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Idea 83

A listing service beside somebody else’s digester.

Anaerobic digestion has been retained in this catalogue in one form only: matching feedstock to existing plants, and matching digestate back out to farms that can use it. Not an own-build. Not a joint venture. Not a plant on this holding at any point.

The decision

Why not build one.

A farm-scale anaerobic digester is a capital project of somewhere between one and a half and four million pounds, with a fifteen to twenty year payback that depends on a subsidy regime, a gas price and a feedstock supply, none of which anybody can forecast for twenty years.

It also converts a farm into an energy business with a continuous process, statutory reporting, a permit, an odour management plan and a very unhappy parish if any of those slip. The operating discipline is closer to a small chemical works than to arable farming.

This estate has a documented history with capital projects that arrive with a planning condition attached. Adding a two-million-pound one with a permit and a neighbour consultation is not a considered risk, it is a hobby.

Both directions

What the listing service would actually do.

SideWhat is listedWho wants it
Feedstock out Maize, rye, whole-crop cereals, grass silage surplus Plants inside about twenty-five miles, which is the economic haulage limit
Feedstock out Vegetable waste and outgrades from the market garden The same plants, at a lower gate value
Feedstock out Spent brewing grain Usually goes to cattle first, and should
Digestate in Whole digestate, liquid Arable farms within about eight miles, because it is mostly water
Digestate in Separated fibre Further, because it travels
Nothing at all Manure and slurry Which stays on the farm that made it, for good reasons
The retained part

Why digestate is worth more attention than the gas.

  1. It is a fertiliser with an image problem.

    Whole digestate carries readily available nitrogen at a rate that genuinely displaces bought fertiliser, plus phosphate, potash and organic matter. On a farm spending forty thousand pounds a year on fertiliser, that is a real number.

    It also smells for about six hours, arrives in a tanker, and has to be applied inside a closed period regime that nobody enjoys reading. Those three facts are why it is under-used rather than over-used.

    The gas pays for the plant. The digestate pays for the field.

  2. The matching problem is genuinely unsolved.

    Plants have digestate they must place. Farms have land that would take it. The two find each other through a haulier, a rep or a conversation in a market, and a meaningful amount ends up placed badly — too far, too late in the season, or on ground already at index three for phosphate.

    A listing with volumes, analyses, dates and distances would improve that, costs nothing to run, and carries no capital risk whatsoever. It is the only part of this idea worth anybody’s time.

  3. And it keeps the estate out of the energy business.

    A listing service can be switched off on a Tuesday. A digester cannot be switched off for fifteen years.

Anaerobic digestion

What is in and what is emphatically out.

Retained

  • A listing for feedstock available, with volume and window
  • A listing for digestate available, with an analysis attached
  • Distance shown before anything else, because it is the economics
  • Nutrient analysis required on every digestate listing
  • A note of the closed periods that apply
  • Free to list on either side

Ruled out

  • Any plant built, owned or operated by this estate
  • Any joint venture, share or investment in a plant
  • Any brokerage, commission or margin on a match
  • Any haulage — that is between the two parties
  • Any warranty about the analysis somebody else supplied
  • Any advice on permits, which is a matter for the Environment Agency
The arithmetic

The numbers that decided it.

£1.5–4m to build a farm-scale plant Capital, before the permit and the neighbours
15–20 year payback On subsidy and gas price assumptions nobody can hold
~8 mile limit for liquid digestate Beyond which you are paying diesel to move water
£0 capital in the retained version Because it is a list
The honest bit

Anaerobic digestion is a good technology, a difficult business and an appalling fit for a farm that already has a planning department on speed dial. The listing survives because it costs nothing and helps somebody. The plant does not survive, and it should not.

The soil this all ends up in.

Cotswold brash, six inches deep, and what it does and does not take.

Next along the route

Applying to supply

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