Future Biogas worked closely with National Grid, which owns and operates the gas grid, officially known as the National Transmission System (NTS). Developers sign contracts with National Grid to supply biomethane, and procure the controls and instrumentation which National Grid installs and runs at the injection sites. The instrumentation is remotely operated from National Grid’s offices in Hinckley, Leicestershire, where engineers can tell the chemical composition of the gas at injection sites and shut off connections if required.
Damien Hawke, network design manager at National Grid, heads the team that connects developers such as Future Biogas to the NTS. He has completed two more connections since the Doncaster facility, notably a plant three times its size developed by ReFood, which processes food waste into biomethane at Widnes, Cheshire.
“We’re supportive of the sector and work with developers and the Energy Networks Association,” says Hawke. “The regime we have for the larger sites is fine but at the smaller sites we’re looking at making the calorific value requirements less onerous to reduce costs.”
The NTS plays a similar role to the high-voltage electricity transmission network. The pipelines that deliver gas to households are split into regions and run by different companies. These regional networks take gas from the NTS at offtake sites. To put the size of biogas plants into perspective, the offtake site in the North West can take up to 20 million m3 of gas a day.
The 2009 National Grid report and its eye-catching 50% figure for biomethane supply in the UK is still used in marketing by biogas companies today. But Hawke admits that the figure was “a bit bullish”.
“Realistically it’s more like 10%,” he says. “But the more biogas from renewables and waste we put in the better. Plus we are also getting more efficient with the way we use gas.”
The size of the contribution to the grid and the technical challenges have not dulled National Grid’s support for the sector. It aims to connect 80 biogas plants during the next seven years. Some 15 more are due to be commissioned during this financial year.
Hawke says: “It’s grown fast from a standing start. This time last year there were no projects. The sector just needs certainty from government as soon as possible. Then we will get a steadier flow of projects.”
Growing sector: Fifteen more plants should be commissioned this year
The government subsidises biogas plants mainly through the feed-in tariff and the renewable obligations certificates. However, regulations were devised in 2011, when there were no plants. Earlier this year, the government launched a consultation on the subsidies, and there has been talk of various overhauls, including banding for different types of biogas plant.
Future Biogas runs three electricity-producing plants in East Anglia, each with a capacity of 5MW, as well as the facility in Doncaster. Mezzullo says: “It’s a lot easier when you make electricity – no one is checking on the quality. With gas you’re effectively injecting into someone else’s infrastructure. But you do get rewarded slightly more for biomethane, a reflection of the fact that it is more complicated to do than electricity.
“The sector is taking huge strides forward. Today we know what size plants we need to build. But we have the added pressure of the government changing the tariffs and the support levels.”
Meanwhile, at the other end of the size scale from Future Biogas is Southampton-based Seab Energy, which has developed a micro-CHP unit that runs from biogas derived from food waste and/or other organic matter. Seab’s Muckbuster and Flexibuster have been developed by a husband-and-wife team, who decided several years ago there was a gap in the market for a system able to produce heat and light for stables from horse manure.
Neither partner had an engineering background, so the system was very much “market-designed,” says chief executive Sandra Sassow. “We sat down with the engineers and said ‘this is how much it has to cost’ and they said that it wasn’t possible to cost the unit when there was no design. We had three different passes at the design, had our final design in six months, and now we’re on our fifth version of the product.”
Seab’s power plant is essentially a mini anaerobic digester and micro-CHP unit in a shipping container. The containerised design has been patented. The plant first pasteurises the waste and converts it into biogas using an anaerobic digester. The gas is then used to generate electricity and produce heat in a CHP unit.
There is no other such system in a container that can be brought in by truck, plugged and piped in and run, says Sassow. “The system won’t be the best fit for every site, but there is a big market for it. Our system is the CHP equivalent of what a laptop is to a mainframe computer,” she says.
The units produce 0.5GWh of electricity a year, 14kW in their smallest variants and up to 65kW in the largest models, and have 90% run time. The larger units cost £350,000 and the smaller ones £220,000. Better power outputs are obtained when mixing food-related waste into the digester. Payback time with food waste in the mix is three-and-a-half years; with just agricultural waste it takes five.
Seab’s units make the most sense in places where there is a lot of waste. The UK produces 290 million tonnes of waste a year, 60% of which goes to landfill. Some 15 million tonnes is food waste. Sassow says the major benefit of her firm’s system is “to stop moving waste around... this is the opportunity to move into decentralised energy systems”.
Flexibusters are being used in the catering, hospitality and food manufacturing industries to process organic waste into energy. According to Sassow, Nasa is even considering using the system on long-haul space flights. The company has installed five units in five years. The oldest system has been running for four years.
The next step is to install a system for domestic use. Blocks of 90 flats could get back up to 30% of their energy costs by using Flexibuster, she says.
“The residential block has to be a similar size to a hotel and it has to be a newbuild. I don’t think people will have a problem with their waste being treated where they live. It’s self-contained.”
There would be environmental benefits to residential systems in terms of CO2 emissions, she adds. Moving waste out of cities causes a massive amount of CO2 emissions. Removing the solid waste from sewage also reduces the amount of energy needed to process it. The idea may seem strange, but such original thinking is needed to combat climate change.
“We are still moving things from one location to another when, if you go back in time, we wouldn’t have done that,” says Sassow. “We have to work out how far can you move and how far should you move. Instead, we tend to look at how we can accommodate the way we are living now. That’s not necessarily the best approach. We need more original ideas.”
Biogas could even be collected, compressed and transported for use elsewhere.
Interestingly, there is a great deal of interest in the units from developing countries in Africa and Asia, and the company expects to make announcements about deals in these markets soon. Sassow says: “There are four main geographies where the markets are very open to different types of solution. These places don’t have a power network and they are leapfrogging from landfill straight to microgrids.”
In the UK, most developers and the National Grid agree that initially there will be a mix of large and small biogas plants, sized and sited optimally to tap into agricultural and food waste streams. This small industry is scaling up and finding its brass in somewhat unglamorous but profitable places and ways.