How much energy storage would Germany need if one hundred percent of the electricity was to be generated by only solar or wind? And how do solar and wind generation numbers compare at different times of year? Is there a chance they do “cancel each other out” in a way which could reduce the need for storage? Well, let`s see how it turns out based on the generation numbers from 2015 collected by strom-report.de!
Wind capacity: 38.000.000kW = 38.000MW = 38GW = 0,038TW
Wind peak: 32.600.000kW = 32.600MW = 32,6GW = 0,0326TW
Wind energy: 85.600.000.000kWh = 85.600.000MWh = 85.600GWh = 85,6*TWh
Wind capacity factor: 30% (based on national maximum peak generation)
Solar capacity: +39.000MW = 39GW = 0,039TW
Solar peak: 25.800.000kW = 25.800MW = 25,8GW = 0,0258TW
Solar energy: 36.800.000.000kWh = 36.800.000MWh = 36.800GWh = 36,8TWh
Solar capacity factor: 16,28% (based on national maximum peak generation)
- The annual energy generation for wind and solar is equal. Ewind = Esolar
- Energy consumption is equal every month
- No losses during charging/discharging
To be noted: The capacity factor numbers are based on the nationwide maximum peak, not the installed capacity, meaning the capacity factors is somewhat optimistic. However, it shouldn’t make a difference for the storage requirement calculations since they are based on the monthly generation relative to the average monthly generation.
Table explained: The table is based on the solar and wind electricity generation data from Germany 2015 in order to figure out how much energy storage would be required. B3 = 43,7 = wind generation capacity factor in January 2015. C3 = Emf = monthly energy factor = 1,46 = energy produced compared to the average monthly production. A number above 1 means to much energy is generated and a number below 1 means to little energy have been generated. C15 = 1,96 = months of energy storage which is required if 100% of Germanys electricity consumption was to be generated from wind turbines. Column F, G shows how things turn out in a scenario where the annual generation is a 50/50 split between solar and wind.
As we can see the solar and wind production cancel each other out quite nicely and the energy storage requirement is reduced from 2/3 months to less than 1 month!
Now, let`s see how many GW of solar and wind Germany need to install if they were to be sole producers of electricity and annual electricity consumption is 576TWh. With a 50/50 split between solar and wind, both producing 288TWh a year we will need X terawatt of wind installed and Y terawatt solar installed:
Since the capacity factor is calculated based on the nationwide maximum peak, the actual capacity installed need to be somewhat higher, a factor of 1,5 should be about right = 165GW of wind and 350GW of solar.
Fun fact: On a day which is both sunny and windy, only 65GW out of 310GW can be used directly, a little more if electricity consumption in general is less during night. The rest need to be stored in some kind of battery or be wasted!