GAS-TO-GRID COMING OF AGE?

Whilst we are all familiar with the idea of green electricity, biomethane, or ‘green gas’, is a relatively new entrant into the energy marketplace. But today, green gas is helping decarbonise gas supply in just the same way as renewable electricity helps decarbonise power generation. Here, I am going to sketch the history of this new fuel, plus look at a few companies that are using green gas as a key part of their environmental strategy.

There are now over 50 biomethane-to-grid connections (BtG) in Great Britain, producing green gas and injecting it into the existing gas grid. With a total of 47 new projects in the last two years, Britain has seen the highest level of BtG growth in the world.

BtG is the process whereby renewable gas is injected into the gas grid, giving Britain an efficient source of green, sustainable energy made from organic material, including food waste. Biogas is produced by anaerobic digestion (AD) plants. This biogas is often burned on-site to generate heat, power or both. But biogas can also be cleaned and upgraded to natural gas standards so that it can enter the gas grid, becoming biomethane.

AD plants are generating biogas from many different sources – such as manures, commercial and industrial waste, slurries, crops and crop residues. Most recently, water companies have started building AD plants which produce biogas from sewage. By using waste, crop residues and sewage to generate energy, we are creating a circular economy, extracting the maximum value from resources and recovering and regenerating products and materials.

Historically, the first wave of AD plants was focused on producing biogas to generate electricity, for which there was a government subsidy. To move to BtG a number of technical issues around injecting biomethane into the gas grid had to be addressed and the producers also needed financial support to make connecting to the grid as attractive as producing electricity.

Incentives for injection

To that end, the Renewable Energy Association (REA) persuaded the government to introduce an incentive for green gas injected into the grid. After much lobbying, in 2011 the Department for Energy and Climate Change (DECC) published details of the Renewable Heat Incentive (RHI), which included payment for biomethane injected into the grid.

The RHI for biomethane was one part of the jigsaw which created an attractive regime to allow BtG innovation to flourish. Biomethane engineering specialist, CNG Services, also worked with gas distribution network companies to find practical ways to connect small producers to the gas grid, and these efforts culminated in the first commercial connection at Poundbury in 2012.

Rainbarrow Farm near Poundbury, owned and run by J V Energen, a joint venture between local farmers and the Duchy of Cornwall, was Britain’s first AD plant to inject biomethane into the gas grid. Biogas production began in March 2012, with commissioning of a 400 kW CHP plant, with injection to the gas grid commencing in October 2012. The annual raw gas production is around 7.5mn m3 (mcm).

Following that there were two further connections in 2013, at Future Biogas’ plant in Doncaster and Vale Green Energy at Springhill Farm in Evesham, Worcestershire. Vale Green Energy was developed, when one of the Photo; An anaerobic digestion plant Energy World | April 2016 21 Gas region’s main producers, Evesham Vale Growers, needed to find a solution to a mounting waste problem and to reduce the cost of heating and power. EU and UK regulations mean that waste generated from its 12 Ha of glasshouses and 800 Ha of outdoor salad vegetables is categorised as industrial waste and, as such, could not be returned to the land as fertiliser.

Vale Green Energy developed an AD plant which went live in August 2013, with a second phase following in 2014. The AD plant turns green waste into energy to heat and light the tomato greenhouses, with the excess being injected into the grid. A by-product of this process is the production of food grade carbon dioxide, which is put back into the greenhouses to aid the photosynthesis process.

Taking off from 2014

It was in 2014 that the new BtG sector really took off, with 22 plants going live. One notable project was Saria’s Refood operation in Widnes, which was the largest BtG development of its kind in Great Britain, generating enough power to heat 12,000 homes. The plant can recycle 120,000 tonnes of commercial and domestic waste food and liquid to generate up to 180 GWh of biomethane every year. Waste food is collected from supermarkets, hotels, restaurants, shops, bars and schools within a 50-mile radius.

Also in December 2014, Wyke Farms, one of the UK’s largest independent cheese producers and milk processors, commissioned the second phase of its biogas project which sees it send up to 7 mcm per year of its upgraded biogas back to the gas grid.

Finally, 2014 saw two water companies starting to produce biogas from sewage. First, Severn Trent opened a BtG plant at Minworth, near Birmingham, which has 16 anaerobic digesters, producing about 80,000 m3 per day of biogas from its sewage treatment processes.

In November 2014 a BtG plant at Bristol sewage treatment works run by GENeco, a subsidiary of Wessex Water, started injecting green gas generated from food waste and sewage into the gas grid. At the same time it installed a gas refuelling plant for a compressed natural gas (CNG) bus. The plant produces 17 mcm of green gas a year. The gas refuelling plant now fuels a ‘Bio-Bus’ that is able to travel 300 km on a full tank of green gas.

In 2015 there were a further 23 BtG connections and by mid-2016, when all the completed projects are at full capacity, there could be around 120mn therms/annum going into the gas grid - equivalent to annual green gas production of 3.5 TWh per year.

The green gas market

The one thing all these green gas producers have in common is that they are not energy companies. There are farmers, waste and recycling experts and water companies producing biomethane, so energy isn’t their core activity. Barrow Green Gas helps them sell their green gas. We hold GB gas shipping and supply licences, so can move the green gas across Britain’s gas network from producers to end customers. We are focussed solely on the biomethane market, helping producers apply for the RHI, which can be a complex process, and trading Green Gas Certificates from producers to buyers.

The Green Gas Certificate Scheme was set up by the REA as a not-for-profit scheme that allows biomethane to be tracked from an AD site to the customer burning gas. Each unit of green gas injected into the grid displaces a unit of conventional gas, and Green Gas Certificates track the contractual rather than physical flows to ensure there is no double-counting from production to end use.

These certificates give buyers the ability to buy green gas across the country and so have helped create an attractive market for biomethane and encourage more gas producers to invest in connecting to the gas grid.

Aside from injecting green gas into the grid for heating, another significant use for green gas is transport. Transport fleets, particularly HGV operators, throughout the country are switching fuels from diesel to CNG. Today, natural gas vehicles (NGVs) offer a 72% reduction in carbon dioxide emissions, ultra-low particulate and NOx emissions as well as big noise reductions. There are also significant economic benefits for fleet owners switching to natural gas vehicles, with savings of between 40% and 50% over diesel.

Biomethane as a vehicle fuel delivers all the benefits of natural gas, but with a clear advantage – it is renewable and sustainable.

One of Barrow Green’s customers for green gas, CNG Fuels, is dedicated to building and operating CNG filling stations. CNG Fuels owns what was the UK’s largest public access CNG filling station in Crewe until it opened an even bigger filling station at Leyland in Lancashire. Waitrose has already switched to vehicles that are fuelled on Bio-CNG to reduce their carbon footprint and are operating trucks from the Leyland CNG station, supported by Green Gas Certificates from AD plants that use waste feedstock, such as ReFood in Widnes.  

Each unit of green gas injected into the grid displaces a unit of conventional gas, and Green Gas Certificates track the contractual rather than physical flows to ensure there is no doublecounting from production to end use

The demand for renewable gas for heating is also rising as gas buyers realise the benefits of switching to green gas. In January this year Wyke Farms announced a partnership with Sainsbury’s to supply green gas for its stores. Wyke Farms will supply a large proportion of the supermarket’s green gas, which makes up 6% of Sainsbury’s total gas use. This will save over 16 tonnes of carbon dioxide emissions per day, or 24,000 tonnes over the length of the supply partnership.

Maintaining the gas grid

Looking at the big picture, Britain is relatively cold and relies on gas, especially for domestic heating. It is beneficial from an economic point of view to maintain the usefulness of both our gas grid and our domestic central heating systems. As biomethane is a renewable gas, it is helping to reduce our dependence on fossil fuels. Further development of biomethane is an efficient way to start to decarbonise the gas grid.

National Grid has estimated that biomethane can supply 5%–18% of Britain’s gas demand by 2020, so biomethane could make a significant contribution to the Climate Change Act target of an 80% reduction in greenhouse gases by 2050. Also, having an additional domestic gas supply helps our energy security as we are not as dependent on gas from overseas.

With Barrow Green Gas now shipping green gas for 26 gas producers, 2015 was a record year for the company as well as the biomethane-to-grid sector. There is every indication that growth will continue as producers and suppliers realise that green gas is the best choice for industry; for heating our homes; and for fuelling trucks and buses.

Tim Davis is the Managing Director with Barrow Green Gas, www.barrowgreengas.co.uk