The Alternative Green Energy Thread

70sbudgie

JKenH said:

Just wondering, how does the efficiency of burning hydrogen to generate electricity compare to using it in a FCEV? Obviously we don’t have either the quantity of hydrogen available or the infrastructure in place to support a mass rollout of FCEVs so it’s just a theoretical question. How would the cost of moving hydrogen in a national network from where it might be generated compare with moving electricity around?

I have heard that there are investigations into converting the existing (now redundant) town gas network to hydrogen. But I understand that the issue is to do with the size of the gas molecule - a methane molecule (and its relatives) is significantly larger than a hydrogen molecule. So all the pipes that are good for natural (or even town) gas, would be too leaky for hydrogen. 

JKenH

UK offshore wind capacity factors.

I copied this link from the G&E news thread.

https://energynumbers.info/uk-offshore-wind-capacity-factors

Fascinating stuff.

On average a capacity factor of 37.1% was maintained for 50% of the time over long term. For 10% of the time in average the CF was only 6.6% and 20% of the time the CF was 12.8%.

Looking at the data for the operational wind farms only three (just) exceeded their long term average in the last 12 months and several sites fell some considerable way short. 

What I found of more interest was looking at the load duration curves* and seeing how the sites as a whole compared to the 5 year averages quoted. The 5 year line suggested 19.5% CFs were maintained for around 70% of the time whereas the graphs for the individual wind farms showed these more commonly to be in the range of 10 to 17% CFs for 70% of the time. Only Hywind Scotland exceeded the all farms average with 22.6% CF 70% off the time. Some farms had less than 8% CF for 30% of the time.

On the whole compared to the long term average the individual farm results seem to be towards higher CFs for a shorter period and lower CFs for longer. 

I think more consideration needs to be given to the period over which usable CFs can be maintained than focussing solely on the average CF over the year or the life of a wind farm. 

*For the image above I attempted a screenshot of as many individual sites as I could manage just randomly clicking quickly fast enough to get as many lines as possible before the sequence started clearing the ones I had clicked on.

michaels

Thank, I looked at the same chart - I think there was a suggestion that we might look for 5x average demand at 100% output for wind - this would be enough to power the UK for 70% of the time leaving a sizeable period when wind would not be enough.

ABrass

The shape of the curves are interesting. The better performing ones have significantly larger periods at very high factors, probably thanks to the modern trend to optimise the turbines for a wider range of speeds rather than peak power. 

JKenH

Solar-to-hydrogen efficiency of more than 9% in photocatalytic water splitting

Our study offers a practical approach to produce hydrogen fuel efficiently from natural solar light and water, overcoming the efficiency bottleneck of solar hydrogen production.

https://www.nature.com/articles/s41586-022-05399-1

JKenH

Comparison of average daily electricity generation sources for 2022 with 2021. Despite the apparent gas shortage we burnt more gas! It was also 1 degree warmer in 2022! Biggest change was wind displacing net imports.

https://www.electricinsights.co.uk/#/dashboard?period=1-year&start=2022-01-01&&_k=n1wj6l

1961Nick

JKenH said:

Comparison of average daily electricity generation sources for 2022 with 2021. Despite the apparent gas shortage we burnt more gas! It was also 1 degree warmer in 2022! Biggest change was wind displacing net imports.

https://www.electricinsights.co.uk/#/dashboard?period=1-year&start=2022-01-01&&_k=n1wj6l

The extra gas consumption is possibly due to the problems France is having with it's nuclear fleet. That could also account for the difference in net imports.

michaels

JKenH said:

Comparison of average daily electricity generation sources for 2022 with 2021. Despite the apparent gas shortage we burnt more gas! It was also 1 degree warmer in 2022! Biggest change was wind displacing net imports.

https://www.electricinsights.co.uk/#/dashboard?period=1-year&start=2022-01-01&&_k=n1wj6l

My first thought was how slowly things change year on year.

My second was that renewables added 1.74gw - if that happened every year for 10 years then that would more than cover the total gas, coal and biomass burn.  Obviously it is not as simple as that for day to day usage but the trend is clear

JKenH

Log burner rule change in England could land users with £300 fines

Households in England face fines of up to £300 and even criminal records if they flout new log burner rules.

https://www.bbc.co.uk/news/uk-64261624

I believe it only applies to smoke control areas (at the moment). You can check this map to see if it affects you. Why is a big chunk of Leeds exempt?

https://uk-air.defra.gov.uk/data/sca/

JKenH

I misunderstood the greenhouse effect. Here’s how it works.

If you thought you knew how the greenhouse effect works watch this video. If you don’t watch it you’ll never know and spend the rest of your life under a misapprehension. Yes the greenhouse effect is real (this isn’t a climate denial video or suggesting the problem is any less real than what we already know). All those simple drawings you’ve seen are all wrong.

I suppose it’s a bit like at school being taught traditional Newtonian gravity then listening to Einstein’s theories on gravity. It’s pretty fundamental.

When you’ve watched it you will probably need to watch the second half again just to make sure you really understand it.

Everything I said above is my view - not something I copied just to grab your attention. 

Enjoy.

https://youtu.be/oqu5DjzOBF8

PS I know some of you won’t watch it on principle (I posted it) but it’s your loss.