Why are you using grass as a feedstock when others are available?
There are many benefits to using grass as a feedstock because it is readily available and consistent in quality – which is vital given the high quality and purity of gas required by National Grid.
Using grass rather than, for example maize, helps to improve soil quality, support food production, replace chemical inputs, cut carbon emissions and is a useful and valuable alternative for local farmers.
Two sources of grass will be used – firstly marginal grassland pasture where available; and secondly a fertility building grass break crop.
Harvesting available marginal grassland pasture can encourage the growth of wildflowers through inherent fertility reduction. This will improve controlled habitats for birds and insects such as pollinating bees – helping increase biodiversity.
Introducing a fertility building grass crop into a rotation over a two to four year period, helps break disease and fungal cycles in the soil environment. Reapplying a natural digestate (created during the AD process) to the soil, will replace synthetic fertiliser usage while improving soil health/condition.
There will also be benefits to the surrounding aquatic environment through reduced fertiliser and other chemicals use which is especially important in the chalk streams and chalk rivers of Hampshire.
Green gas is virtually carbon neutral and will replace high carbon fossil fuel gas which will help to reduce the emissions.
It is evident that the local rural economy will be helped with an injection of £3 million annually in the form of supply contracts and employment.
Considerable research supports this approach, with DEFRA and Natural England promoting this process as a “greening” measure. The Farming and Wildlife Advisory Group with the Countryside and Community Research Institute have confirmed its merit as an ecosystem service with their payment for ecosystem services pilot, funded by DEFRA.
How will you prevent the plant causing a shortage of grass in the area and driving up the price of silage?
The green gas mill would only require two per cent of land in a 15 kilometre radius. We would use marginal land that is little used for grazing and/or grow a fertility building grass break crop: neither source will have an impact on grass silage availability.
How can you be sure that all the grass can be collected from within the 15 kilometre catchment and you won’t have to go beyond it?
Based on the discussion Ecotricity have had with local farmers, they are very confident that they can source supply contract within 15 km of the green gas mill (GGM).
How many farmers have said they will supply grass and how many tonnes and acres does this amount to? Are they all inside the 15km catchment?
That’s commercially confidential, but we are very happy with interest so far – all of which comes from inside 15 km.
It is also pleasing that the planning application for the sustainable energy centre including the GGM has been supported in writing, by the NFU and Country Land and Business Association.
Have these farmers signed contracts yet? Will they have contracts for the life of the plant?
Ecotricity cannot sign contracts until we have planning permission. Pre contract agreements will be conditional on planning consent being granted with an aim to produce sufficient feedstock for the first year of gas production, before we ramp up to a full feedstock supply in subsequent years to enable continuous gas production.
How much will farmers be paid per tonne of grass and who will pay them?
Ecotricity are happy to discuss this with individual farmers and landowners.
How will you ensure that grass is taken from marginal land rather than anywhere else?
Ecotricity are introducing an opportunity to arable farmers who would not normally farm livestock to firstly grow a break crop profitably using a fertility building grass crop; and secondly to produce an improved return from their marginal grassland while still achieving their stewardship requirements.
It is not the intention to become competitive with existing grassland farmers.
Isn’t marginal land very valuable for flora and fauna – and taking grass from these areas could damage their ecology?
To maintain its biodiversity, marginal land has to be managed. Timely harvesting of overburden prevents fertility build up and strengthened species dominance, which is necessary for the diverse balance that allows flora and fauna to flourish. Failure to graze – which is natural marginal land management – is not good for the specific ecosystem. Timely cutting will be the successful substitute.
How will producing grass for the plant stop soil run off from farmland?
Grass leys when established provide an over winter mat which serves as a run off impedance and a sponge route to the subsoil through improved soil structure and deep rooting systems from any cultivated herbage.
What is the value of grass digestate compared with, say, digestate made from animal manure?
Digestate from animal manures is very similar in analysis to grass silage produced digestate. Both sources are the plant nutrient residues in the form of soluble mineral salts taken up from the soil in the previous crop. However, digestate from animal manure has not had the free ammonia modified into ammonium salts which is achieved in the AD process. Consequently, although both animal manure and digestate are of equal value, animal digestates are more odorous as a result of greater ammonia volatility.
How and where will the plant be connected to the gas grid?
Ecotricity will pay for the local gas grid to be extended almost two miles to the GGM at Sparsholt College.
Which routes will be used to take the grass to the plant and which routes will be used to take the digestate away?
This will entirely depend on which farm the feedstock is coming from and the digestate going to. The suppliers will be dispersed throughout the surrounding area, so the farm traffic will not all be using the same roads or the same parts of roads until they get to Westley Lane which leads into the college. What we can say is that the tractors and trailers making the deliveries will not be coming through Sparsholt village.
How will the college’s energy costs be reduced by the plant?
The college is likely to make a minimum saving in its energy costs of about £60,000 a year at current wholesale gas rates – but of course it depends on the price of gas in the wider markets. While there is a current lull in the price of energy, the inevitable trend has historically been upwards and consequently our savings are likely to be a great deal higher than this in future.
What is the connection between the plant and the new training centre? Is Ecotricity paying for both?
The new sustainable energy teaching and demonstration centre is concerned with the full range of sustainable energy technologies and not just anaerobic digestion. This will provide a focal point for learning and skills development for this important curriculum area. Ecotricity is paying for all of the GGM infrastructure and associated costs and is co investing in the teaching and demonstration centre with the bulk (£1.2 million) coming from the Enterprise M3 local enterprise partnership.
Which subsidies are being used to finance the development, and how much will they contribute to the total cost? Will subsidies completely cover the cost over the life time of the plant?
The GGM may receive support under the renewable heat incentive, but this is not yet certain.
Pictured: Tim Jackson (left) and John Torvill discuss plans for the anaerobic digestion plant