How much wind and solar does Germany need?
The debate over how to reform the Renewable Energy Act, the supporting pier of Germany’s Energiewende in the power sector, was dominated by talk about alleged runaway costs. Reducing the costs was thus the official main reason for forcing renewables into growth corridors. One question was, oddly, never raised: how much wind and solar does Germany actually need to build in order to reach its 2050 targets?
Goals of the Energiewende
Let us first recall the 2050 goals. By mid-century, German energy policy aims to reduce greenhouse gas emissions by 80-95%. In order to reach this goal the German government wants to meet at least 80% of the German electricity demand (2013: 25.4%) and 60% of its final energy consumption (2013: 12.3%) with renewable energy sources in 2050. While the domestic German energy debate mainly rages over the question whether or not these 2050 targets are enough, they are considered very ambitious internationally.
Luckily, there is an overwhelming consensus that Germany has to transform its entire energy system to reach these goals. Besides adding renewables to the energy supply, the overall energy consumption has to be reduced significantly, especially in the building and transport sector. Space heating demand is to be reduced by renovating building stock. The electrification of large parts of transport and portions of the remaining heat demand are to reduce our dependency on fossil fuels further.
How much wind and solar is required?
A Fraunhofer ISE study from November 2013 analyzed what a cost-optimized energy system would look like in 2050 that meets the minimum requirement of German energy policy, a reduction in greenhouse gas emissions by 80% compared to 1990.
The resulting energy system was centered on wind and solar power as the main source of primary (electric) energy and distributed CHPs (large & small) as the main source for dispatchable power to guarantee security of supply 24/7. Despite relatively conservative assumptions for the cost and performance of many elements, the system achieved comparable system costs as today.
This thoroughly simulated future German energy system would require 472 TWh of primary electricity from wind and solar power (2013: 83 TWh). This energy would for the most part be utilized to meet current (conventional) electricity demand, charge EVs and to power heat pumps. So how many GWs of installed capacity would be required to achieve this six fold increase in variable renewable electricity generation?
|Renewable Technology||TWh||Full-load hours||GW in 2050 (as of July 2014)|
|Wind onshore||217||1800-2800||77.5 – 120 (34.0)|
|Wind offshore||112||3500-4300||26 – 32 (0.6)|
As mentioned before, the study used conservative assumptions about capacity factors for its simulation and resulting cost estimate , resulting in high requirements for installed GW (see table above).
In a subsequent article, we’ll investigate how much wind and solar power Germany has to build every year to get the required amounts of energy by 2050, when it has to start doing so and how the new growth corridors fit into all of this. (Thomas Gerke)