The switch to renewables is at risk


Following the German government’s heroic decision to phase out all of the country’s nuclear power plants in the next ten years and to undertake a massive expansion of renewable energies, there was a surge of optimism among all those keen on pressing ahead with the switch to renewables. But now reality has brought everyone down to earth with a bump.

The Renewable Energy Act surcharge keeps rising, power shortages could happen this winter, the expansion of offshore wind energy use has come to a virtual standstill, and the same is true of work on constructing powerful transmission lines from north to south. Furthermore, negotiations between Germany’s federal and state governments have shown that the aims of the two sides are incompatible and that there have not been enough discussions with neighbouring countries.

The current growth in renewables has been unplanned, but it must not be allowed to continue this way. A proper structure is needed because the balance between solar, wind and biomass energy increasingly determines which grids, storage facilities and additional power plants will produce a costefficient overall system.

As well as having to take new sources of renewable electricity into account, Germany also needs to think about the newcomers that are likely to be consuming this power. They will include electric vehicles in the transport sector and electrical heat pumps that provide building heating, hot water and process heating.

The combination of electrical heat pumps and cogeneration is one example of the major impact that these considerations could have. As solar and wind continue to grow, electricity surpluses are on the increase and some of this power can be used to operate electrical heat pumps. The thermal inertia of a building’s cladding makes it possible to distribute and store heat for several hours. The indirect result is a thermal storage solution for electrical energy – and it comes at a very low cost.

Conversely, cogeneration, which is normally heat driven, can be used to feed electricity into the grid when there is a deficit – providing that there is no demand for heating and that the cladding absorbs and stores the produced heat. This kind of flexible approach requires intelligent grids, and work on getting them ready for use must keep pace with the development of renewable energies.

Correct planning would probably remove the need for any measures to maintain the capacity of Germany’s conventional power plants. This would lead to further savings. If photovoltaics continues to expand as fast it has been doing so far, the situation regarding storage facilities and fastresponse gasfired power plants would also start changing rapidly. Photovoltaic energy is currently fed into the grid to offset midday peak demand. However, there will soon be a surplus at noon – and this will have a significant impact on storage facilities and peakload power plants. Germany urgently needs to analyse how best to divide the individual forms of renewable energies and their regionally distributed capacities to arrive at the most costefficient overall solutions.

In terms of windenergy use, we should weigh up the benefits of installing more turbines in southern Germany. Yields would be lower than in the north, but the electricity wouldn’t have to travel so far to reach consumers. Similarly, it is very likely that boosting offshore use would have a positive effect. Offshore turbines have a much more stable feed-in capacity than those onshore. This has great advantages for the energy system, even though installing the transmission lines is a more complex and expensive task. In order to avoid a further explosion of energy storage costs, we need a very detailed analysis of which strategy is best suited to making use of electricity surpluses.

Load management with variable tariffs, and the conversion of electricity into heat or gas must be aligned in a costefficient supply system. We can only think about developing and introducing storage facilities once we have identified the best strategy. This strategy should also include the optimum combination of energy sources, storage facilities and consumers, as demonstrated in the Kombikraftwerk (combined power plant) project.

A systematic and dynamic analysis of the overall system must clarify the advantages and disadvantages of individual strategies. Previous efforts in this area have fallen far short of what is needed, and must be significantly increased. The switch to renewables will only be affordable – and thus achievable – if the system is optimised. We need political measures to steer the overall processes.

However, these measures must be based on the findings of scientific analyses. The emerging need for quantity control at the regional and sector levels should not induce policymakers to simply abandon the Renewable Energy Sources Act in favour of other instruments such as quota regulations. Experiences with such regulations in other countries have shown that only the large energy suppliers benefit and that the cost of producing electricity is by no means lower than it is under funding from the Renewable Energy Sources Act.

It is worthwhile maintaining the advantages of the current Act (the public’s direct involvement in investing in and operating power plants) and to supplement these benefits with the option of quantity con trol. The reference yield model for wind energy and the flexibility premium for the demandbased feedin of electricity from biogas plants show that quantity control is compatible with the Act.

Transforming the energy system – and not just the electricity sector, but also the two other important sectors of building heating and transport – is far more complex than, say, planning and building a power plant. We all know that if the costs of building a new power plant are to remain within budget, whole teams of planners with vast technical expertise have to work to strict schedules to synchronise the completion of all of the important construction stages.

So just imagine how much more intensive the planning will have to be if the epic feat of making the switch to renewables is to actually succeed! no power plant can be built on political targets alone. It is high time to set up a professional planning team. We do not necessarily need a new ministry to pool the current responsibilities of the existing ministries. However, we do need a professional coordinator who receives from Chancellor Merkel all the authority needed to steer the switch to renewables. 

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