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Solar farms

Thursday, 31 January 2013 11:04

Solar farm at Watchfield Solar farm at Watchfield Photo: © Jane Tomlinson

Renewable energy is desirable in principle, but not at unacceptable cost to the countryside, or to the economy.

CPRE Oxfordshire is opposed in principle to solar farms for the damage they do to the countryside and landscape, particularly in Areas of Outstanding Natural Beauty (AONBs) and the Green Belt.  We do not consider that the minimal benefit they offer in terms of renewable energy is sufficient to offset the environmental harm they create or the otherwise useful land that is lost.

CPRE Oxfordshire will support relatively small discrete developments on the roofs of existing buildings, or in other sites where they are effectively concealed by existing development or the lie of the land, and do not involve the loss of land useful for agriculture, recreation or biodiversity.

Read our policy in full. (pdf)

Plus, here's some useful background info:

Solar farms both create very significant environmental and amenity damage for very meagre returns in the form of CO2 free energy – and at very considerable cost to the economy.

While solar panels are relatively low – perhaps eight to ten feet from the ground --- they are extremely inefficient, especially in the climate of Central England. As a result, vast areas of landscape have to be covered with panels, and industrialised, to generate any significant amount of energy. For example a recent application (subsequently withdrawn) for a solar farm in Oxfordshire at Beckley would have covered 74.5 hectares, 180 acres, of rural countryside. Developments are usually likely to involve useful agricultural land being effectively taken out of production.

How solar works

A commercial solar panel converts the sun’s radiation into electricity. Underlying efficiency in doing so is typically around 20%. Its rated output assumes full sunlight, at mid-day, on the equator. Oxfordshire, however, gets a lot less solar radiation than that.

The sun is further away here than in the tropics, and its rays therefore have more atmosphere to travel through, which reduces the strength of radiation at ground level. We also have considerable cloud cover, which has a similar effect. As solar panel developers say, solar radiation will always get through, but in fact this only to some extent. The differences in insolation, that is sun’s energy available, between one part of the world and another is very substantial.

None of them of course approach the solar panel standard of continuous noon day equatorial sun, but Oman on the Gulf gets twice as much as Oxford. Mexico City gets more than Oman. (Try it yourself at http://solarelectricityhandbook.com/solar-irradiance.html.) This shows each country or city with its 'equivalent equatorial sunlight' hours.

Another problem for us, unlike the tropics, is that while solar panel performance in summer, when the sun is in our hemisphere, is usually not unacceptable, it falls away to insignificance in winter. Sunlight hours are fewer, and, as the sun is then over the Southern hemisphere, even on sunny days the solar energy has to travel through twice as much atmosphere, which dissipates its power.

Solar panels are effectively useless at night.

All this means that solar energy is very expensive to generate. Like wind farms, solar farms require huge subsidies, paid by you and I, to make them attractive to developers. This is done by the Government forcing power suppliers to use an ever increasing percentage of very expensive renewable electricity, or pay a fine if they fail to do so.

Currently wind energy is costing all of us twice as much per unit as ordinary electricity - and solar energy has to be subsidised twice as much as wind.

Not only is renewable energy expensive of itself, but the fact that its output varies according to whether days are sunny (or windy for turbines), additionally, solar is effectively “off” every night, and most of the winter. Electricity can only be used at the time it is generated, it cannot be “stored”, so all this means that, in order to keep the lights on, back up capacity from “normal” power stations is required. This typically comes from gas-fired plant, but the intermittency of wind and solar inevitably makes the back-up plant intermittent as well, thus making it less efficient and putting up its unit price also.

Some maths

The process of calculating the likely output of a solar farm is a relatively simple case of multiplying the “rated output” of each panel (from the manufacturers, in the case of the Beckley proposal 178 watts in equatorial sunlight) by the average daily solar irradiance hours for Oxford (2.9) from the website referred to in the previous section and then by the 365 days in a year. This means that each panel at Beckley would produce around 190 kw/hours of electricity a year.

There would be 50,668 panels on the 74.5 hectares so the total output of the "farm" would be approximately 9.5 million kw/hours.

Renewable energy promoters like to talk of their output as "homes powered", and given that the average home uses 4,500 kw/hours a year the solar farm output would be equivalent to the usage of 2,000 homes (although there would be hardly any in the winter or at night). This is would be a tenth of an acre of solar panels per household. There are 260,000 homes in Oxfordshire so providing them all with solar power would require 26,000 acres of countryside to be covered with solar panels.

The "homes powered" figure is misleading however because two thirds of the electricity we use – for travel, street lights, shops, offices, industry - does not go through domestic meters. Adding this back increases the land take required to 78,000 acres, 12% of the total land area of the county.

It is true that the underlying power for solar, the sun, is free, and the same goes for wind. It also goes for all fuels though. The cost lies in extracting and converting them, and the cost for solar is very high indeed.

Not just the economic cost, but the environmental cost. It involves losing huge tranches of precious countryside, and blighting valuable landscapes, for very little return.

Planning matters

The thrust of the new National Planning Policy Framework is pro-development and pro-renewable energy. It also recognises the importance of protecting the countryside.

It requires that Authorities "take account of the different roles and character of different areas, protecting the Green Belts around them, recognising the intrinsic character and beauty of the countryside and supporting thriving rural communities within it; (and) support the transition to a low carbon future in a changing climate while ensuring that adverse impacts are addressed satisfactorily, including cumulative landscape and visual impacts."

"Great weight should be given to conserving landscape and scenic beauty in National Parks, the Broads and Areas of Outstanding Natural Beauty, which have the highest status of protection in relation to landscape and scenic beauty."

"The Government attaches great importance to Green Belts. The fundamental aim of Green Belt policy is to prevent urban sprawl by keeping land permanently open; the essential characteristics of Green Belts are their openness and their permanence. When located in the Green Belt, elements of many renewable energy projects will comprise inappropriate development. In such cases developers will need to demonstrate very special circumstances if projects are to proceed. Such very special circumstances may include the wider environmental benefits associated with increased production of energy from renewable sources".

All this shows clearly that the Government, pro-development as it is, recognises the need for the benefits of the development to be weighed against the environmental and other harm it would create.

The benefit of solar farms is small in the context of the amount of land they industrialise and effectively take out of farming use; in relation to the harmful landscape impact they create; and, in the Green Belt, to the loss of openness.

Renewable energy is good in principle, but not at any cost to the countryside and the amenity of its residents.

Article by Michael Tyce, Chairman, CPRE Thame


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