In many biogas plants you do get heat as a waste product. Waste product? Yes the huge biogas engines burn the biogas to create electricity. The energy will be used locally or is injected to the national grid. Everybody who did stand next to a car engine after a hundred miles trip knows that engines get hot. And since those biogas engines are supposed to run 8000 hours a year they produce a lot of heat. Some heat might be used locally to heat the house or swimming pool of the farmer but the rest isn’t used. It is also hard to safe the heat or transport it long distances. So heat is certainly an income stream which is in many cases overlooked in the UK.
What can we do with the heat?
Don’t run your biogas engines next to a farm where literately nobody lives.
If you run your biogas engines (I’m not talking about the entire plant – engines to burn the gas and create electricity and heat only) right next to your farm it will be out of place and far away from the point where energy and heat is consumed. The nearest point with a huge demand might be the next village. Transport of the biogas is solved via a gas pipeline. In the village the gained electricity will still feed into the national grid but will be used locally and the heat could be transported via district heating grid to local houses. In bigger communities you might be able to heat schools, sports facilities, swimming pools, medical or community centres.
To put that in some context: One 500kW biogas plant gains two million cubic metres of biogas. After running it through the gas engines it will create four million kWh electricity and 4.4 million kWh heat per year. This is the equivalent of 440,000 litres of fuel oil and it is enough to provide power to 1000 households with 4 people. The generated heat will provide another 150 warm and cosy homes. And thats why it is important not to run gas engines in the middle of nowhere. If you just heat your farm house and the chicken barn it will be a huge heat waste.
I know a lot of people will come forward now and complain about the huge extra investment for the gas pipe. I understand that it is a long process, local landowners along the rout are involved and bureaucratic barriers have to be lifted. But if you include this planning before you build you plant, talk to local authorities and schools – I’m sure all can benefit.
If there is a high demand to learn more about such heat usage examples I’m happy to list a couple of realised projects here soon.