Part twenty-eight

Sustainability Speak   

Renewable Energy Strategy 

• The strategy outlines a scheme to enable the UK to meet its projected 15% renewable energy target by 2020.
• If the programme goes ahead, nearly one third of electricity will be generated from renewable items.
• Looking at ways to make the development of anaerobic digestion plants a cost effective process.

Anaerobic Digestion Plants (ADs)

AD is a process which enables organic matter to be broken down by bacteria in the absence of air. Organic matter and biodegradable wastes – animal waste, feedstock, food waste, etc – is placed in a digester (a warmed, sealed airless container) for between 10-25 days. The materials ‘ferment’ and produce methane and solid called the digestate, which in turn can be separated out into fibre and liquor.

AD occurs naturally in the sediment of lakes and ponds, swamps and peat-bogs, and the intestines of animals. It is one of the oldest biological processes in the world, and has been used for the treatment of sewage sludge for decades. Most modern sewage treatment plants include methane catchment and digestate production as part of the overall process/cycle.

Once cleaned of contaminents (e.g. heavy metals), the biogas (methane) can be used in a boiler/furnace, gas engine or turbine, or further refined for use in gas powered vehicles and CHP plants.

The digestate can be returned to farms for re-use as a soil conditioner and fertiliser.

Other proposals include extending the Renewables Obligation Certificate system until 2040.

Renewables Obligation Certificate (ROC)

Currently in force until 31 March 2027, an ROC is issued for each megawatt hour (MWh) of eligible renewables output generated. An ROC is a green certificate issued to an accredited generator for eligible renewable electricity generated within the UK and supplied to customers within the UK by a licensed electricity supplier. The Renewables Obligation is the main support scheme for renewable electricity projects in the UK. It places an obligation on UK suppliers of electricity to source an increasing proportion of their electricity from renewable sources.

Suppliers meet their obligations by presenting ROCs to Ofgem on an annual basis. Where suppliers do not have sufficient ROCs to meet their obligations, they must pay an equivalent amount into a fund, the proceeds of which are paid back on a pro-rated basis to those suppliers that have presented ROCs.

 “Renewable energy is key to our low-carbon energy future. We need to radically reduce greenhouse gas emissions, as well as diversify our energy sources. As part of this move to a ‘low-carbon economy’ we need a step change in renewable energy use in heat, electricity and transport over the next 12 years”.

John Hutton, Secretary of State for BERR