We Brits haven’t properly understood the scale of the German Energiewende, or energy transition. A recent seminar at Germany’s Environment Agency (Umwelt Bundesamt or UBA) assessed whether the country could stop using fossil fuels entirely by 2050 and concluded it is technically feasible to produce all the country’s energy (and not just electricity) from renewable sources without using biomass, nuclear or carbon capture. This would mean generating about 3,000 terawatt hours (TWh) of renewable electricity and converting most of this into methane (Power to Gas) or methanol/butanol (Power to Liquid). This is six times current electricity generation from all sources. And it assumes a 50% reduction in Germany's total energy use. Are they mad? I think they probably are. But Germany society is strongly behind the Energiewende and we shouldn’t underestimate the ability of a determined, resourceful and technologically sophisticated country to achieve almost unimaginable growth in renewable energy. What looks to us like impractical dreaming may eventually work.

Looked at as a multiple of existing low carbon generation, the target numbers are even more startling. In 2013, German wind produced 47 TWh and solar 30 TWh. Hydro added a further 15 TWh. In total, these renewable sources provided 92 TWh, or about 3% of what the Agency says will be needed to decarbonise the economy in 2050. Large scale expansion of hydro power is not an option. So wind and solar will have to be expanded about 40 fold to cover all the country’s energy needs.

It should be said that the UBA seminar papers avoided any detailed discussion of how the country will grow PV and wind to meet the huge need for electricity at mid-century. A 40 fold expansion of PV would mean that over half of German grassland would carry photovoltaic panels but nobody mentioned this. Of course some energy can be imported, but since most other countries in Europe will attempting their own form of Energiewende there won’t be much surplus to go around.

The nature of the ambition.

The UBA seems to have decided that a low-carbon future critically depends on using electricity to completely replace gas and motor fuels. Whereas the UK talks of converting to electric cars and using electric heat pumps to provide home heating, Germany is committing to using power as the raw material for renewable methane and for renewable liquid fuels. (Older articles on this web site have looked at the reasons why the natural gas grid is the only conceivable way of storing surplus electricity generated on very windy days).

One paper at the symposium examined the relative storage capacities of the existing electricity system in Germany (this is almost entirely hydro-electric power schemes that pump water uphill when the grid is in surplus and then let it flow down again at times of shortage) and compared it with gas and oil storage networks.

The argument is compelling: large scale seasonal storage of electricity can only be achieved by converting power into gas, through electrolysis and methanation, or into methanol/butanol using similar processes. Whatever advances we can possibly expect in batteries or other conventional technologies won't provide more than a tiny fraction of the energy storage we will need. Complete decarbonisation, the UBA seems to be saying, will need huge investment in today’s nascent power to gas and power to liquids technologies.

The graphic below makes repeated appearance in the symposium papers.

To replace all carbon fuels with renewable electricity, much of it converted to other energy carriers, necessarily involves large conversion losses. Turning surplus power into methane, and then burning it a gas-fired power station to regenerate electricity, recreates less than a third of the original energy. But if an advanced society, such as Germany or the UK, really wants to decarbonise, there really is very little choice. We have to accept the wastage of energy entailed because intermittent renewables will otherwise need huge backup from fossil fuels.

The scale of what is envisaged

The seminar saw estimates of the amount of primary energy needed to create the fuels a modern economy requires. The table below gives the figures.

	Primary energy needed	Final energy created from this
Electricity	550 TWh	460 TWh (1)
Gas	1110 TWh	300 TWh
Liquid fuels	1280 TWh	520 TWh

(1) For electricity, the difference between primary and final energy arises from grid losses and from the losses in pumped hydro and in using some electricity for making methane, prior to conversion back to electricity.

The Germans are saying no to nuclear, but also to CCS and biomass. In one paper from a UBA employee, CCS is called ‘unsustainable’, an attitude remarkably at variance with the UK position. Biofuels of all forms are rejected for similar reasons. So all energy (not just electricity) comes from renewables in 2050 and the UBA sees PV and wind as being the dominant source. The need is for almost 3,000 Terawatt hours of electricity to provide this.

Today Germany has 36 GW of PV, compared to around 3 in the UK. This technology 5.3% of total electricity production in 2013. Wind power supplied about 8% of all electricity need from 33 GW of turbines, about four times the UK’s capacity.

To supply just Germany’s current electricity demand, not the total energy need that the UBA suggests, would need a sevenfold increase in turbines and solar panels. This is not impossible, particularly if Germany successfully moves into offshore wind, which is currently a negligible fraction of its wind capacity. But can Germany reasonably aim to then increase renewable electricity a further six fold to produce the power for methane and butanol production as well? I’m sceptical.

There’s one other important point. Whether or not Germany achieves the ambition of 100% renewable energy, avoiding biofuels and other questionable sources, it is now very focused on developing conversion technologies that turn large volumes of electricity into gas and liquid energy carriers. There is no discussion whatsoever of this in the UK. Time to start learning from the German focus on this critically important issue?