Hi there, @mowcius
I believe that, at present, methane from fossil fuel sources sells for around 4p per KWh, and the cheapest methane from biomass sources sells at around 9p per KWh. That’s the gas that comes from plants with a generating capacity of more than 5MW. The smallest plants, with capacity less than 2.5MW, sell at around 10p per KWh (based on feed-in tariff rates). That’s quite a difference! Fortunately that’s where two things come into play, the economy of scale and improvements in technology. The bigger the plants that get set up around the UK, the cheaper they can produce energy, which brings prices down fairly steadily. Biogas is a fast developing field technologically, with new membrane technology for sewage waste gas extraction and proprietary microorganisms used for methane reclamation from a variety of sources being constantly developed.
Since the government influences the price of biogas heavily through their feed-in tariffs, and given the guaranteed prices for generators are set numerous years in advance, I believe the chances of biogas increasing in price significantly are fairly slim, even leaving aside the stuff I mentioned in the last paragraph. Most anaerobic digestion and sewage gas reclamation plants are built to last for a long time, meaning that the number of biogas generators is pretty much guaranteed to increase, rather than decrease, which should mean prices either decrease or stay the same for the foreseeable future. Which is lucky! I don’t know what we’d do if the price of biomethane increased suddenly, but I do know that we’d hate to raise everyone’s prices, no matter what. It would be a tricky decision, if it ever looks likely.
Personally speaking, I agree with you completely on the difficulty of removing gas from our energy mix completely. The main advantage of gas, overriding everything else really, is that gas power stations are so responsive. They can increase their output in seconds to match spikes in usage, which is invaluable compared to sources such as nuclear, which can take minutes or hours to increase the same amount, or renewable sources such as wind and solar whose outputs can’t be controlled. The increasing efficiency and use of batteries is going to be a big help, as they’ll let us smooth the grid much more easily. I don’t think we’re ever going to get rid of gas, though (not until nuclear fusion gets up and running) which means that we’re going to have to ramp up our biogas production. We are fortunate in the amount of farming we have in the UK; all that farm waste, in addition to improving sewage gas reclamation and cleaning, is a massive resource which we aren’t yet tapping. The biomethane that we can reclaim from those sources will be a huge asset in taking the place of the fossil fuels we’re currently using.
Massive chunk of text there! I find all this stuff fascinating