Before I talk about where can we get 187GW of low-GHG capacity, I think it is worth outlining the carbon cost of all the methods. The numbers below are for the complete life-cycle of the plant, from extraction of raw materials an fuel through to decommissioning costs:
- Coal: >1,000g/kWh. 800g/kWh can be achieved with gasification technology. 200g/kWH may be possible with Carbon Capture and Storage.
- Oil: 650g/kWh.
- Nuclear: ~5g/kWh
- Wind: ~5g/kWh
- Wave and tidal: 25-50g/kWh. High due to large amount of steel required
- Solar-cells: 58g/kWh. High due to extraction of silicon from sand.
For bulk generation, I’m going to rule out water and solar-cells as they are significantly worse than both nuclear and wind. For small local systems, solar-cells are useful; I’m less convinced by wave and tidal.
This leaves nuclear and wind as the two low-GHG options.
There are two options for new nuclear power stations: the AP1000 and the EPR (the ACR-1000 and the ESBWR were initially considered but the proposing companies withdrew them from consideration). The AP1000 and the EPR have both completed phase 3 assessments by the government and both have moved to phase 4 (completion June 2011) with recommendations for design changes. For now, I’m going to look at the numbers for the EPR because it has a higher capacity (1650MWe versus 1154MWe) and is European.
Before you moan that I’m obviously pro-nuclear because of how much detail I provided compared to the amount for wind, I did this because nuclear power is contentious! Wind is not contentious and there are several suppliers.
There are three extreme scenarios for generating the full 187GW from low-GHG sources: all-nuclear and all onshore or offshore wind:
- Using the EPR would require 114 reactors.
- Using 10MW offshore wind would require 18,700 turbines (covering roughly 1,000 square kilometres).
- Using 5MW onshore wind would require 37,400 turbines (covering roughly 2,000 square kilometres).
Hopefully this demonstrates that both approaches have issues! With nuclear, the main issue is public concern over safety; with wind, public concern about aesthetics.
That feels like enough for now (and I need to go to work:-)). Still to come: cost, sites, and transition from current situation, carbon sequestration, etc.