A brief history of Anaerobic Digestion
It’s been a known fact for centuries that combustible gas is generated when organic waste is allowed to rot. Records show that communities have been harnessing its benefits for hundreds of years. As early as 900 BC, biogas was being used to heat bath water in Assyria. We also know that one of the first AD pioneers was Van Helmont, who discovered that flammable gases could evolve from decaying organic matter in the 17th century. In 1776, Volta resolved that there was a direct connection between how much organic material was used and how much gas the material produced.
Later in 1808, Sir Humphry Davy established that cattle manure produced methane. These early discoveries were put into practice around 1859 by a leper colony in Bombay in 1859. The technology finally reached the shores of the UK in 1895. Exeter became the UK’s home of AD when biogas was recovered from the sewage system and used to fuel street lamps. The first dual purpose tank for both sedimentation and sludge treatment was later installed in Hampton in 1904.
The early 20th century also saw the first patent issued in Germany for the Imhoff tank, which today we’d recognise as an early form digester. The 1920s, saw the emergence of closed tank system which replaced the common use of anaerobic lagoons. Awareness of AD increased throughout the 1930s, as Microbiology became a recognised science and drove research into understanding the conditions needed to optimise AD.
The development of AD has often correlated with the fossil fuel market. The OPEC Oil Crisis during the 1970s, inspired many to seek energy source beyond fossil fuels. The US Congress passed acts, requiring companies to purchase energy from qualified AD facilities. Cornell University was the first to build America’s plug flow digesters that were able to digest manure from 60 cows – this spurred on 140 AD facilities to be build across the USA. The 70s also saw China having over 6,000,000 small scale digesters on farms.
Welcoming in the 2000s and the Renewables Obligation was introduced in England, Scotland and Wales. This Obligation outlined that electricity supplier had to increase the proportion of electricity produced from renewable sources. Eight years later, the UK Climate Change Act set an 80% cut in greenhouse gas emissions by 2050. The UK was the first to set a legally binding framework to cut carbon emissions. The following year, the Committee on Climate Change called for the UK Government to effect a step change in the pace of reductions in greenhouse gas emissions. This was also the year that ADBA was formed by Lord Redesdale and ten founder members.
The following years saw significant moments for AD in the UK. In 2010, Feed in Tariffs for renewable electricity were introduced. One year later the Committee on Climate Change Renewable Energy Review recognised greater potential for biogas from AD and the Anaerobic Digestion Strategy & Action Plan highlights actions to help support industry development.
Last year in the UK, over 100 million tonnes of biodegradable material were processed through anaerobic digestion, that’s enough to power one million homes. In five years, AD facilities in the UK have grown by 500%. AD could generate 10-20 TWh of heat and power per year by 2020. To put this in context, the UK's largest power station Drax sold 27.1 TWh of electricity in 2012. AD could represent 3.8-7.5% of the renewable energy we estimate will be required in 2020.