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Agriculture harvesting grass for gas

Published on May 24th, 2018 | by Andy Miles


Gas From Grass Could Be An Eco-Friendly Biofuel

May 24th, 2018 by  

Originally published on EVObsession.

In January of this year, I wrote 2 major articles relating to climate change and what can be done about it. I am now writing follow-up articles about some aspects of that. One item I mentioned was the use of biofuel. Some purists argue against the use of biofuel, on the basis that the source crops replace either food crops or plantings such as forests, which are essential for filtering CO2 from the atmosphere. They also point out that pollution from burning biofuel is not much better than pollution from burning fossil fuels, although that depends on how efficiently they are burnt.

harvesting grass for gas

The main argument for biofuel is that the CO2 released is CO2 that was stored in the source crop not long ago, and is therefore circulating the CO2 rather than generating it. This is in contrast with CO2 from fossil fuels, which is CO2 that was taken from the atmosphere millions of years ago and is now added to the CO2 in the current atmosphere. This is what makes burning biofuel much better than burning fossil fuels. I would agree that the ideal is not to burn any kind of fuel, but for practical reasons there is bound to be a transition period while systems that burn fuels are replaced with all-electric systems. For some purposes, it might be the case that fuel burning systems cannot be replaced at all, or at least for a long time in the future.

As for the argument about biofuel source-crops replacing plantings that absorb CO2, that would only be the case where forests, for example, are cleared to grow biofuel source crops, which need not be the case. It can be a case of utilizing existing, relatively unproductive land, which would not be prime agricultural land, and so better utilizing that land by using it for biofuel. It seems that most of the negative opinions about biofuels are just the sort of thing that might come from the fake news pages of some pro-fossil fuel propagandist, as they are that kind of half-truth, where although they could in the worst-case scenario be detrimental, there is no reason why that worst-case scenario should ever occur.

In relation to biofuel, I specifically made reference to my interview with Dale Vince, the managing director and founder of the UK energy firm Ecotricity, which provides renewable energy to its customers at 100% for electricity, and currently 12% for gas. In that interview, he made the bold claim that given access to the land, he could produce biogas sufficient for the needs of 97% of Britain’s homes, provide thousands of jobs, thousands of acres of wildlife habitats, and all without using any prime agricultural land. Farmers who provide feedstock for the gas-mills would get back the solid residue as a natural fertilizer and soil conditioner, saving them the financial and environmental costs of using artificial fertilizers. Also, turning a field over to a wildflower meadow for a season in a system of crop rotation greatly enhances the soil and breaks the continuity of crop diseases.

The Ecotricity Report

Ecotricity commissioned a study to look into Green Gas Mills to see just how much potential they really had, and report the results. The results were better than they imagined. The report found that green gas made from grass could potentially power 97% of Britain’s homes, employ 75,000 people, and inject £7.5 billion into the rural economy every year.

Green gas would cut carbon emissions, help to create an an energy independent Britain, support food production by improving soils, creating wildlife habitats, providing an additional income to farmers and giving them natural fertilizer from the residues of the process.

In the short term, green gas can play a key role in helping to meet the UK 2020 renewable heat target by delivering 12% of heating demand.

How Green Gas Works


Image Credit – Ecotricity

These are the steps –

Step 1 – Source the fuel

Harvest naturally occurring grasses from land previously used for grazing livestock and lower quality arable farmland, creating new wildflower meadows in the process, so increasing biodiversity and providing environmental benefits at the same time.

Grass can be grown in rotation every few years as a break-crop on lower quality arable land that farmers currently use to grow feed crops for livestock. This will actually improve the quality of the soil and bring it back into food production through the addition of the natural fertilizer from the waste product of the gas mill.

Step 2 – Take it to a Green Gas-Mill

The grass provides a consistent source of organic material, enabling the production of a high quality Green Gas using a process called Anaerobic Digestion (AD). The way that Anaerobic Digestion works is pretty simple. Organic material (called a ‘feedstock’) is broken down by bacteria in an oxygen-free container, producing two main end-products: biogas and a rich organic fertilizer.

Some AD plants in Britain burn the biogas to produce electricity in small on-site generators. Ecotricity Green Gas Mills go one step further. The biogas is ‘scrubbed’ (mostly, that means having some CO2 removed) and upgraded to the UK’s high environmental and safety standards to produce bio-methane, which can be fed directly into the national gas network to replace fossil-fuel methane that’s used for heating and cooking in UK homes. That’s the beauty of the Green Gas Mill: you can be cooking on Green Gas, and you won’t even notice any difference.

Revolutionary Gas

We will never remove the carbon from the UK economy if we cannot remove the carbon from our heating, which accounts for around 45% of our total energy use. Bio-methane production is already growing rapidly. In 2012, the UK did not have a single bio-methane gas mill, however, by the end of 2015 it had 50 mills producing an estimated 2.5TWh of renewable heat energy, which is enough to supply heat to 190,000 homes.

A typical Green Gas Mill at 5MW will require about 3,000 acres of grassland to supply 3,500 homes with all the gas they need. That’s less than one acre per household. The construction of 1,000 Green Gas Mills, each of 5MW capacity, would be enough to make up the current shortfall against our 12% target and would create around 15,000 jobs and pump £1.5 billion into the rural economy.

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. This would require the construction of 5,000 Green Gas Mills, each of 5MW capacity, which would be enough to supply 97% of British households, create around 75,000 jobs, and pump £7.5 billion into the rural economy. This would involve a massive scaling up of Green Gas, but it shows how big the potential is. Green Gas Mills can decarbonize UK heating and help tackle climate change.

What is revolutionary about these Green Gas Mills is the use of naturally occurring grasses as a feedstock to produce truly renewable gas that recycles existing CO2 in the atmosphere that’s been absorbed by the grass over a very short cycle. So, unlike with fossil-fuels, CO2 is not being added to the atmosphere, just constantly recycled. Land is not being used that would be used for growing food, trees are not being used, which have a long recycling period, and are better used for absorbing atmospheric CO2, and neither are food crops. Wildflower meadows are also being created, which will provide wildlife habitats especially important for pollinators and other beneficial insects.

All this will give extra income to farmers, improve the land, and provide thousands of jobs. Jobs are scarce in rural areas in the UK, and rural communities are in terminal decline, so this new industry could be a real life-saver. It is also very hard for hill farmers to make a living out of sheep farming, and meat-eating is in decline, so some hill farmers could convert to producing grass for gas, providing a new lease of life. They would need to develop or source light machinery for harvesting grass on hillsides, as heavy harvesters are for flat fields.

They might also need to experiment with grasses and other meadow plants that would thrive in the poor thin stony soils found on the typical hill farm. Grass for each Green Gas Mill is sourced from non-food producing land within 10 miles of each plant. The outputs of the green gas-mills are simply Green Gas, and an excellent natural fertilizer, which can be returned to farmers’ fields, improving the soil quality and reducing the need for harmful synthetic fertilizers that are bad for the environment.

Greening gas now…

Ecotricity was the first energy company in Britain to supply green gas. It’s 12% green now, and that percentage will grow as it starts to build its grass-fed Green Gas-Mills. Ecotricity launched its first Green Gas-Mill project in Gloucestershire in 2015, with a second at Sparsholt College in Hampshire in October 2016, and it is to develop a third Gas Mill in Somerset that will generate enough green gas from grass to power up to 2,500 homes, while a fourth is also due to be unveiled very soon.

Dale Vince, Ecotricity founder, said:

“We are at the beginning of a revolution in gas, not from fracking but from farms; there’s a whole new industry waiting to be created here, meaning more jobs, and plenty of economic benefits. We can’t continue using gas from fossil fuels, we are running out, and causing climate change; the great thing about green gas, like green electricity, is we can still live the way we’re used to, but we can do so in a sustainable way. Making green gas from grass doesn’t compete with food production, it actually supports it, and the farmers working the land. It also helps wildlife, creating new habitats and there’s enough non-food producing farmland in Britain, in principal, to meet 95% of the gas we need, this way. The strength of public opposition to fracking is crystal clear, and it’s only increasing as well as the significant environmental and health impacts, it’s just an unnecessary risk which we can avoid entirely by pursuing Green Gas.”

Green Gas Benefits

1. Boosting the rural economy and supporting our farmers. As farm incomes are falling across the board, Green Gas Mills bring significant economic benefits to local rural communities. Each Green Gas Mill will create around 30 jobs, contribute £1.5 million per year, or £30 million in their operating lifetime, to the local rural economy.

2. Enhancing the food productivity of arable farmland by improving soil health. The varieties of naturally occurring grasses which can be used in the Green Gas Mills can enhance the food productivity of arable farmland, and improve soil-health when used in crop rotation cycles. They also produce an organic fertilizer as a co-product of the process, which can be used to turn lower quality land only suitable for growing feed for livestock into more productive land suitable for growing food crops for humans.

3. Creating habitats for wildlife. Since 1930, it is estimated that Britain has lost 97% of its flower-rich grassland, which has caused the decline of many species which play a vital role in the ecosystem. Green Gas Mills will help to reverse this trend by creating an economic argument for the stewardship of species-rich grassland.

4. Reducing UK reliance on fossil fuel imports. While the UK’s gas consumption overall is going down, the amount we are importing is going up as the North Sea gas runs out. The UK Oil and Gas Authority has projected that by 2030, the UK could be importing three quarters of all our gas. Green Gas Mills have the potential to change that.

In Conclusion

This idea seems to have many benefits, with this gas being a relatively clean biofuel which will enhance agriculture and wild-life habitats, will not use prime agricultural land or food crops, and which will not add to atmospheric CO2. It will replace fossil fuel currently being used with an otherwise identical fuel, so enabling current household equipment to continue in use during the transition to all electric households, and it will provide clean gas after that where a need for its use remains. It seems extraordinarily perverse of the UK Government to be forcing fracking on the British People, who are almost unanimous in their opposition to it, when this safe and beneficial alternative is available.

The one question I had after reading the various documents produced by Ecotricity is what happens in the middle of winter, when, as we all know from our lawns, grass does not grow. Winter is the time of greatest demand for gas for heating, but the time of least plentiful supply of grass. I asked them about this, and they said surplus summer grass is stored for winter use, just as farmers store hay. Failing that, anaerobic digesters are not fussy about the feedstock, and will use any organic material available, including waste from farms, food waste, garden waste collected by Local Authorities, and even waste from sewage processing plants. There is no reason for the digesters to go hungry, even in the depths of winter, and it is far better to process organic domestic waste in digesters where it can produce methane as a fuel, rather than putting it in landfill where it will produce methane directly into the atmosphere.

As far as I am aware, Ecotricity is managing to run its digesters purely on their intended crops, without recourse to emergency rations.

You can read the full Green Gas Report here:

Green gas report (PDF, 2 MB) ,

You can watch interviews between Ecotricity founder Dale Vince, and Robert Llewellyn, in which Dale talks about Green Gas-mills.

Reprinted with permission.

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About the Author

As a child, I had the unrealistic expectation that I would learn about, and understand, absolutely everything, during the course of growing up. Now, at the other end of life, I am fully aware of how much I have not learnt, and do not understand, and yet, remain interested in everything. My education, starting with an arts degree, and going on to postgraduate studies, in everything from computer science, to hypnotism, reflected my broad interests. For 20 years, I worked in local government, and am now retired, living in North Leicestershire in the UK, with plenty of time for doing whatever I like. I have always had a keen interest in everything alternative, which includes renewable energy and energy efficiency and, of course, electric vehicles. So, naturally, I have taken ownership of an EV, now that they are affordable and practical forms of transport. Writing is also one of my great pleasures, so writing about EVs and environmental issues, is a natural evolution for me. You can find my work on EV Obsession, and CleanTechnica, and you can also follow me on twitter.

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