Sustainable poo, of course! Here at Good Energy we are keen to support all kinds of ways to generate green electricity, and this now includes buying energy from farm waste. Amazingly even sewage sludge can be turned into renewable electricity and piped into the national grid.

Want to know how it works? See the techy bit below.

Biogas to renewable energy

Biogas is produced through a process called Anaerobic Digestion (AD). This is a natural biological process carried out by bacteria in the absence of air, by which organic material is broken down into stable fertiliser and useful biogas. These anaerobic bacteria are an integral component of nature’s waste management and are commonly found in soils and deep waters, as well as in landfill sites.

How does anaerobic digestion work?

The break down of organic compounds is achieved in a soup of many types of bacteria including those that generate carbon dioxide and methane.

The organic waste is broken down into sugars and amino acids by enzymes similar to those found in our mouths that help digest our food. These sugars are then fermented to produce volatile fatty acids and then converted by various types of bacteria into biogas, a mixture of carbon dioxide (40%) and methane (60%) and other trace elements.

While there are many ways of building anaerobic digesters, the basic principle takes a feedstock that is fed into a completely enclosed tank, which is heated and regularly mixed.

What do you need to make biogas?

You need what are known as feedstocks. Organic feedstocks are very flexible, ranging from farm manures and sewage sludge to catering wastes and food wastes comprising uncooked and cooked food, meat and bone. The feedstock then goes through the process of anaerobic digestion. This is the process of creating optimum conditions for bacteria growth. As time goes by the feedstock is digested (eaten) by these bacteria that in turn generate two byproducts - digestate and biogas.

The biogas is then ready to be burned in a combined heat and power unit to produce electricity and heat. Normally a biogas engine can gain an electrical conversion efficiency of up to 35% with the remainder being available as heat.

So there you have it, renewable energy from poo.