New Green Jack New Green Jack

51 responses to “We are not British Gas”

    • Justin Noe

      Hi Dale,
      All sounds like your really rocking the boat good and proper! Fantastic. Just out of curiousity are you able to pipe methane or biogas directly into the natural gas network? Or do you have to build a seperate network?

        • dale Vince

          Hi Justin, the gas can be injected into the existing gas grid, that’s one of the most exciting aspects of this – it mirrors the situation with green electricity – no new grids needed just new sources.


            • Justin Noe

              It’s seems all so perfect. Let’s hope natural gas will be obselete some day soon. I think it would be facinating to open one of your gasmills to the public like your Ecotech centre. Maybe this makes me look like a little sad green geek. I don’t care.

            • alex hewitt


              Fantastic , great , brilliant etc etc Green gas from AD is the way to go.

              So your thoughts with regard to Stroud having an incinerator instead of investing in a local AD unit or better still just allowing someone to build one without their investment in return for a gate fee per tonne at about half the landfill tax level.

              I am really looking forward to tricorn house to be developed, that is one building that was born ugly!!!



        • Brian Reynolds

          I have just signed up to green gas having been an ecotricity customer for about five years. I think it is great that a small company has ruffled the feathers of an old outdated utility company such as British Gas. My gas is supplied by British Gas at present and although I have no real beef with them it always annoys me when I receive my bill to see the charges but behind all this is no commitment to green energy. Well done Ecotricity – carry on ruffling British Gas!!

    • Helen

      I got cold called by British Gas last week to ask why I didn’t get electricity from them. I said I was with Ecotricity and he said that they had a green tariff and did I know that Ecotricity didn’t supply only renewable electricity. I explained that I did know that but you used the money to invest in more wind turbines. He sounded quite miffed!

        • dale Vince

          Thanks Helen, sounds like you got one of the more decent cold callers – we hear all sorts of stories, some of these guys will say anything.


            • James

              I dont know if British Gas have the word ‘Investment’ written anywhere within their whole company, do they?

              Maybe in the folder named ‘BIG FAT SHAREHOLDERS ONLY’

    • Nick Palmer

      Hi Dale,
      I wonder if you might be watching companies like
      Ceramic Fuel cells? link to Bluegen modules

      Supplying your natural or biogas to homes that have one of these CHP fuel cell modules would enable the house to become a net exporter of electricity to the grid (Ecotricity’s bit of it?) while the point-of-use conversion of gas into electricity avoids electrical transmission losses and also enables the “waste” heat to be used for hot water .
      Just a thought…

      Nick Palmer

      For the planet – and the people – because they’re worth it

      Blogspot “Sustainability and stuff according to Nick Palmer”

        • dale Vince

          Thanks for this NIck. I’ve not seen these Bluegen modules before.

          I think CHP is a good idea and you’re right it saves transmission losses.

          But in terms of fuel efficiency it’ll give typically 80% (including the hot water) whereas using gas directly to heat water will give (from a good condensing boiler) about 90% – making it a better use of fuel.

          CHP beats large scale gas burning for electricity, even without taking losses into account – Combined Cycle Gas Turbines have fuel efficiency of about 60%


            • Nick Palmer

              Hi Dale,
              Your point about point of use direct gas heating of water being significantly more efficient than a CHP for heating water or the house is of course correct. I know you know your stuff!

              The electricity needed for non heat functions in a house is mostly generated, wind power excluded, at between 30-40% efficiency. Most of that heat gets wasted. Gas run CHP saves most of that heat.

              I was trying to suggest that having hundreds (start small, get bigger later!) of distributed electrical generators, feeding their excess juice into the grid and running on your AD gas might be a new business model that would fit in nicely with Ecotricity’s method of expanding the renewable installed infrastructure. Having distributed hyper-local systems fits in better with sustainability concerns…

              Nick Palmer

              For the planet – and the people – because they’re worth it

              Blogspot “Sustainability and stuff according to Nick Palmer”

                • dale Vince

                  Hi Nick, I get what you’re saying for sure, and I don’t disagree….:)

                  Such a thing would be a significant improvement in efficiency terms over the current method of electricity production (and distribution). The current (typical) method is heinously wasteful.


    • Susan Seymour

      I’m considering your invitation to be one of the first people to sign up to your Green Gas and have been looking at the discussions here.

      One thing that worries me a bit is the suggestion that some of the input would be waste food. Surely we should trying to reduce the waste of food rather than creating a market for it. With all the embedded carbon in growing, fertilising, transporting, processing food, it’s hardly a zerocarbon source. I’m in the middle of reading Tristam Stuart’s book at the moment which is what put it in mind.

      My other query is about the pricing model of having a higher price for the first units and then a lower one for the rest as it does not encourage lowering energy use. A friend uses Equigas who don’t do this, and like some companies they don’t subsitute this for a standing charge, and their charges are much lower than British Gas.

        • dale Vince

          Hi Susan, understand your concern.

          But we’re def not intending to create a market for food waste.

          The thing is food waste exists and creates disposal problems, currently it goes to landfill, in the future that will probably be banned and plenty of waste operators would like to incinerate it – along with other waste.

          Using food waste to make gas is probably the best thing that can be done with it.

          The other thing that might be useful to know is that in order to use food waste to make gas it has to be collected separately – it has to be segregated.

          We’ve been discussing this with one Council and they tell us that in a pilot scheme they ran (of segregated food waste collection) – volumes of food collected fell by about 15% over time. Their belief was that when people could see the food they were wasting, they wasted less. That might be a very good upside.

          The other thing they tell me is that if they collected food on a permanent basis (as opposed the trial) they would expect to reverse the current cycles whereby recyclables are collected every two weeks and general waste every week – so that recyclables including food would be a weekly collection and the residual bit (for landfill) every two weeks – presumably because the residual waste would become the minority. I quite liked the thought of that.

          I hear what you say on unit pricing and Equigas. All I can say on that front is we’ve chosen to price match British Gas because most people are with them. And of course we use our bill monies to build new sources of green energy – we can’t be the cheapest supplier and do that at the rate we currently do. We aim to give a fair price with the greenest possible outcome.


            • Jonathan

              Hi Dale,

              Caerphilly council in Wales has weekly collections of food waste. I’m not entirely sure what they do with it. Perhaps they could be one of your sources?


                • Jenny

                  Hi Dale,
                  Bristol City Council also has weekly recycling and food waste collections and only biweekly for “normal” rubbish….its very encouraging and since they started this system we onl y have about one binbag a week of non-recyclable stuff!
                  Perhaps Bristol could potentially be one of your food waste sources too? They are quite set on becoming the greenest city in Europe – well, if they stop this WB40 palm oil power plant going ahead that is – so they may be open to suggestions like this.
                  I am very excited to hear about the new gas provision…do you have any idea of the kind of time span we are looking at before you will be able to offer a joint gas-electricity tariff?


                    • dale Vince

                      Hi Jenny,

                      Thanks for the heads up on Bristol Council,. We hope to build our first project here in Stroud with our council, Brissol is close enough though – virtually our backyard. We’ll keep an eye on it.

                      WRT time span – We’re rolling our gas tariff out ‘gently’ while we make sure things work like we want them to. We’re past the early test phase though and any Ecotricity customer can now add gas to their electricity supply – over 2,000 Ecotricity customers have already signed up as of last week.

                      Within another few weeks we should have gas fully integrated into our web site and processes and available to everybody – customers and non customers alike.

                      Things should get interesting then.

                      There’s nothing to stop you joining us now if you want.


                    • Alison

                      Just to add to your list of councils Bath & North East Somerset is going to start weekly food waste collections from October.
                      By the look of things finding the raw material will be the easy part of making green gas!

    • Alexandra Deegan

      Britain’s national energy strategy is dysfunctional…. even Ofgem has finally figured that one out….

      LNG is going to be a high risk strategy game….

      And the 62m UK peeps, their children and grand-children deserve better than that….

      But heck, we’d rather have ex PM’s working for JPMorgan, The Carlyle Group et al…

      Meanwhile we play puppy-dawg to the American’s in other ways too…

      Yep coprotocracy rules…. so stand up people…. defy it…. put yer hard-earned duckets the way of folk and company’s that have a longer-term view….

      Like Dale and Ecotricity….

        • Jonny Holt

          Hello Alexandra,

          We can make coprotocracy work for us. If Dale allows farmyard manure to be used in the green gas project, the poo will give us the power.

          Best regards,


          P.S. Dale, please can you answer my question of 9th December – repeated below – under “Green Gas is here” about use of farm slurry?

          From a moral perspective is it so different from selling electricity originating from coal or nuclear in the brown portion of Ecotricity’s fuel mix?

            • Nick Palmer

              I suppose you are referring to the fact that most cattle slurry comes off farms that are energy intensive and/or use concentrated feed, no doubt originally grown with the use of lots of fossil fuel derived fertilisers etc.

              Whatever the source of the slurry, power from it would displace fossil or nuclear fuelled generation. This is good if the slurry would have otherwise been disposed of – even better if it would have been allowed to decompose “freely” because that would liberate lots of methane – a powerful global warming gas.

              If the slurry came from an organic farm, then the “embodied energy” in the slurry should be somewhat less. In the future, as more energy is supplied from green sources, the embodied fossil fuelled energy proportion of slurry (and digestible waste generally) will reduce. We are not very far on the way there yet but patience will bring it about.

              Sometimes objections are raised to green initiatives because it’s simply not possible for them to be perfectly “sustainable” right from the start. While society is still run on unsustainable lines, and all the methodologies and business practices that have evolved to fit that scenario still remain predominant, there will often be contradictions when introducing green ideas.

              For example, try setting up a recycling scheme and some joker with a calculator will attempt to work out that the energy you save recycling XYZ is marginal and they claim you might as well incinerate it.

              Such calculations often ignore lots of other factors such as habitat and scarce resource depletion etc but mostly the fact that once people start to recycle they almost automatically start living a less wasteful life – they make different purchasing decisions etc.

              These factors never appear in the simplistic LCA’s (Life Cycle Analyses) that our joker with a calculator does and yet they are a vital part of peoples’ learning how to live “sustainably.”

                • Nick Palmer

                  I forgot to say that on an organic farm, of course, most if not all of the slurry etc is used directly as organic fertiliser and so there is nowhere near as much”waste” to be treated.

                  The digestate (what remains) from an AD plant, of course can still be used a fertiliser/soil improver but that from a conventional farm may not (AFAIR) be applied to food crops because it contains various hormones/antibiotics etc from the intensive methods used these days. That certainly applies to human manure…

                  Modern farms are energy intensive so I think a good move for them would be to have their own in-house AD plants to generate their own heat and power thus leaving little spare slurry for Ecotricity type operations.

            • dale Vince

              Hi Jonny, sorry if I missed your question.

              I see Nick’s response on this below and I’m guessing that he may be right, in terms of where you’re coming from on this one – it being an embodied energy/carbon thing. That’s not my biggest issue though.

              My problem with farm waste is a moral one. I believe that it is only intensive farms (factory farms) that produce an excess of animal waste – and that organic farms do not.

              I’m against all factory farming for moral reasons, I think it’s a crime against nature actually. So it’s for that reason that there’s a big question mark over the use of farm waste.

              I say question mark because it’s something that requires further research/investigation to be sure and there may of course be exceptions out there. But if what I’m currently told holds true, then we wouldn’t use farm waste to make our green gas.


                • Jonny Holt

                  Hello Dale,

                  Not exactly – my real point is more about the polluting properties of methane emanating from the slurry and your fortunate position of being able to mitigate the harmful effects on the environment and climate. The embodied energy content of slurry, though evidently important from a power generation point of view, is secondary to my main concern.

                  I fully understand your moral reticence about having anything at all to do with industrial agribusiness. However I think there is this other moral issue to be considered. If any person is in a position to do so, should they not act to alleviate the problem?

                  Does the one moral imperative trump the other?

                  Best regards,


                    • dale Vince

                      Hi Jonny, interesting question and dilemma.

                      From a methane point of view I understand that 95% (or so) of the methane emissions of slurry occur during storage on farms, as opposed to spreading on the land – when it’s out in the air it doesn’t make methane it’s only when air is excluded that that happens. I thought that was interesting to know.

                      Could we and if so should we utilise farm slurry is how I see your question.

                      First ‘could we’ – It takes a great deal of waste to feed an AD plant big enough to make enough gas to be worth scrubbing up and grid injecting. For example the scheme we’re working up for Stroud would take all the food waste in the whole of Gloucestershire and more.

                      The amount of slurry on a farm, even a large farm is not going to be sufficient I think, for an AD plant with gas injection (as a rule). Add to that the fact that many or most farms are quite remote from the gas grid. It looks unlikely.

                      Farms can harness their BS and other stuff and (mini) AD it for use of the gas on the farm though – that’s a neat and pretty economic way to go.

                      Coming to the ‘should we’ – I get what you’re saying, maybe we have the opportunity at ecotricity to tackle a problem, even though we oppose the roots of the problem should we not intervene? I think not. The problem is agri farming, it’s an offence against nature even before you factor in climate change – it’s bad practice and it has to stop. it will stop in time of that I’m sure.

                      Even if we could use slurry for our green gas (which doesn’t look so likely) – we wouldn’t. Farming could and should clean it’s own act up – first thing would be to stop storing the stuff anaerobically – that might be an easy enough step to take and would deal with the methane problem, without vegan intervention……:).


                    • Damien Ducourty

                      An illustration to Dale’s point about better farming practise:

                      “If you suspend a cow in the air with buckets of grain, then it’s a bad guy,” Harttung explains. “But if you put it where it belongs — on grass — that cow becomes not just carbon-neutral but carbon-negative.”

                      Read more:

        • MW

          We took our eye of the long term picture too.

          Britain faces ‘oil crunch’ within five years, Richard Branson warns

          The North Sea is producing half as much oil as it was 10 years ago, that’s the real issue that gets totally avoided in the political debates about energy!

          1999 ~3 Million barrels per day
          2008 ~1.6 Million barrels per day

            • Justin Noe

              What’s just as worrying is that as a nation we are hell bent on extracting oil and gas from the Falkland Isles!
              Everyone gets exited at the fact that we could pay off national debt and forgets that it would completely undo any good we may have done to reduce CO2 levels.
              I find the rush for greed and short sightedness of the whole thing overwhelming and disturbing. When will we ever learn that short term fixes never help you in the long run?
              The hippocracy that we’ll tackle climate change yet we’ll forage for fossil fuels is incredible. I guess it’s like crack coccaine, hard to give up!
              Hope Dale will help the addicts before they take a turn for the worst.

    • Chris

      I’m sure this won’t be the first time one of the Big 6 come running at you Dale. Tell them all to go to hell and carry on doing what you’re doing. They will never get the level of customer loyalty that you’re able to encourage through Ecotricity’s policy of reinvestment.

      British Gas are such a bunch of cowboys in my opinion. Every so often they’ll launch ‘crazy biggest ever price cuts’. Then once they’ve hooked half the nation through media might alone, they hike up the bills and milk you dry.

    • Paul Luton

      On the Ecotricity site the claim is made that “the waste from six cows will power and heat a house for a year”. If that is over the lifetime of the cows it is misleading. If it is six cows in a year then the “for a year” is redundant – the same will apply over the following year etc.

        • paul

          Hiya Paul,

          We put this to our facts and figures bod, and he says:

          “Hands in the air Paul, you’ve spotted our deliberate mistake.

          Basically, the slurry produced over a year by six cows is enough to generate sufficient biogas to meet the heat needs of an average household, around 20,500kWh. We arrived at this figure using an assortment of Defra cow slurry facts and biogas generation figures. Somewhere along the way this morphed into the same 6 cows now producing enough gas to not only heat the house but also to generate the electricity to light it.

          This was one of a number of stats that we came up with in the early days of this project to help illustrate the benefits of biogas. As we don’t support the idea of biogas generation from commercial cow slurry this fact really is a bit redundant, interesting but redundant, so we’ve gone back and removed it from the site to avoid any further confusion.

          Thanks for pointing it out to us.”

          Hope that clarifies things? Thanks again for your comment..


    • Steve Telford

      Hi Dale, On monday I telephoned BG with my final gas reading. The lady on the telephone then asked me why I was leaving GB, when I told her I got my electricity fron Ecotricity and now I was getting my gas from them and the reason was it was green and not paying FAT CATS she just replyed “OH”. Do you think the staff a BG have been primed with no answer.

      Keep up the good work.

        • dale Vince

          Hi Steve, thanks for this and good to have you with us.

          BG wise – Reckon you just got lucky and got someone who didn’t have a scripted answer for that.


    • Ole

      Hi Dale,

      I would like to draw your attention to two really interesting concepts:

      1.) Renewable Power Methane:

      The basic concept of “renewable power methane” is based on the mutual linking of the power grid with the natural gas grid.
      Renewable power (e.g. surplus wind power) is converted via electrolysis into hydrogen.Hydrogen is combined with CO2 and converted into methane in a thermochemical synthesis (methanation). In this way, renewable electrical energy is stored as chemical energy in existing storage capacities (natural gas grid), which is an advantage vs. hydrogen.

      The concept of Renewable Power Methane is described in detail in the dissertation of Dr. Michael Sterner”Bioenergy and renewable power methane in integrated 100% renewable energy systems”. I recommend it strongly. It can be downloaded here:

      The company SolarFuel is in the process to make it commercially available (unfortunately the homepage is only in german):

      2.) “ZuhauseKraftwerke” (home power plants):

      many small gas-fired electricity-led CHP-units, dispatched as one big virtual power plant; cooperation of german green electricity supplier Lichtblick and VW; more details here:

      I really would like to know what you think about these two concepts (which could work really well together, I think). Isn´t it maybe something for ecotricity?

      Best regards from north germany


        • MW

          Ole, you don’t need to go the extra step of turning electricity into methane. When it’s windy the wind turbines will displace natural gas fired electricity and effectively ‘create’ this saved natural gas. We want to avoid energy conversions where possible as you would probably lose about half your energy by going from electric -> hydrogen -> methane.

          A much better idea is to use (wind) electric powered heat pumps to heat buildings instead of natural gas, it also gives you a lot of potential storage for example if you knew you where going to have a windy week and then a still weekend you could use the heat pump to heat your house/hot water tank a few degrees warmer than normal and then you wouldn’t need heating for a couple of days when it was still.

          There is a microbe that will convert CO2 to CH4 when electricity is introduced to it! Very strange

          It claims an 80% efficiency which is pretty good for energy storage.

        • dale Vince

          Thanks Ole, that’s very interesting.

          My first thoughts were about the overall efficiency. It’s the key to any attempt to store energy.

          I’ve not looked at the paper but I see Nick has and says (further down) that the efficiency is not too bad – which is a surprise.

          There’s a lot of work going on right now on grid scale energy storage – it’s part of the answer going fwds IMO.

          Another part of the answer is something I like to think of as Intelligent Demand – something quite the opposite to our current energy on demand model.

          A combo of storage and smart demand could go a long way.


    • Nick Palmer

      I looked at this paper because I suspected that the electrolysis of water followed by methanation of CO2 wouldn’t be very efficient overall but no – it proves to be not too bad, which was rather surprising…

      I think the concept has something. A possibly symbiotic technology would be the formation of raw silicon from sand using concentrated solar power in high irradiance areas such as deserts. Silicon can be transported more or less like coal. Silicon can then be used to generate hydrogen which can then be used in the methanation processs or directly in fuel cells etc.

    • Zach Angelo

      Interesting post on renewable methane energy ole, thanks for your input!

    • Rahul

      Is it not a bit odd that you’re still “shaking things down” ? The excitement is waning somewhat 1.5 months after going live and still not generally available and I think you have thrown away a bit of the marketing hype you did so well to generate. It’s bad for business not to mention the environment!

      Have you hit a snag in the plans ?

        • dale Vince

          Hi Rahul, Nope no snags.

          It’s actually a far more complex job that you might imagine once you get down to the detail – and it takes several months to have run through the majority of processes for the first time.

          Like billing for example, until 3 months down the road you can’t know if your billing system actually will produce good bills on time and accurately.

          A good experience for our customers is more important to us than speed or size. We’re busy making things excellent before we allow too many people to sign up.

          And things are excellent, we’re very pleased with progress.

          I’ve no concern that this is bad for us, it’s quite the opposite I think.


    • Chris

      I never know where to post more general comments like this on ZC, so I hope you’ll forgive me for posting here. I’ve just come across this website which enables the user to undertake a survey of party policies without knowing who they’re ‘aiming for’. The results are guaranteed to surprise. What’s more, the 30,000+ surveys done so far have produced an overwhelming majority for the Green Party! In 2nd place somes the Lib Dems!

      So what’s going on here, do we not actually vote for who we actually want?! .. Anyway I thought it was encouraging. Maybe it will also help people realise that the Green party isn’t just about being green.

      (PS. Worth noting, the opinions in this post are mine and are nothing to do with Ecotricity!)

        • TR

          That site looks really cool. Not had time to go through it fully yet, but it looks the type of thing that everyone should consider.

    • Matthew Toseland

      What happened with this year’s Which Green? Ecotricity is down to £78/customer! I thought Ecotricity guaranteed to match every pound you spend on your bill with a pound (most of it borrowed) spent on new windmills? Still number one, but way behind where you were – financing problems??

    • Jeffrey Lam

      And I guess that’s why not many (none if I remember correctly?) were built last year then?

      Digressing a bit, if you built the turbines at the unfavourable exchange rate then they would cost you more… and then ecotricity’s WhichGreen figure would go up wouldn’t it? But then that would be counterproductive on reducing the UK’s GHG emissions.

      I look forward to hearing about more turbines going up, but maybe it is wiser to wait until favourable finance and exchange rate conditions come…


        • dale Vince

          Hi Jeff,

          We did build one windmill in 2009, the one powering B&Q.

          When we build at an unfavourable exchange rate we basically build a project which is financially weaker than it would or should have been – and that’s locked in for probably 15 years (it’s debt period) – that does hamper our ability to build more windmills later.

          There’s a balance for us to strike – we can’t stop building until the exchange rate recovers, but we can’t just build as we did before (the rate crashed) – in some cases our projects just cant be built at this x rate though.

          We’ll build some this year, but not as many as we’d like.


    • Mr. A McElwee

      Mr. Vince
      Am considering switching to green gas but – and I’m no expert here, gas is gas and when it burns it gives off CO2. Creating gas from waste is a good thing but for the fact that in burning it adds to the CO2 problem. Much better to harness true renewables to generate electricity. Or am I barking up the wrong tree? I’m all a bit confused I have to say

        • dale Vince

          Hi There Mr McElwee,

          You’re right, burning gas gives off CO2.

          The gas you’re using currently is a source of CO2 that’s been locked up for a few billion years, so it’s a net addition to the atmosphere, in that respect, when it’s burnt.

          The gas we’re going to make will come from food that’s been grown (and thrown) much more recently – in the growing process it absorbs CO2 from the atmosphere, part of which at least gets released when we burn it. You could consider it more or less carbon neutral in so far as the carbon absorbed to grow the food is re released on burning the gas. Broadly speaking.

          Plus of course the CO2 in the food would be released in any event by the process of decomposition.

          I agree with you that making as much renewable electricity as we can is the right thing to do – but we do have waste sources that can be turned into green gas which we can use instead of fossil gas – and I think we should use these also.

          And if you buy gas now (which it sounds like you do), it’s fossil gas, you can only be improving things by switching to green gas – even if it’s only a stop gap until you switch your gas supply off and run only on electricity (which I think many of us will have to, or choose to, do in the future).

          Hope that helps.


    • Justin Noe

      Not sure if anyone spotted this article in New Scientist but what a great opportunity for Ecotricity!

      Bugs will give us free power while cleaning our sewage:

      You might think a constant supply of fresh air would be essential for a sewage treatment plant, but some bacteria cannot stand the stuff. These bugs could be the key to cleaning waste water so efficiently that the process could generate power rather than consume it.

      In conventional sewage plants, micro-organisms digest solid waste in “activated sludge”. They convert the organic matter into methane but leave liquid waste containing ammonium and phosphates, which must be removed before the water can be poured into rivers.

      Existing treatment plants use a lot of energy to get rid of the ammonium. The process uses bacteria that convert ammonium into nitrate, and the bugs that do this need oxygen, which must be constantly supplied to the treatment tanks by electric pumps. The nitrate is then converted into nitrogen gas by still more bugs, known as denitrifying bacteria. These require methanol, which must also be added to the mix.

      This process consumes an average of 44 watt-hours per day for each person who adds waste to the sewage system. This can add up to megawatts in a big city.

      Cut out the middle bug:

      But now Gijs Kuenen at Delft University of Technology in the Netherlands and colleagues are developing a technique that cuts out the energy-consuming processes. The key is a recently discovered type of bacteria that can munch ammonia without oxygen. So-called anammox bacteria short-cut the nitrogen cycle by converting ammonium directly into nitrogen gas.

      One by-product of this process is methane, which Kuenen proposes to harvest and use as fuel. The team calculates that, far from consuming energy, the process could generate 24 watt-hours per person per day. “This is about trying to make waste water treatment plants completely sustainable, in the sense that they could even produce energy, which is not the case in present treatment facilities,” says Kuenen.

      This month the team will begin building a pilot plant to demonstrate the technology at the Dokhaven waste water treatment plant in Rotterdam, the Netherlands, working with from Radboud University Nijmegen and water purification firm Paques, based in the Dutch town of Balk.

      Michael Wagner, a microbiologist at the University of Vienna in Austria, points out that anammox bacteria were discovered only 20 years ago and hold great promise for a new generation of sustainable waste water treatment plants. “The anammox story shows how fundamental discoveries by microbiologists can revolutionise waste water treatment,” he says.