We could feed our homes with kitchen waste. Here is what must happen

Imagine if you could power your kettle using the energy generated by vegetable cuttings that decompose silently in your kitchen’s compost bin. This reality may not be so distant with the growth of biogas technology.

Biogas is a green alternative to fossil fuels that not only helps reduce toxic emissions, but also provides clean and cheap energy. It is made from a mixture of methane, carbon dioxide, and a little hydrogen sulfide and water vapor, all produced by microbes that live off organic raw materials in a sealed digester.

The efficiency of the system depends on the size and insulation capacity of the digester, as well as the amount of methane produced from the “raw material”, which can range from carrot leaves and onion peels to yard waste.

Biogas is “green” because it reduces greenhouse gas emissions into the atmosphere from the decomposition of food waste. Instead, these gases are stored and used to generate heat and electricity, making the energy produced from waste more sustainable.

Yet although biogas has been promoted for a few years as a way to help reduce carbon emissions – and was in fact used to power households as early as the 10th century BC (to heat bath water in the Middle East) – it still only accounted for around 0.004% of total EU gas consumption in 2019. So why is absorption so low and what can be done about it?

Digesters in practice

Micro-digesters (between 2 and 10 cubic meters) can supply individual household systems for up to 12 hours per day, while large 50 cubic meter digesters can be connected to the local gas network to support communities up to 250 hours.

The diagram below shows how these systems typically work: the pipe at the top of the image would normally lead to a community gas tank or appliance.

How they work in practice

[Photo: Wikimedia]

An example of an innovative small-scale biogas system is the methanogen micro-digester. There’s one at Calthorpe Community Garden, a multi-functional urban community center in Islington, London. The unit is located in a remodeled shed next to a vegetable garden. Energy, generated from the food and garden waste of the surrounding houses, is supplied to the center hob through a pipe.

The digester is run by community volunteers, whose mission is to improve the physical and emotional well-being of residents living in the vicinity of the center by encouraging them to grow food and spend more time in nature.

An even more ambitious initiative is underway on the Swedish island of Gotland, where an eco-village, Suderbyn, has been created using zero carbon materials. A community-run digester has been installed to generate heat using the community’s food and agricultural waste. Inspired by the success of Suderbyn, similar sites were launched in the UK at Hockerton, near Nottingham and Grimsby.

The absorption problem

But why aren’t more digesters appearing? Our research aimed to understand the challenges responsible for the slow adoption of this technology.

To better understand people’s attitudes towards biogas, we conducted a study on EU biogas production in Europe. Our research, conducted through interviews and consultation workshops, found that one of the barriers to stopping the use of biogas was stigma resulting from a poor public understanding of the technology and of its advantages.

People we spoke to were concerned that the local digesters would give off an unpleasant smell or that their industrial appearance would spoil the landscape. In fact, many digesters are quite small and would only produce odors if the system broke.

Other obstacles include the lack of technical expertise in constructing or maintaining digesters, the lack of incentives to attract local businesses, and the high cost of the digester, which, depending on its size, can cost between 12,000 and £ 158,000.

For this reason, help from the local government will be crucial in bringing biogas to the masses. They should help with the financial cost or provide seed money to groups interested in setting up biogas systems. The councils should also facilitate the collection, handling, transport and storage of food and garden waste, which usually takes place weekly; and deal with obstacles, such as obtaining a building permit for larger digesters.

Community engagement with projects like this is also vital. Biogas initiatives, especially the larger ones, can only become successful if there is trust and cooperation among the community members who would manage the system and share its spoils. A motivated community and supportive local policies are necessary ingredients for a biogas project to thrive.

Using biogas to produce renewable energy has the potential to dramatically accelerate decarbonization – reducing a country’s carbon output – helping to make the energy supply chain more sustainable in the long run. But without government support, the future of biogas remains uncertain.

Dr Ananya Mukherjee is Associate Researcher in Sociology at the University of Surrey. This article is republished from The Conversation under a Creative Commons license. Read the original article.

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