Can we make gas?
John Newson
Gas is very convenient and is the established way to heat our buildings in winter, which is 45% of total energy use. The North Sea gas fields are depleted and gas is increasingly imported. We don’t want to frack deep rocks in Britain to force out shale gas – a dangerous technology that has already caused a series of earth tremors in Lancashire.
The alternative is to make “green gas”, at scale, from renewable processes at the surface, instead of pumping up fossil gas that releases fossil carbon and accelerates climate change. The gas system provides an already existing way to store and distribute energy which could help make use of intermittent renewable sources of energy.
There are several approaches to making Green Gas (methane).
- Sewerage gas. The water industry can feed into the gas network in future from sewerage works. Digestion by bacteria makes the methane in enclosed tanks, instead of releasing it into the air. This methane is being injected into the gas grid, for example at Coleshill near Birmingham and at Didcot sewerage works 1. Animal waste from livestock is used to make gas on farms and this is widespread in Germany.
- Grass to gas – an approach being trialled by Ecotricity. Grass also makes a consistent product that can be put into the grid; instead of feeding grass to cattle, it could be digested and made into gas 2. People should be eating less meat and dairy for health reasons and that would release grassland for energy crops. It would need about 1 acre of grassland to heat a household, according to Ecotricity. Organic wastes from the food industry, paper making and others can also be digested and used for gas.
- Wind to gas. This method would use excess wind electricity at night and in winter months, instead of wasting it or turning off the turbines. Electricity can drive the electrolysis of water, splitting it into hydrogen and oxygen. Some hydrogen can be mixed into the gas supply but beyond that hydrogen could be combined with carbon dioxide from the air to make synthetic methane, using the Sabatier process. The Centre for Alternative Technology sees this as a key technology in their Zero Carbon Britain Plan 3.
All the three methods exist on a small scale and show great promise to move us from fossil gas that releases greenhouse gases towards home-grown and renewable green gas. A report for National Grid some years ago showed that half of current gas could be replaced by green gas (so we would also need to become more energy efficient).
Refs 1 http://www.cngservices.co.uk/index.php/services/biomethane/the-didcot-project
2 https://www.ecotricity.co.uk/our-green-energy/our-green-gas/how-green-gas-works
3 http://www.zerocarbonbritain.org/en/component/k2/item/149?Itemid=276
