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London Climate Protests

Discussion in 'Speaker's Corner' started by crinkleshoes, 17 Apr 2019.

  1. Angilion

    Man of Honour

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    The article 4K8KW10 linked to stated that the current offshore wind capacity (theoretical maximum, assuming perfect conditions) of the USA is 50MW.

    Wikipedia says it's 42MW. https://en.wikipedia.org/wiki/List_of_offshore_wind_farms_in_the_United_States

    CNBC says it's 30MW. https://www.cnbc.com/2019/12/13/us-has-only-one-offshore-wind-farm-but-thats-about-to-change.html

    Wikipedia includes the 12MW offshore wind farm that the CNBC article says is due by 2022. Maybe it was finished early.

    I think you might well be right, but I hope something less wasteful can be devised. Hydrogen is a very bad choice for energy storage, but it might be the only scalable option. Hopefully not, but it might be.
     
  2. Mercenary Keyboard Warrior

    Capodecina

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    I think the point of hydrogen is it will be an alternative fuel, certainly for things like HGVs or similar, I could imagine longer range cars being hydrogen/electric hybrids

    Energy storage I posted a link on here sometime back about a site liquifying air. So when excess electricity it just compresses the air into a liquid form and stores in a tank. When demand goes up the process is flipped and the liquid air is used to expand driving turbines generating electricity.
    It was IIRC 70% efficient. Which whilst not great bring options. Highly scaleable, doesnt require anything rare earth. Leaks would be somewhat less of an issue than most other known storage apart for of course a catastrophic failure would be somewhat nasty in the absolute local area to the tanks.

    Ah found it
    https://www.highviewpower.com/wp-co...view-Brochure-November-2017-Online-A4-web.pdf
     
  3. Angilion

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    Hydrogen is the opposite of a fuel - it requires far more energy to create, store and transport hydrogen than can be obtained from it. It might be used as a very wasteful energy carrier for vehicles, but it can't be a fuel unless something radically new is invented.

    The existing systems are ~40% efficient, which is terrible. The 70% efficient systems are theoretical. It looks promising, though. The main loss is through the changes in temperature caused by compression and expansion of air and that's well understood and could be managed a lot more effectively than is done in the existing systems. Put the system in a disused mine and there's a lot of space without borking the local ecosystem and containment in the event of a catastrophic failure.
     
  4. Mercenary Keyboard Warrior

    Capodecina

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    Ok I have seen better on the efficiency, be good to see some other sources, got some please?

    When you consider :
    "Modern gasoline engines have a maximum thermal efficiency of more than 50%,[1] but road legal cars are only about 20% to 35% when used to power a car. In other words, even when the engine is operating at its point of maximum thermal efficiency, of the total heat energy released by the gasoline consumed, about 65-80% of total power is emitted as heat without being turned into useful work, i.e. turning the crankshaft.[2] Approximately half of this rejected heat is carried away by the exhaust gases, and half passes through the cylinder walls or cylinder head into the engine cooling system, and is passed to the atmosphere via the cooling system radiator.[3] Some of the work generated is also lost as friction, noise, air turbulence, and work used to turn engine equipment and appliances such as water and oil pumps and the electrical generator, leaving only about 20-35% of the energy released by the fuel consumed available to move the vehicle."

    assuming we are talking of scalign renewables up and up and up, so having large excesses and large troughs having the requirement to be able to store the excesses even 40% seems fine to me

    I think you may have your own definition for fuel there.
    Wiki states "A fuel is any material that can be made to react with other substances so that it releases energy as heat energy or to be used for work." Which would mean that hydrogen is a fuel
     
  5. PlacidCasual

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    I'd have to do a bit of research but my gut feel concern as a mechanical engineer is that physical storage like compression or heat are woefully low in energy density when compared to chemical reactions. So whilst I blasé about storage costs for hydrogen the storage costs for liquid air could be very high compared to hydrogen. The expansion heat requirements are not insignificant and the maintainability of the systems will not be minor. The lack of moving parts for fuel cells is a major advantage in this regard.
     
  6. D.P.

    Caporegime

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    Coal power plants are only about 30% efficient
     
  7. MikeTimbers

    Soldato

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    Location: New Eltham, London

    We need way more tidal power as a country. Very disappointing to have seen that harbour tidal wall barred by government in Wales. Reliable energy generation irrespective of season or weather. Unless something happens to the moon, guaranteed for "ever".
     
  8. PlacidCasual

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    This is inaccurate. Even with FGD Drax will be 37%+ efficient. A new build coal station super high critical can achieve high 40’s% efficient before FGD, SCR or CCS. A good new single shaft CCGT will be 59-60% thermally efficient.
     
  9. Angilion

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    I'm not talking about the theoretical efficiency of the theoretical compressed air energy storage systems referred to in the PDF you linked to. The theoretical efficiency of those theoretical systems is ~70%.

    I'm talking about the compressed air energy storage systems that actually exist, such as Huntorf. Which has an efficiency of ~40%. Here, for example, is a paper regarding what the efficiency is and how it might be improved.

    https://warwick.ac.uk/fac/sci/eng/r...esentations/lueckert_caes_london_12062016.pdf

    That would be relevant if people were proposing to use petrol engines as bulk energy storage for the grid. Which nobody is doing. Because (amongst other reasons) it's not efficient enough.


    If you give me £1000 and I give you £300 of it back, then I have given you some money. Which would mean that I am giving you money.

    But I wouldn't really be giving you money, would I?
     
  10. Mercenary Keyboard Warrior

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    You might not have been, but it seems a reasonable thing to see where they could likely get to.
    Shock horror as things can be significantly improved from early versions
    Seing as I was the one who brought it up maybe we should not automatically revert to what you believe as opposed to what anyone else thinks by default, no?

    Was really to just get a benchmark in place, for how low conversion of energy is accepted as ok.

    I suspect a lots of fuels are a lot lower on actual efficiency when taking all energy used to make them available and when their actual percentage of actual energy converted into the task at hand (ie ignoring wasted heat etc) than people suspect.

    I have no idea, literally no idea how you manage to turn that.

    So maybe link something that supports your view because right now your view seems to go against dictionary and wiki type views.
    I have never heard of anyone suggesting to qualify as a fuel it needs to return more energy than is used to make it available.

    That tends to be an efficiency measure not a measure of if its a fuel to me.

    Seems a very odd view to me.
     
  11. Angilion

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    You claimed that existing systems had a 70% efficiency. You stated that such systems exist, now, in the present. That was an untrue statement.

    I was very restrained in my response. I don't have to be. If you continue to spew out silly insults that have no connection to reality, I won't be as restrained in the future. Or I'll just put you on ignore. Whichever I see fit to do at the time.

    What I will not do is give unthinking and uncritical support you demand for whatever theoretical systems you promote.

    Note my original comment on the theoretical energy storage system you wrongly claimed exists:

    What we need is real solutions to problems, which requires acknowledgement of those problems. Not adoration.

    But you chose a benchmark for a completely different situation. Supplying energy to a vehicle is very different to bulk energy storage for the grid. Firstly, the efficiency of grid scale storage will have a bigger effect. Secondly, grid scale storage doesn't have to be highly mobile so it should have higher levels of efficiency. The two contexts are very different. It would be good to have more efficiency energy carrying for vehicles, but it's less important and much harder to do.

    I think you're right about that. There's a definite trend to use a theoretical maximum efficiency rather than a real world usage efficiency.

    One is an energy source. The other is an energy carrier. I used a simple analogy to illustrate the point.

    Seems like a very sensible view to me. There is an important difference between an energy source and an energy carrier. You can call them both anything. "Fuel". "Bob". "Wibbly doodad". Anything at all. But they remain different things.
     
  12. Mercenary Keyboard Warrior

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    You seem very angry about something not sure what exactly, I did say IIRC.
    You can be as restrained as you like or not.
    Ignore me if you want, I dont care, if it makes your happy fire away princess.

    Again I disagree my point was as a society we accept poor energy efficiency, the use matters little.

    So even if we were at 40% now its still not materially out of line with existing tech. It seems a somewhat bizarre problem to have that the efficiency of conversion is low when we accept this poor level for other things.
    I am sure being 99.999% would be better but if thats not achievable then if the best we can do is 40% then so be it.

    I mean you seem to be arguing that theoretically 70% is achievable so whats the issue here.

    Your analogy was terrible and irrelevant to the matter at hand.

    It might make sense to you, I guess.
    For the consumer they are all energy sources, where they come from, how they are formed, which physical form they present in, are all somewhat irrelevant to what they actually present as to the consumer.

    https://www.energy.gov/eere/fuelcells/hydrogen-fuel-basics

    Repeatedly this site refers to hydrogen as a fuel. IIRC fossil fuels are also referred to as energy carriers since their form defines that function.
     
  13. 4K8KW10

    Sgarrista

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    "Climate change and falling prices are driving a revolution in solar, wind, and other renewables. Here's everything you need to know:

    Can renewables replace fossil fuels?
    Renewable energy sources like solar, wind, and hydroelectricity are already overtaking fossil fuels as the dominant means of power generation in some parts of the developed world. In 2019, 72 percent of power plant additions utilized renewables, according to the International Renewable Energy Agency (IRENA). For the first time, the European Union generated more electricity (38 percent) from renewables in 2020 than from fossil fuels (37 percent)."
    https://theweek.com/articles/967613/boom-green-energy
     
  14. PlacidCasual

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    This is true but it underplays how vital fossil fuels remain and the cost we are having to bear to achieve it. We still have enough fossil and nuclear to back up peak demand but displace it with lavishly subsidised renewables. The truth is without the market being rigged in their favour and the subsidies no renewables would exist they’re business plan would be destroyed every time the wind stops. I’m not saying they aren’t worth pursuing but let’s not overplay how far we’ve come. If every fossil plant turned off for the day tomorrow society would fall apart.
     
  15. Murphy

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    If only there was some way to store the energy they produce.
    Yea and if everyone stopped using steam power and gas lighting for day back in the 1800's society would've also fallen apart.
     
  16. JeditOjanen

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    Hydrogen vehicles fall into the category of redirected energy use. They aren't more efficient than petroleum vehicles, but they remove the pollution of the energy creation from the cities where the vehicles are used to locations where it doesn't matter as much.

    That said, hydrogen buses are scary as hell. They sneak up on you. Something so big shouldn't be so quiet.
     
  17. 4K8KW10

    Sgarrista

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    Hmm, probably the wind never stops in the North Sea.
     
  18. Mercenary Keyboard Warrior

    Capodecina

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    So your saying since the 70s something has changed and when they had rolling blackouts then they were somehow different to now?
     
  19. PlacidCasual

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    Simply not accurate. North see lows in winter are a frequent event. Statistical analysis shows we should expect 3 three day periods each winter where wind generation falls below 10%, one of which will probably be below 5%.

    In response to the other comments my comment about the criticality of fossil power was in respect to getting carried away with headlines about majority renewables and fossil free days. They are only possible because the market favours renewables in law not on a commercial basis, contracts make them sure fire investments and the Government is paying to keep fossil power hanging around to save us when the wind don’t blow.
     
  20. Mercenary Keyboard Warrior

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    Yeah as much as we need to move to renewables, i think thats not up for debate, its going to need :

    A vast oversupply for the low periods, I mean heavily overcast not very windy days are uncommon but not like 1 in 10 years (snowy days being a good example)
    or, a backup, but how will this be financially viable
    or, enough viable off peak storage to provide a few days worth of capacity

    Which is where the hydrogen bit makes a lot of sense. It can be used to generate a strong supply of "fuel" when there is capacity, but can be turned off for the odd occasions of there being sustained lack of input to the grid
    A more joined up, active, variable priced grid should hopefully also help with people being encouraged to use the peaks and avoids the troughs of generation.
    Certainly those less well off will be highly incentivised by this

    The other equation could come from international lines. The suns always shining somewhere, the winds always blowing somewhere etc Whilst iirc the realistic range is somewhere in the very low 1000s of miles for supply right now its not impossible this could go up a lot.

    We are probably approaching the point where switching the balance much further is going to get interesting.