5 ms·

Great post - I've been looking for a serious update to Mackay's numbers for ages. One thing in curious about: developments in fixed wind turbines tech mean th

by RobinL 3y ago

Great post - I've been looking for a serious update to Mackay's numbers for ages. One thing in curious about: developments in fixed wind turbines tech mean they are economically viable in more locations (e.g. deeper water) so can cover more area. But how much more do they produce per square km of deployment than Mackay's estimates? In his book, he has a nice section explaining that bigger turbines have to be spaced out more, so whilst theyre cheaper, they don't produce as much more energy as the headline 'output per turbine' would naively suggest. But modern turbines are higher, so they presumably 'catch' more wind, and windspeeds are more consistent higher up. But I'm curious how big an effect this is.

cycomanic 3y ago
I don't MacKays estimates but the cited study seems to assume a capacity factor of 50% for a 15 MW turbine. Average turbine capacity of turbines installed in 2021 was 7.4 MW but all manufacturers seem to have 15+MW designs in the work [1]. So the projection is slightly optimistic IMO. The capacity factor seems slightly more optimistic at 50% as worldwide average seem to have fluctuated between 35 and 45% [2]. Although other numbers are closer to 60% for the UK [3] [1] https://www.energy.gov/eere/wind/articles/offshore-wind-market-report-2022-edition https://www.energy.gov/eere/wind/articles/offshore-wind-mark... [2] https://www.statista.com/statistics/1368679/global-offshore-wind-capacity-factor/ https://www.statista.com/statistics/1368679/global-offshore-... [3] https://windeurope.org/about-wind/daily-wind/capacity-factors https://windeurope.org/about-wind/daily-wind/capacity-factor...
- yodelshady 3y ago
  Source [3] seems highly suspicious. There's ~24 GW of wind capacity in the UK, the vast majority offshore, and according to Elexon Portal (https://www.elexonportal.co.uk https://www.elexonportal.co.uk, a good public frontend at http://gridwatch.org.uk/ http://gridwatch.org.uk/), which gives realtime grid data, the maximum production was 10. So an average cap factor of 39% is, well sorry it's wrong. And time and time again renewables always seems to take optimistic, if not ludicrous estimates. Mackay's papers is indeed 15 years old, and what do we have now? Extremely expensive power, backed by fossil gas, because if wasn't, people would die. Avoiding 2 deg C and ecosystem collapse is not even vaguely possible anymore. In that time, 40 years ago, France got to 17 g / kWh. That's not a success and, for the literal trillions of ESG money spent, someone should be held accountable for that.
leoedin 3y ago
Wind turbine size has an incredible effect on total power generation. The generated power is subject to the square of the blade length, and the cube of the wind velocity (which generally increases as you get further from the ground). Costs don't increase exponentially - so it's better to have fewer big turbines than many small ones. The result is that the wind industry (offshore - onshore is limited by physical size constraints) has been consistently getting bigger every year. https://www.energy.gov/eere/articles/wind-turbines-bigger-better https://www.energy.gov/eere/articles/wind-turbines-bigger-be...

by RobinL 3y ago

cycomanic 3y ago

I don't MacKays estimates but the cited study seems to assume a capacity factor of 50% for a 15 MW turbine. Average turbine capacity of turbines installed in 2021 was 7.4 MW but all manufacturers seem to have 15+MW designs in the work [1]. So the projection is slightly optimistic IMO. The capacity factor seems slightly more optimistic at 50% as worldwide average seem to have fluctuated between 35 and 45% [2]. Although other numbers are closer to 60% for the UK [3] [1] https://www.energy.gov/eere/wind/articles/offshore-wind-market-report-2022-edition https://www.energy.gov/eere/wind/articles/offshore-wind-mark... [2] https://www.statista.com/statistics/1368679/global-offshore-wind-capacity-factor/ https://www.statista.com/statistics/1368679/global-offshore-... [3] https://windeurope.org/about-wind/daily-wind/capacity-factors https://windeurope.org/about-wind/daily-wind/capacity-factor...

yodelshady 3y ago
Source [3] seems highly suspicious. There's ~24 GW of wind capacity in the UK, the vast majority offshore, and according to Elexon Portal (https://www.elexonportal.co.uk https://www.elexonportal.co.uk, a good public frontend at http://gridwatch.org.uk/ http://gridwatch.org.uk/), which gives realtime grid data, the maximum production was 10. So an average cap factor of 39% is, well sorry it's wrong. And time and time again renewables always seems to take optimistic, if not ludicrous estimates. Mackay's papers is indeed 15 years old, and what do we have now? Extremely expensive power, backed by fossil gas, because if wasn't, people would die. Avoiding 2 deg C and ecosystem collapse is not even vaguely possible anymore. In that time, 40 years ago, France got to 17 g / kWh. That's not a success and, for the literal trillions of ESG money spent, someone should be held accountable for that.

leoedin 3y ago

Wind turbine size has an incredible effect on total power generation. The generated power is subject to the square of the blade length, and the cube of the wind velocity (which generally increases as you get further from the ground). Costs don't increase exponentially - so it's better to have fewer big turbines than many small ones. The result is that the wind industry (offshore - onshore is limited by physical size constraints) has been consistently getting bigger every year. https://www.energy.gov/eere/articles/wind-turbines-bigger-better https://www.energy.gov/eere/articles/wind-turbines-bigger-be...