Gas and carbon offsetting.

I’ve recently decided to give Bulb a try having been with Good Energy for over 5 years.

Both suppliers supply 100% renewable electricity and a percentage of biomethane gas.

Good Energy, despite their percentage of bio gas being lower (currently 6% vs 10%), have for many years now carbon offset 100% of the gas supplied through excellent community schemes in less fortunate countries (

Do Bulb have any plans to do something similar?

With a lot of people’s energy use in the winter being primarily from gas, a significant proportion of all Bulb users’ energy is potentially not green at all…

Hi @mowcius, our current setup enables Bulb to offer renewable energy at very competitive market prices. As we grow we’d like to increase our green gas supply as much as possible providing that this does not compromise on value for our members.

Hi @johnatbulb, thanks for the reply. That was pretty much what I expected.

Are you able to give an idea of what the market price difference is between biomethane and ‘dirty’ gas?

If the price increased by a significant margin, would simply you look to increase customer prices or would you ever consider decreasing the quantity of biomethane in the supply?

Do you have any personal thoughts on the matter? As all electricity becomes cleaner in the future (as it has time and again been shown to have the potential to be so much cheaper), gas will become the dirty energy that might be quite hard to shake.

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 :slight_smile:

Hi @“David at Bulb”, many thanks for the lengthy response!

On removing gas from our mix, I was more thinking of the residential use for heating and cooking more than the responsiveness of the power stations but you make a very good point.
Perhaps as the electricity gets cheaper and gas most likely becomes more expensive, people will shift to electric boilers and hobs, with almost all biogas being used for responsive power generation instead.

On the farming front, personally I hope that in the future the ethical and environmental impacts of eating large quantities of meat become more of a consideration. The reduction of methane and carbon dioxide from farming fewer animals will make a bigger impact than using their excrement to produce greener gas!

Any idea on what the percentage difference in yield is between human and animal waste? I’ve heard it’s pretty significant which doesn’t make it particularly commercially viable at present.

Hi @mowcius, always happy to talk renewables!

I think you’re right about residential gas use decreasing, especially when improvements in domestic battery technology and decreasing solar panel costs mean people can generate cheap electricity in house, I think that’ll really push people to replace gas powered heating and cooking with electric versions. That way we can reserve biogas for power stations, and cut down on natural gas usage overall.

Farming wise, awareness of the greenhouse gas costs of farming has definitely been increasing in the last few years. We’ll still be able to produce biomethane from the waste from plants, such as the inedible matter left over from wheat farming. It’s not as efficient as using animal waste, but when livestock farming accounts for as much as 15% of global greenhouse gas production I think that’s a trade off worth paying! The artificial meat production, as demonstrated in China recently I believe, is certainly one to watch as it has the potential to be a lot more efficient than livestock farming!

As I recall, the plant based diet of livestock results in waste which can generate methane at much higher quantities than human waste, meaning that it is much more viable at the moment to use animal waste, when it’s already present in large quantities. I don’t believe I’ve ever seen any comparative figures, although there has been some research into the use of human waste for energy production in third world countries ( where there is less agricultural waste available. One other advantage of using agricultural waste, and one that remains for plant waste as well as animal waste, is that the byproduct of biogas production is a highly effective fertiliser, since the nitrogen compounds which are required in fertiliser aren’t touched by the microorganisms which create the methane.

Hi @“David at Bulb”, I did personally consider an electric boiler when my gas one blew up two years ago but sadly the cost difference between gas and leccy, coupled with the non-insulated nature of my house (something I’m working on!) sadly made it prohibitively expensive. I’ll be going all electric for cooking soon though as it’s so much more efficient and induction cooktops have come on in leaps and bounds since the early days.

I’m not sure retrofitting this house with solar panels would make much sense though (only a few m2 of roof that faces South) but I’ve always suspected that the overall efficiencies of large scale renewable generation is probably greater than personal energy generation. Doubling the output of a wind turbine for example presumably does not take double the quantity of materials or have double the amount of generation loss.
I wonder if there are any papers on the embedded carbon of a few hundred personal generation setups (large ones providing 100% or more of used power) compared to a medium sized offshore wind turbine.
Maybe the significant disctribution losses of the grid have a big impact? (which seems to be around 8% from what I can find)
I would say local medium-large scale distribution possibly then makes the most sense but it appears most of the power losses are regional anyway (national only being 1.5% or so).

Do you know if the government have changed their stance on local generation and supply though? I’ve not been following recently.