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Mark
Joined: 13 Dec 2007
Posts: 845
Location: NW England
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emordnilap
Joined: 05 Sep 2007
Posts: 13546
Location: way out west
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 Posted: Fri Mar 10, 2017 11:19 am Post subject: |
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| Little John wrote: | Primarily, in what way does hydrogen consumption bring overall energy consumption levels down? Especially, since it takes more energy to harvest hydrogen into a usable form than is contained in the hydrogen itself.
Secondarily, assuming the answer to the above is that is doesn't bring the overall energy consumption down, but it does allow storage and transportation of renewable energy in a way that is not currently possible, then I need this explaining in more detail because I don't currently see how hydrogen does this any better than any other renewable energy storage/transportation method. |
Maybe it's in the same way as tar sands don't make sense at all - apart from the end product is a more (currently) usable product than its inputs. Likewise, from an input versus output point of view, a simple one-use battery is a thoroughly stupid idea.
In other words, humans selfishly miss the bigger picture, as usual.
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The human appears to have no idea what its ideal diet should be; has self-inflicted diet-related diseases; causes extensive environmental destruction through basic food production & creates pathogenic infestations that widely infect its food supply. |
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emordnilap
Joined: 05 Sep 2007
Posts: 13546
Location: way out west
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| Posted: Fri Mar 10, 2017 5:30 pm Post subject: |
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The human appears to have no idea what its ideal diet should be; has self-inflicted diet-related diseases; causes extensive environmental destruction through basic food production & creates pathogenic infestations that widely infect its food supply. |
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Little John
Joined: 08 Mar 2008
Posts: 5428
Location: UK
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| Posted: Fri Mar 10, 2017 10:40 pm Post subject: |
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I have lifted this summary directly from that report:
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Hydrogen has a key role to play in the energy system of the future, where supply (centralised / decentralised / renewable / low carbon / large scale / small scale etc. etc.) and demand are flexibly and responsively interconnected, and the links between previously disparate sectors (heat, power, transport) are optimised. |
This is waffle with absolutely no concrete details whatsoever about how hydrogen is to play this "key role".
| Quote: | | More specifically, the conversion of currently wasted renewable energy to hydrogen via electrolysis offers a range of grid balancing services, as well as helping to deliver decarbonisation across heat, power and transport. |
What wasted energy and how is its conversion to hydrogen more energy efficient than other methods of conversion? Again, this is not explained.
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1TWh of electricity can produce nearly 18,000 tonnes of hydrogen, which is sufficient to fuel 90,000 hydrogen fueled cars each travelling 12,000 miles per year. |
This means nothing in the absence of a comparison to the alternatives. Not least of which is to use the electricity directly to power such vehicles.
| Quote: | | Delivering the right mix of storage solutions, including hydrogen, requires a rigorous review of the full energy system, so that current barriers can be addressed holistically to ensure the most cost effective outcome. |
More waffle
In short, the only issue that could possibly make something like the mass adoption of hydrogen fuel make any sense would be if there was an immense amount of energy leakage from elsewhere in the system such that hydrogen provided the basis for storing that energy in a way that would be otherwise extremely difficult to achieve. If so, then I would love to hear about it and specifically the numbers involved. |
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johnhemming2
Joined: 30 Jun 2015
Posts: 1782
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| Posted: Sat Mar 11, 2017 8:26 am Post subject: |
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Hydrogen can be good storage for people who are not on the electrical grid. That, however, is not mass storage.
https://en.wikipedia.org/wiki/Fuel_cell
| Quote: | | The energy efficiency of a fuel cell is generally between 40–60%, or up to 85% efficient in cogeneration if waste heat is captured for use. |
Similar to a thermodynamic cycle really except that you end up with electricity rather than torque. |
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clv101
Site Admin
Joined: 24 Nov 2005
Posts: 7499
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| Posted: Sat Mar 11, 2017 9:51 am Post subject: |
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| johnhemming2 wrote: | | Hydrogen can be good storage for people who are not on the electrical grid. That, however, is not mass storage. |
Can it really? Do you know of anyone generating and storing hydrogen off grid? Compression, material science and risk of explosion are three things that seem to make hydrogen a particularly poor energy storage medium for those off-grid.
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johnhemming2
Joined: 30 Jun 2015
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Catweazle
Joined: 17 Feb 2008
Posts: 2190
Location: Little England, over the hills
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| Posted: Sun Mar 19, 2017 11:40 am Post subject: |
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| This is more useful to stop people within the M25 from choking than it is to actually reduce global emissions. Business as usual. |
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adam2
Site Admin
Joined: 02 Jul 2007
Posts: 5926
Location: North Somerset
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| Posted: Sun Mar 19, 2017 12:30 pm Post subject: |
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I feel able to state as a certainty that at present batteries are better than hydrogen for domestic scale off grid energy storage.
Lead acid batteries are cheap, simple and sold everywhere, unless abused they are reasonably safe.
The used batteries are recycled via any scrap metal dealer, and the price of lead is an incentive to actually recycle them.
Energy storage via hydrogen requires electrolysis plant, a high pressure compressor safe for hydrogen, a high pressure tank, and a fuel cell. NONE of this equipment is available affordably, and "off the shelf" and suitable for DIY installation. The pressure vessel will require formal testing and certification at significant expense. And you still need a battery as well, though smaller.
Better still is to reduce the need for energy storage in off grid premises by so far as possible using the energy as available.
It is much cheaper to store dirty laundry until energy is plentiful, than to store electricity in a battery bank to work a washing machine on demand.
It is cheaper to run an electric grain mill when energy is plentiful and to store the flour, then store electricity and mill on demand.
It is much cheaper to store heat for space or water heating, than to use stored electricity for heating.
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