values for volume of fluid, which is because the needed fluid in acceptor cell is more than what is in the donor cell [3].

**Figure 3.** Schematic view of donor‐acceptor approach [4].

In order to be assured that volume of fluid is between zero and one, the amount of fluid or volume of fluid in donor cell should be used to regulate the estimated fluid transferring between two adjacent cells [5].

One drawback of donor‐acceptor method is that this method changes any finite gradient into step, and consequently increases the slope of the surface model in the direction of flow. This problem was alleviated by proposing a method to consider the slope of interface for flux transferring in adjacent cells by Hirt and Nichols [6]. For this purpose, a donor‐acceptor equation was proposed so that it could detect the direction of the flow in interface and then define the upwind and downwind cells accordingly. Thereafter, this model was expanded

for 3D domains by Torrey et al. [7]. The Surfer method is one version of volume of fluid which deals with merging and fragmenting of interfaces in multiphase flows [8].

The volume of fluid method is one of the most popular methods for anticipation of interfa‐ ces, and many researches have been conducted based on this method including dam break, Rayleigh‐Taylor instability, wave generation and bubble movement [6, 9–12]. This method was modified in 2008 to get more accurate results by considering diagonal changes in fluxes of adjacent cells for structured grid domains [13, 14].


**2. Current situations in key countries**

In the year 1896 Henry Ford used pure ethanol as a fuel to run his first car. After that in 1908, he designed another famous car, i.e., Ford Model T, it is capable of moving with both combination of gasoline and ethanol [6]. Brazil was one of the largest country to implement the bio-fuel programs in the production of ethanol fuel from sugarcane in the world [7]. In the year 2006, Brazilians are utilized 18% of ethanol fuel for their country's road transport sector and by April 2008, more than 50% of fuel consumption for the gasoline market. Up to 2005, Brazil was topper in the world to produce alcohol fuel, when it was surpassed by the United States. Both the countries together (Brazil and the United States) are responsible in the year of 2011 for 87.1% world's alcohol fuel produced [8].

However, China was directly campaigning alcohol fuel in five central and northeastern major cities in order to reduce consumption of fossil fuels. These cities are Zhaodong in Heilongjiang province, Luoyang, Nanyang in central China's Henan province, Zhengzhou, Harbin and northeast China. In the present situations, compared to any country in the world the United States produces and consumes more alcohol fuel. These days, majority of the cars on road in the United States can run with alcohol fuel and motor vehicle manufacturers already produce vehicles designed to run on much higher ethanol blends. The major countries were given in **Table 1** based on the annual production of alcohol fuel [9].

**Annual production alcohol fuel from different countries in the year of 2014 to 2016 [9] (Million US gallons per year)**

#### **Table 1.**

*Annual production alcohol fuel by various countries.*


**1. Introduction**

### **1.1 Definition of sarcopenia**

The term sarcopenia comes from the Greek words "*sarco*," which means muscle, and "*penia*," which means loss, and was used for the first time by Dr. Irwin Rosenberg, director of the "Research Center on Aging" at Boston University (USA) which in 1989 stated: "*the most dramatic and significant age-related physical decline was the loss of lean body mass*" (**Figure 1**) [1, 2].

Thus, sarcopenia was initially defined as "*normal and involuntary loss of muscle mass due to aging*" (Rosenberg, 1989).

This definition was based on the conceptual framework that states that the decline in muscle strength due to aging was due to a parallel decline in muscle mass. However, as the field of sarcopenia progressed, studies showed that the loss of age-related muscle strength outweighed the loss of muscle mass [3], so a definition of sarcopenia based only on muscle mass was not sufficient [4]. It was

#### **Figure 1.**

*Loss of muscle mass and strength due to aging (modified from: ADAM©, atlas of human anatomy. Todd R. Olson, 1997).*

more precisely defined as [5]: "*Decrease in muscle mass and strength due to aging*" (Morley et al., 2001).

Since then, the number of scientific publications has increased. In those, among other findings, its possible causes and consequences were identified, and the concept of sarcopenia has evolved as different definitions emerged among researchers [6, 7]. Still, there was still a lack of a definition of sarcopenia that would be suitable both for use in research settings and in clinical practice, until significant progress was made in 2010 thanks to a joint publication by the European Working Group on Sarcopenia in Older People [8] (EWGSOP) in which sarcopenia was defined as: "*A syndrome characterized by a gradual and generalized loss of skeletal muscle mass and muscle strength with the risk of causing adverse outcomes such as physical disability, poor quality of life and even mortality*" (Cruz-Jentoft et al., 2010).

This new definition incorporated sarcopenia not only the loss of muscle mass and strength but also its consequences on physical performance [5, 9] and for many years, it was the definition that was used in most studies as a reference or "*gold standard*" for the diagnosis of sarcopenia [10].

In October 2016, the World Health Organization gave a new advance to this condition, since through the International Classification of Diseases in its 10th revision (ICD-10-CM) recognized sarcopenia not as a geriatric syndrome but as a disease (muscular), with the code M62.84 [11, 12]. This forced it to revise and update its definition again.

In the 10 years passed since the initial work of the European group in 2010, researchers and clinicians have explored many aspects of sarcopenia, and expert groups around the world have published complementary definitions of sarcopenia [13–15]. However, the more recent definition and the current one are the one proposed by this same group [16–21] who, in a review carried out in 2019, defined sarcopenia as "*A progressive and generalized skeletal muscle disorder that*

*Prevalence of Sarcopenia According to the Method Used to Determine Physical Performance DOI: http://dx.doi.org/10.5772/intechopen.100467*

*occurs with aging and is associated with a greater probability of adverse outcomes such as falls, fractures, physical disability and even mortality*" (Cruz-Jentoft et al., 2019).

Despite all these advances, international expert groups from around the world still do not reach a consensus on a definition of sarcopenia that is widely accepted, although they have agreed on the mechanisms and clinical implications of sarcopenia [22, 23] and especially in the fact that muscle mass, muscle strength, and physical performance are important components for the diagnosis of this disease and that therefore, all these parameters must be measured [4].

### **1.2 Clinical consequences of sarcopenia**

The clinical consequences of sarcopenia are basically due to loss of strength and muscle mass, not only in terms of functional disabilities, fractures, hospitalizations, and increased mortality [24], but also in quality of life [25].

In terms of human health, sarcopenia increases the risk of falls and fractures [26, 27] and impairs the ability to carry out activities of daily living [28]; it is associated with heart disease [29], respiratory disease [15], and cognitive impairment [30]; and leads to mobility disorders [13]; it contributes to a decrease in the quality of life [31] and ultimately death [26].

#### **1.3 Sarcopenia categories**

Sarcopenia is a disease with many causes and variable outcomes. In some people, a clear and unique cause of sarcopenia can be identified, largely attributable to aging, but in other cases, other causes can be identified. In this way, defining the sarcopenia categories as primary and secondary can be useful in clinical practice [8, 16].

Sarcopenia can be considered "primary" (or age-related) when there is no obvious cause other than aging. Sarcopenia is considered "secondary" when there are one or more obvious causes other than aging [16].

Sarcopenia staging is a concept that can help to guide its clinical treatment, in this way it can be categorized according to its severity in the following states [16]:

Identifying the stages of sarcopenia helps in selecting treatments and setting appropriate recovery goals. Staging can also support the design of research studies that focus on a specific stage or changes in stages over time [8].

### **1.4 Parameters that define sarcopenia and variables that measure these parameters**

The parameters that define sarcopenia are the amount of muscle and its function. The measurable variables are muscle mass, muscle strength, and physical performance [8].

Muscle mass can be expressed as total body skeletal muscle mass or as appendicular skeletal muscle mass, which is the sum of skeletal muscle mass of arms and legs [16].

Muscle strength refers to the amount of force that a muscle can produce with a single maximal effort [35].

The concept of the physical performance was defined for the first time to evaluate objectively and from a clinical point of view, how an individual performed different activities of daily living or physical tasks, as opposed to scales based on asking questions about the ability to perform these task [35]. However, since then, the concept of physical performance has evolved, and today, it is mainly related to ambulation and transfers [35], forming part of the most current definitions of sarcopenia.

The most up-to-date definition of physical performance was provided by Beaudart et al. [35] in 2019, who defined it as: "*A function of the whole body objectively related to locomotion*" (Beaudart et al., 2019).

#### **1.5 Measurement of sarcopenia parameters**

Currently, there are a wide variety of tests and tools available to measure the parameters that define sarcopenia [22, 36, 37], cost, availability, and ease of use, determine whether they are better adapted for clinical practice or more useful for research [8].

The selection of tools may depend on the patient (disability, mobility), access to technical resources in the setting where the tests are performed (community, clinic, hospital, or research center), or the purpose of the tests (monitoring of progression or follow-up of rehabilitation and recovery) [16].

Accurate measurement of muscle mass is a fundamental step to detect cases of patients with sarcopenia, and various techniques can be used for its quantification, but choosing one of them is not easy since all existing methods have advantages and disadvantages [38].

Nuclear magnetic resonance, computerized axial tomography, dual-energy X-ray absorptiometry, bioelectrical impedance analysis, determination of urinary creatinine excretion, and anthropometry are available [19].

There are few well-validated techniques to measure muscle strength, some assess upper extremity strength, and others lower extremity, and although the latter are more important for gait and physical function, and the two have been shown to be highly correlated [35]. Again, cost, availability, and ease of use determine whether techniques are best suited for clinical practice or useful for research purposes [8].

For the assessment of physical performance, there are a wide variety of tests. Short-distance walking tests can be used, such as the 2.4, 4, 6 m, or up to 10 m, or long-distance walking tests such as the 400-meter walk test, or the 6-minute walk test.

Other tests of physical performance are also the time up and go test (TUG), and the short physical performance battery (SPPB) [23].


**3. Bone graft healing mechanism**

The main component of bone healing is the selection of the materials for the bone graft. Bone grafts have different bone-forming capacities; therefore, we need to understand the mechanisms of bone regeneration for the grafts used at the recipient regions. The requirement of the region can be determined in advance and the graft is chosen accordingly. Bone healing in the region where the graft is placed is supported through osteogenic, osteoconductive, and/or osteoinductive mechanisms.

#### **3.1. Osteogenesis**

Osteogenesis is defined as the formation of bone in the region where osteoblasts and osteoblast precursors do not have bone tissue. New bone formation occurs when osteoblasts and osteoblast precursors are produced by cancellous bone and bone marrow. Osteogenesis (bone formation) is characterized by the presence of living osteoblast cells in the graft material. The only bone graft with osteogenesis is the autogenous bone [20]. Autogenous bone grafts, also called autografts, are grafts transplanted from one site to another. The most effective type in terms of osteogenesis is cancellous bones, due to the migration of bone cells at high concentrations. Autografts have been observed to have bone formation capacity even when bone tissue is placed underneath the skin [21]. Vascularization of the graft site is necessary for continued osteogenesis. Some studies have reported loss of osteogenic properties of free autogenous grafts without vascular support within 5 days and that they continued osteoinductive and osteoconductive effects at the end of the study [20, 21]. Therefore, free autogenous bone grafts show osteogenic characteristics only for a few days. We should pay attention to the viability of the cells when placing the autogenous graft in the recipient region. Once the autogenous bone has been obtained, it should not be left in the dry area, and if possible, it should be used as soon as possible with saline in a sterile environment [22].

#### **3.2. Osteoinduction**

Osteoinduction is an active process in which the bone graft causes the bone-forming cells to penetrate the recipient region and stimulates them to form new bones. Osteoinduction refers to the ability of the graft to send a signal to attract, proliferate, and differentiate early-lineage cells (e.g., mesenchymal stem cells or osteoprogenitor cells) into bone-forming cells, resulting in the formation of a mineralized bone. Bone morphogenetic proteins (BMPs) support these signals. BMP is measured as the amount of picograms in the normal bone. In recent studies on osteoinduction, Urist et al. isolated BMP, a soluble glycoprotein. They described BMP as a growth factor of the transforming growth factor (TGF)-β family and as an inductive agent. They also reported that at least 15 different types of BMPs were found, and the most important were BMP-2 and BMP-7 [23]. BMP is naturally released during trauma or the regeneration process and acts as an osteoinductive agent.

the cells and blood vessels can reach the receiving region. The vascular support in the organization of the cancellous bone in the graft is 30% better than that in the cortical bone [26].

Hard Tissue Regeneration Treatment Protocols in Contemporary Oral Surgery

http://dx.doi.org/10.5772/intechopen.74944

145

Prostheses that are supported on maxillary dental implants are now the optimum way to give patients an admissible quality of life. In cases with a vertical insufficient alveolar bone, a maxillary sinus lift with a bone graft using a crestal or lateral approach is needed. Elevation of the sinus floor permits the correct number and length of endosseous implants to be applied

Previous studies proved that dental implants related to maxillary sinus augmentation have a satisfactory long-term success and survival rate [28]. Implant application may be simultaneously combined with maxillary sinus lifting procedure as a" one-stage" surgery, or sinus lifting may be conducted at first, and implants are then applied as a" two-stage" operation. There are many options for graft material to augment the maxillary sinus. Autogenous grafts can be harvested from the chin and ramus intraorally or iliac crest, calvarium, and tibia extraorally. The disadvantages of autogenous grafts are resorption rate and morbidity. Allografts (cadaveric bone) are harvested and different techniques such as irradiation and freeze-drying are used to reduce antigenicity. Allografts are found in tissue banks. Xenografts consist of anorganic bovine or equine bone. The organic components of these types of grafts are chemically removed and a mineral scaffold is obtained. Alloplasts are synthetic materials; there are many types of structures of alloplastic grafts such as micro- or macroporous, dense, amorphous, or crystalline grafts. Structure and porosity directly influence the performance of the material [29].

Following tooth extraction, alveolar bone remodeling begins by means of vertical and/or horizontal bone resorption [30] so that a proper prosthetic and esthetic position of dental implants can be influenced. Alveolar socket preservation techniques have been introduced to conserve

• In cases where implant placement needs to be postponed for >6 months for some reason;

There are various graft materials used in socket preservation surgery such as autografts, allografts, xenografts, alloplasts, or platelet concentrates. Allogenic bone is described as the

• Implant placement needs to be delayed for patient- or site-related reasons;

for adequate mechanical support of the atrophic posterior maxilla [27].

**4. Bone augmentation techniques**

**4.1. Sinus lifting**

**4.2. Socket preservation**

and

the alveolar bone vertically and horizontally [31].

Socket preservation could be considered when:

• If partially fixed pontic site is planned [32].

Demineralized bone matrix (DBM) allograft materials have osteoinductive healing mechanisms. DBM allografts can provide a matrix for bone cells to infiltrate and produce bone. Its healing mechanism manifests through osteoinductive pathways, and bioactive molecules stimulate mesenchymal cells to differentiate into bone-forming cells [24].

#### **3.3. Osteoconduction**

Osteoconduction is described as the growth of a superficial bone on a surface. Osteoconductive materials are biocompatible and have an osteoconductive surface: on its pores, in its ducts, or in its tubes. Materials with osteoconductive properties form a matrix and guide osteogenesis. Grafts with osteoconductivity have no bone formation capacity and can only function as a roof for bone formation. If osteoconductive materials are placed in ectopic areas such as subcutaneous bones, bone formation does not occur and the material remains unchanged or resurfaced [22]. Examples of osteoconductive properties are autografts, allografts, xenografts, calcium sulfates, calcium phosphate cements, ceramics, collagen, and synthetic polymers. It is also known that bone graft materials may be supplemented with materials such as exogenous growth factors, to create inductive effects [22].

#### **3.4. Creeping substitution**

Creeping substitution indicates the movement of new tissues through channels made by blood vessels invading a transplanted bone. The dynamic healing and reconstructive process of bone transplantation was described by Axhausen in 1907; he reported that bone transplants undergo necrosis. The necrotic bone is then replaced by the new bone via creeping substitution [25].

Improvement of the graft material differs according to graft type in terms of duration and content. Vascular support in the recipient region and the survival rate of cells in the graft have a direct impact on graft recovery. Morphologically, the cortical bone, which is the tight structure around the haversian and Volkmann channels, consists of circular, parallel, and interstitial bone lamellar. The cancellous bone is porous and trabecular in shape and contains the bone marrow. There is a less surface area in the cortical bone than in the cancellous bone; therefore, the cells and blood vessels can reach the receiving region. The vascular support in the organization of the cancellous bone in the graft is 30% better than that in the cortical bone [26].


*Article* **Energy Self-Sufficient Livestock Farm as the Example of Agricultural Hybrid Off-Grid System**

**Grzegorz Augustyn, Jerzy Mikulik \* , Rafał Rumin and Marta Szyba**

Department of Business Informatics and Management Engineering, AGH University of Science and Technology, 30-059 Kraków, Poland<EMAIL_ADDRESS>(G.A<EMAIL_ADDRESS>(R.R<EMAIL_ADDRESS>(M.S.)

**\*** Correspondence<EMAIL_ADDRESS>Tel.: +48-603-353-250

**Abstract:** Contemporary agriculture has become very energy-intensive and mainly uses electricity, which is needed for technological processes on livestock farms. Livestock faeces are burdensome for the environment due to the release of methane into the atmosphere. This article presents the concept of a self-sufficient livestock farm as an off-grid energy circuit that is a part of the agricultural process. The key idea is to obtain an energy flow using the concept of a smart valve to achieve a self-sufficient energy process based on a biogas plant, renewable energy sources, and energy storage. During the production process, a livestock farm produces large amounts of waste in the form of grey and black manure. On the one hand, these products are highly harmful to the environment, but on the other, they are valuable input products for another process, i.e., methane production. The methane becomes the fuel for cogeneration generators that produce heat and electricity. Heat and electricity are partly returned to the main farming process and partly used by residents of the area. In this way, a livestock farm and the inhabitants of a village or town can become energy self-sufficient and independent of national grids. The idea described in this paper shows the process of energy production combining a biogas plant, renewable energy sources, and an energy storage unit that enable farmland to become fully self-sufficient through the energy flow between all constituents of the energy cycle being maintained by a smart valve.

**Keywords:** biogas energy; solar energy; hybrid biogas plant; renewable energy; circular economy; off-grid systems

#### **1. Introduction**

Methane is the basic component of natural gas, the combustion of which causes less carbon dioxide emissions than is the case with other fossil fuels (coal, lignite, and peat). Methane is formed during the anaerobic digestion of organic matter. One of the major sources of methane is waste from livestock farms. Methane emitted in natural processes has a negative impact on the environment as it has a carbon dioxide equivalent of 25 times. Methane emissions can be reduced by fermenting the organic matter in biogas plants [1]. Biogas is a mixture of methane (40–85%), carbon dioxide (16–48%), and other gases present in trace amounts. The content of methane in biogas is influenced by the fat content of the substrate. Its high content results in biogas with a high methane content. The biogas yield is influenced by the fermentation temperature, retention time, substrates used, load, decomposition technology, and the pre-treatment of raw materials [2,3]. As a result of the fermentation of organic material, clean and cheap fuel in the form of biogas is produced. It can be used for heating, lighting, and powering machines [1]. Fermentation, however, is an unstable process as it may be disturbed by an increase in temperature in a fermentation chamber, overproduction of volatile fatty acids, and chemical contamination, e.g., with pesticides or heavy metals [4]. The by-product of this process is digestate, which is a valuable organic fertilizer that is a source of easily digestible nutrients for plants [3,5,6]. Biogas plants, unlike other renewable energy sources, are multi-energy systems as they

**Citation:** Augustyn, G.; Mikulik, J.; Rumin, R.; Szyba, M. Energy Self-Sufficient Livestock Farm as the Example of Agricultural Hybrid Off-Grid System. *Energies* **2021**, *14*, 7041. https://doi.org/10.3390/ en14217041

Academic Editor: Tomasz Rokicki

Received: 30 August 2021 Accepted: 14 October 2021 Published: 28 October 2021

**Publisher's Note:** MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations.

**Copyright:** © 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).

produce biomethane, which, after combustion, provides electricity and heat through the process of cogeneration [5]. Electricity is usually sold to the national grid, and heat, when distributed into the local district's heating grid, is used to heat the biogas plant's buildings and the farm [7]. Cogeneration combustion is not the only possibility for the usage of biomethane. After cleaning, it can be injected into the natural gas network. In a compressed form, it can be used as a fuel for cars with CNG installations [2,3,5,8]. It can also be converted into biohydrogen in a steam reforming process.

By utilizing organic waste, biogas plants are flexible sources of energy that reduce the amount of greenhouse gases emitted into the atmosphere as they burn fossil fuels. Therefore, they are a part of circular agriculture (circular economy) and contribute to the concept of sustainable development. This concept organizes agricultural production according to the following principle: Resources—Agricultural Products—Renewable Energy Sources, with an emphasis on recycling and reuse of waste and by-products instead of traditional and extensive production [9]. Biogas plants are popular in many countries as they have an advantage over installations producing energy from the sun and wind. The production of biogas is not affected by climate-related risks. Biogas can also be stored for later use. Producing biogas from farm waste and using it for personal use is especially popular in countries with no universal access to electricity and heating networks due to large due to large distances between buildings [6,10].

The global energy industry is moving towards energy storage systems and renewable energy installations placed close to end users. Such an approach fosters greater independence from imported energy sources and diversification of energy sources [2]. Balda et al. proposed in Japan a project of a self-sufficient farm, which would generate electricity, heat, and fuel to meet its own needs. The research presents a version of a self-sufficient farm that optimizes the size of a biogas plant in accordance with its specific demand for food and fuel. In such farms, crops are used to produce food or fuel, and their residues are used to generate electricity and heat through cogeneration [11].

Due to climatic conditions and long distances, renewable energy should come from autonomous, interconnected, small biogas plants. The produced electricity and heat would be used to power and heat households. In biogas plants, raw biomass and liquid waste from cattle, pig, sheep, and poultry farms would be used as substrates. Approximately 95–99% of the generated heat energy would be used to heat housing and livestock buildings for cattle and to support the fermentation processes. About 40–42% of the electricity would be used in cattle buildings for technological processes, and the rest by biogas plants and homes [10].

In Asian [2,6,12,13] and African [1,2,6] countries, small household biogas plants, in which animal droppings are used as substrate, are popular. The fermented substrate (digestate) is transported to the fields as fertilizer with a high nutrient content [14]. Crude biogas is stored and used directly for cooking, or is used in cogeneration to produce electricity and heat. It can also be used to power absorption chillers for cooling purposes. Electricity and heat are used locally, or fed into the grid [15,16]. Purified biogas is used to power cars, buses, and trucks [1].

In the EU countries, the energy transformation is carried out in order to reduce greenhouse gas emissions, improve air quality, and stop climate warming. This is the main goal of sustainable agriculture programs in many European Union countries, including Poland. Livestock farms with biogas plants generate electricity and heat from local organic substrates. The heat is used to heat the farm buildings and to support local heating networks [17]. By generating electricity and heat in a biogas plant, the use of fossil fuels and associated greenhouse gas emissions can be reduced [5].

The support of the development of biogas plants in Germany can be observed in the form of subsidies granted to biogas plant operators. In addition to such incentives, the decision to build a biogas plant can be affected by environmental, social, and economic factors. The availability of feed for farm animals is also an important part of the decision to build biogas plants, as there is a concentration of biogas plants in regions with a high density of livestock in Germany [15].

Biogas can also be produced using biodegradable municipal waste. Such waste is an important substrate and, when combined with cattle manure in a 1:1 ratio, it can generate a large amount of biogas [13]. Biogas produced from waste in rural areas around cities has great potential to meet the energy needs of cities. In the case of combined heat and power generation, there is a problem of low heat consumption by biogas plants. On average, a biogas plant uses 50% of the heat produced. In Germany, only 10% of biogas producers use more than 50% of the heat. The remaining amount could be used to heat houses and buildings in the vicinity of the biogas plant [2].

The European Union has developed a sustainable economy plan known as the European Green Deal. The activities described therein concern, inter alia, counteracting climate change and environmental degradation. This can be achieved through a sustainable climate policy that fosters the development of a modern, resource-efficient, and competitive climate-neutral economy by 2050. Economic growth will then be independent of the use of natural resources. Such sectors as energy, transport, agriculture, construction, and all industries will be transformed. The greatest emphasis is placed on the transformation of the energy sector [18,19]. Conventional coal-fired power plants will be gradually replaced by renewable energy installations [20]. There is a methane strategy in the European Green Deal which focuses on its reduction in energy, agriculture, and waste sectors, as these are the areas where methane emissions are the highest. The use of a cross-sectoral approach will help target actions in each area, exploring synergies between sectors, e.g., through the production of biomethane released in landfills or on animal farms. Biomethane produced in biogas plants from various types of biodegradable waste such as animal faeces, green and kitchen waste, and waste from the agri-food industry, can be the catalyst for energy conversion [21]. Among the European countries, Poland also has a great potential for biogas production, given the similar natural conditions to those of Germany. According to the data collected by the Energy Regulatory Office (ERO), in March of 2021, there were 120 agricultural biogas plants in Poland with a total capacity of 117.98 MW (average power 0.98 MW) and a biogas production capacity of 490,143.199 m3 [22]. This constitutes approximately 10% of the estimated potential at approximately 5 billion m3 [23]. The development of biogas plants was limited by the lack of local spatial development plans, which do not take into account places for the construction of installations which use renewable energy sources. This, combined with the misconception that biogas plants need to be large, meant that they were built only in voivodeships with large farms and large livestock farms [7].

#### **2. Renewable Energy Solutions (RES) in On-Grid and Off-Grid Micro Networks Considerations**

The main disadvantage of renewable energy is its unreliability and the inability to work efficiently due to the intermittent and fluctuating nature of the processes, which usually leads to system oversizing, thus increasing the investment cost. For this reason, hybrid renewable energy systems (HRES) are built. Their popularity has grown due to the effectiveness of eliminating the disadvantages of RES systems based on a single source. A hybrid system consists of at least two power systems of different origins (renewable and fossil fuels), an energy storage unit, and electronic devices controlling them. The main advantages of HRES are greater reliability, better efficiency, increased energy storage capacity, lower energy costs throughout the life cycle, and minimization of greenhouse gas production [22,23]. Hybrid systems producing electricity can take a form of a microgrid. This is a locally controlled energy system that uses:

There are two types of microgrids: on-grid and off-grid. The former are connected to the national power grid, the latter are autonomous and operate outside of the national power grid. The combination of photovoltaic technology and other RES with a biogas generator can be a profitable solution that may power even the most remote and sparsely populated rural areas. Such a hybrid system is optimal and less expensive than the traditional one. In off-grid networks, energy is generated by photovoltaic panels and a biogas generator, and stored in a battery bank. The batteries should have the capacity to power buildings for a certain number of days without sun, wind, or biogas [15,24].

Developing microgrids in which renewable energy is used has many environmental benefits, such as reducing the overall energy consumption, improving energy efficiency, reliability of energy supply, reducing transmission losses, voltage control, and an increased security of the energy supply. HRES support the implementation of sustainable development with the use of renewable energy [25]. The climatic risk is the occurrence of long interruptions in the supply of electricity from the national grid caused by damage stemming from weather factors, e.g., strong wind, snowfall, or freezing rain. Its occurrence and ailments are reduced by HRES microsystems independent of the national network, which are also an energy reserve for this network [26].

In rural and sparsely populated areas, terrain and economic considerations play an important role in the planning of the power grid. Attention is paid to the production of energy from renewable sources, which are easy to install, have a higher rate of energy use, lower transmission losses, and lower operating costs [24,25]. In addition, the use of environmentally friendly renewable energy sources in rural areas can reduce environmental pollution also in surrounding towns. The use of alternative energy sources makes communication more accessible and minimizes dependence on fossil fuels, which in turn reduces the negative impact on the environment [22,26].

Ghenai et al. proposed a microgrid for the city of Sharjah in the United Arab Emirates that uses renewable energy from a hybrid solar-biogas system. It consists of photovoltaic panels, a biogas cogenerator, batteries (lithium-ion batteries), as well as inverters. In the PV—Photo Voltaic system, two-axis tracking devices have been added to maximize the system's output power. The study took into account the effect of temperature on the operation of PV systems. Its efficiency decreased with increasing ambient temperature (high summer temperatures in Sharjah) and the accumulation of dust on the solar panels (desert region). The study presented a simulation and modelling analysis for the design of energy-based microgrid systems. The results showed that the hybrid system can provide up to 14% of the total annual electricity demand in the city of Sharjah, with the percentage of energy generated by photovoltaic panels being 74%, and 26%from a biogas cogenerator [27]. Hybrid grids can be used in sparsely populated areas, where large distances between farms make the construction of traditional energy networks unprofitable. The government of India took up the challenge to provide a stable and continuous power supply to all farms. For this purpose, an integrated energy system was created consisting of a wind turbine, photovoltaic panels, and a biogas generator. The systems were connected to a control panel, which transmitted the electricity to the battery. The battery was charged when the wind turbine and solar panels produced power. It was used to cover the energy needs of households. However, the capacity of the wind turbine and the PV system was insufficient to meet the buildings' needs. To meet the demand, a biogas generator was added, which became the source component of the hybrid system [28]. In response to the challenges of rural electrification in Sub-Saharan Africa, a completely renewable off-grid energy system was developed. It included wind turbines, a photovoltaic panel, and a biogas generator installed in Djounde in the north of Cameroon. The hybrid system was optimized, and the simulation performed confirmed the cost-effectiveness and environmental benefits of the proposed system compared to the existing solutions. Electricity supplied to the agricultural sector helped solve the main problem in the area, poor agricultural productivity, through the use of electrical appliances in agricultural production and processing of agricultural products [29]. In Bangladesh, a hybrid system consisting of a photovoltaic module, a biogas

generator, a biodiesel generator, and an energy storage device was developed. The system established a reliable energy supply, reduced environmental pollution, ensured more efficient use of energy, and reduced maintenance costs. The HOMER (Hybrid Optimization Model for Electric Renewable) software was used to evaluate the performance of the hybrid energy system. Cow manure was used as the substrate for this biogas plant. [30]. Similarly, the research described by Buragohain et al., focused on a biogas plant using cow manure as a substrate [31]. Additionally, for the Bangladeshi areas, Chowdhury et al. designed a hybrid system consisting of PV panels, a biogas generator, and batteries to store electricity. This made the system more economical, as it could generate electricity on cloudy days. Research has shown that the proposed hybrid system is more cost-effective and reliable for rural areas [24]. Oluwaseun et al. proposed an electricity generation system that, as the previous one, was also based on PV panels and a biogas plant. In this case, manure from 1000 pigs was used as a substrate for biogas production. The research showed that electricity generated in a biogas plant is more effective and reliable for rural areas than is the case with solar energy. The results also showed that burning biogas provides more energy compared to solar energy [27]. To produce biogas in a hybrid installation, apart from animal manure, other substrates constituting biodegradable waste can be used. Such a system was designed by Habiba et al., who used kitchen waste from dormitories and hostels located on the university campus to produce biogas. PV panels were installed on the roofs of these buildings [32]. In rural areas, biomass from animal manure is readily available. Its abundance makes it a viable option to use it as a potential source of substrates for electricity generation in countries with significant amounts of animal excrement [23]. On the island of Java, a hybrid system consisting of a PV plant and a biogas plant was proposed. Electricity was produced by PV panels in the dry season (April–August) when the sunlight was the most intense (123–1075 W/m2 ). The energy generated in this way could be stored in batteries and used by the inhabitants of the island when energy was not produced by PV panels. In the aforementioned biogas plant, cattle manure was used as a substrate for the production of biogas and electricity, which was obtained as a result of cogeneration. The strategy behind a hybrid system is that, while PV panels produce electricity during the day, the biogas plant generates it at night. As a result, both RES systems complement one another, constituting the optimal hybrid power system for the island [29]. Furthermore, the solution creates a system of effective distribution of energy generated from renewable sources. It is possible to build hybrid energy grids parallel to the commercial grid. This solution can make electricity successfully distributed to rural and urban areas, which would solve the electricity problem [15,29].

An important role in hybrid and off-grid solutions [24,26,29,30,33–38] and systems is played by energy storage units. The evolution of the energy market towards micro production of electrical energy and heat implicates certain problems with unpredictable energy production profiles and its balancing in hybrid systems. Energy storage units are one of the solutions to be considered in this area, as they can help with momentary energy balancing and energy production fluctuations in small and medium hybrid systems [15,28,33,39]. Such energy storages are now entering the consumer market and are commonly used with photovoltaic systems. Some of the energy storage solutions include lithium-ion batteries, battery cells, or hybrid batteries based on hydrogen technology which can accumulate electrical energy to balance unstable energy sources such as photovoltaic installations during their cooperation with power grids. Small to medium capacity energy storages can be particularly helpful for small to medium installations starting from 3 kWh up to 60 kWh, or even more for commercial markets [40]. This direction shows how to properly apply and manage energy storage solutions in small and medium renewable energy production systems to achieve better balancing and comply with local energy market regulations.

#### **3. The Idea of a Hybrid Off-Grid Autonomous System**

Hybrid, off-grid, autonomous energy systems are based on renewable energy sources such as wind, solar, and biogas, as well as energy storage options to provide uninterruptible power supply to the recipients (farmlands, households, etc.) and to satisfy their energy demands. Considerations in previous chapters show that there is a need to manage energy sources in hybrid systems to render them as independent from the national power grid as possible. The electrical energy produced by a biogas plant can be used to power the grid when variable renewable energy, such as solar or wind energy, is introduced into the energy system. This is also as biogas (methane) can be easily stored and produced on demand [8]. Biogas storage tanks are connected to an installation that transfers the product to cogeneration engines, where electricity and heat are generated. A biogas storage facility makes electricity and heat production flexible, as the storage size is directly linked to the efficiency of the biogas plant [5]. Hybridization of energy sources on a farm increases the reliability of the energy system combining two or more sources of energy. Additionally, the system can include energy storage units to create an autonomous (self-sufficient) off-grid energy system. However, such a solution requires constant management and monitoring of the parameters of the system's elements.

The idea shown in this paper combines a biogas plant and renewable energy sources, as well as an energy storage unit to create an autonomous, self-sufficient hybrid power system managing the energy flow through the use of a smart valve. The smart valve's role is to manage and provide routing between all elements of the system: the biogas plant, a renewable energy source, and the energy storage unit. Routing the correct source of energy to the recipient (households and agricultural facilities such as barns, glasshouses, and farm buildings on the farmland) as well as managing the way it is routed (directly to the recipients or to the storage device) is the key aspect of the solution.

For further considerations and simulations, our off-grid network consists of a medium size cattle farmland with 20 cows, ten households, a biogas plant, a renewable energy source using PV of 10 kWh, and an energy storage unit.

Figure 1 below presents the energy flow between all elements of the system proposed for further considerations. It is connected to the power grid. Energy and heat produced through a biogas plant are routed to the following recipients: glasshouses, farm buildings, and households. Households are connected to the system, but they do not belong to the farmland and are considered external energy loads. The biogas plant is also a direct source of energy for farmlands, as it utilizes the overproduced CH4 and CO2. The photovoltaic circuits constitute additional components to produce and support the facilities and individual consumers when possible. It is noteworthy that in this solution electrical energy cannot be stored, so an additional source from the power grid network is needed should the biogas plant or PV circuits produce no energy.

**Figure 1.** Diagram of energy flow (heat, electric power, manure, and CH4 )—produced on a medium-sized cattle farm with an on-grid connection.

The idea and main focus of the research is to connect all components of the system, the biogas plant, a renewable energy source, and the additional energy storage unit, in one hybrid system where the energy flow and routing are managed by a smart valve in a way that allows for autonomous off-grid functionality. This idea is shown in Figure 2.

**Figure 2.** Diagram of electric power flow produced on a medium-sized cattle farm with an off-grid solution, an energy storage unit, and a smart valve supporting energy routing.

> The smart valve plays a key role in this self-sufficient system. It manages the energy routed to/from respective elements of the system. The valve is responsible for adjusting the energy flow and the storage decisions during periods of overproduction. The operation of the valve is based on a three-way input controller with negative feedback. The energy produced by the biogas plant and a photovoltaic source is routed by the valve in two ways:

The function of the valve is to ensure that the system is balanced so that all energy loads (farmland and households) are satisfied; in other cases, it charges the energy storage device. Its functions are based on the coefficients which are adjusted to the current energy demand, production, and storage capabilities.

The valve's operation and systems are shown in Figure 3.

P ∑P − ∑Pୖ

P = [a\* P + b\* Pେ + c \* Pୋ] − Pୖ

**Figure 3.** Energy routing through a smart valve—inputs and outputs.

In this case, we can describe its functionality based on the energy balance with its main condition:

$$P\_{\rm NET} = \sum P\_{\rm OUT} - \sum P\_{\rm REAL} \tag{1}$$

Furthermore, we can expand the equation into the following form:

$$\mathbf{P\_{NET}} = \left[\mathbf{a} \ast \mathbf{P\_{PV}} + \mathbf{b} \ast \mathbf{P\_{CO}} + \mathbf{c} \ast \mathbf{P\_{MAG}}\right] - \mathbf{P\_{REAL}} \tag{2}$$

where: POUT—produced and stored electrical energy, PNET—balanced electrical energy, PPV—electrical energy from a PV source, PCO—electrical energy from a cogeneration process, PMAG—electrical energy from an energy storage unit, PREAL—electrical energy sum for all energy recipients, and **a**, **b**, **c**—regulation coefficients based on a simulation (can be defined through a prediction and optimization process with artificial intelligence calculations including prediction, distortions, and disturbances coming from local conditions, environment, and manure/CH4 production fluctuations).

To achieve proper operation of the system, **a**, **b**, **c** coefficients must be set up in a way to achieve the most efficient energy routing for energy received from a biogas plant (cogeneration), a PV source, or an energy storage unit. All coefficients should have values that maintain the energy balance of the system, make it fully autonomous, and—based on the energy profile from sources and loads—provide proper values to maintain the system's functionality without using external energy from a national power grid to meet the energy demands of the farmland and households.

We can see that **a**, **b** cannot be negative, as energy cannot be returned to the source, but **c** can be positive or negative, as the energy storage unit can be the receiver or the source of energy (depending on the overall capacity of the unit). In this way, we can define coefficients' limits as (3):

$$\begin{array}{c} \text{A } \epsilon < 0, 1 > \\ \text{b } \epsilon < 0, 1 > \\ \text{c } \epsilon < -1, \; 1 > \end{array} \tag{3}$$

They can change over time, depending on the resolution of the data, which means that their values fluctuate within the limits based on the predictions and optimization of the energy usage and production. If there is no energy demand, all energy production is routed to the energy storage unit, which will be expressed as: **a = 0**, **b = 0**, **c = 1**, and the unit will be charged for future use to meet the momentary energy demands and requirements. It is noteworthy that when coefficient **c** is positive, the energy storage unit is charged, and when negative it becomes the power source. This is why we can balance the circuit knowing the **a**, **b** coefficients (based on the source profile) and by providing the charging profile based on coefficient **c**.

The coefficients depend on the time instance, and are connected with the biogas plant's energy production profile over time and PV energy production profile over time.

It is also a part of the process to predict and select the proper capacity of the energy storage unit to cover the energy demand of the system when energy is not produced. This will be explained and estimated during the simulation in the following chapter. When the energy production is greater than the system can accept and surpasses the capacity of the energy storage unit, energy can be routed to the power grid to be retrieved later during, e.g., service and conservation works.

Based on the considerations above, we can define the following conditions for balancing the process for an autonomous off-grid process with a smart valve as:

$$
\Delta \mathbf{P}\_{\text{NET}} = \mathbf{0} \tag{4}
$$

which means a fully independent, self-sufficient energy system in an off-grid state. When PNET > 0:

This idea can be proposed to, e.g., medium or small farmlands and a certain number of households to keep the system off-grid by the efficient management using a smart valve. In this way, there is also no need for the households to use a backup power source (such as a fossil fuel based one). The following simulation will show how the process can be described based on certain values and data.

#### **4. Simulation**

The simulation will be processed using the following assumptions and based on the calculations for a specific size of farmland and number of cows:

Table 1 shows that 20 cows can generate a substantial amount of biogas which can be turned into a heat and power process very efficiently.

**Table 1.** Energy products from manures for a specific number of cattle.

Own study based on Source: [41].

Considering data from Table 2, the carbon equivalent (eq.) [42–47] for manure was defined as the amount of coal that needs to be burned to generate 42,184.8 kWh of electricity for the same amount of electricity produced by a manure-powered biogas plant. The carbon equivalent (eq.) for slurry was defined as the amount of carbon that needs to be burned to generate 19,530.0 kWh of electricity for the same amount of electricity produced by a slurry-powered biogas plant.

Own study based on Source: [41].

Table 2 shows that the amount of CO2 released to the atmosphere during the coal burning process is greater than in the respective biogas burning process. For example, biogas from manure released 23.7 Mg CO2 into the atmosphere, while coal combustion

released 39.6 Mg CO2, both generating the same amount of electricity, amounting to 42,184.8 kWh.

On the other hand, the biogas burning process from the slurry released 10.9 Mg CO2 into the atmosphere, and the coal combustion equivalent produced 18.3 Mg CO2. Moreover, if we assume that 1 g of methane released into the atmosphere has an equivalent of 25 g CO2, the combustion of methane from manure generating 42,184.8 kWh will release 23.7 Mg CO2 into the atmosphere. In this process, 12,960 m3/year of biomethane, which corresponds to about 226 Mg CO2, does not reach the atmosphere. Thus, in total, for manure biogas we obtain a negative CO2 equivalent of approximately −203 Mg CO2. If we consider the case of biogas from slurry generating 19,530 kWh, which releases 10.9 Mg CO2, the process prevents 6000 m3/year of biomethane, which corresponds to about 105 Mg CO2, from being released into the atmosphere. This amounts to the negative CO2 equivalent from slurry biogas to stand at about −94 Mg CO2. This shows the possible net reduction in biogas' impact on the environment and is based on the literature examples [48–51] of such negative values of the CO2 equivalents through the usage of biogas plants or biomass itself.

Table 3 shows the possibilities of biogas production from different types of substrates of agricultural and food origin [52–54]. Manure and slurry were selected for considerations and simulations, as they are the most commonly generated waste in cattle breeding in our geographic region and are significantly harmful to the environment. For this reason, they are the primary source of methane emission into the atmosphere, but can be utilized for the production of biogas as a fuel for biogas plants (Figures 4 and 5).

**Table 3.** Production of biogas, biomethane, electricity, and thermal energy from selected substrates.

Own study based on Source: [41].

Drawing from the assumptions above, we were able to define and use the profiles of energy production by a biogas plant and a photovoltaic installation during a 24 h cycle, which is shown in Figures 6 and 7 with a trend line. We also show the comparison of electrical energy production profiles from these sources combined during one day.

The energy production profile depends on the supply of substrate for cogeneration and the further combustion of biogas in the cogeneration process. Therefore, the energy generation process is not constant and depends on the daily operating mode of the farm (milking hours, feeding hours, and maintenance hours).

The next step in our simulation was to calculate the total of electrical energy produced over 24 h to define a 24 h profile of electrical power that can be retrieved from all power sources (Figure 8). These values are required as inputs to our virtual regulation valve.

**Figure 5.** Heat and electric power production from 20 cows on farmland. Own study based on Source: [41].

**Figure 6.** Biogas plant's electrical energy production profile during a 24 h cycle for farmland with 20 cows. Own study based on source [55].

**Figure 7.** The 10-kW photovoltaic installation's electrical energy production profile during a 24 h cycle. Own study based on source [55].

As a next step, we needed to define the energy requirement profile for the recipients over 24 h. Our recipients were:

The average size of the household is 150 m2 . These profiles (Table 4) are taken from the literature [31,55] and available sources.

**Table 4.** Daily electricity and electricity demand.

**Table 4.** *Cont.*

\* RES—Renewable Energy Systems. Own study based on source [55].

The calculations are based on regular usage during a working week (Monday–Friday). These data series are shown in Figures 9–11, where we can see separate energy usage profiles for the farmland and individual recipients, as well as the summary of energy demand which will be the input for our smart valve.

We have defined all inputs for the simulation to outline the amount of energy needed to charge the energy storage unit and to cover the energy demands at times when energy production is unable to fulfil the recipients' needs. To properly calculate the value of the energy loading or discharging the energy storage unit, we needed to take into account the loading process of the energy storage unit.

Our idea was based on the rule that an energy surplus can be used to charge the energy storage unit in an hourly cycle. In this way, we were able to recharge and prepare the unit for a high energy demand when no energy was produced by a biogas plant or photovoltaic installation (e.g., during the night).

This can be expressed through the formula below:

$$\mathbf{C\_{n}} = \frac{\mathbf{P\_{MAG\_{init}}}}{\mathbf{P\_{MAC\_{init}}} + \sum\_{n=1}^{24} \left(\mathbf{P\_{MAC\_{init}}} + \dots + \mathbf{P\_{MAC\_{n-1}}}\right)} \tag{5}$$

where PMAGinit—the initial energy storage value at the beginning of the cycle, n—following hour of the daily cycle from 1 to 24, and Cn—the regulation coefficient for the energy storage unit's management function of the valve.

**Figure 10.** Electrical energy requirement/consumption profile for farmland and individual recipients and a summary of the energy usage for the analysed energy flow circuit. Own study based on source [55].

Our simulation, based on the input data, is shown in Figure 12 below. The energy storage accumulates energy when its surplus allows, and returns it to the system when the recipients need it. In the previous chapter, we mentioned that the energy storage unit's capacity selection would be estimated, and now we can see that as we store more than 40 kWh, and the storage unit needs to release energy at almost 30 kWh over 24 h, a reasonable size of the unit is twice the maximum of the energy stored or used by it. In this case, it would mean more than 80 kWh. Using the common commercial size of the storage unit, the practical approach would be to use distributed consumer size units with, e.g., a 10-kWh capacity for each recipient (household), which would grant 100 kWh of storage in total. Energy storage units with a 10-kWh capacity can be built-in in every home as a part of the system. We also need to consider the case when we start our simulation and operation with a given initial value of the energy storage unit to avoid energy shortages caused by an empty storage unit. We assume in the simulation that the initial value of the unit should be half of its full capacity, which amounts to 50 kWh. This is also included in the above formula (5).

191

**Figure 11.** Electrical energy requirement/consumption profile components for farmland and individual recipients and a summary of the energy usage for the analysed energy flow circuit. Own study based on source [55].

The energy storage grid management based on the distributed 10 kWh storage network in each of the 10 homes is to be examined further, but our goal was to calculate the coefficients for the smart valve to define its operation over the 24 h cycle. This simulation of **a**, **b**, **c** coefficients is shown in Figure 13.

In our simulation, all energy from the biogas plant and photovoltaic installation is used in the system once produced, therefore the **a** and **b** coefficients are 1 or 0 in given instances. Coefficient **c** changes over time and takes values from a = [−1; 1] range, as stated before. This set of coefficients can be adjusted over time using, e.g., artificial intelligence or prediction and optimization based on profiles of usage over time for specified farmlands and the number and types of recipients. However, it is now visible that these coefficients can manage the smart valve's operation, rendering the proposed system independent from the power grid and keeping it self-sufficient in terms of energy production and consumption.

C୬ = Pୋ౪ Pୋ౪ + ሺPୋ౪ +⋯+Pୋషభሻ ଶସ ୬ୀଵ We can also notice that if we observe 2 days (48 h) as the simulation interval using the same input data, the coefficient **c** becomes stabilized, and the daily cycle repeats its profile (Figure 14). It is to be further investigated how to optimize the system and apply or adjust prediction algorithms to achieve a better match to the loads' profile and the energy storage unit's capacity.

**Figure 12.** Electrical energy values simulation for all participants of the circuits on the virtual valve including the energy storage management.

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A complimentary result of the implementation of the smart valve concept to achieve an off-grid, autonomous, self-sufficient hybrid system presented above is that we can estimate the reduction in CO2 emissions as compared to the electrical energy produced by a conventional fossil fuel powered plant covering the power requirements of the recipients in the system—the farmland buildings during operation and 10 households. The comparison of these values is shown in Table 2. As the fossil fuel powered plant, we used heat and power plant in Kielce located in the southern part of Poland, with an installed electrical power of 17.6 MW and annual electrical energy production of 91,508 MWh (as per 2020, based on data published on the website).

#### **5. Conclusions**

The idea of an off-grid, self-sufficient, autonomous hybrid system for the agricultural area with a biogas plant, supported with renewable energy PV circuits and an energy storage unit managed by a smart valve, allows for efficient energy management and nearly full usage of the biogas and biofuel production for cattle farming, and can satisfy the energy consumption needs of individual consumers (households) in the area. Even considering that it cannot be a fully off-grid solution, and an electric power network is still used as a backup for the system, proper management enabled by the smart valve capable of managing the energy flow and its distribution grants a possibility to efficiently manage the energy. The calculation and set up of the valve's coefficients, taking time into consideration, allows the system to be independent of the national power grid and ensures the full usage of the energy produced by the biogas plant and renewable energy sources. There is also no

need to use additional fossil fuel sources as complementary energy sources for households or farmland buildings.

Our simulation showed that, with proper energy storage values and calculation of coefficients for the smart valve, we could achieve a self-sufficient, off-grid system that could power external recipients such as individual homes, satisfying the energy demands of farmland at the same time.

As the smart valve management plays a key role in the system, further examination and investigation are necessary to research the possibility to apply more advanced algorithms (e.g., prediction or optimization). The proposed system and calculation method for the smart valve's operation can be adapted to on-site or off-site solutions.

Renewable energy sources give a great chance not only for the creation of autonomous hybrid systems in small village areas, but also to minimize environmental pollution by removing conventional power sources based on fossil fuels, utilizing the waste produced by farmlands at the same time.

The idea of an autonomous, self-sufficient, hybrid energy system based on agricultural farmland can be extended to other types of farmlands and villages. It allows for the application of artificial intelligence to maintain energy routing and storage by applying the smart valve concept. This also allows for the addition of alternative renewable energy sources, such as wind plants or water plants, to the system. The smart valve, with its coefficients, can be used to control the process of energy routing and balancing in modern automation and control systems to provide energy management for such systems and their future versions. The idea also allows more control over balancing the process of unstable energy production from a biogas plant and renewable energy sources to supply electrical energy to the local loads (households and farmlands) to achieve a self-sufficient system with a hybrid architecture and energy storage options.

The biogas-based process additionally allows for a significant reduction in CO2 emissions in comparison to coal combustion emissions. When we take methane's equivalent of CO2 emissions coefficient which is released into the atmosphere, we can observe a possibility to additionally reduce the impact of methane's influence on the environment. It is clearly visible, when we use a formula where 1 g of CH4 greenhouse gas is equal to 25 g of CO2 greenhouse gas emissions, that the reduction in methane greenhouse gas emissions constitutes a significant reduction in a CO2 equivalent, even considering the amount of CO2 burned in a cogeneration process. The result of the process reduces greenhouse gas emissions, and can lead to negative CO2 emissions equivalent.

**Author Contributions:** Conceptualization, G.A., J.M., R.R. and M.S.; methodology, G.A., J.M. and R.R.; software, G.A. and R.R.; validation, G.A., R.R. and M.S.; formal analysis, G.A. and J.M.; investigation, J.M.; resources, R.R. and M.S.; data curation, J.M. and M.S.; writing—original draft preparation, G.A., J.M., R.R. and M.S.; writing—review and editing, J.M.; visualization, R.R. and M.S.; supervision, J.M.; project administration, J.M.; and funding acquisition, J.M. All authors have read and agreed to the published version of the manuscript.

**Funding:** The study was carried out as part of a research project financed by the statutory grant of the AGH University of Science and Technology in Krakow for the maintenance of research potential.

**Data Availability Statement:** Not applicable.

**Conflicts of Interest:** The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results.

#### **References**


**5. Conclusion**

Our case report has fulfilled the challenge in the literature to improve upon traditional shaping methods, especially to justify the added costs [4, 10]. Furthermore, our report suggests that the possible applications of CAD/CAM techniques have not yet to be exhausted. At the current state of the art, we believe that the application of CAD/CAM techniques for osseous recon‐ struction in the field of maxillofacial surgery should not be restricted to obviously complex reconstructions.


**2.5.1 Injection in exhausted or declining oil reservoirs**

The option for injection in oilfields where production is waning serves another function besides carbon sequestration: it maximizes oil recovery. This process is called enhanced oil recovery (EOR). The standard production process always involves injection of water to maintain the producing pressure. The EOR process, shown in Figure 10, involves injection of water and CO2 in alternation. The CO2 injection increases the oil's fluidity, releasing the oil stuck in the rock pores, while the water, which is by nature not compressible, pushes the oil toward the producing well.

An example of the injection of CO2 in EOR projects is the Weyburn project, located on the border between Canada and the United States. It has been in operation since 2000. The CO2, with 95% purity, captured in a coal gasification plant in Beaulah, North Dakota, is carried by a pipeline to an oil production field in Weyburn, Saskatchewan, where it is injected (Zouh et al., 2004). Figure 11 shows the pipeline in yellow that connects Beulah and Weyburn. The red dots show possible derivations for use of the CO2 in new EOR projects in the region.

Carbon Capture and Storage – Technologies and Risk Management 249

Fig. 12. Weyburn Historical Oil Production - Source: Cenovus Energy (2011)

Statoil in its Sleipner natural gas field in the North Sea.

prompted Statoil to develop the geological capture project.

MtCO2 had already been stored by the end of 2008 according to Statoil.

Saline aquifers exist in the great majority of the world's regions. Since this water cannot be used for drinking or farming, the option to store CO2 in these aquifers appears very promising. The first project to capture carbon of this type was developed by Norway's

According to Statoil, the percentage of CO2 in the natural gas of its Sleipner field is approximately 9% (BGS, 2011), which is above the level tolerated by its consumers. In 1991, the Norwegian government introduced a tax of US\$ 50 dollars per tonne of CO2 emitted. These two aspects combined (standards required by consumers and government taxation)

Physically the project is composed of two platforms. On the first one the natural gas rich in CO2 is extracted. This gas is sent to the second platform where the CO2 is separated by chemical absorption, then compressed and injected into a saline aquifer located 1000 meters beneath the seabed. According to the projections of a special report of the IPCC (IPCC, 2005), the total storage capacity of the Sleipner project is 20 MtCO2, of which nearly 11

For the storage of CO2 in coal beds to be feasible, this process must be associated with the production of methane from the bed. The injection of CO2 enhances the production of methane, hence the name enhanced coal bed methane recovery (ECBM). The process is being studied by, among others, the Swiss Federal Institute of Technology (ETH) and other research organizations funded by European Commission and US Department of Energy (US DOE). These studies aim to obtain the necessary knowledge to apply the

**2.5.2 Saline aquifers**

**2.5.3 Coal beds**

technology in large scale.

Fig. 10. Enhanced Oil Recovery (EOR) Process

Fig. 11. Carbon pipeline linking Beulah and Weyburn – Source: Cenovus Energy (2011)

Figure 12 presents a graph of oil production in Weyburn since the start of the operation in December 2010. The brown area represents the increase in output because of the EOR process if the process had not begun in 2000, production in December 2010 would have been approximately 10 thousand barrels per day (10 kbopd). The EOR boosted this output in December 2010 to roughly 28 kbopd.

Fig. 12. Weyburn Historical Oil Production - Source: Cenovus Energy (2011)


**1. Introduction**

The rising spate of phenomenon and disaster associated with the global warming and resultant extreme weather events in the 21st century have beamed attention on climate change in most national and international discourse. Across the world, the rising incidence of various environmental, ecological and atmospheric disruptions such as extreme heat, heat wave, wildfire, heavy winds, hurricane, heavy rain, storm surge, flooding, rising sea level, snow storm, landslide, drought, etc. have been largely attributed to the unusual fluctuations of weather elements and the climatic system. The havocs wrecked by these events endanger humanity, environment and economic system of nations and as a result, reports oftentimes present a universal dimension of the phenomenon. According to the World Bank [1], climate change portends severe

dangers to all living things, the entire ecosystem and infrastructure. Furthermore, countries around the world are persistently affected by the unusual patterns of dangerous climate events. Apart from the qualitative description of the magnitude, the phenomenon has also been buttressed with scientific proof and quantitative assessment of the impact [2], averred that prior to industrial revolution, the amount of atmospheric carbon-dioxide (CO2) was within 260–280 part per million by volume (ppmv), but have risen by about 36 per cent to about 380 ppmv in the last (20th) century. In the same manner [3], found that since the arrival of industrialization, the concentrations of methane (CH4) and CO2 have risen by 70 per cent beginning from 1970 to 2004. The [4] concluded that the rise in global temperature often referred to as global warming is real. The report further affirmed that the mean earth heat has increased by 0.76°C and sea level has risen by 17 cm in nineteenth century. Likewise, some world's leading climate scientist in 2008, strongly advocates urgent reduction of CO2 emission [2] to forestall calamity. According to the experts, "*paleoclimate* signal and current climate fluctuations suggest that there is need for reducing atmospheric carbon-dioxide from its current 385 ppmv to at most 350 ppmv, else, the consequences would be irremediable tragedy [5].

The gap between the elite and the poor is getting wider as a result of the havocs of the climate change. As the hazards strains the financial resources of the rich, it further impoverish the poor, thereby aggravating their vulnerability. As often revealed in reports, the cost of climate fluctuations calamity across the globe is usually enormous. For instance, flooding in Sante Fe, Argentina displaced one-third of the city population and affected 27,928 households [6]. Damages were approximated at US\$ 1 billion: US\$ 752,000,000 in manufacturing, animal husbandry, agriculture and trade sectors; US\$ 180,000,000 in infrastructure damages while societal loss was put at US\$ 91,000,000 [6]. In Nigeria, the destructive pattern of inclement weather elements have aggravated socio-economic and infrastructure damage and loss. [7] recorded that an estimate of US\$ 45 million was lost annually in twelve states due to erratic heavy winds, heavy rain and storm surge in 16 years. By implication, the sum of US\$ 2.2 billion was lost across the thirty-six states and the federal capital territory within the period. The report further showed that the overall financial loss as a result of the rising precipitation and heavy wind rose from US\$ 23.6 million to US\$ 82.2 million between 1992 and 2007, with the highest of USD91.5 million in 2006 and lowest of US\$ 17.97 million in 1994 respectively. Across the globe, coastal cities are witnessing unprecedented rise in sea level, massive flooding, horrendous storm/hurricane, severe erosion, saltwater incursion and disruption in sedimentation formation [8]. It was further revealed that tropical gales upset 1.4 billion people, which constitutes 24 percent of the riverine settlers. Furthermore, in 2010, floods tragedy in Pakistan and Chile affected about 18,102,237 and 134,000,000 people, caused 1985 and 1691 deaths and damages estimated at US\$ 9.5 billion and US\$ 18 billion respectively [9]. Hurricane Katrina that ravaged New Orleans in 2005 also caused the death of 1833 persons, displacement of 500,000 people and a loss of US\$ 125 billion. In Senegal, the World Bank estimates the value of assets exposed to flooding at about €40 billion (Forty billion Euro), twice the Gross Domestic Product of the country [10]. According to [11], over the past ten years, climate change has caused about 3852 catastrophes, the death of more than 780,000 and displaced over 2 billion people with property worth more than US\$ 960 billion lost to the tragedy.

Arising from the above, the reality of climate change and its huge financial implications of the consequences become very conspicuous. Reports across the world according to [12] showed disturbing pattern of climate change consequences.

#### *The Nexus of Climate Change, Urban Infrastructure and Sustainable Development… DOI: http://dx.doi.org/10.5772/intechopen.107283*

Nonetheless, public discourse generally has attributed disparate level of urgency to issues of climate change thereby prioritizing it above other critical economic and environmental debacles that threaten human existence. Davenport et al. [13] stated that up to 70 member states of the United Nations significantly prioritize climate change risk above security risk. Nations have essentially ascribed the various socio-economic, ecological, environmental, political and security problems to climate change. [14] observed that most countries face economic, political, and social hardship resulting from uncertainties occasioned by climate change hazards. According to [15], countries like Turkey, Brazil, Egypt and Iraq are confronted with security risk triggered by the conflict among armed forces due to the consequences of climate change. A notable example of security challenge of continental significance is the herders' militancy in Nigeria whose violent clashes with farmers have always claim lifes and properties.

Whilst not playing down the danger that climate change poses, it is important to know that the spate of havocs wrecked by climate change events in recent times is as a result of aggressive industrialization and urbanization in the last two centuries. Besides, there are numerous challenges in rural and urban areas around the world that have undermined human dignity and normal/decent existence over the years. These challenges have been aggravated in recent times by climate change. The diverse socioeconomic, political, environmental and security challenges in different countries are first and foremost, symptoms of policy failure, bad governance, mismanagement and lack of political will especially in developing countries. These consequently get complicated by the erratic climate manifestations. In this regards, the universal perspective of climate change hazards tends to obfuscate the experience at regional and local levels. Therefore, prioritizing climate change problems over other basic societal challenges engender the risk of mis-characterization, misplaced focus, waste of scarce resources, death and damages to properties and environment. Certainly, climate change according to [8] is intricately connected to urbanization, but not the most severe environmental issues facing humanity. Hardoy and Pandiella [16] concluded that climate change has put the already vulnerable urban settlements under enormous stress thereby making the situation require quick and comprehensive approach to resolve the problems. The socio-economic and environmental problems facing developing nations include acute poverty, widespread illiteracy, insecurity, gender inequality, environmental pollution, infrastructure deficit, unemployment and poor governance to mention a few. In the light of the foregoing, it becomes imperative to put in context the diverse challenges that confront developing countries and develop a comprehensive framework to resolve them. Finding solutions to these issues engender the resilience of human settlements against the impact of climate change in Nigeria and other developing countries.

## **2. Theoretical framework: theory of change**

This study is anchored on the postulations of the theory of change as explained in [17, 18]. The theory of change according to [19] has a wide range of possible uses in developing, managing and evaluating interventions that are meant to produce a desired long term change. Reinholz and Andrews [20] described a set of assumptions that should be taken to achieve a long term goal as well as the linkages between the activities and results of an intervention program. Davies [21] stated that theory of change is a process that is meant to evolve an articulated sequence of events that will eventually usher in the expected outcome. The study further described the theory as

a strategic map that shows the multiple interventions required to produce immediate results and are pre-conditioned to a long time change. It depicts the pathway that is consistent to producing the impact expected to support the desired long term change. In the application of the theory of change, [22] suggest that to accomplish a successful change, there is need to empower the driving forces and weaken the restraining forces. This according to [22] could be achieved through the following:

The relevance of the theory of change to the current study is contained in the inherent popular interest to tackle the environmental and ecological hazards unleashed by global warming. The incidence of climate change has been debated in the past decades, however, the reality is being established by the ominous signs of its impacts globally. Notwithstanding, the hype about the phenomenon in developing countries distract attention from issues that are grave, grievous and constitute daily threat to human existence in this part of the globe. As such the study believe in prompt intervention as enunciated in the theory of change and align with [22] to empower the driving forces and weaken the restraining forces especially for the developing nations. This could be achieved by developing appropriate policy and developmental interventions in the areas of urbanization process and infrastructure delivery based on the principles of sustainable development. This would ultimately reinforce the capacity to withstand and combat the periodic barge of climate change in less advanced countries.


**8. Microbial diversity study in the atmosphere of the Iberian Peninsula after a Saharan dust intrusion**

Four aerobiology sampling flights took place during February and March 2017 using the CASA C-212-200 aircraft from INTA. The study focused on microbial diversity in the atmosphere of the Iberian Peninsula during and after a Saharan dust intrusion. Flights took place under four different conditions: (1) during a strong Sahara dust storm that reached the north of the Iberian Peninsula, from February 22 to 24, 2017 (February 23, 2017) (**Figure 7**); (2) following precipitation (February 28, 2017); (3) following a dry period (March 8, 2017); and (4) along the northern coast of Spain (March 9, 2017). In each flight, samples were collected at different altitudes, and air samples were obtained simultaneously at ground level. A total of 20 samples were collected and are being analyzed. Cell presence was observed by scanning electron microscopy (SEM), and bacterial diversity is being studied by DNA extraction, 16S rRNA gene amplification, and Illumina MiSeq sequencing. Results are being analyzed via bioinformatics and biostatistical software (MOTHUR, SPSS, STAMP, CANOCO, and PAST) which will allow us to compare the results between the different flows and scenarios.

Although this study is not yet finished, some data can be advanced in this chapter. **Figure 6** shows SEM microphotographs obtained from samples in different scenarios. In general, the samples obtained during the days of dust intrusion (flight

**Figure 7.**

*Saharan dust intrusion. Dust pours off the northweat Afrincan coast and blankets the Iberian Peninsula, 23 February, 2016. NASA satelital imagen via MODIS.*

of February 23) appear completely covered with mineral particles. In these cases, more biological cells were detected than in the rest of the days. In the particular case of samples from the marine coast flight, more diatoms were observed (**Figure 6E**).

The analysis of diversity using the Shannon index showed that, in all cases, diversity was greater on days of Saharan dust intrusion, both in the samples taken from the ground and those taken at higher altitudes with the aircraft. This indicates that Saharan dust contributes microorganisms that are not present in the atmosphere on a daily basis. Diversity analysis showed phylum characteristics of soils, being *Alpha*- and *Betaproteobacteria* the most abundant classes. All of the analyses performed showed that bacterial diversity detected at ground level and in-flight samples during the dust intrusion event were similar among one another. The genus taxonomic levels of *Sphingomonas*, *Geodermatophilus*, *Methylobacter*, *Rhizobiales*, *Bacillus*, or *Clostridium* were present in every sample, but their sequences were more abundant in the case of ground samples and dust intrusion samples collected during the day flight. However, sequences of the genus *Flavobacterium*, *Streptococcus*, or *Cupriavidus* were most abundant in the case of samples collected during flight.

Preliminary conclusions show that bacterial diversity of airborne bacteria during days of dust intrusion is higher and similar to bacterial diversity commonly detected in soil samples. Further analyses are being conducted with these samples to obtain a complete description of the evolution of bacterial diversity during those days.