In following energy and climate-change discussion threads here dKos, there have been arguments back and forth about the great experiment being conducted in Germany. As I'm sure most are aware who are interested in such matters, Germany decided to accelerate its plan to shut down nuclear power within its borders while continuing to invest heavily in what are conventionally referred to as renewable power sources (i.e. wind, solar, hydro). This action was almost certainly precipitated by post-Fukushima politics. The 2012 statistics are in according to the Fraunhofer Institute for Solar Energy Systems in a publication dated January 4 and they tell an interesting story.
Installed solar capacity increased by 29% from 2011 to a very respectable 32.38GW, and energy production from solar was up a whopping 44% for 2012 clocking in at 27.94 TWh. Wind did not fare anywhere near as well as capacity increased only 1% to 29.44 GW and energy production for 2012 actually dropped by 6% to 45.867 TWh.
One very interesting piece of information can be teased from these numbers, and that is the mean capacity factor for these very significant investments, i.e. what fraction of each GW of capacity built can be considered delivered, when averaged for an entire year across an entire nation. Since there are 8760 hours in a year, we find that solar's mean power contribution is 3.189 GW, which is only 9.85% of capacity. Similarly we find that wind's mean power output is 5.236 GW, which is 17.8% of capacity. This is surely one of the most realistic measures of the effectiveness of these renewable technologies in delivering energy. It also shows the magnitude of how much the grid must be able to respond to variations in weather as there must be 5-10x's more capacity built than what is received on average.
Intermittent swings in power output measured in 10's of GigaWatts has significant, unpleasant implications for the grid. Without massive storage systems, this variability has to be managed using dispatchable power sources, which invariably means burning fossil fuels. A 10% capacity factor means the power has to come from somewhere else 90% of the time, but the system must be capable of accommodating a 10-fold periodic surge in supply. Variability to accommodate renewable inputs necessitates inefficient use of the backup systems, further increasing costs throughout the system (it is a tad ironic to call something that provides 80-90% cover for an unreliable source a "backup" source of power!).
These statistics also show coal use for power generation had increased by 9.8% and soft/brown coal use (the really nasty stuff) by 7.0% over 2011. With total German coal consumption for 2011 in excess of 250 million tons, the majority of which used for power generation, this increase represents tens of millions of tons of extra carbon dioxide emissions (Note: 1 ton of carbon burned generates 3.67 tons of CO2). Adding insult to injury, Bloomberg reported that Germany is planning to construct 10GW of new coal and gas-fired generation this decade.
Production from nuclear power dropped more than 8% in 2012 due to the accelerated phase-out schedule.
I wish Germany well in its ambitions toward environmental responsibility in its key national energy systems. The data so far hasn't been kind to their efforts.