Slashdot Mirror
How Orkney Leads the Way For Sustainable Energy (theguardian.com)
An anonymous reader shares a report: It seems the stuff of fantasy. Giant ships sail the seas burning fuel that has been extracted from water using energy provided by the winds, waves and tides. A dramatic but implausible notion, surely. Yet this grand green vision could soon be realised thanks to a remarkable technological transformation that is now under way in Orkney. Perched 10 miles beyond the northern edge of the British mainland, this archipelago of around 20 populated islands -- as well as a smattering of uninhabited reefs and islets -- has become the centre of a revolution in the way electricity is generated.
Orkney was once utterly dependent on power that was produced by burning coal and gas on the Scottish mainland and then transmitted through an undersea cable. Today the islands are so festooned with wind turbines, they cannot find enough uses for the emission-free power they create on their own. Community-owned wind turbines generate power for local villages; islanders drive nonpolluting cars that run on electricity; devices that can turn the energy of the waves and the tides into electricity are being tested in the islands' waters and seabed; and -- in the near future -- car and passenger ferries here will be fuelled not by diesel but by hydrogen, created from water that has been electrolysed using power from Orkney's wind, wave and tide generators.
Orkney was once utterly dependent on power that was produced by burning coal and gas on the Scottish mainland and then transmitted through an undersea cable. Today the islands are so festooned with wind turbines, they cannot find enough uses for the emission-free power they create on their own. Community-owned wind turbines generate power for local villages; islanders drive nonpolluting cars that run on electricity; devices that can turn the energy of the waves and the tides into electricity are being tested in the islands' waters and seabed; and -- in the near future -- car and passenger ferries here will be fuelled not by diesel but by hydrogen, created from water that has been electrolysed using power from Orkney's wind, wave and tide generators.
If everyone harvested the wind and the waves, there'd be no wind and waves. This solution simply does not scale.
Put in large systems that run off the currents in the ocean that fill up tanks full of hydrogen so that automated ships can come dock with them and move the hydrogen around? Sounds like a great idea to me. I'm glad they thought of this.
--
“Time and tide for nae man bide” – Unknown
Hydrogen is a way of storing energy the same as a battery. Today batteries are better in every possible way except possibly air travel. Hydrogen is dangerous, hard to store and hard to transport. Again, except possibly for air travel, hydrogen is either expensive or less efficient to turn back into mechanical energy.
True, but the reason hydrogen storage is still interesting is that the storage capacity you can achieve with hydrogen based completely dwarfs anything you can achieve with batteries, hydro storage or practically anything else at the moment. The round trip efficiency is currently between 30-40 %, it can realistically be increased to 50% in the near future. If you recover the stored energy by burning the hydrogen in in a combined cycle gas power plant the efficiencies is as high as 60%.
Hydrogen has about 142 MJ per kg, about 3X that of diesel and gasoline. Which themselves are about 25X that of LiPo batteries (the best, mass-producible rechargeable batteries out there). Making hydrogen about 75X the energy density of the best battery packs. Batteries are terrible for aerospace uses, and even for vehicles where hydrogen could be recharged in a matter of a few minutes, requires a LOT less mass for motion (meaning more efficient and easier on the roads), and simpler to build (as you can use a fuel cell and then drive electric motors). Why would you want to carry around 800 kg of batteries when you could do 12 kg of hydrogen? The weight savings in terms of wear-and-tear on roads and tires is massive.
Browsing at +1 - no ACs, I ignore their posts. So refreshing!
Lithium batteries have a round-trip efficiency of about 95%.
For hydrogen, it is about 60%.
So lithium wins for most applications.
Hydrogen wins when weight is a really big concern. So it may make sense for aviation.
Hydrogen also scales well, since big tanks have a better volume-to-area ratio. So it may make sense for ships.
For static applications like grid-storage, sodium-ion or vanadium-redox may be better than either lithium or hydrogen.
But for cars or smaller, lithium batteries are the way to go. You will never see a hydrogen fuel cell in a cell phone.
Hydrogen wins when you need to store store truly massively amounts of excess energy which is something you cannot currently do with batteries. That is the one big thing what still makes Hydrogen interesting despite the low conversion efficiency. If you are producing huge amounts of excess energy and can't store it in battery arrays, storing it as Hydrogen at 50% round trip efficiency is still better than letting all that energy go to waste assuming you can do the hydrogen conversion cost effectively. The currently most sensible thing to do with this hydrogen is use it to power always on gas power plants to supplement solar and wind power and then use the energy to charge cars or whatever else it is you need the energy for. This, again, assumes that you can do the round trip conversion of electric energy into hydrogen cost effectively.
Hydrogen wins when you need to store store truly massively amounts of excess energy
Actually, it is usually not the best solution. Pumped storage and compressed air have better efficiency and need less capital investment. Vanadium-redox will give much better efficiency, and can scale with just a bigger tank.
If hydrogen made sense for grid storage, profit seeking companies would be doing it. They aren't.
Hydrogen storage only makes sense when weight and/or power density are more important than efficiency.
Nope. You get about 9.7MJ/L for compressed hydrogen, and about 40% of that (4.3 MJ/L) for LiPo batteries. Hydrogen is much more efficient by weight and volume.
And if you need 700+ kg of tank to store your hydrogen - you're doing it wrong. Here's a massive 850L tank that would be equivalent energy storage to about 4800 kg of batteries - and it weighs 215 kg. Not even close.
Browsing at +1 - no ACs, I ignore their posts. So refreshing!
Are you familiar with the Aquion Saltwater battery? http://aquionenergy.com/techno...
I haven't really dug into it, but it sounds like the technology is at the very least a *lot* cleaner than the existing options, and possibly no more toxic than the ambient environment.
--- Most topics have many sides worth arguing, allow me to take one opposite you.
1. For every turbine erected, cut down a tree, so the total wind blockage remains constant. Ban the planting of new trees.
Even if your comment wasn't completely absurd in the first place, the Earth loses 18.7 million acres of forests per year .
So yeah, there's already plenty of "wind changing" going on, more so than we could ever erect enough windmills to counteract.
they cannot find enough uses for the emission-free power they create
How about using all their excess electricity to make the next generation of wind turbines to replace the ones they bought from an industrialised country?
Generating their own electricity is nice, but it doesn't make them self-sufficient. They are completely dependent on places with mines, steel plants, manufacturing and development to send them the equipment to generate electricity and to maintain it. If they wanted properly sustainable energy, they would have produce the wind turbines on their islands.
But that would require a fully industrial society which their small population could not support.
politicians are like babies' nappies: they should both be changed regularly and for the same reasons
What about the combustion engine and complex drivetrain? With an electric motor you shave a lot of weight. No fuel pump/plumbing, no radiator, no water pump, no belts, no alternator, no exhaust system, very simple fixed gearbox, smaller 12V battery, no engine oil, and of course no engine block with pistons and spark plugs and all the rest of it.
Also a lot lower maintenance.
const int one = 65536; (Silvermoon, Texture.cs)
SJW, n: "Someone I don't like, and by the way I'm a fuckwit" - AC
Correct, but also missing the effect of geographic distribution. Turns out that when you have enough capacity over a wide enough area the capacity factor of the fleet as a whole goes up a lot. Throw in some battery backup to smooth output and handle peaks and you have a capacity factor close to coal or nuclear.
Obviously you still want a mix of energy sources, and long distance transmission lines, but 4x overbuild for capacity is likely excessive.
const int one = 65536; (Silvermoon, Texture.cs)
SJW, n: "Someone I don't like, and by the way I'm a fuckwit" - AC
Thing is a nice dyke across the Pentland Firth could extract enough tidal energy to power the whole of Scotland, and be utterly predictable as to it's output. Just stick in some additional pumped storage (plenty of capacity for that in Scotland) and we would be sorted. Now sure that dyke is going to cost, but they want 30 billion GBP for a nuclear power station with less capacity.