Why do we need renewable energy?

In the effort to tackle and mitigate the effects of climate change there is a consensus that it is of vital and urgent importance that we cease to use fossil fuels as our prime source of energy and achieve a zero-carbon energy system as soon as possible.  It is also widely accepted that there will be an expansion of electrification although some alternative methods of energy transmission and storage, such as hydrogen and synthetic fuels will also play their part. The demand for electricity will increase significantly, largely due to the requirements for heating (replacing the use of gas) and for the charging of electric cars. This will stretch the existing electrical infrastructure.

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The requirement to cease the use of fossil fuels will result in an increase in the generation of power using renewable sources and the increased use of the electricity system to transport and distribute power. For the most part, renewable energy sources are intermittent in nature which creates issues with the balance of supply and demand required in order to maintain a stable electricity supply system. Energy storage systems can be used to help offset imbalances of supply and demand and are expected to be increasingly used in the future. The supply and demand balance can also be aided by judicious control and timing of demand, referred to as the “Demand Side Response” (DSR).

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Renewable energy systems include:

• Power generation sources

• Energy storage and

• Management of demand-side response.

 

Power generation sources include:

• Wind (offshore and onshore),

• Solar,

• Tidal,

• Hydro,

• Geo-thermal,

• Bio-fuels.

 

Energy storage systems categories include:

• Mechanical - pumped hydro storage, other gravity-based, compressed air, flywheels.

• Electrochemical – batteries of many types including flow batteries.

• Chemical – electrolysers and fuel cells, hydrogen, ethanol, biofuels

• Thermal – low and high temperature

• Electrostatic and magnetic - supercapacitors, super magnets.

 

Generation and storage systems are typically connected to the electrical power distribution system and usually require electrical power converters to transfer energy backwards and forwards in a controlled manner between the electrical system and the various forms of energy generation and storage. In order to commission and maintain such systems, a basic understanding of the function and control of power electronics-based power conversion and electro-mechanical machines is required.

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