Cullen Buie, MIT
At the moment, there isa big debate going on about the fact that the UK needs more energy, can't decide where to get it from. One of the options is solar panels and wind turbines which offer really low carbon ways to generate power, but they only work when the sun shines or the wind blows. To make sure we’ve got power 24 hours a day, we need a way to store the energy that they generate and until now, this has been really expensive. However, writing in the journal Nature Communications this week, scientists from the Massachusetts Institute of Technology think that they’ve found a new and really cheap form of battery based on bromine solution. Dominic Ford spoke to Cullen Buie all about his idea.
Cullen - So, the great thing about this battery is that it gets the performance of systems with a membrane, but it eliminates the cost of the membrane. So, this is the next we have to no membrane which is one of the most expensive components of the cell.
Dominic - So, what's this membrane doing in the battery?
Cullen - So, the membrane is in the battery to separate the reactants. So you have reactions happening either side of the system and so, you need to separate those reactions or else they would happen spontaneously and you wouldn’t be able to get any useful energy from it. What we propose is a membraneless hydrogen bromine batteries. So, batteries are typically characterised by their chemistry. We have this hydrogen bromine chemistry which actually isn’t new. This chemistry has been around and known since maybe the ‘70s and people have been excited about it because of the cheap and abundant reacting materials, and the potential for high efficiency. The problem is that it’s very difficult to design a membrane that will last for the thousand of cycles and that is low cost. So, it’s been limited by largely the materials because this hydrogen bromine battery makes hydrobromic acid which is difficult to work with for some membrane materials. Conversely, maybe 10 years ago, a research group at Harvard invented these membraneless systems. So, they were the first to propose eliminating membranes altogether and using fluid mechanics in order to keep your reactants separate. The issue there was that they used chemistries that- they didn’t produce a lot of power. So, it was interesting, but for the most part, the industry has disregarded these cells because they never produce enough power or energy in order to make them practically viable. So, what we’ve done is taken these two technologies which have kind of been sitting on the shelf effectively and put them together. And by putting them together, we get a hydrogen bromine system that now eliminates its issues with the membrane. And so, by eliminating the physical structure, we eliminate one entire component and all of its associated costs and complexity.
Dominic - Now, you're using bromine. Why is that so especially cheap?
Cullen - So, bromine is all over the world. It’s in saltwater. So, any place where you have a large body of saltwater, you're effectively, as a by-product of harvesting other things from saltwater, you get a lot of bromine.
Dominic - I know you're invisaging this battery for use with renewable energy generation. Why is it so important with renewable energy farms to have these large batteries?
Cullen - You have no control over when the sun is shining. Demand varies throughout the day. So, if you could couple storage with these intermittent sources like solar and wind, you can store the energy when it’s not being used and then sell it back to the grid when it is being used.
Dominic - When I think of new battery technologies, I think of cell phones and iPads, and so on. How do the needs of renewable energy farms compare to what you need for say, a cell phone?
Cullen - They're much more cost restrictive. So, the battery in your cell phone or in your laptop is probably at least 10 times more expensive than what you would like to see for something that’s going to go grid scale.
Dominic - I guess I find that quite surprising actually because you think if you're building a huge wind farm say, you’ve got a lot of infrastructure there. You're pouring concrete for these windmills. I would’ve thought the cost of the battery on the back of that would be relatively slight cost.
Cullen - Our prevailing battery technologies are still very expensive. They use a lot of precious metals. They use things that are difficult to contain or control. And so, when you talk about that large scale, it’s difficult to make it scale and make it affordable.
Dominic - Is lifetime also an issue here? I mean, I'm thinking, if you're building something in the remote desert to harness solar power or you're building an offshore wind farm presumably you don’t want to be replacing those batteries every few months off the back of that renewable energy farm.
Cullen - Yeah, you nailed it right on the head. Lifetime is absolutely an issue. You want thousands of cycles, maybe 10,000 cycles. So, you mentioned batteries before. How long does your battery actually operate? Maybe you get a year or two and then after 2 years, you notice all of a sudden, it can't hold any kind of charge. That would be unacceptable for something like a grid scale application.
Dominic - And the other problem that we have with cell phone batteries is the memory effect where if you're only ever half discharging it, then it doesn’t tend to hold its full charge any longer. That I guess is also something you’ve got to avoid in these batteries that are being charged when the sun shines and discharged when it’s cloudy.
Cullen - Yeah, you'd like to minimise all those effects, so it’s a very challenging problem. What we presented is just one more way and the novelty in this one is that we’ve eliminated one of the more costly components in the battery.
Dominic - How long do you think it would take to get this from the lab into the field? I mean, if you're saving a lot od money, if this is very cheap then presumably, the energy companies would be very keen to use this as soon as possible.
Cullen - I would say, 5 to 7 years. We’re talking about developing a new battery, a new type of battery. New batteries don’t come out very often and part of the reason is, battery development is hard.
Excellent technology, with serious economic consequences.
But look how terribly dangerous nuclear power is probably as many as 100 people have died as a result of nuclear mishaps since 1940 syhprum, Wed, 28th Aug 2013
My goodness! That's almost a whole day's toll of coal miners, or ten minutes at Aberfan.
Many of the "wind farms" are being built in places that get quite regular wind such as at the coast, or the Columbia gorge, although undoubtedly it varies somewhat with weather.
The big problem with wind is that power output depends on the cube of the wind speed, so a windmill with a nominal rating of 100 kW at its optimum wind speed tends to produce less than 15 kW averaged over a year, even in the best UK onshore locations. Offshore you can get about 20% of rated power but the maintenance costs are ridiculous. You can't make it go much faster than its optimum because the blade speed is limited to the speed of sound at the tip, so if you use big wings to squeeze the last drop out of a gentle breeze, you have to feather it in a gale (drag force increases with v^2, so you need to minimise the angle of attack to prevent damage), and a small fan will only produce useful power on the few days when it gets really windy.
Storage of electricity has always been problematic. Liquid and gaseous/liquified fuels store much more densely and safely (because the atmosphere is a vast, omnipresent "free" repository of the other energy-producing ingredient: oxygen; it also doubles as a toxic waste dump - it's a pity we have to breathe the stuff!).
Another thing to consider.
Using primary electricity for space heating is insane. It is the most expensive and most flexible form of energy we have, and really shouldn't be squandered. A properly insulated and correctly sited new build, even in the British Isles and the northern US states, doesn't require any space heating at all. A school in Chester, built some 50 years ago with airspaced double glazing, has never used space heating, and modern insulators are a lot better.
Creeping socialism, dammit. alancalverd, Thu, 29th Aug 2013
Here, rainfall is strongly seasonal. And, thus river flow also is seasonal. Thus, more hydroelectric energy is generated during the winter. Therefore, there are actually benefits of using electric heating when there is more electricity being generated.
In Quebec, the provincial hydroelectricity agency prices electricity so cheaply everyone uses it to heat their houses. The government then declares a loss which is made up by billions in equalization payments from the rest of Canada. No creeping socialism there, it's rampant. grizelda, Sun, 1st Sep 2013
Talking of socialism...
Well yes obviously renewable energy can provide 24-hour power with an energy store back-up but there's no need to re-invent the wheel here folks.
Present UK grid capacity is about 80 GW. It is sensible to plan for 100 GW in the foreseeable future.
Hi Alan and thanks for your feedback.
1400 GWh (5.04x1015 J) of pumped hydro storage would be quite an engineering feat!
Hi chiralSPO and thanks for your feedback.
This is the 8th consecutive day with wind below 2 GW - your storage system is looking a bit marginal.
Not on today's grid it doesn't. Solar panels mean that the fossil fuel production goes down during the day, and the car pulls it back up at night. So the net carbon footprint is zero, or negative, even if you're not putting the electricity directly into the car.
A lot of the 'unmetered' wind and (more so) solar is actually on the grid, and metered, but there's no real-time monitoring of them, so the graphs don't include them. Basically the individual installations are too small.
The only thing I disagree with in the model is that you're assuming only wind and pumped storage.
Thank you for your feedback wolfekeeper.
National grid do a far g(r)eekier version:
I imagine the solar figures are estimates based on weather and PV installation data: the national grid need a model of it to improve their demand estimates.
Part of the problem for electric car users is the distance between filling stations. If you take the M25 and M4 from South Mimms to Reading, it's "only" 50 miles, with no service stations in between. The next station westwards is a further 20 miles, out of reach for most hybrids on "battery only" and marginal for medium 100% electrics. So if we have 500 electric cars parked at either station (not unusual) we will need 500 charging points, not 2. If you have slowmoving traffic in winter you can expect to find a fair number of automotive corpses around the motorways.
No need for a drawing, thanks. I first drew a hybrid car (actually it was a bus) 60 years ago and would very much like to own one, preferably with a gas turbine rather than a reciprocating engine as prime mover.
I have no idea why you think the government would need to pay for this.
The revenue argument is clear, but how are you going to raise £3billion capital for a venture that depends on everyone else buying an electric car before your hardware is obsolete? Market penetration (outside of the urban weekend ecowarrior clique) will be poor until the recharge network is complete.
Look, none of this is rocket science; apparently it is for you, but I think everyone else reading this thread will understand that there's no fundamental problem, and I haven't even mentioned that you can order backup generators up to 250 megawatts, off-the-shelf items, to power recharging points during peak time if you're a bit shy on grid connection. The electricity itself is not even the expensive bit, it's installing the plug-in points, and as I say, they're self financing; and it's good to have a backup generator anyway, in case the grid goes down.
No, but buying shares in services stations might be profitable. wolfekeeper, Mon, 13th Apr 2015
Chicken! This is, apparently, a self-financing no-brainer, led by an acknowledged expert. You should be selling shares, not buying them! alancalverd, Tue, 14th Apr 2015
You think you could get planning permission for that massive salt-water tank? There are better technologies on the way which will wipe out the point of it before it could be built. David Cooper, Wed, 15th Apr 2015
The scale of this 64 GW dam project can best be appreciated by comparison with the Hoover Dam with a peak output of 1.4GW, and Drax power station (4GW). The largest hydroelectric station in the UK is 0.3GW at present. Admittedly these are fairly historic structures, so a fair comparison would be with the 22 GW Three Gorges Dam
Mere scale is virtually never a reason not to do something. You should look at stuff like cost per person, and the timescale over which it would be built instead. wolfekeeper, Fri, 17th Apr 2015
Scale is important because this project requires capital input. There is obviously no physical reason why it can't be done but the practicality is that you need enough money up front to start the work, with a sufficient promise that it will be funded to completion. Failing that, a project will run into the sand as lack of continuing funding means delay, which increases costs and makes further funding less attractive.
I’ve updated my post to include more detailed estimates for the reservoir volume, maximum flow rate, energy storage and power capacity.
The production of concrete generates 410 kg of CO2 per m3.
I agree that nuclear power is an excellent, low carbon energy source that should be taken better advantage of. However, that doesn't get you completely away from the energy storage problem. Nuclear plants have a very constant output, that can only be modulated a little bit, and quite slowly (as far as I know). While this can be used to provide a large portion of the base load, it is ill-adapted to the variability in consumer demand for electricity. Energy storage technology is still required for peak shaving and peak shifting, if you don't want to have some gas- or coal-fired powerplants that get cycled on and off as needed... chiralSPO, Sat, 18th Apr 2015
We could get rid of a lot of the sudden peaks in energy demand by getting rid of soap operas. David Cooper, Sat, 18th Apr 2015
There is certainly a place for pumped energy storage in an all-nuclear system, but as the ramp-up time for a nuke is a matter of minutes (the trick is never to shut the reactor down completely, and baseload is about half peak in the UK), you don't need to store the entire grid demand for 5 days, just half the demand for an hour or two. This was the philosophy behind Dinorwig, and it works very well.
Nuclear is a non starter; renewables are growing far faster and that's not changing any time soon.
At the moment I can't remember who to attribute this to, but there is a quote or saying out there along the lines of:
Plants are actually not that good at photosynthesis; their conversion efficiency for solar energy to plant energy is only about 1-3% or so, whereas solar panels are ~15-45% or more. Some of that is probably because they need the energy for metabolism; but the end result is the same; they suck for what we as humans want from them. wolfekeeper, Sun, 19th Apr 2015
Canal lining and boulder trap
maybe build a solar highway/belt around the equator? floating kind? jccc, Mon, 20th Apr 2015
Back to square one: it's 21 April, and so far only 4.5 days this unexceptional month with wind sufficient to generate 2 GW - the running mean is less than 10% of capacity. Time, I think, to review the statistics: as I suggested a few pages back, you need at least 14 days' storage at mean demand if you are going to use electricity as a reliable power source.
You can't assume that metered demand is being met by unmetered input - that would be ridiculously generous of the suppliers, and anyway, as Gridwatch states, unmetered supply is already shown as a reduction in demand, so you mustn't double-count it! Furthermore it is generally the case that unmetered wind is small power for local consumption and therefore will not contribute significantly more to the grid as large windfarms are built to absorb your taxes.
I didn't double count it, I added it to both the demand AND the generation sides of the equation, and doing that is quite valid.
We already explained to you that you that average daily mileage of cars is only 20-30 miles, and that that only needs 5 kWh per car, per day. Meanwhile the minimum electric car has a 25 kWh battery...
According to HM Government (or at least the Department of Energy and Climate Change), 36% of current UK energy use is for transport. If I am repeating falsehoods, they come with great authority.
As we have already pointed out to you, but you have pointedly 'forgotten', again, windmills and solar panels are not heat engines and the solar/wind/battery/electric motor power system is much, much, much more energy efficient than going the antiquated heat engine route.
SS, you are so beautiful, as your science! jccc, Thu, 23rd Apr 2015
Presumably with 290 GW of peak wind, you'd have spare energy a lot of the time. I mean the standard capacity factor is about 25-35%, so you'd be averaging more power than you actually need- it's sized for the periods when the wind is a bit anemic. So at 25% CF, that's 72GW average, whereas the normal demand is 35-55.
On floating platforms, solar power, power-to-gas and energy storage ...
"The UK has reached the limit on hydro" (paraphrased) said Andrew Neil questioning the parties' energy and climate change spokespersons on the BBC's Daily Politics, first broadcast on 20th April and rebroadcasted earlier today on BBC Parliament.
It needn't be a balloon. A steel can will do quite nicely, and it doesn't need to be very deep under the ocean: the domestic gas supply pressure is only a meter of water gauge or less. The deeper it is, the more efficient, but large steel cans are very cheap and easy to make. alancalverd, Sat, 25th Apr 2015