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Green Gasmills fact sheet

What are green gasmills?

Green gasmills are an exciting way to make sustainable, low carbon gas that can be used in the boilers we already have in our homes and businesses.

It’s proven technology, powered by anaerobic digestion. The mills are fed with grass from herbal leys and we harvest the biomethane gas it produces – it’s a bit like a cow’s stomach. The waste is used as fertiliser to grow more grass, so there is no need for expensive fossil fuel derived fertilisers.

Green gas recycles atmospheric carbon and does not release any additional fossil carbon into the atmosphere as the carbon contained in biomethane is biogenic and part of the carbon cycle.

How can green gasmills contribute to meeting the UK’s net zero target?

Green gasmills save nearly 87% of greenhouse gas emissions when compared to current North Sea natural gas and synthetic fertiliser use. This could be reduced further with automation and well-monitored systems – saving up to 99% of emissions by 2050.

Do green gasmills take vital land away from farming and food production?

No. The plants used to feed the green gasmills (herbal ley mixture species) don’t need agricultural land quality land to grown, so they won’t compete with food production.

Some farmers may choose to grow them in rotation with crops on arable land, to improve their land’s soil health and increase food productivity.

How much land will green gasmills need?

The UK has 6.46 million hectares of suitable grassland, which is enough for around 5,400 green gasmills. This would provide up to 236.5 TWh capacity - enough energy to heat 98.8% of British homes if they’re made energy efficient.

This assumes green gasmills with approximately 5MW capacity, requiring 1200 hectares of land each in line with current technology.

How does green gas production compare with North Sea gas?

The green gas potential – as green gasmill technology develops – of herbal ley species on the suitable UK grassland itself is 247.2 to 482.5 TWh, with an average of 288.5 TWh. This green gas potential could be increased to 579.2 TWh by adding seaweed.

This significantly exceeds the UK’s gross natural gas production from the North Sea (438.3 TWh).

As diet habits change to free up more grassland, green gas potential could even rise to 923.1 TWh by 2050, over double the North Sea figure.

How many green gasmills would it take to replace the gas we import from Russia?

It would take just 358 green gasills with 430,000 hectares of grassland to replace all the gas the UK imports from Russia.

How much will green gas cost compared to natural gas?

The price of green gas is expected to be around £70 per MWh, but this can be reduced to £54 per MWh with technological advancements and the addition of seaweed. That’s half the cost of current natural gas prices (May 2022).

What’s more, green gasmills use the existing gas infrastructure that’s already in place, as well as the gas boilers we have in our homes and businesses. This makes green gasmills a much more viable option than heat pumps to solve the UK’s heating needs. (You can find a detailed green gasmills versus heat pumps comparison at the bottom of this page.)

What impact will green gasmills have on local communities?

Each green gasmill will generate approximately 30 jobs and £3 million in annual feedstock contracts for farmers.

In total, they’ll create nearly 162,000 jobs for rural areas and generate £16 billion for the rural economy.

What impact do green gasmills have on nature?

Green gasmills are a wonderful chance to support wildlife and boost biodiversity by providing a pollen and nectar-rich habitat for bees and other insects in those areas growing feedstock plants for the mills, such as rich herbal leys.

The feedstock plants will also capture carbon from the atmosphere and provide habitat for wildlife by reusing grassland that would otherwise be abandoned.

Which is better: green gasmills or heat pumps?

As things stand, changing from a gas boiler to a heat pump won’t save consumers any money. In fact, it will almost certainly increase bills by over 50% as things stand today. Given the recent doubling of fuel prices across the UK, the percentage of households in fuel poverty is climbing rapidly so this is a serious concern.

Green gas uses the gas boilers that many of us already have in our homes and businesses. There’s no need to strip out perfectly good equipment and install expensive replacements if we can use what we already have.

One of the problems with heat pumps is that they work best in well-insulated and airtight buildings. A quarter of the UK’s dwellings are of traditional solid wall construction and aren’t well suited to the low temperatures delivered by heat pumps.

Heat pump are also less efficient at delivering domestic hot water than space heating, as they have to do more work to raise the temperature of the delivery medium. The overall effect is that heat pumps will be running at lower efficiencies for a greater percentage of their operation time. This increases both the carbon emissions and the cost of running the heat pump.

In the table below, you can see the figures for green gasmills versus heat pumps. The bottom two lines demonstrate the dramatic cost different between the two.

Green Gas Scenarios
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The Climate Clock is a version of the Doomsday clock that has been running since 1947 - this tracks the risk of global man-made disaster, through man made technology (like nuclear weapons) - displaying the minutes and seconds left before midnight, when disaster strikes. The climate crisis is a small part of the calculations made.
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