What is the point, to set a specific target for renewable power production? To say in so many years we will produce x% from renewable sources sounds like central planning in the Soviet Union.
Within the European Unions Emission Trading System (EU ETS) targets for renewable energy production are completely useless. Through the EU ETS any reduction of greenhouse gas emission frees emission allowances for others to increase emission elsewhere. Germany’s targets for power to be produced from wind turbines, solar panels, biomass and the like are a multi billion € hobby.
Even if there would be no Emission Trading System, it is by no means clear, how much greenhouse gas emissions could actually be saved by renewable sources. Wind and solar power production fluctuates heavily. As long as we have not feasible way to store power these fluctuations have to be compensated by “conventional” nuclear plants and plants fired with fossil fuels. This “up and down” operation reduces substantially the efficiency which can be achieved by the conventional plants, which we still need.
As we all know bio fuel and bio gas is rarely produced by horse pulled ploughs and manual harvesting. Usually farmers use machinery and fertilizers to grow corn. Whether there actually is some greenhouse emission reduction with bio gas compared to simply firing fossil gas depends on the specifics of the particular producer as the quality of the soil, climate conditions, size of the field etc.
The recently achieved production cost reduction for wind and solar power is remarkable. But low interest rates also play a substantial role. We have to calculate again when interest rates climbed back to usual levels.