By Hugo House, Good Energy
At Good Energy, we've begun our project to assess and improve sustainability at River Cottage. We'll be doing a detailed evaluation of their consumption of energy and resources, but we've already identified one key area for improvement, and that's the way they cook. RC use LPG - Liquefied Petroleum Gas - to fuel their cookers. LPG is an excellent cooking fuel, but it is a fossil fuel and burning it is contributing to climate change.
So, is there a fuel that's as manageable and responsive as gas that doesn't harm our environment? Of course, 100% renewable electricity is a zero-carbon fuel that can provide the necessary heat, but even the best induction hobs don't offer the flexibility that professional chefs require. It has to be gas, so is it possible to source ‘green' gas?
The natural gas that we extract from the North Sea is methane, CH4. Burning it in air creates two new compounds: water vapour (H2O) and carbon dioxide (CO2). It began to form millions of years ago when organic life in our seas died and began decomposing on the seabed with the help of bacteria. When organic matter (like small sea creatures) decomposes without any oxygen present (like on the sea bed) the process that occurs is called Anaerobic Digestion. Its byproducts are carbon dioxide and methane, which were stored beneath the seabed until mankind started extracting them in the twentieth century.
Nature's process of Anaerobic Digestion (AD) can be replicated artificially. More than 4000 AD systems operate in Germany and interest is growing fast in the UK. Using ‘feedstocks' of food waste, animal slurry or energy crops (like maize), or a combination of these, bacteria inside the AD digesters go to work, breaking down the feedstock to create biogas. This biogas is burned and the energy used to drive a turbine to generate electricity. The residual heat is often put to use drying grain or heating greenhouses for example.
When biogas is burned to create energy, it returns the same amount of CO2 to the atmosphere as if the feedstock had decomposed naturally. This means that properly managed biogeneration doesn't disturb the carbon balance and doesn't contribute to climate change. The AD process creates another byproduct - the digestate - a highly nutritious, pasteurised, organic fertilizer that can be applied to farmland. So far so good ... as AD can use waste food, it can help to divert some of the 20 million tonnes of food waste produced annually in the UK from landfill.
So AD has the potential to be a win/win solution! The next step is surely to identify an AD system, get some biogas from them, and see if the chefs at River Cottage can cook on it...
Luckily, of the small number of AD plants in the UK, a few are quite near River Cottage. We spoke to the farmer, told him our plan which raised a smile and then we started to talk logistics. Unfortunately we got snagged on a problem.
The biogas created by AD is a mix of about 60% methane, 40% CO2 and some traces of other gases like hydrogen sulphide. This burns just fine at the generation end of an AD system but if you want a flammable gas suitable for cooking on, it won't work. You need to ‘scrub' biogas so that you are left with pure biomethane. As you might have guessed, scrubbing gasses isn't a question of getting on your hands and knees with a bucket of water; it involves a bit more chemistry.
So unfortunately this promising path we were exploring has reached a dead end. We need to find a supply of biogas that's been cleaned up and turned into biomethane. Next we need to find a safe method of getting it pressurized or liquefied and into a transportable canister. Anyway as one door closes, another is opening. I may have found our purist... or scrubber! Watch this space....
hi there looking at these posts it seems from what is supposed to be a positive blog on sustainability has quickly changed to be negative thanks to a few people who need to learn a few bits before they condemn what RCHQ and co. are trying to achieve.
Firstly when you talk about the rating of an appliance you need to take into account MAXIMUM DEMAND, which is an allowance for diversity for appliences A great example which seems to have fueled a few posts here is the rating of a cooker based on the fact you wont use every hob and have both ovens at full wack at one time. Lets use the 6kw cooker example, the equation for calculating the current demand for an appliance is done by taking the wattage so a 6kw is 6000w then divide by the voltage (230) and you have the ampage of 26amps. But then apply the diversity allowence for a cooker which is 30% of initial current plus 10amps so that works out as 17.8amps, which then works back as 4.1kw, which would be how much energy would be used if the cooker was going for one hour. But like the good people at good energy say most cookers are much less than 6kw, infact as appliances become more efficient the less current they use. Most ovens I install these days come fitted with a plug! so they must use less than 13amps even without diversity added even my range style cooker with 2 ovens, 2 grils is 4kw which when diversity is added is 3.5kw. However different circuits have differnt diversity allowance, lighting for example has 66% of total demand based on filament lighting, use low energy lights and the extra savings are obveous. instant water heaters have no diversity unless you own more than three whereby the 3rd has a factor of 25%. Normal power or heating has a diversity of 100% up to 10amps then 50% of anything in excess of that. NOTE all these allowences are based on the normal usage based on an average household whos normal use is to work out what correct size cables to install. Im sure if you have invested in any re-newable technology like a wind turbine you'll being much more cautious with you consumption and use far less than the electrical regulations deem as normal. Twelve normal 100w filament lights with diversity added draw nearly 800watts, compare this to low energy lights of eqivalent brightness is 132watts, new appliences use up to 20% less than one of an older age. so its easy to see where cutbacks can be made in order to be able to use your home brew power to full advantage
Thanks for the late reply,
Do you also send your Bills out late,?
Shame the Efficient Architects don`t reply to questions.
Hi Jim et al
We’ve tried our best to answer most of the questions that follow each blog, but I see you posted a couple more after our last responses.
To answer those questions here:
1. Proven specialise in smaller wind turbines, they don’t make the large commercial ones.
2. Regarding the power needed to run a cooker, we’ve done the following calculation: A standard electric cooker has a typical rating of 1kw. This means that at full capacity it will use 1kw (or 1000w) of electricity for each hour it is in use. Let’s say you use your cooker for on average 1/2hour per day. That works out to 182.5kw over the year (1kw x 0.5hrs x 365 days), and well within the 6833kwh capacity that we expect the turbine to generate. I think you may be getting confused between kw and kwh. So another way of looking at it would be: A 6kw turbine working at full capacity for an hour would generate 6kwh of electricity – which would be enough to power six 1kw ovens for one hour, say.
Hope this helps.
See if i`ve got this right,
Good Energy pays the Turbine owner 15p per unit they generate,including what they use themselves,in RC`s case between £900 and £1500 pounds based on generating between 6 and 10,000 units a year
So to get maximum benifit from installing a Turbine,one would do best by running everything off Electricity,central Heating,Hot Water,Cooking and lighting of course.
What baffles me now is,if Satalite Architects are advising on efficiency at RC,
What on earth do they need a Biomass boiler for the heating and Solar panel for pumping the water ,if you pay RC 15p for every unit they produce including what they use,
The cost of the biomass boiler and intallation of the Solar system was a total waste of money and resources.
Others here,more clued up on Electricity than myself,reckon that this 6kh Turbine would not run an Electric Cooker,
Is this so?
Jim,
There wasn't a lot of midges at all. I was there during the day though, might change at night. Its flowing water. Not fast flowing, but flowing.
Hi Jim,
We reckon a well sited 6kW turbine should be able to produce between 6000 and 10,000 units or kilowatt hours of electricity. We make this calculation based on the ‘capacity factor’ of the generator. Good Energy works with over 650 microgenerators, a good number of whom are 6kW wind turbines. Their average capacity factor on turbines at this size comes out at 13%.
The capacity factor expresses the percentage of time in a year at which a generator is operating at maximum power. So, a wind turbine will be working at different levels of intensity over a year, some days at full power, others day not at all. At the end of the year, you can record your total generation and express this as a capacity factor. The calculation will go as follows:
0.006 (size of turbine in MW) x 8760 (hours in a year) ÷ 100 x 13% (assumed capacity factor) = 6833kWh
As stated, the capacity factor we are using is an average of 6kW wind generators that Good Energy is working with. I think it is quite conservative given the good positioning of the River Cottage turbine but its best to wait for a year and use the actual data for River Cottage.
With regards to being able to power a home, the official Ofgem (Office of Gas and Electricity Markets) figure for average annual domestic electricity consumption is 3300 units. So our cautious estimate of a 6kW turbine being able to provide enough power for a four bedroom home can be comfortably met.
With regards to having a surplus to sell to the grid, this is not the system we recommend of turbines of this size. What Good Energy’s HomeGen scheme does is pay generators 15p for every unit they generate, including the units they use on site. We find this encourages microgenerators to use what they produce (which is more efficient) and not look to export their power.
The final point I must make is that wind turbines only provide expected levels of generation if you have a good wind resource. I know it’s obvious, but many people install turbines without sufficient research into what their wind resource is likely to be and end up making much less energy than they expected.
I hope this answers your questions.
Cheers Gav,thanks for photo,
Did you get to see the Reed Beds?
Where they plastered with Midges?
Jim, I took a picture of the River Cottage Wind Turbine just for you! Sadly you can't post it here so it'll have to go in a Question or on my Blog.
For the rest of the lives of most on this Forum,Coal will still be the biggest generator of Electricity in the UK,and more likely for a lot longer.
I believe Usk Mouth has been purchased by EDF or Eon,another burner of coal.
The weekend the Unempoyed Tree dweller brigade were protesting at the Ffos y fran opencast site at Merthyr,against coal production,the Police presence was huge,does make you laugh,25yrs ago,they were battling with Miners trying to save thier livelihoods,now they are protecting Coal production.
I'm not entering this at all.Wait for one of the furnace ops at Drax to open his mouth Bio mass uh!There are an awful lot of folk making an even more awful lot of money out of the energy crisiss Go nuclear go now build them gently and safely.Not sling them up willy nilly and stand back watching for the leaks as we usually do in the UK Its going to happen sooner or later. Georgee