The Government is about to publish a ‘Gas Strategy’ alongside the imminent Energy Bill. In that strategy, if reports are to be believed and if the pact between Treasury and DECC is followed through, we will hear a lot about unabated gas, gas hubs, gas into the 2030s, shale gas and so on. I doubt somehow, that we will hear much about a strategy for the development of ‘green gas’ which, estimates suggest, could support as much gas into our grids over the next twenty years as the much vaunted ‘shale gas revolution’ that may well feature in the gas strategy in the form of a green light for fracking.
So in case you don’t, here’s a brief note on at least a component of what an alternative gas strategy might look like. The key points of the strategy go something like this:
- Support the rapid expansion of Anaerobic Digestion plants of all sizes (the plant pictured above is sited on a large dairy farm) able to produce biogas from an input of animal, food and plant waste
- Inject the proceeds into the gas grid (or produce road fuel for large trucks)
- Save thousands of tons of CO2 emissions (the biogas comes in at about net 11g CO2 per kwh compared with a minimum of about 400g for shale gas)
- Replace fracked gas or imported liquid natural gas with a locally produced secure supply
- Er, that’s it.
I think that stands up quite well as a strategy, don’t you think? And it gets a bit better when you compare it with proposals now under way to drill and ‘frack’ for relatively high carbon mineral gas.
There is something of a co-incidence here, in that the claims for anaerobic digestion and shale gas in the UK are not that far apart. Utilising much of the UKs biodegradable waste for AD they could supply about 10% of the country’s domestic gas requirements; utilising most of the recoverable shale gas could supply, subject to depletion, about 10% of the UKs overall gas requirement. But compare, for a moment, the economics of the two methods of putting that gas into the grid, setting aside all the other issues about carbon, etc.
One shale gas well costs between £6 -10 million to drill and frack (Cuadrilla’s test plant near Blackpool is costing about £10 million). It is difficult to assess total output of gas, but the average well in Texas at the moment is producing about 2 million cubic meters of gas per year, with much of it depleting fast as drilled wells tend to do after about five years of production.
One large farm size Anaerobic Digestion plant costs about £2million to build (the BV dairy plant pictured cost £2.3 million) and then provides a steady stream of gas from then onwards, varying only to the extent that cows stop producing manure or people stop eating food. The first plant currently operational and injecting gas into the grid (the Poundbury plant in Dorchester produced about 850 cu mtrs of gas in
a day an hour in November, which grossed up over a year, represents a bit more gas produced over a period than the average shale gas well.
Oh, and by the way, you have to factor in the by-products. A shale gas well will consume between two and seven million gallons of water and around five thousand gallons of chemicals per frack, much of which (the ‘flowback’ water) has to be treated and adds to the cost of the well drill. An AD plant produces varying amounts of digestate, depending on its size, which has to be disposed of by, er, spreading on land as a soil improver at a cost of….nothing, and some water, which goes back into water courses.
So I think we can come to the somewhat startling conclusion that it might well be a better long term business proposition for Cuadrilla, if they wish to invest in gas in Britain, to fund and build four AD plants rather than drill a large hole near Blackpool. And it certainly would get the alternative gas strategy seriously under way. Somehow though I don’t think it will happen: not immediately, anyway.