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A Tale of Two Low-Carbon Grids

Among advocates of low-carbon energy production there are often competing views on how the power grid of the future should look like. Some countries like France have a strategy that is heavily based on nuclear power to decarbonize the energy system, while other countries like Germany or Switzerland have a strategy that explicitly excludes the construction of new nuclear plants focusing instead on a combination of variable renewable energy sources like wind, water and sun. Both require additional sources of flexible dispatchable power generation to exactly match supply and demand at any time.

Assuming we were to build a new low carbon power grid to cover Germany's current electricity consumption, how much would the refusal to include nuclear generation in the mix actually cost?

For this augment our previous simulation/optimization scenario with a fictitious 100% capacity factor baseload generator, operating a different costs to see how the optimal mix would change:

For the cost estimate of solar and wind generation as well as long and short duration storage, we are using the same assumptions as in this previous post. It is hard to find reliably all inclusive numbers for energy cost from new construction nuclear plants in Europe. On possible data point might be the CfD of about 110 Euro over 35 years which the British government is committing to pay for the electricity generated by the Hinkley Point C plant currently under construction, even though it is not clear how much of the construction and operating cost this compensation will be able to cover. 

At an all inclusive production cost of about 90 Euro per MWh, there would be a tipping point, where nuclear baseload generation plus some flexible storage results in a lower system cost a solar, wind plus (hybrid) storage configuration.

120 90 60
Load (total / avg / peak) 465.6TWh / 53GW / 76.3GW 465.6TWh / 53GW / 76.3GW 465.6TWh / 53GW / 76.3GW
Generation (total / avg / peak) 550.5TWh / 62.8GW / 190.7GW 502.8TWh / 57.3GW / 104.8GW 493.5TWh / 56.3GW / 59.9GW
Generation PV / ONW / OFFW / BL 35.9% / 53.9% / 10.2% / 0.0% 13.9% / 23.3% / 8.0% / 54.8% 0.0% / 2.7% / 0.0% / 97.3%
Annual Cost / Cost per MWh 47.1B€ / 101.2 €/MWh 45.3B€ / 97.3 €/MWh 33.1B€ / 71.2 €/MWh
System Efficiency 84.6% 92.6% 94.4%
Surplus 2.9% 1.2% 2.3%
Storage contribution 96.3TWh (20.7%) 37.6TWh (8.1%) 24.7TWh (5.3%)
SDS Power 31.2GW 9.1GW 6.8GW
SDS Capacity / Duration 189.1GWh / 6.1h 56.4GWh / 6.2h 43.1GWh / 6.4h
SDS contribution 39.6TWh (8.5%) 209 cycles 11.4TWh (2.5%) 202 cycles 11.0TWh (2.4%) 255 cycles
SDS capacity factor 0.14% 0.14% 0.19%
SDS LCOS 72.8 €/MWh 75.0 €/MWh 59.1 €/MWh
LDS Power (charge/ discharge) 40.7GW / 48.9GW 18.3GW / 28.7GW 7.1GW / 14.5GW
LDS Capacity / Duration 24360.9GWh / 498h 12508.8GWh / 435h 12638.5GWh / 870h
LDS contribution 56.7TWh (12.2%) 2 cycles 26.2TWh (5.6%) 2 cycles 13.6TWh (2.9%) 1 cycles
LDS capacity factor 0.13% 0.10% 0.11%
LDS LCOS 158.7 €/MWh 182.1 €/MWh 204.1 €/MWh

There seems to be no significant synergy benefit from the combination of nuclear baseload generation with wind and solar, except for a small amount of wind generation to better match the seasonal imbalance due to higher energy demand in winter.

Even though both approaches could result in a low-carbon grid, the lack of obvious diversification benefits between variable renewable production and constant nuclear production could present a challenge for policy makers to combine all the technologies in an optimal way.