How ‘eco’ are Ecotricity’s plans for Green Gas Mills?




Last week Ecotricity, who supply my household electricity and gas, announced ambitious plans for Green Gas Mills which would produce gas from grass.

The pitch is that green gas could replace or displace fracking (the environmentalist’s bete noir) and produce virtually carbon-free gas without affecting food production and by the way, help produce wildlife-rich habitat too. In time, we could produce all our domestic gas needs in this way.  Sounds amazing?

The search for green fuels is becoming a bit like the alchemists’ search for the philosopher’s stone which will turn lead into gold – there are certain practical difficulties which need to be overcome and it’s looking a bit tricky although some still live in hope of success.

Is green gas the latest in a list of green fuel ideas to come a cropper against the harsh reality of life? As with biofuels and using biomass for energy production the tricky thing is that you need a lot of land to produce a lot of energy and, in case you haven’t noticed, we live on a crowded planet where land is at a premium (look at the price of agricultural land if you want to see how much of a premium).

Ecotricity say that you need about, but less than, an acre of land to provide gas for a home. I live in a rural town of c8000 people (say 4000 homes) so we would need, say, 3500 acres of grass for our green gas, which is about 5 square miles.  I’ve had a look at the map and we could just about fit in our 3,500 acres before we get to too many other towns and villages but that’s going to leave the likes of Thrapston and Higham Ferrers a bit short of land for their gas production. Imagine the area of land one needs to supply a proper town, let’s say Northampton, with a population of 200,000+ which might need c90,000 acres of land for its gas production. Or the whole county of Northamptonshire, county of squires and spires, with a population of 690,000 souls. If they are living in 300,000 homes then they need c375 square miles of land for their gas. Now Northamptonshire has an area of c900 square miles so we are talking, already, of using over a third of it for green gas production.  But England, let’s stick to England, is bigger than Northamptonshire and has more people: England has 53 million people (let’s say c25 million homes) and a land area of c50,000 square miles (of which c38,000 square miles will be farmland rather than woods or towns). England needs c36,000 square miles (c23,000,000 acres) of grassland to produce gas for every home in the land (and I know that not everyone has gas, but if it really were carbon neutral then maybe they should!) and so, whichever way you look at it, there is going to be competition between green gas production and food production.

We aren’t remotely self-sufficient in food in this country although perhaps we could be if we ate a very dull diet and ate less of it and ate a lot less meat (and increased food production from the seas) but we can’t be self-sufficient in food and self-sufficient in gas from the same land and so there is competition and it will be an economic competition.

The great thing about coal mines, North Sea oil and fracking is that they don’t take up much land. Obviously the bad thing about them is that they don’t help you tackle climate change.  The good thing about nuclear power stations is that they don’t take up much land and do help you tackle climate change, but they have other snags which I reckon I could live with.  The good thing about using plant matter for fuel is that it does help you tackle climate change but the bad thing  is that it takes up so much land that you can’t feed yourself, which is potentially another way of dealing with anthropocentric climate change.

These calculations are back of the envelope and I am happy to be challenged about them, but they aren’t going to be orders of magnitude wrong. In fact they are pretty much the same as in the Ecotricity report’s Executive Summary but they reach the conclusion that ‘In the long term, with domestic gas demand expected to fall, each 5MW Green Gas Mill should supply almost 5,000 homes. Meaning Britain should have enough suitable land to supply the overwhelming majority of household heating using Green Gas Mills fed by grass – all without reducing Britain’s agricultural production. The construction of 5,000 Green Gas Mills, each of 5MW capacity, would be enough to supply 97% of British households‘.

There is no wonder that those who have commented on Ecotricity’s plans are a bit luke-warm or downright sceptical:

As long as it’s not competing with food production, green gas like this project can be really helpful in getting UK on to a cleaner and lower carbon path. Agriculture need not simply be part of the problem in tackling climate change, but shows innovation can mean it’s part of the solution, and improve wildlife habitat at the same time.’
Doug Parr, Chief Scientist and Policy Director of Greenpeace UK (my highlighting in red)

The sooner we can stop using gas from fossil sources, the greater our chances of avoiding runaway climate change. Right now, we’re still very dependent on gas to heat our homes – and we need as much of it as possible to come from biological sources, rather than from fossil fuels. So it’s really good to see Ecotricity’s latest Green Gas initiative in this incredibly important area.’
Jonathon Porritt, environmentalist

As the UK ratifies the Paris climate agreement, we must not start up a new fossil fuel industry by backing fracking. We welcome every effort to help people heat their homes without relying on fossil fuels. Energy produced from agricultural and food waste will play an important part in a low-carbon future, and experiments in the use of other renewable and widely available biodegradable materials, such as in Ecotricity’s Green Gas Mills, could be a step in the right direction. We look forward to seeing how the Mills can work to generate energy, support farmers and encourage positive uses for marginal and fallow land without compromising food production.
Tony Bosworth, Friends of the Earth Energy Campaigner (my highlighting in red)

Hmmm. As if silage cutting is not doing enough ecological harm already … Looks like another biomass disaster to me‘ @georgemonbiot

I don’t find Ecotricity’s figures convinving. The search for the philosopher’s stone of green energy continues.




29 Replies to “How ‘eco’ are Ecotricity’s plans for Green Gas Mills?”

  1. As we move to more sustainable living could grass biofuels play a part in the MIX of our 100% renewable energy future? It would look more appealing if homes used 50% less energy.

    If we consider what it could replace then again it begins to look more appealing. What better way to cut our carbon footprint and increase food production for our growing global population is there than stopping eating beef? That is surly the future should the world do what is needed to mitigate climate change and introduced a Carbon Tax.

    So as we all turn our back on beef could grass production be the ideal alternative land use? Is Doug Parr of Greenpeace right to claim it could help improve wildlife habitats at the same time? I can imagine that it could. I welcome the experiment. I think with good regulation it could be a win win for all in the future.

    1. “we all turn our back on beef”

      Who is “we”? FAO project global meat consumption to double by 2050.

      Intensification of marginal grassland is going to be good for wildlife habitats. Yeah right.

      Greenwash, like Miles says

      1. “We” is the future sustainable population of the world. Forgive my optimism I trust that we wouldn’t have assigned our planet to such doom by 2050.

  2. this idea has been around for at least five years, and possibly longer. It’s just that Ecotricity have come up with a practical proposal – well, practical on some levels.

    As far as I can see, the Ecotricity grass to gas project is based on growing high sugar perennial rye grass as catch crops on arable land. Within the 15km radius from each biogas plant, imagine a metapopulation of rye grass leys winking on and off on each arable field across that area. The ley might be grown once every five years or ten years. Each time that field grows grass for biogas, a load of trailers then have to be drawn from the field to the gas plant. We see it here, as Poundbury has a biogas plant mostly powered by maize grown within a 15km (or thereabouts) radius of the plant. The roads get clogged with tractors and trailers for that time of the year.

    The idea that low intensity, wildlife-rich grassland is going to be managed, or created, to produce feedstock for the gas plant is, I think it’s safe to say, greenwash. Yes there might be a meadow that is mown for the cameras, but the vast bulk of the feedstock will be perennial rye grass, grown with fertiliser, and possibly herbicide too. There’s a very good reason for this – energy budgets. To qualify for the renewable energy subsidy, the biogas plants will have to show that there is a net benefit to producing biogas, in terms of greenhouse gas emissions. High sugar perennial rye grass produces much more energy per kg than wildflower meadow hay, which offsets all those GHG’s emitted by the tractors driving to the biogas plants. Or that is the theory anyway – I have my doubts personally that the figures really do stack up. I did some calculations for biogas maize which suggested that they didnt.

    Biogas plants running on human and domestic waste make sense on number of levels. Biogas plants running on animal manures make much less sense, but while we have millions of cows in this country being maintained in intensive systems which produce more waste than the land can cope with, there might just be a short term case for them. Biogas plants running on crops grown specifically for this purpose make no sense, unless there is a generous subsidy to be collected.

  3. The nuclear option may be fine for us, but what about the mess it leaves for future generations.
    Now, if you like fag packet calculations, try this.
    Take the money it will cost to build a French/Chinese nuclear plant and use it to put solar panels on every suitable roof on farms, industrial sites, offices, schools etc. Oh, and maybe bung in the money from HS2. That makes an interesting read!

    Or perhaps we could just harvest heather and burn that inside instead of out!

  4. Mad.
    The obvious answer is to cut demand and build houses with 100% insulation and massively invest in re-insulating the existing housing stock. Banning new Trident and new Hinkley (what about the latter’s monumental decommissioning costs 50 years hence?) would easily pay for zero emission buildings and at the same time give everyone their own roof over their heads. (Maybe even a turf roof for some.)
    Another answer is to invest +++ in the CO2 scrubbing of flue gases. There are at least three nascent technologies: conversion to carbonate; fertiliser or polymer, each one of these products of sequestration being usefully sold on. They sound fantastic or are they too good to be true? (R4 did a good programme on them last week – can’t find it unfortunately)!divAbstract

  5. The sums look pretty identical to trees as biofuel: if you covered the whole country you might just about produce enough energy. We still have perhaps 1 million tonnes pa of wood in neglected woodland that, if removed, would actually improve biodiversity, reversing the decline in the much loved species of the early coppice succession.

    However, what this debate betrays is once again the zero sum of competing single purpose landuses – and the assumption that food continues to be the dominant product of the land – both of which are wrong. We need to be looking for win-wins – conservation wetlands that check the flood (once again relevant), riverine forests that first slow the flow, second are places for people to go from towns and cities and third, almost a bi-product, produce timber and fuel. And if we want to continue eating lots of meat, grass grown looks a much better prospect than grain grown.

    1. Personally I’d much rather see more dead wood in our woodlands than less. A lot of woodland sites are now having problems holding on to ecologically vital dead trees and prone timber through the big increase in ‘green’ wood stoves – this is on top of the problem of too many people seeing dead wood as unsightly and too many orgs rushing to appease them by hiding it away rather than educating them. As George Monbiot mentioned in ‘Feral’ we have a massive conservation problem re saproxylic or dead wood specialists, a far bigger issue than that of struggling farmland birds in my opinion (and the removal of dead wood may well be having negative influences on many woodland birds such as willow tits) so I think it’s dangerous saying we can remove timber from existing woodlands – rather it was left to rot naturally, and a 100 year old oak ‘sustainably’ harvested to make rustic garden benches isn’t going to become an ancient 500 year old specimen, I’d much rather see a new bench made from recycled plastic produced from plastic debris picked off the world’s beaches and seas – which is the truly greener option? There’s a massive amount of wood waste stuck in skips going to landfill that would be a much better source of fuel for a stove (in which case I’d love to have a stove if it was fuelled by genuine wood waste). Coppicing can increase biodiversity, but even more so if as much cut wood as possible (preferably all of it) is left in situ too. I’ve been on conservation tasks where brash has been burned just because that’s what they’ve always done or to prevent honey fungus taking hold!

  6. Where is the mention of properly insulated homes here? Given that both this mammoth “green” project and nuclear power require huge upfront costs would the money not be better spent on insulating homes; UK is still way behind Scandinavia with regard to home insulation? If this plan relies on subsidy and fossil fuel based fertilisers and fungicides where is the gain?
    Using less energy should be the starting point for any investment but then energy companies are not much interested in selling less energy.

  7. AD is in principle a Good Thing – but should be reserved for centralised community schemes to process high energy wastes like fats, oils and food waste, IMHO

    Miles has mentioned some issues related to traffic. There are further logistical issues with grass-fired gas plants. Gas production has to be all year round, but grass doesn’t really do that so it will need storage before use. To avoid aerobic fermentation losses of carbon dioxide and the respiratory losses that start as soon as grass is cut it needs ensiling asap. In gert big silos. Then there is the potential pollution from effluent – which must be collected if it flows (but it could be digested).

    The digesters produce gas and digestate wastes. The digestate is separated into fibrous waste and liquid. The solids can be further composted (you could recover some heat from that, while the ammonia pollutes the air) and returned to land, used for peat-free growing media or turned into briquettes for domestic fuel – all processes needing further bulk transport by road. The liquid fraction will contain a lot of the the reactive nitrogen that was in the grass at the outset and will need storage until such time it can be transported by road back to farmland for spreading on crops at an appropriate time.

    In Nitrate Vulnerable Zones this means storing digestate liquid in gert great lagoons that will also collect rainfall from October to February. By the time National Slurry Spreading Day arrives on the 1st of March there will be maximum potential for water pollution by run-off from saturated soil. BOD is BOD whether it’s renewable or not.

    The main purpose of Ecotricity is to suck money out of the subsidy teat.

    1. Agree with most of that Filbert, but I have often wondered, mused even, if grass powered AD could be of some use in the eastern arable counties, particular on ‘farmed-out’ low SOM arable land which is begging to be put back to grass/clover leys for several years. The fibrous digestate fraction could also be utilised on low SOM arable land. As liquid fraction can be pumped up hill and down dale quite efficiently for several miles – the key is having some high N demand spring crops to inject within pumping distance thus avoiding the inefficiency and cost of rubber on tarmac. But as you point out substantial storage is required and that is expensive, and likely to more expensive in the areas where low SOM is most likely

      There is also potential to add some by-products into equation – this must be better then having them hauled across the country and fed to cattle in sheds..

      1. IIRC it was EA’s refusal to believe that SSAFO compliance was enough to permit the safe development of that megadairy or -piggery in Lincolnshire – such was its confidence in the gold-plated Regulations it regulates.

  8. Re-Nuclear Power:
    As someone who spent a large part of working life trying to put right the environmental problems of the coal industry, why does everyone seem to ignore the far greater problems of Nuclear Power. Nuclear waste; de-commissioning; uranium mining; possible terrorism attacks; – not to mention the capacity for accidents – Chernobyl/3 Mile Island/Windscale/Fukushima and all the other events we never hear of? These problems could be with us for thousands of years. As others mention, we should reduce our use by insulation, more efficiency and all new buildings should have compulsory renewable energy features etc.

    1. “These problems could be with us for thousands of years”
      Northern, I think that the ‘us’ in that sentence is the problem. These problems won’t be with us, but with our children and grandchildren etc. Who looks to the future nowadays? Create whatever mess you like and leave it to others to sort out!
      At least with turbines, solar, insulation, the products get better and more efficient all the time and the mess we leave for the future won’t be anywhere near so toxic.

  9. I’ve just written a short report about Ecotricity’s ‘green gas from grass’ plans for Biofuelwatch: (before coming across this article). Based on figures contained in a peer-reviewed study which Ecotricity themselves cite in a planning application, they’d need 10.2 million hectares of land used to grow enough grass to replace current domestic gas use in the UK. Mark Avery is absolutely right: The competition with food would be enormous!

    1. So what’s the answer to our national gas use? The summary of the above “report” gives no clue – there are undoubtedly bad biofuel option and it right the downsides are thought about, however where are the positive alternatives?

      1. David B – use less is the best answer. But there is no one single answer. Life is more complicated than that.

    2. I just read your article. ” … requires the CO2 contained in the biogas – up to 45% of the total volume – to be emitted straight into the atmosphere, without burning.” Please tell us of a process that emits carbon dioxide into the atmosphere after burning. And why it is used in fire extinguishers.

  10. I’ve yet to discover a carbon balance analysis for this method of energy production that crucially takes account of the fact that when biogas – the product of AD – is cleaned to make biomethane. 40% of the gas is discarded to atmosphere. And the discarded gas is Carbon Dioxide. Is that factored into the ‘carbon neutrality’ of the whole process?

    We fret over the 5-12% leakage rate of methane from fracking operations, yet apparently a much higher leakage of CO2 is acceptable because it’s renewable energy.

    Already over a fifth of UK farmland growing maize is supplying AD plants. Government was intending to keep an eye on the use of food crops used to feed AD plants because of the land-take. It should be doing the same with grass.

    1. “Is that factored into the ‘carbon neutrality’ of the whole process?”

      Take one molecule of glucose and give it some AD and you get three molecules of carbon dioxide and three molecules of methane. Burn the methane and you get three molecules of carbon dioxide and six molecules of dihydrogen oxide. In total you now have the six carbon atoms that you first had in the glucose, all as carbon dioxide. But you had the opportunity to use the energy in the methane along the way.

      Or do nothing to the one molecule of glucose and let bugs respire it away completely to six molecules of carbon dioxide and six of dihydrogen oxide. There is more heat available but you lost it.

      It’s all cyclic carbon. It’s all available for photosynthesis – again.

  11. At least Dale is trying to find and fund solutions – could it be better explained, yes. Is it better than doing nothing, probably. Is Lord Avery helping, who knows?

  12. “The great thing about coal mines, North Sea oil and fracking is that they don’t take up much land.”

    I actually had to read this twice. Fracking doesn’t take up much land? You seriously need to research fracking in greater detail, I’m afraid.

    In order for fracking to be anyway economically viable, it requires thousands of wells. It has a high level of spatial intensity. Then you have all the accompanying infrastructure as well, such as the pipelines, compressor stations, condensor units, and, in some cases, ethylene crackers. I thought it was common knowledge that vast swathes of land have been destroyed in northern America and Australia. It’s very worrying that a UK environmentalist is so uninformed about the impact of this industry.

    Feel free to email me if you need links to peer-reviewed research on the land disturbance impacts.

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