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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.
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.
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%.
I'm not against wind turbines per se, but believing that they can be used everywhere as effectively as the British Isles is a bit of wishful thinking. When isn't the British coast windy after all?
Certainly they'd be useful on the US coasts (where a good portion of the population helpfully is), but not all geographic locations are like that.
Ditto for solar: great bit of kit that should be deployed in more places, but some areas get less sun that others.
More of both, but let's be realistic as to where these things can be useful and on whether they can solve all of our energy problems.
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.
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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.
Except that the same mass of hydrogen takes up a HECK of a lot more volume.
And once you factor in the mass of the containers and other hardware needed to secure hydrogen, the advantage per mass is no longer as clear either.
Agreed - hydrogen is a difficult fuel to work with, which sets a lower limit on how far you can scale it down before competing technologies become far more attractive. I'd love to see it take off for grid-scale energy storage though. And islands like these, that don't have a lot of other options, would seem to be a good place to refine the technology.
--- Most topics have many sides worth arguing, allow me to take one opposite you.
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.
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.
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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.
Sheesh.
This isn't anything like Denmark because they don't have a cable to send the excess power anywhere. So they're going to see if storing and transporting it as Hydrogen is economical. It's not clear to me that it will be, but they seem to think it's worth a try..
Orkney is where testing is done under wet dream conditions that maximize energy production from wind, wave, and tidal flows. Population 22K, so 'energy too cheap to meter', but we've heard that before. Imagine some clever ape just came up with the idea of building dams and using water constrained outflow to generate electricity. Locals would have energy abundance until the power could be spread out. Articles would be written about how hydro dams were going to power the endless growth of industrial society. Bottomline reality check, XKCD bitches: all the hydro that exists, is being built or could be built (assuming billions of humans agree to move to higher ground) won't power life as we know it now, let alone empower continued growth. Not one hydroelectric dam has been built using hydroelectric power. Not one energy producing system on Orkney was made using alternative energy from Orkney or anywhere else. It was made, like all dams (Teslas, PV panels, industrial agricultural products aka food...) almost entirely from fossil fuels. The energy return from tidal is high, higher even than hydro, but alternative energy sources are not alternative to the larder of planetary fossil fuels we are burning through in a flash of geological time. http://www.sustainable.soltechdesigns.com/emergy-yield-ratio-matters.html
Get on the page. OP and I are referring to the energy budget of planet earth, not the energy consumption of humans on it. OP claims if we humans went 100% renewable we humans would absorb/consume all the energy in the wave, wind systems and they would stop. I call BS on that, human energy consumption is pathetically insignificant to that of the total planet. I think you know this already from the solar panel example, or from my lightning example. As we seem to share the same view, would you care for a toke
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.
Multiple-assertion citations required.
Current best processes for water electrolysis (PEM or alkaline electrolysis) have an effective electrical efficiency of 70–80%. Hydrogen fuel cells have an efficiency of 70-80%. So best case is 0.8*0.8 = 64%. Plus you need copious energy to compress or liquify the hydrogen for storage, which lowers the effective efficiency even more.
Vanadium-redox has a RTE of 65-75%.
Pumped storage has an RTE of 70-80%.
In practice, compressed air has an RTE of about 70%.
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.
Vanadium redox batteries require about 10 tonnes of Vanadium, an element priced in troy ounces per MWh of capacity. For something small like an island, just call Elon. That's the right scale for Li+. Either that or use a bunch of recycled auto batteries if you really want to save on price.
"Those that start by burning books, will end by burning men."
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
Bear in mind that these are small islands off the north coast of Scotland. They have a dialect word "yarfast" meaning "tied down so it won't get blown away". https://books.google.com/books...
You are lost in a twisty maze of little standards, all different.
Why would you want to carry around 800 kg of batteries when you could do 12 kg of hydrogen?
You forgot the weight of the hydrogen tank and the fuel cells. There are many whys. One, hydrogen is soluable in many metals which makes building effective tanks surprisingly difficult. Then there's the issue of filling via very high pressure hoses, something which is a rather different prospect from liquid hydrocarbons or just plugging in. Then there's the infrastructure required to either create or ship hydrogen. It's easy for electricity: for day to day use, you can charge from an ordinary circuit at home, with relatively few filling stations required. You're dependent on filling stations for hydrogen. There's also the lower efficiency of round tripping via hydrogen, making every refill more expensive.
People have tried hydrogen cars before. They're certainly doable. Turns out battery ones are just more practical at the moment.
PS your signature pegs you as a shrill moron.
SJW n. One who posts facts.
The problem is however very visible in the current issues we're having with CO2. The CO2 we're adding to atmosphere is insignificant compared to the natural cycle. But it's apparently enough to overcome the tolerances within the biosphere, and cause rapid enough increase of CO2 to cause a rapid global warming.
It's almost certain that same can be said about extracting raw kinetic energy from the very same system. We can likely do it to some extent "for free" because it will fit within tolerances of the system, just like we can emit quite a lot of CO2 before we overload the tolerances. But beyond that, there will be a chain reaction. So theoretically, that is most certainly an issue.
Practically, at this early stage of development of these forms of power generation, it's likely well within the tolerances, and should remain like that for a long time. But then again, that's the exact same thing that best scientists in their fields thought less than a century ago. Science will likely advance enough to be able to provide some approximation on the relevant numbers in a few decades to a century. Right now, it's almost certainly not a cause for a worry when we have much greater problems, like global warming, to deal with.
FTFA :
Today the islands are so festooned with wind turbines ...
I'm dropping any idea of visiting there as a tourist*. The place must look like an industrial estate.
* Perhaps they see that as a plus point.
"extract" .. from what and where does it go ? does it disappear? Well goodbye first law of thermodynamics.
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
I wish their site had more technical detail. It would be interesting to compare it with low temperature sodium sulphur, which is the other big player in grid scale batteries. Similarly it's pretty good on the environmental front, the only real down side is that "low temperature" means about 100C so it does require heating to operate. As ever it's a trade off between build cost, running code, efficiency and environmental sustainability.
const int one = 65536; (Silvermoon, Texture.cs)
SJW, n: "Someone I don't like, and by the way I'm a fuckwit" - AC
Why large swathes of the desert? What about all the roof space in cities? Say a 3kw system per house, millions of houses means gigawatts of power. Industrial roofing, malls, office blocks, you could build a superstructure over car parks to support panels, all that is a very large space.
I am not a robot. I am a unicorn.
Russian? Pillock? Or did you go for the double?
Would it be pure hydrogen, or would it get used to create methane, which would be easier to handle and use as a mobile fuel, especially for ferry-type watercraft?
Convert it to methane? It makes it a lot easier to store and transport.
It's not a just a way of storing energy, it's also a valuable chemical feedstock, and its synthesis will be necessary if we want to get rid of fossil fuels in the chemical industry.
Ezekiel 23:20
Hydrogen goes in a tank. https://en.wikipedia.org/wiki/...
At a density of 71 kg/m^3, and a temperature of 20 K.
Ezekiel 23:20
And if you need 700+ kg of tank to store your hydrogen - you're doing it wrong. Here's a massive 850L tank [mahytec.com] that would be equivalent energy storage to about 4800 kg of batteries - and it weighs 215 kg. Not even close.
Are you serious? That tank is the equivalent of a 100 kWh battery. Just like the one you get in some Teslas. Are you claiming that those Teslas weigh over 4800 kg?
Ezekiel 23:20
...the story doesn't mention anything about subsidies and/or tariffed rates. Is this that rarest of beasts, unique in all the world, a commercial wind turbine installation built for the purpose of generating a profit?
Of course not! https://www.theguardian.com/en...
"The Scottish government warned this week that if Westminster ruled out allowing onshore windfarms in the Western Isles, Orkney and Shetland to compete for subsidies, £2.5bn of investment would be put at risk."
Anyone who's worried that wind and solar power will have their morally elevated "sustainability" marred by fiscal sustainability can relax.
By the way, I wonder what wind and solar (and tidal in the case of the Orkenys) has done to the cost of electricity?
Minutus cantorum, minutus balorum, minutus carborata descendum pantorum.
Here is some info to back some of this up:
https://arstechnica.com/scienc...
Adding turbines would reduce the load on non-renewable energy, a net positive. In fact, the Altamont pass in the East Bay Area is a very well-utilized wind farm that could easily be expanded
The Allegheny Front in Pennsylvania is another place where wind is being exploited. Along the front, the wind pretty much never stops. And we're not finished either. Hasn't been any talk of building new fossil fuel turbines lately.
Fun stuff: Some folks have been yapping about "What do you do when the wind turbines wear out?" as if they have stumbled upon some fatal flaw. Well if you have a field of hundreds of individual turbines, you just go up and refurb or replace them one by one.
As compared to a worn out coal or gas powered turbine? I suppose they never need replaced....
The shepherds did so well protecting the flock that the sheep no longer believed that wolves existed.
Hey, I'm all for continuing to use gas and diesel! It's a great source. I am a firm believer that we are experiencing climate change, but that it is dominated by natural cycles - our little bit of CO2 in the air is not a driver of much of anything natural - just political.
However, hydrogen is quite a bit better than batteries. You said that
the same mass of hydrogen takes up a HECK of a lot more volume. And once you factor in the mass of the containers and other hardware needed to secure hydrogen, the advantage per mass is no longer as clear either.
That is not correct. Hydrogen storage, as compared to battery storage, is about 60% more efficient by volume, and around 25X more efficient by weight. Batteries are volume and weight inefficient, kind of a "last resort" thing...
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They have too much power now, at least that's what TFS stated. So if they have excess power - compression is irrelevant.
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Fuel cell. Incredibly efficient, extremely simple - and you get power right out. You don't need a reciprocating engine.
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Hydrogen has a LOT more energy (about 75X as much) by weight than LiPo batteries. Changes things a bit, doesn't it?
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See above - hydrogen tanks and valving is really not that heavy. A couple hundred kg to carry the equivalent of a tonne or two of batteries. Hydrogen has ~75X the power density by weight - that leaves a BIG overhead factor for a tank or valving system. As far as infrastructure - we have one now, with tens of thousands of refilling stations all around.
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If they're using electrolysis, I would assume pure hydrogen. Synthesizing methane/ethynol/etc. involves considerably more complicated infrastructure, while hydrogen is quite simple and requires only water as an input material - you can synthesize it with nothing more than a glass of water, a 9V battery and some very corrosion resistant electrodes. Presumably a grid-scale system would be more sophisticated, but a lot simpler than creating a more complicated fuel.
--- Most topics have many sides worth arguing, allow me to take one opposite you.
There is another tank on that page, that stores 52L of hydrogen. That's about equivalent to a 132kW battery - double the typical Model 3. And the tank weighs in at 38 kg. My point stands - compressed hydrogen is MUCH more efficient space and weight-wise than batteries.
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Not really, if you pull your numbers out of your ass like you just did above.
Ezekiel 23:20
Check the bottom tank on that page - 700 bar, 52L. Given there are 9.17 MJ/L for compressed hydrogen, that's about 476 MJ of energy. At ~278 Wh per MJ, that is equivalent to a 132 kWh pack - about double a Model 3. So a small, 38 kg tank has the same energy storage as a pair of Model 3 battery packs. Tell me again why batteries are good? Less energy density (by weight or volume), a lot longer to charge, and provably more damaging to the environment (the environmental cost of making a 132 kWh battery pack is huge compared to the electrical energy needed to compress 52L of hydrogen).
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Run the numbers yourself. A little 38kg, 52L tank holds about the same energy as 132 kWh of batteries (given that there are 277W per MJ). But that's OK - stay ignorant, my friend - stay ignorant!
Browsing at +1 - no ACs, I ignore their posts. So refreshing!
That is not correct. Hydrogen storage, as compared to battery storage, is about 60% more efficient by volume, and around 25X more efficient by weight.
...and the tank you've linked above is comparable to a 100 kWh Tesla automotive battery, at about half the mass and twice the volume. So it's not 60% more efficient by volume, but 50% LESS, and not 25x more efficient by weight, but only 2x as much. Liar, liar, pants on fire...
Ezekiel 23:20
Agreed on wanting more information. From what I recall, possibly from other sources as well, the Aquion battery is made from relatively common, nontoxic materials, can be made for a similar price to lead-acid, with a similar energy/weight ratio, but lower energy/volume. So not really suitable for mobile applications, but with great potential for grid and home use.
And then there's the unrelated liquid metal batteries - I don't recall hearing of any commercially available models yet, but they seem to hold the promise of simplicity, effectively unlimited lifetime (since the normal mechanical damage associated with charging can't form in liquid) , and extremely high charge and discharge rates. Of course, operating at temperatures that keep the metals liquid makes them unsuitable for many/most applications, but the grid potential is immense.
--- Most topics have many sides worth arguing, allow me to take one opposite you.
There is another tank on that page, that stores 52L of hydrogen. That's about equivalent to a 132kW battery - double the typical Model 3. And the tank weighs in at 38 kg.
*That* tank is equivalent to a 35 kWh battery, HALF the typical Model 3. TWO of them would be equivalent to a Model 3. A 200 kW fuel cell stack would add another 100 kg. All three would occupy about 250 liters of volume. Model 3's battery has around 360 liters, making it 45% mode voluminous. However, it can *also* be placed more out of way, since its smallest element is less than ten centimeters long, whereas those tanks have a 33 cm diameter. It actually forms Model 3's floor.
Ezekiel 23:20
Run the numbers yourself. A little 38kg, 52L tank [mahytec.com] holds about the same energy as 132 kWh of batteries
Well, I did. That tank is cited as containing 1.5 kg of hydrogen, which is worth around 35 kWh in your typical fuel cell, NOT 132 kWh. Your math skills suck.
Ezekiel 23:20
Hydrogen has ~75X the power density by weight
Absolutely not. Two tonnes of batteries today have a power output of almost 2 MW. That requires around a 1000 kg fuel cell today. So it's at best 2x as much, and only if you completely discount the storage which might easily almost double that. So it's maybe in the 1.5x ballpark for power density.
Ezekiel 23:20
> Today batteries are better in every possible way except possibly air travel
What about the materials used to make batteries? Are those materials available in near limitless amounts?
What about the processing and disposal of those materials?
I would think that electric is also quieter.
But what about the material to make the battery? If the whole world started using batteries for everything, would there eventually be a shortage of such material? Also have to consider the disposal of such material. Is such material considered hazardous?
Well, there's for example enough lithium in sea water to make a 170 MWh battery for every person currently living on this planet. Is that enough?
Ezekiel 23:20
Why large swathes of the desert? What about all the roof space in cities? Say a 3kw system per house, millions of houses means gigawatts of power. Industrial roofing, malls, office blocks, you could build a superstructure over car parks to support panels, all that is a very large space.
Because that only gets you about 10% of the way there. Cities don't actually cover a huge amount of space. So when some says it will take 12% of the land to put solar, you should think that means 2x as much land use by humans and much less for nature. Also, GW are nice but we measure grid level electricity usage in 1,000s of terrawatt hours. Look into the problem yourself and you will start making fun of everyone for their lack of math. Hint, more solar and wind means natural gas.
"Those that start by burning books, will end by burning men."
Hint, more solar and wind means natural gas.
It's one way to deal with intermittency, but the requirement can be offset with a balance of renewables and continental-scale HVDC too, demand shaping, storage, and some residual generation from other sources, for example natural gas, hydroelectric and perhaps nuclear to provide an assured baseline such as the reduced demand overnight when solar does not generate and there is a chance wind will not.
The Fully Charged YouTube channel has a number of reports from Orkney. https://www.youtube.com/watch?v=FXe1hBvlylw&list=PLzD0K2OhbVfGCtXeA6iAQ3ufh2W84t2Gy
Currently most hydrogen is created from methane, so turning it back into methane seems fairly pointless. If you could create hydrogen from water and create other fuels with it, employing carbon, then methane may not be the best choice either as it also needs to be compressed to provide decent volumetric storage, even after it has been produced. You'd really want to go for longer chain molecules for storage and room temperature, but then you lose benefits such as potentially lower pollution, but then burning hydrogen in air still results in NOx which is now recognised as an issue. You're better off working on improving electric cars from an efficiency and pollution perspective.
All the grid scale stuff is abundant and easy to recycle, e.g. lithium and sodium.
const int one = 65536; (Silvermoon, Texture.cs)
SJW, n: "Someone I don't like, and by the way I'm a fuckwit" - AC
Check the bottom tank on that page - 700 bar, 52L. Given there are 9.17 MJ/L for compressed hydrogen, that's about 476 MJ of energy. At ~278 Wh per MJ, that is equivalent to a 132 kWh pack - about double a Model 3. So a small, 38 kg tank has the same energy storage as a pair of Model 3 battery packs. Tell me again why batteries are good? Less energy density (by weight or volume), a lot longer to charge, and provably more damaging to the environment (the environmental cost of making a 132 kWh battery pack is huge compared to the electrical energy needed to compress 52L of hydrogen).
Most people don't want their car to blow up. Hydrogen is difficult to store and requires you cooling it so it actively requires continuous input of energy to keep it stored. Its best use is for grid scale storage but requires certain energy market conditions to be profitable. Basically, the energy prices need to swing at least 2x per day due to other intermittent power sources. Good news is that that happens in CA and Germany most days. Bad news is that nobody other than energy traders want the prices to swing that much everyday so its hard to invest in up-front infrastructure costs when you can't be certain such market conditions will continue. Same problem for most other storage schemes, unless you can be certain that energy market will continue to be very volatile, you can't risk such a large amount of capital on something that might become useless at some point in the future. Operating the Helms pumped storage is like printing money for PG&E yet there are no plans for them to build another one. There are 2 private plans for pumped hydro in CA but they are small, years away, and highly speculative as their cost of raising capital was on par with nuclear.
"Those that start by burning books, will end by burning men."
See above - hydrogen tanks and valving is really not that heavy.
quote the numbes then. It's not going to be as heavy overall but it's not as light as you're making out. It's not a 75x difference.
A couple hundred kg to carry the equivalent of a tonne or two of batteries.
It's reached the stage of needing actual hard numbers.
Hydrogen has ~75X the power density by weight
ITYM energy density.
that leaves a BIG overhead factor for a tank or valving system.
Well no. Hydrogen has more or less fixed costs for the valving and fuel cells, and a linearish scaling for the tanks (surface area goes by the square, volume by the cube, but the wall thickness has to increase too) and actual gas. The scaling factor is smaller than batteries.
The batteries have a zero overhead and a higher linear scaling factor.
But er're not in the unlimited region, so there's a tradeoff. What is the weight of a BEV versus the weight of an equivalent HEV, all things considered?
As far as infrastructure - we have one now, with tens of thousands of refilling stations all around.
No, there are 39 in the entire US (mostly in california)
https://www.greencarcongress.c...
SJW n. One who posts facts.
Agreed on wanting more information. From what I recall, possibly from other sources as well, the Aquion battery is made from relatively common, nontoxic materials, can be made for a similar price to lead-acid, with a similar energy/weight ratio, but lower energy/volume. So not really suitable for mobile applications, but with great potential for grid and home use.
And then there's the unrelated liquid metal batteries - I don't recall hearing of any commercially available models yet, but they seem to hold the promise of simplicity, effectively unlimited lifetime (since the normal mechanical damage associated with charging can't form in liquid) , and extremely high charge and discharge rates. Of course, operating at temperatures that keep the metals liquid makes them unsuitable for many/most applications, but the grid potential is immense.
Very poor energy density. 1/100th that of Lithium-ion. Basically would require more land than the solar or wind that its backing up per watt hour of storage. Its nice for remote small/cheap solar though and very environmentally friendly.
"Those that start by burning books, will end by burning men."
Hydrogen has about 142 MJ per kg, about 3X that of diesel and gasoline.
Yes, but the issue is MJ/litre, not per kg in a practical sense for creating cars.
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.
Assuming that's just the weight of the tank, it contains 60kg of liquid hydrogen. So the energy contained is 60*142MJ in 215+60kg, so the actual energy density is 31MJ/kg. For petrol that's still about 180L, or 40 gallons, which is not really typical of the typical car. So if you scale it down by a factor of 2.5 to a more typical size, the petrol tank will weigh only a few kg, so petrol density will fall to maybe that 31MJ/kg, but the storage of hydrogen will be less efficient as the surface area of the tank will be relatively greater. So in terms of energy density, taking into account containment, hydrogen's a bit worse than petrol. Not hugely so, but significantly. Then you have to take into account the need to carry around about 80kg of containment for a car, which is an extra person always in the car, which will affect MPG, plus the size required and the extra drag induced.
This is not to say hydrogen isn't viable, just that it's not nearly as good as you are suggesting in terms of energy density.
Hey, I'm all for continuing to use gas and diesel! It's a great source. I am a firm believer that we are experiencing climate change, but that it is dominated by natural cycles - our little bit of CO2 in the air is not a driver of much of anything natural
CO2 has pretty much doubled. By what mechanism does that not have the effect now it had in the past, and not the one demonstrated by physics?
They may have too much power in the Orkneys but unless it is transported to the mainland it's not necessarily particularly useful for the generation of hydrogen, except for the Orkneys, as the islands are remote. The issue is more than a grid hookup to the mainland is required so the Orkneys can sell the energy to mainland Scotland, and that's likely to be easier to manage than a plant to compress and pipe hydrogen to the mainland where it wouldn't currently have an obvious use, or filling up ships with bottles of the stuff.
476MJ in 38kg, plus the mass of the hydrogen, about 3.7kg for the hydrogen. So that's 476/(38+3.7)=11MJ/kg, compared to petrol, with a tank, of about 30MJ/kg. It's not going to win against denser fuels.
Fuel cells are about 50% efficient, so the 11MJ/kg hydrogen tank produces about 5.5MJ/kg at the wheel (assuming no other losses). A good diesel or petrol car is about 30% efficient, so it's producing 9MJ/kg at the wheel, based on fuel and containment weights. You'd have to take into account the overall vehicle efficiency, so weight of transmission, engine, fuel cell, overhead of heating and cooling, etc., to make a full comparison fully fair. You might get some improvement for hydrogen if using a fuel cell as it could use an electric drive train that could be shared with electric cars in a fleet.
Look further down the page - a 38kg small tank with 132 kWh storage.
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The fact it's doubled, and we've seen nothing more than temperatures around the time of the 1930s... Perhaps there is more to the system than the simplistic model - like the impact of clouds, for instance?
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Link above showed the tank to be 38 kg.in weight. For a ~132 kWh storage tank. That's pretty darn light.
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How heavy is the battery pack in a Model 3? We know that two of those battery packs are about the same as the 38 kg tank I linked - are you claiming that the battery packs on the Model 3 are just 38 kg, or even 76 kg?
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What about the fuel cells? I'm not going to deny that hydrogen will be lighter than bateries, but someone upthread expressed incredulity and asked why when there is a 75x difference. There is't a 75x differenece all things considered and the additional downsides outweigh the difference in energy density.
SJW n. One who posts facts.
From the energy system of biosphere and into rotational motion of the wind turbine.
That would require a tank capable of storing 6 kg of hydrogen, but the table for that tank says 1.5 kg.
Ezekiel 23:20
How heavy is the battery pack in a Model 3?
Around 360 kg. However, it's designed to be flat and have a low CG, so it's mostly out of the way (under your feet). Cylindrical tanks and the fuel cell stack would require some room either in the front or in the back.
We know that two of those battery packs are about the same as the 38 kg tank I linked
We know it's the other way round; you need two of those tanks with 1.5 kg hydrogen in each to store an equivalent amount of electricity that one Model 3 battery pack can store, plus a 100 kg fuel cell to power Model 3's 200 kW motors, or a 170 kg fuel cell to power the 350 kW performance model. So it's something like 180 kg or 250 kg for the hydrogen equivalent of the 360 kg battery pack. Is a 110-180 kg mass difference relevant? I suppose you could argue that it's 10% of the mass of the vehicle, but that doesn't seem prohibitive. It's also easier to "refuel" at home. Plus, your hydrogen vehicle would *still* require a battery for regenerative braking, so the difference shrinks even further.
Ezekiel 23:20
He overestimates the energy per tank by a factor of four anyway; the page he links cites it as a tank for 1.5 kg of hydrogen. And even if he was right, a 132 kWh battery pack would still not weigh 38*75=2850 kg. That would make the 100 kWh Teslas impossible. They do NOT weigh four tonnes empty.
Ezekiel 23:20
Oh, sorry, a small mistake... The *volume* of the Model 3 battery pack is 360 liters, the mass is around 450 kg. So it's a 200-270 kg difference, before you add a battery into your fuel cell vehicle for recuperation. A typical hybrid car can easily have a 70 kg battery for that purpose (Prius has a 80 kg, 4 kWh battery, for example). So that shrinks it down back to 130-200 kg difference between a BEV and your FCEV.
Ezekiel 23:20
So we agree - you need a lot more mass and volume of batteries to equal a hydrogen tank. The hydrogen tank can be filled in a matter of minutes, and with a fuel cell approach you can use electric motors - no need for an ICE. Again, why would you want batteries if hydrogen is available?
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We don't even use LNG in vehicles, only CNG because dealing with any cryogenic fuel is counter-productive if you have to store it for any length of time. Add to that the fact that there is more hydrogen in a litre of anhydrous ammonia than there is in a litre of liquid hydrogen. Unless you need a really high Isp engine, LH is a terrible fuel.
Hydrogen storage, as compared to battery storage, is about 60% more efficient by volume
I was comparing hydrogen to ICE, not to batteries. Hydrogen surely beats batteries in many ways, but I don't see it having many operational advantages over petrol/diesel.
The fact it's doubled, and we've seen nothing more than temperatures around the time of the 1930s...
It's much warmer than the 1930s. What evidence do you have for it being no warmer (temperature records for just the USA don't count as the USA is a very small proportion of the globe).
Perhaps there is more to the system than the simplistic model - like the impact of clouds, for instance?
You do realise that clouds are modelled, don't you. And you do also realise that Hansen's projections from 1988, for what is very close to the RCP 8.5 emissions profile we've actually seen have been very accurate. So now you need to explain why you think that the models, which have been accurate over the last 30 years are somehow not accurate.
Because unlike the hydrogen tank, the battery is filled in *seconds* of your time. You just plug it in at home and don't care about it. Also, no need to drive around to find a hydrogen pump.
Ezekiel 23:20
I have, and that's yet another problem added to the two I mentioned. Fortunately I'm not the one suggesting that we should be doing that.
Ezekiel 23:20