A new concept for using local waste resources to provide local renewable gas has been drawn up by National Grid.
The blueprint for what are being called an Urban Energy Centres sets out a nationwide solution to providing renewable heat by efficiently harnessing the energy output from an integrated waste management system.
The concept outlines how waste streams from homes and businesses could be turned into renewable gas to maximise energy recovery:
o A centre, which could be sited at an industrial park on the outskirts of a town or city, would take segregated food waste from the local area and treat it in an anaerobic digester.
o Other municipal, and commercial & industrial waste would be processed in a mechanical biological treatment (MBT) plant. The remaining biodegradable waste would enter a gasifier to produce syngas - a synthetic gas. Syngas is turned into pipeline quality biomethane and injected into the gas grid locally.
o A plant could provide heat for around 45,000 homes in the local area.
The potential urban energy centre outlined in the report would take 100,000 tonnes a year of food waste as well as 547,500 tonnes of mixed municipal, and commercial and industrial waste. Because of the integrated energy system within the centre, the overall energy recovery of the plant would be almost 90% compared with the average efficiency of existing biomass to energy plants in the UK of less than 25%. This solution would represent a great step in improving our utilisation of valuable waste resources.
The total capital cost of this plant is projected to be £367 million giving a cost of £62 per megawatt hour for the biomethane produced and injected into the gas grid. National Grid estimates that about 10 energy centres would be needed to process waste in London and so one such plant might service a city the size of Liverpool. The plants could provide about 10% of the heat demand in these towns and the model is scalable so smaller plants could be built to locally service many other towns and cities.
Mark Fairbairn, National Grid's executive director of gas distribution said:
"We've carried out this exercise so that the huge potential of renewable gas from waste can be visualised. As well as helping the country to deliver renewable energy targets of 15% by 2020, these centres would improve security of supply and provide a clean and efficient process for managing waste.
"However, this only becomes feasible if the Government introduces a renewable heat incentive (RHI) payment for renewable gas that makes it commercially viable. Also support will be needed to develop gasification technology alongside a review of waste policy to ensure that energy recovery from waste is maximised at all plants in the UK.
"Based on this kind of delivery model, the UK could take the lead in this area of renewable energy, helping to create a new industry and jobs, as well as making a positive difference to our environment."