Fossil fuel power station is also beneficial to the environment. In some instances, torrefaction of biomass may be needed if biomass is the material the converted fossil fuel power plant will be using. Improving energy efficiency of a coal-fired power plant also reduces emissions. For example, emissions can be reduced by upgrading existing plants or building new high-efficiency, low-emissions plants. Such plants emit almost 20% less CO than a subcritical unit operating at a similar load. Over the longer term, HELE plants can further facilitate emission reductions because coal-fired plants operating at the highest efficiencies are also the most appropriate option for carbon capture
Fuel cell account. Fuel cell vehicles running on compressed hydrogen may have a power-plant-to-wheel efficiency of 22% if the hydrogen is stored as high-pressure gas, and 17% if it is stored as liquid hydrogen. Fuel cells cannot store energy like a battery, except as hydrogen, but in some applications, such as stand-alone power plants based on discontinuous sources such as solar or wind power, they are combined with electrolyzers and storage systems to form an energy storage system. Most hydrogen is used for oil refining, chemicals and fertilizer production and therefore produced by steam methane reforming, which emits carbon dioxide. The overall