After many false starts, hydrogen power might now bear fruit • Hacker News Board

Re: After many false starts, hydrogen power might now bear fruit

#341

Post by kolinko » Thu, Jul 09, 2020, 10:55 PM UTC

jitendrac wrote: post #16

I think article missed a really large sector which uses coal and produces millions of tons of co2 each year, That is cement industry. Heating clinker to produce cement is energy intensive long process, where big investments towards technology for using Hydrogen can be fruitful.

Energy emissions are responsible for just 40-50% of emissions for cement. The rest is due to co2 released from limestone.

So even with carbon free heat production cement industry would still generate a lot of co2 :/

Re: After many false starts, hydrogen power might now bear fruit

#342

Post by FabHK » Fri, Jul 10, 2020, 4:49 PM UTC

azdle wrote: post #88

FabHK wrote: post #84

Earlier quoted context omitted.

Regarding [1], the article quotes production costs of USD 50/MWh for renewables, and USD 100/MWh for coal (graph 3). You/[1] is saying that with storage costs of USD 150,000 per MWh, renewables can be competitive? It doesn't compute, unless I misunderstand something.

Just from your numbers, it sounds like it's a good deal as long as you need to (grid) store less than 1/3 of your generated/consumed energy.

There's a factor of 1000 there.

Re: After many false starts, hydrogen power might now bear fruit

#343

Post by labawi » Sat, Jul 11, 2020, 12:51 PM UTC

Jedd wrote: post #314

labawi wrote: post #292

Earlier quoted context omitted.

> doesn't need more water >improves magnificently with high temperatures Thermal solar is a solar heat energy source + classic steam turbine. The efficiency of a thermal->electric converter (turbine) is largely governed by the difference between the hot and cold side. Increasing both the hot and cold side temperatures equally would not increase efficiency, AFAIK it would actually decrease efficiency, and without lots…

> Increasing both the hot and cold side temperatures equally would not increase efficiency ... Hence the C in CSP. Contemporary molten salt CSPs operate at ~700C, so the difference between the concentrator and ambient air temperature would be 3% (at 25C) and 6% (at 45C). In other words, a 3% difference. Perhaps measurable at the output, but certainly not significant. New CSP designs are coming along that are working…

I was merely pointing out that CSP efficiency likely doesn't increase with increasing ambient temperature, it's just inherently more tolerant.

As an aside, your calculations are improper, even though results are close enough. 0℃ is merely 273.15K and the temperature at which water tends to freeze. E.g. PV efficiency is usually quoted at 25℃ (or 300K), so at -20℃ they could generate cca 120% of "max" (rated) capacity.