...that worked all the time. (cf wind power. Britain has the best geography for wind power in Europe! We can get the turbines generating 27% of the time rather than 15%-20% of the time!)
Energy storage stations like the pumped reservior stations can be made with current technology (and should be!). Also there's a fair amount of work going into reversible fuel-cell based stations where a low-energy molecule is split in two during times of high-generation, stored separately, and then recombined at times of high demand. For example hydrogen+oxygen/water.
I was just thinking a few days ago about energy policy. There seems to be an awful lot of nonsense out there from various groups. If I ruled the UK (TM) I would:
Start building more fission reactors right now, with an expected twenty-five year lifespan.
Halt vitrification and similar sequestering activities of high-level waste, and store above ground in pure form.
Plough money into actinide-burning research (essentially neutron bombardment of long half-life fission products to force decay) so that it will be available to destroy radioactive waste when energy is no longer an major issue (actinide burning being highly energy-expensive).
Start arguing with EU to move excess farmland rapidly toward energy crops, particularly short-rotation coppiced willow, and similar high-yield products. (30% of the nation under coppiced willow could supply all electricity demand).
Start building energy stroage stations of dual-reservoir kind, and push forward research on reversible fuel-cell binary storage stations.
Remove planning restrictions on the building of incinerators and wind-farms.
Build many more off-shore wind farms.
Incrementally replace GDP with GPI in spending and fiscal decisions.
Seafloor mounted turbines in tidal streams don't work all the time, but do work every day. At least until they break down, and being under salt water and deep enough not to interfere with shipping is a tricky maintenance environment. And they might have more ecological impact than windmills, if not as much as tidal barrages.
Pumped reservoirs are very important in Spain, Switzerland and Scandinavia. (But not, as far as I know, in Slovenia or Slovakia.) The First Hydro Group's pumped storage stations at Dinorwig and Ffestiniog attract envious glances up and down the land for the prices they can attract for their electricity. I suspect there just aren't (m?)any more places in the UK where similar stations could be economically built, noting the tons of smaller-scale schemes in place in Scotland, else people would already be building them.
Please provide links to information on fuel-cell based stations - they're just things I haven't heard much about.
Full disclaimer: I work for px limited (http://www.pxlimited.com/).
SeaGen (http://www-tec.open.ac.uk/eeru/natta/renewonline/rol56/3.htm) is pretty promising, but the capacity looks very small indeed - and the next stage of the project is for 77 MW of capacity. (Even the scheme's boosters reckon that taking advantage of the Bristol Channel, North Wales and Merseyside etc., the most that could ever be produced is about 4 GW.) Considering that the demand of the UK varies roughly between 20 GW at very lowest and 60 GW at highest, I think that while this is promising - possibly the most promising development among the renewables, though only time and development will tell how reliable it is - it's only a small part of the solution.
It's expensive, too, even as renewable solutions go.
This was a calculation I made myself, some years ago, from sources I had around at the time on energy density, etc. I'll try to do it again, and post the results. Unfortunately, 30% of the country isn't suitable for the growing of it, but I think it does point out the practicality of bioenergy.
Yes, it's true, offshore wind is insanely costly, :(, but running out of fuel is going to be an expensive issue, too.
I was really considering parochial question of Britain's energy security. But yes, they too are going to need to come up with something that doesn't depend on their rather tantrum-prone former colonial power.
To correct myself, the UK could have about 6 GW, not 4 GW (http://www.tidalelectric.com/Projects%20UK%20Potential.htm) of tidal energy. Not bad, but only a part of the solution.
Ah yes, various forms of Giant Battery Technology. I did some sums on this, and concluded that if you were to collect all the UK's discarded car batteries for a few years, you could build a square-mile sized facility that might be able to store a signifigant fraction of the required energy. In practice one would want several facilities to ease grid load and avoid a Buncefield-sized hazard if someone shorts it out.
(Batteries from scrapped cars are theoretically hazardous waste, but in practice are often just crushed with the car or otherwise dumped. (http://www.publications.parliament.uk/pa/cm200102/cmselect/cmtrdind/299/299ap14.htm))
That's an interesting approach, I'd not thought of that! It should be quite efficient, if the inverter could be made efficient. There ceratinly are efficient DC invertsers, as many HVDC power lines use them. Or the DC could be sold to the aluminium smelting industry (do we have one?) or some other industry who usually take big hits during rectification.
In practice, I suspect that the likely early storage solutions will use hydrogen and then use hydrogen as a heat-fuel. A wind station with electrolysis or fuel-cell equipment could generate H2 and heat for CHP (or sulphur/iodine cycle, or something), and not be grid-connected at all. I wonder what the efficiency of a setup like that might be?
Why on earth would they do that, and throw away 80% of the energy? Even the lead-acid batteries manage about 60-70% efficiency.
http://www.efcf.com/reports/E04.pdf - not checked the numbers, and it's in the context of cars rather than powerplants, but it looks pretty awful. Getting electricity out of fuel cells appears to be only about 50%; burning it you'll be limited to less than that by the Carnot cycle.
I've done quite a bit of reading on this which I've not bothered to collate, and the more I do the more hydrogen looks like a red herring which is being pushed by people who haven't looked at the thermodynamics and natural gas producers. For example, if you have electricity, it's almost always cheaper most economical to transport it somewhere useful than it is to make H2 out of it and transport that. If you want to store it, then think "battery" and design from there using the most appropriate battery chemistry (Various other novel storage techniques exist, but getting high enough energy density without storing it in chemical bonds appears to be a hard problem).
The most ingenious overall solution I've heard so far is to get people to use more hybrid vehicles with large onboard energy storage systems, then plug them into the grid when parked with smart meters so they can charge when the wind farms are producing lots and sell electricity back when demand is high.
If anyone is going to do this, it'll be Denmark first; they already have a few times a year when they produce more than 100% of demand from wind (but they rely on Scandinavian hydro power for baseline and windless days).
I don't think it's a very good option, but it's what will happen first, I think, because there's a migration path from fossil fuels to hydrogen, and because of (cryogenic) hydrogen's excellent energy density and relatively simple shipability in terms of Joules per second per pound. There are plenty of applications where the desired outcome is heat, it's the majority of the energy budget.
You're only limited by the carnot cycle in closed-loop heat-engine type applications, which I don't think is the majority of energy consumed (which I would guess is probably space and industrial process heating).
It's a path whereby lots of things can easily be phased in and out. Moving from burning to using fuel-cells at the consumer end, migration from mineral oil to electrolytic production, and so on, can run at market pace.
It would be more sensible for peak-chopping to have the regenesys type plant like the one which was out at Little Barford (till it closed as part of "corporate strategy") which could generate 5MW and store 120MWh using a giant battery type approach using tank-stored pumped elecrolytes and other weird shit. It was about the size of a supermarket.
The paper you reference concerns the generation of electricity from hydrogen, which is inefficient, particularly if you don't recover the heat. The electrolysis of water is around 75-80% effiicient in practical systems, as I understand it. I think that the conversion of electrical power to hydrogen, and the burning of hydrogen for space-heating (displacing electrical demand for such) would be a major way to reduce fossil fuel demand.
That and ground-source heat pumps, which reduce fuel consumption by a factor of around three.
I wasn't suggesting it for electricity peak chopping. And the way to make cars efficient is to use the train.
Hmm. http://www.dti.gov.uk/energy/inform/energy_consumption/ ; space and water heating does seem to be about 50% of non-transport energy consumption, and 80% of domestic energy consumption.
However, given renewable electricity as a starting point, why convert it to hydrogen and lose 20-25% when you could just heat the space with electricty? Especially given that you can't run the heat pumps on hydrogen. Converting it just so you can store and deliver the hydrogen heat out of sync with the generation is peak-chopping.
Coppiced willow is one of the few sources of renewable energy that doesn't generate electricity directly and is directly useful for space heating, which seems like a pretty good idea. Clean Air Act gets in the way of the direct solution; might be some milage in chemically converting it to CNG.
If you're not using renewables, you might as well burn them directly or in (micro-)CHP.
As for using the train, the network is already very near capacity ...
This (http://www.countryguardian.net/RAENG%20Report.htm) suggests that 10% of UK farmed area under rotation coppicing would provide about 9GW, eventually, but perhaps 1-2GW during initial development.
Oh, excellent. It's good to know that it's being investigated more thoroughly: there seems to be a lot more data about than there was a few years ago. My figures were just astronomy type calculations based on annual consumption in TWh, etc. The thing that annoys me is discussion of things like photovoltaics in their present form (or any near-future one, as far as I can tell) in the same breath as, say, wind or biofuel.
Your figures are a bit disappointing, but, still, I guess it would be a significant contribution to (I assume) the 100-200GW required, say, fifty years hence. pjc50's comment about using fuel sources like this for space-heating makes a lot of sense, too.
It would be interesting to try to collect together data in one place about these things. For example, annual electricity consumption in terms of both power and energy, to see the effects of peaking, etc.
There appear to be several organisations sort-of doing this ... 8-)
(defra and cranfield among them).
One question that's interested me in the past is how much hedge/wood a single household would need for heating/cooking purposes on a sustainable basis; I currently have no good intuitive estimate for this - whether it'd be (say) the 20m hawthorn/yew hedge down the side of our house, or (say) a couple of acres of woodland.
I'm fairly certain our hedge wouldn't see us through a cold winter - you're looking at perhaps five medium-sized split logs a day for perhaps 100 days, to heat a house, if you're not too worried about being a bit chilly some of the time, and rely on warm clothing rather than central heating.
The problem is that the electricity you're given as a starting point is intermittent and cannot be easily stored. To store it you need it in a form other than electricity (in some form). If it's converted to a form such as a fuel then it can be stored, but subsequently be used to serve energy needs in the form of heating. That part of the process is, effectively, 100% efficient, the only loss is in the conversion of electricity to hydrogen. Electrolysis has a performance figure that's comparable to a round-trip in many storage stations, the difference being that the storage stations generate electricity, and the hydrogen heat.
Fuel Cell or Stirling Engine electricity generation for domestic (non-heat) electricity demand can probably be made very efficient in a micro-CHP form, as the excess heat is used for, well, heating.
The problem with using the generated electricity from, say, a windmill is that the wind is an intermittent source of power and requires backup capacity or storage stations (which are difficult to build). The problem with backup capacity is that it's difficult to arrange for most renewables (some biofuels being an option) because they don't rely on a massive reserve of fuel, as fossil fuels do, but on variable environmental sources or cyclic or incremental processes which generate fuel at a certain maximum rate.
The problem at the moment with storage is that it also has inefficiencies (Ffestiniog, for example, has a cycle efficiency of around 75%), and many involve considerable greenhouse emission in its own right. (For example, if a dam lets a lake grow and shrink with demand and storage, then it accumulates bio-material each time it ebbs, which decays anaerboicly into methane. The process of passing the water through turbines and pumps tends to liberate the disolved gasses and the process then repeats. There's one IPCC scientist (Eric Duchemin) who claims that the greenhouse emissions exceed the equivalent of an oil-powered station. (Not that this is a real issue when considering only the fuel-scarcity problem).
It makes more sense to me to use excess off-peak demand to generate hydrogen at 75% efficiency and then burn it at home than to store it and retrieve it at 75% efficiency, transport it across the grid, and then convert it to heat at the far end. The main difference being the need for building lakes up mountains (of which there is a finite and small supply) with one solution but not with the other. There will be a need for storage stations for non-heat electricity demand, of course.
I don't think that building railway lines is beyond us. The same could be said of the national grid!
The problem with repositories I've found are that most of them only archive the information they've comissioned (you can usually find stuff in the UL, but that's a bit of a needle and haystack type issue), and they all seem to be bound up in large reports (I think a certain amount of funding must necessitate a certain weight of paper) which mean it's difficult to extract the figures. I realise that serious researchers need the full information, but it would be useful to have an almanack type compendium.
I would be interested if you find out the wood figures.
I think we're on the same wavelength here with the baseline problem; but I'm still suspicious of the practicality & efficiency of hydrogen storage (both compression and cooling are quite difficult to get reasonable density) and transport. I guess we'll know in 20 years time :)
how about encouraging small scale fuel cells running off natural gas (household size). then you'd get rid of transmission losses. (especially if you fed back to the local grid)
I think people tend to over-do the issues with transmission losses. As far as I can tell, the grid is about 96% efficient. That's pretty good, and makes me wary when people talk about reactive losses, because little differences elsewhere in the system can easily make more of a difference than reactive losses.
(For example, electricity you generate in micro-CHP has to go through two house's electricity connections, rather than one house and one national network. I imagine a fair proportion of reactive loss is in the home (lots of wire joints, poor quality wire, quite high current/area), so does it work out best? I don't know.)
The big thing for me about micro-CHP, though, is that the heat generated with your electricity isn't wasted, which makes it very efficient in total-energy terms, it doesn't go "up the power-station chimney". I worry, though, that little units of anything tend to be less efficient than their big cousins, so I wonder what's going out of the house flue.
With hydrogen-powered CHP, the hydrogen could have been generated environmentally too (by wind-farms during off-peak times, say). The electricity part of the generation would be a bit loopy in efficiency terms (as pjc50 points out), but no worse than using a storage station, and so much household energy is space-heating anyway).
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(no subject)
Date: 2006-01-02 12:03 pm (UTC)(no subject)
Date: 2006-01-02 01:17 pm (UTC)(Until then some of the nice, small, clean, modern nuclear power stations would be good.)
(no subject)
Date: 2006-01-02 04:25 pm (UTC)You may be right about the nuclear stations.
(no subject)
Date: 2006-01-02 04:37 pm (UTC)There should be more of these things!
(no subject)
Date: 2006-01-02 04:50 pm (UTC)Well, it would be a start.
(no subject)
Date: 2006-01-02 05:25 pm (UTC)(no subject)
Date: 2006-01-02 05:38 pm (UTC)Please provide links to information on fuel-cell based stations - they're just things I haven't heard much about.
Full disclaimer: I work for px limited (http://www.pxlimited.com/).
(no subject)
Date: 2006-01-02 05:51 pm (UTC)It's expensive, too, even as renewable solutions go.
(no subject)
Date: 2006-01-02 05:56 pm (UTC)Source, please?
(I actually hope you're correct!)
Build many more off-shore wind farms.
V v costly, but sadly, virtually everything is at least v costly.
(no subject)
Date: 2006-01-02 06:10 pm (UTC)Yes, it's true, offshore wind is insanely costly, :(, but running out of fuel is going to be an expensive issue, too.
(no subject)
Date: 2006-01-02 06:37 pm (UTC)(no subject)
Date: 2006-01-02 09:23 pm (UTC)(no subject)
Date: 2006-01-02 11:53 pm (UTC)(no subject)
Date: 2006-01-03 07:11 am (UTC)(no subject)
Date: 2006-01-03 09:46 am (UTC)(no subject)
Date: 2006-01-03 04:32 pm (UTC)(Batteries from scrapped cars are theoretically hazardous waste, but in practice are often just crushed with the car or otherwise dumped. (http://www.publications.parliament.uk/pa/cm200102/cmselect/cmtrdind/299/299ap14.htm))
(no subject)
Date: 2006-01-03 04:53 pm (UTC)In practice, I suspect that the likely early storage solutions will use hydrogen and then use hydrogen as a heat-fuel. A wind station with electrolysis or fuel-cell equipment could generate H2 and heat for CHP (or sulphur/iodine cycle, or something), and not be grid-connected at all. I wonder what the efficiency of a setup like that might be?
(no subject)
Date: 2006-01-03 05:46 pm (UTC)http://www.efcf.com/reports/E04.pdf - not checked the numbers, and it's in the context of cars rather than powerplants, but it looks pretty awful. Getting electricity out of fuel cells appears to be only about 50%; burning it you'll be limited to less than that by the Carnot cycle.
I've done quite a bit of reading on this which I've not bothered to collate, and the more I do the more hydrogen looks like a red herring which is being pushed by people who haven't looked at the thermodynamics and natural gas producers. For example, if you have electricity, it's almost always cheaper most economical to transport it somewhere useful than it is to make H2 out of it and transport that. If you want to store it, then think "battery" and design from there using the most appropriate battery chemistry (Various other novel storage techniques exist, but getting high enough energy density without storing it in chemical bonds appears to be a hard problem).
The most ingenious overall solution I've heard so far is to get people to use more hybrid vehicles with large onboard energy storage systems, then plug them into the grid when parked with smart meters so they can charge when the wind farms are producing lots and sell electricity back when demand is high.
If anyone is going to do this, it'll be Denmark first; they already have a few times a year when they produce more than 100% of demand from wind (but they rely on Scandinavian hydro power for baseline and windless days).
(no subject)
Date: 2006-01-03 06:24 pm (UTC)You're only limited by the carnot cycle in closed-loop heat-engine type applications, which I don't think is the majority of energy consumed (which I would guess is probably space and industrial process heating).
It's a path whereby lots of things can easily be phased in and out. Moving from burning to using fuel-cells at the consumer end, migration from mineral oil to electrolytic production, and so on, can run at market pace.
It would be more sensible for peak-chopping to have the regenesys type plant like the one which was out at Little Barford (till it closed as part of "corporate strategy") which could generate 5MW and store 120MWh using a giant battery type approach using tank-stored pumped elecrolytes and other weird shit. It was about the size of a supermarket.
The paper you reference concerns the generation of electricity from hydrogen, which is inefficient, particularly if you don't recover the heat. The electrolysis of water is around 75-80% effiicient in practical systems, as I understand it. I think that the conversion of electrical power to hydrogen, and the burning of hydrogen for space-heating (displacing electrical demand for such) would be a major way to reduce fossil fuel demand.
That and ground-source heat pumps, which reduce fuel consumption by a factor of around three.
I wasn't suggesting it for electricity peak chopping. And the way to make cars efficient is to use the train.
(no subject)
Date: 2006-01-03 07:11 pm (UTC)However, given renewable electricity as a starting point, why convert it to hydrogen and lose 20-25% when you could just heat the space with electricty? Especially given that you can't run the heat pumps on hydrogen. Converting it just so you can store and deliver the hydrogen heat out of sync with the generation is peak-chopping.
Coppiced willow is one of the few sources of renewable energy that doesn't generate electricity directly and is directly useful for space heating, which seems like a pretty good idea. Clean Air Act gets in the way of the direct solution; might be some milage in chemically converting it to CNG.
If you're not using renewables, you might as well burn them directly or in (micro-)CHP.
As for using the train, the network is already very near capacity ...
(no subject)
Date: 2006-01-03 11:28 pm (UTC)(no subject)
Date: 2006-01-04 11:22 am (UTC)Your figures are a bit disappointing, but, still, I guess it would be a significant contribution to (I assume) the 100-200GW required, say, fifty years hence.
It would be interesting to try to collect together data in one place about these things. For example, annual electricity consumption in terms of both power and energy, to see the effects of peaking, etc.
(no subject)
Date: 2006-01-04 11:49 am (UTC)There appear to be several organisations sort-of doing this ... 8-)
(defra and cranfield among them).
One question that's interested me in the past is how much hedge/wood a single household would need for heating/cooking purposes on a sustainable basis; I currently have no good intuitive estimate for this - whether it'd be (say) the 20m hawthorn/yew hedge down the side of our house, or (say) a couple of acres of woodland.
I'm fairly certain our hedge wouldn't see us through a cold winter - you're looking at perhaps five medium-sized split logs a day for perhaps 100 days, to heat a house, if you're not too worried about being a bit chilly some of the time, and rely on warm clothing rather than central heating.
(no subject)
Date: 2006-01-04 12:08 pm (UTC)Fuel Cell or Stirling Engine electricity generation for domestic (non-heat) electricity demand can probably be made very efficient in a micro-CHP form, as the excess heat is used for, well, heating.
The problem with using the generated electricity from, say, a windmill is that the wind is an intermittent source of power and requires backup capacity or storage stations (which are difficult to build). The problem with backup capacity is that it's difficult to arrange for most renewables (some biofuels being an option) because they don't rely on a massive reserve of fuel, as fossil fuels do, but on variable environmental sources or cyclic or incremental processes which generate fuel at a certain maximum rate.
The problem at the moment with storage is that it also has inefficiencies (Ffestiniog, for example, has a cycle efficiency of around 75%), and many involve considerable greenhouse emission in its own right. (For example, if a dam lets a lake grow and shrink with demand and storage, then it accumulates bio-material each time it ebbs, which decays anaerboicly into methane. The process of passing the water through turbines and pumps tends to liberate the disolved gasses and the process then repeats. There's one IPCC scientist (Eric Duchemin) who claims that the greenhouse emissions exceed the equivalent of an oil-powered station. (Not that this is a real issue when considering only the fuel-scarcity problem).
It makes more sense to me to use excess off-peak demand to generate hydrogen at 75% efficiency and then burn it at home than to store it and retrieve it at 75% efficiency, transport it across the grid, and then convert it to heat at the far end. The main difference being the need for building lakes up mountains (of which there is a finite and small supply) with one solution but not with the other. There will be a need for storage stations for non-heat electricity demand, of course.
I don't think that building railway lines is beyond us. The same could be said of the national grid!
(no subject)
Date: 2006-01-04 12:12 pm (UTC)I would be interested if you find out the wood figures.
(no subject)
Date: 2006-01-04 12:25 pm (UTC)(no subject)
Date: 2006-01-04 12:27 pm (UTC)(no subject)
Date: 2006-01-04 12:59 pm (UTC)(For example, electricity you generate in micro-CHP has to go through two house's electricity connections, rather than one house and one national network. I imagine a fair proportion of reactive loss is in the home (lots of wire joints, poor quality wire, quite high current/area), so does it work out best? I don't know.)
The big thing for me about micro-CHP, though, is that the heat generated with your electricity isn't wasted, which makes it very efficient in total-energy terms, it doesn't go "up the power-station chimney". I worry, though, that little units of anything tend to be less efficient than their big cousins, so I wonder what's going out of the house flue.
With hydrogen-powered CHP, the hydrogen could have been generated environmentally too (by wind-farms during off-peak times, say). The electricity part of the generation would be a bit loopy in efficiency terms (as
Sorry, I'm waffling randomly now, :).