3 ms·

Actually, this isn't very complicated compared to a modern high-efficiency gas (combined cycle) powerplant or coal (integrated gasification) powerplant, especia

Actually, this isn't very complicated compared to a modern high-efficiency gas (combined cycle) powerplant or coal (integrated gasification) powerplant, especially when you take into account the exhaust cleaning systems to remove NOx and CO and other nasties that those existing options need. As I understand it, the new research needed to make this happen is on making new components work (like the high pressure supercritical combustor they mention in TFA). The process complexity isn't anything remarkable. As for PV: we are nowhere close to having feasible mature solutions for large scale day-to-day (or even intra-day) energy storage. Take the "world record" Tesla system in Australia that gets talked about a lot. In the hypothetical (and IMO entirely unfeasible) scenario where Australia switches to PV to replace coal and gas, and you wanted to use this Tesla solution to store energy from one day to the next to cover just a 20% variability in PV electricity production, you'd need to install more than 10 000 such facilities, at a cost of the order of magnitude of 1 trillion USD. For Australia alone. So since we don't have that kind of energy storage, we need at the very least 40-50% baseline generation capacity from gas turbines (CO2-emitting or clean), hydroelectric and nuclear power.

mhandley 8y ago
If you're trying to cover a 20% variability in PV from day to day, isn't it cheaper to just 20% overprovision PV? You can use the spare electricity on good days for desalination or aluminium smelting, or something that doesn't mind an intermittent cycle.
- rhino369 8y ago
  PV output at different stations are pretty highly correlated. I also think that variability is a lot more than just 20%. I think there is 50% variation between December and July in most of the USA just based on sunlight.
  - pjc50 8y ago
    Yes, seasonality is big and gets bigger the further north you go. I'm at 56N and recorded data to make a graph: https://flatline.org.uk/daystats.html https://flatline.org.uk/daystats.html
- martinald 8y ago
  In the UK low winter PV production is something like 5% of summer peak production. That means you would need to 20x overprovision solar in winter, plus you have a massive problem that you have 20x overgeneration in summer months (what do you do with all that energy?). Battery storage doesn't help with this, as you'd need an absolutely enormous amount of storage to net off summer production with winter usage, and the batteries would basically be full for months then ran down in winter, to never be charged again until summer, so probably one cycle a year. UK has good wind resource and does generate a lot through that, but it also tends to be less on very cold winter days (when power requirement is at its peak). Overall I think the best option right now for the UK is something like 50% PV/wind, 25% nuclear baseload and the rest natural gas peaking plants. Even this would be very expensive, the peaking plants will be turned on and off a lot (high maintenance costs) and sitting idle probably throughout the entire summer.
  - adrianN 8y ago
    You could always use surplus energy to extract carbon from the atmosphere and turn it to liquid fuel.

mhandley 8y ago

If you're trying to cover a 20% variability in PV from day to day, isn't it cheaper to just 20% overprovision PV? You can use the spare electricity on good days for desalination or aluminium smelting, or something that doesn't mind an intermittent cycle.

rhino369 8y ago
PV output at different stations are pretty highly correlated. I also think that variability is a lot more than just 20%. I think there is 50% variation between December and July in most of the USA just based on sunlight.
- pjc50 8y ago
  Yes, seasonality is big and gets bigger the further north you go. I'm at 56N and recorded data to make a graph: https://flatline.org.uk/daystats.html https://flatline.org.uk/daystats.html
martinald 8y ago
In the UK low winter PV production is something like 5% of summer peak production. That means you would need to 20x overprovision solar in winter, plus you have a massive problem that you have 20x overgeneration in summer months (what do you do with all that energy?). Battery storage doesn't help with this, as you'd need an absolutely enormous amount of storage to net off summer production with winter usage, and the batteries would basically be full for months then ran down in winter, to never be charged again until summer, so probably one cycle a year. UK has good wind resource and does generate a lot through that, but it also tends to be less on very cold winter days (when power requirement is at its peak). Overall I think the best option right now for the UK is something like 50% PV/wind, 25% nuclear baseload and the rest natural gas peaking plants. Even this would be very expensive, the peaking plants will be turned on and off a lot (high maintenance costs) and sitting idle probably throughout the entire summer.
- adrianN 8y ago
  You could always use surplus energy to extract carbon from the atmosphere and turn it to liquid fuel.