More and more people are recycling and it is becoming easier to recycle more materials but still there will always be some residual waste that has not been sent for recycling. However, there are technologies whereby this ‘waste’ can be converted into energy, for example electricity, which can be fed into the national grid or heat, which local industries can use. In the recent Waste Policy Review 2011, the government stated that it wants to break down the barriers to further development of anaerobic digestion, which is one of the technologies which can produce energy from waste. This is part of the coalition government’s wider commitment of working towards a ‘zero waste’ economy.
Defra has recently announced that funding will become available to boost investor confidence in new anaerobic digestion (AD) facilities. This funding will amount to £10 million and it will be made available in a special loan fund [1]. The fund was announced as part of Defra’s Anaerobic Digestion Strategy and Action Plan which was published to help overcome the barriers to adopting the technology [1]. Even though anaerobic digestion is not a new technology – for the past 100 years sewage sludge has been treated using the technology – what is new is the fact that it is used for treating other waste with purpose-grown crops [2].
What is anaerobic digestion?
Anaerobic digestion is the break down of organic matter by micro-organisms in the absence of oxygen [2]. The resultant products of the process are biogas and digestate (a nitrogen rich fertiliser) and these are what can be harnessed to produce energy.
The biogas which is produced can be used to power Combined Heat and Power plants or burned to produce heat [2]. The digestate can be used as a renewable fertiliser or soil conditioner [2]. Below is a diagram of an anaerobic digestion plant, explaining how it is configured to produce energy [2].
http://www.defra.gov.uk/publications/files/anaerobic-digestion-strat-action-plan.pdf
Not only does anaerobic digestion result in less waste being diverted to landfill, it also means that we can create energy from it. By creating more plants such as these, the UK become more self reliant in terms of its energy supply. With the price of fossil fuels increasing, the UK needs to address issues of our energy security and technologies such as the above will help to provide the answer. However, work does need to be done to educate people more about the technology and break down the common ideas that such plants are purely burning waste. Yes, they are not always the most attractive features, but in times of increasing energy insecurity they provide a means for a home grown energy supply.
Anaerobic digestion uses organic waste which would otherwise be sent to landfill and release potent greenhouse gases such as methane. Another advantage is that anaerobic digestion provides a much more reliable source of energy compared with other renewable technologies such as wind and solar power [2].
While there is growth in anaerobic digestion plants, the government has recognised that it needs to do more to break down the barriers to such growth. This means not only providing funding but also addressing the public perception of such technology. There is no doubt that the UK is lagging behind other European countries in its take up of renewable technology and part of this is down to consumer perception. Government and society need to address the issues, otherwise the UK will be left lagging in a world where energy security is becoming an ever increasing concern.
References
[1] Sustainable Business Magazine (July 2011, issue 174) [Digital Edition].
[2] Anaerobic Digestion Strategy and Action Plan: A commitment to increasing energy from waste through Anaerobic Digestion (2011). Department of Energy and Climate Change and Defra
