The news last week that Germany once again has broken its own solar generation records sounded like good news for the environment. But behind the headline the broader picture for Energiewende is looking decidedly less rosy.
Renewable generation from solar and wind for the first seven months of 2013 is down on the same period last year, according to data from Franunhofer Institute for Solar Energy Systems.
Generation from solar is up 1.3 TWh, but this is more than countered by a 3.3 TWh drop in generation from wind, making an overall reduction in generation from these renewables of 2.0 TWh.
Not mentioned in the Fraunhofer data is the contribution of biomass. Considered by some environmentalists as a controversial energy source, biomass is a longstanding component of German electricity generation. Biomass generated about the same amount of electricity as wind in 2012, so a similar contribution is probable in the first seven months of 2013.
Nuclear generation is up slightly on the same period last year. But the biggest changes are seen in fossil fuel generation. Gas generation is down a massive 5.6 TWh. Some of this fall is the consequence of increased solar generation. Gas tends to be used for peaking power, and to fill in the gaps when solar and wind aren't generating well. With more solar generation there is less space for gas in the generation mix.
Displacing fossil fuels with solar is good, but gas is the 'least worse' form of fossil generation, in terms of carbon emissions, and it is the only form of fossil generation showing a decline. Brown coal and hard coal, amongst the most polluting forms of generation, see a combined rise in output of 7.5 TWh, with brown coal being used for baseload demand and hard coal meeting a mix of baseload and peaking demand.
Nuclear still the leading ultra-low carbon generation source
It is worth bearing in mind, given the frequent articles on solar records being broken, as to what the current generation mix is in Germany. While coal dominates the generation mix, nuclear - despite the closure of some reactors in 2011 - remains the largest source of ultra-low carbon generation, generating more than twice the amount of electricity generated from either wind or solar - or for that matter gas.
Over the rest of the year solar output will decline, so by the end of the year the output is likely to be only a tenth of its peak summer levels. Wind may fill the gap some of the time, but with more variability, with gas generation likely to increase to fill the remaining peaking demand (based on 2012 performance), leading to an overall increase in carbon emissions per unit of electricity produced.
Solar has been effective in displacing peaking generation from gas, but for constant baseload generation Germany relies on brown coal and nuclear. The reactors closed in a kneejerk decision in 2011 could have generated around 30 TWh of electricity between January to July, displacing brown coal and avoiding the emissions of around 30 million tonnes of carbon dioxide.