Comments by "Mikko Rantalainen" (@MikkoRantalainen) on "The Big Misconception About Clean Energy" video.

I agree. Finally somebody understands that the only realistic long term objective is to allow everybody to use more energy but do it in sustainable way. As for the sensible ways to do that, wind and solar need LOTS of energy storage capability, nuclear and hydropower are basically the only green energy sources that do not require additional energy storage. We should be building Tesla Megapacks or similar stuff everywhere right now. That's because nuclear (fission) power is not sustainable either with current light water reactors and all hydropower that can be practically built has already been built. The whole world could go with solar and wind if we had good enough energy storage capability. As in ability to store electricity for half a year. One possible solution is to build so much solar and wind that you can use extra electricity to generate artificial fuel (basically get hydrogen with electrolysis with water, combine with CO2 from various sources to generate ethanol which is very stable and easy to store for long term storage). Forget people talking about storing hydrogen. The tanks required for that are so expensive that it makes zero sense. The big problem with liquid energy storage (as in fully synthetic ethanol or methanol or gas or diesel or kerosine) is that we don't have fuel cell technology for the scale we need. We would need 500 MW fuel cells when the current state of art is close to 1 MW for hydrogen and probably way less than 0.1 MW for ethanol.
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@davestagner I think flow batteries with huge tanks would be a nice solution in the long run for grid storage. However, we need to start doing something today and huge Li-ion fields are proven solution that does work. It's more expensive than some potential future solutions but those future solutions may still turn out to be sour. I don't think that we should build just li-ion systems in long run because that technology is obviously far from perfect, too.
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@davestagner I totally agree. The reason I keep asking about efficiency is that when you combine electrolysis to generate the hydrogen, some yet-undefined process to convert hydrogen to combustible fuel and regenerating electricity after storage, you have to multiply efficiency of each step to get the total efficiency. I think you could get close to 40% for fuel to electricity step at least in theory, electrolysis is about 70% so these combined already puts max efficiency to 0.4 * 0.7 = 0.28 or 28%. The process that converts hydrogen to combustible fuel is only going to reduce the total efficiency. And I want electricity at all times, not only when it's windy or sun shines, so the whole system must be designed and implemented for the worst case situation. And that's when you have to generate your whole peak power purely from the fuel. And it currently seems that even 5x the price is way too much for the market to bear, which would be possible with 20% total efficiency. An max theoretical efficiency with energy storage system in fuel format is close to 28% as I explained above. If somebody can come up with a catalyst that improves the efficiency of electrolysis and we can produce e.g. high efficiency direct methanol fuel cells, then situation might change. A possible alternative is to simply manufacture 10x cheaper solar panels and use very ineffective process to generate the fuel for the storage and worst case usage. 10x cheaper solar panels do not happen fast, though.
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@rjfaber1991 I agree that I presented a bit simplified version but the major point I was trying to express is that we need energy storage systems. Everything else is easy and there're lots of possible solutions there. And I totally agree that we shouldn't use just a single method for everything.
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@rjfaber1991 I think we mostly agree, indeed. As for the hydrogen, I think it's poor storage medium but it might be usable for short term storage when you don't need lots of storage capacity nor high current output. The problem with pure hydrogen is that you have to keep it really cold or it cannot stay in liquid form. And in gaseous form it leaks through even metal walls and requires really heavy and expensive tanks. One interesting behavior of pure hydrogen is that even in liquid form it contains less hydrogen per litre than ethanol in bucket in room temperature. That alone is enough to make it pretty poor energy storage medium. As an extra problem for hydrogen, the fuel cell technology is still highly expensive. Unless I've misunderstood something the fuel cells are even more expensive than the hydrogen tanks. And I'm talking about "green" hydrogen here (that is, hydrogen created with electricity instead of from natural gas or other fossil sources). If you still have some fossil processes that output hydrogen as side-effect, it's definitely sensible to use that hydrogen for energy instead of venting it into the atmosphere.
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@vblaas246 Is there any public info about real world efficiency of that process? How much electricity is needed to store energy as fuel and convert is again to electricity? For example, if you put 10 kWh electricity into the process, how many kWh are you expected to be able to recover after the fuel is stored for e.g. 3 months? Is the total efficiency even 20%?
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@jonb5493 Which fuel cell allows 50% RTE? Does some real world hydrogen car have that good fuel cell setup?
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@jonb5493 I think best modern car diesel engines have efficiency near 40% and theoretical max around 55%. Of couse, those numbers can be achieved with only one optimal RPM for a given engine so real world efficiency will be less because you want to control the RPM.
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@drjojo5551 You can definitely get enough total energy from wind and solar if you have good storage system for the energy. The problem with wind and solar is that those energy production methods are really unstable and depending on where you live, the total production may be nearly zero for weeks or months at more or less random times. You have to use energy from energy storage for that time. Right now, Australia has maybe the most advanced electricity storage systems and their setup lasts about 5 hours nationwide if I remember correctly.
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