A power system designed around renewable energy must both be flexible and allow for power storage. Rather than relying on “baseload” power like coal and nuclear, Germany is trying to switch to a supply-based model.
The switch to renewable electricity will be technically challenging because solar and wind power are not dispatchable, meaning that you cannot turn wind turbines and solar panels on the way that you can ramp up coal and plants to match power demand.
The general problem is that the exact amount of electricity that is needed at a given moment has to be available at that moment, lest the grid collapses. We have therefore traditionally tailored power production to demand.
A number of solutions are possible – improving the grid structurally, better managing when and how we use electricity, and working on ways to store power from renewables.
The need for flexibility
The most important element to switch from “baseload” power like coal and nuclear to renewable energy is flexibility. Rather than planning energy production based around demand, Germany is trying to switch to a supply-based model. Even still, there will need to be a way to provide power when sun and wind production is low.
European energy integration is one solution, especially in light of Germany’s limited energy storage capacity. The EU has been pushing for power grid integration at the European level via the “Clean Energy for All Europeans” package: the idea is that better connections across Europe will be able to balance out shortages and surpluses as more renewable energy comes online. There is a huge potential for interconnection: for example, one project called Nordlink is scheduled to come online in 2020, creating a 1.4 gigawatt connection between Norway and Germany.
In general, the future of Germany’s electrical grid and its power storage will depend on its coal phaseout, which remains undecided. The faster the coal baseload will be phased out the less the electrical grid will need to be expanded, and installing more distributed renewables will help balance it out. But in any case, the country will need to both expand its electrical grid and power storage, according to the Öko Institute.
Storing renewable energy
Germany has a few options when it comes to backing up renewable energy. Industrial-size battery storage plants have taken off in the past years, and Germany is trying to position itself as a European center for factories where these batteries are produced. Germany also plans to use eventually use sustainable biogas and hydrogen made from excess wind power and solar power. Solar and wind power could be stored as a gas (called “power to gas” or P2G), allowing it to be used as a motor fuel, for heat applications, or to produce dispatchable power. Similarly, pumped storage (hydropower) and natural gas are switched on when necessary. Finally, “smart grids” will help tailor power demand to the available renewable power supply – the opposite of what we do now.
Expanding the German grid
While energy experts agree that the German electrical grid will need to be expanded for renewables to make up a greater part of power supply, there is no consensus on what exactly needs to be done. Some estimates put the amount of new lines that need to be built at 5,900 kilometers, whereas others believe half of that would suffice.
Furthermore, the renewables sector itself has an interest in making the energy transition affordable and has therefore come up with a number of inexpensive alternatives to extensive grid expansion. In addition, people do not want to live near power lines, so public input is needed for planning – and that requires greater transparency.
The current German grid is divided up as follows:
The transit grid is the ultra highvoltage level at which Germany is connected to its neighbors and power is transported across long distances, consisting of some 35,000 kilometers. The distribution grid consisting of the following:
- Some 77,000 kilometers of high-voltage lines for conglomerations and largescale industry.
- Some 479,000 kilometers of medium-voltage lines for many large facilities such as hospitals.
- Some 1,123,000 kilometers of low-voltage lines for households and small businesses.
Germany has four investor-owned utilities (50Hertz, Amprion, TenneT and TransnetBW) operating the four sections of its transit grid, but there are some 900 distribution grid operators.
At the moment, a lot of wind power is in the north and a lot of solar is in the south. On particularly windy days, the North-South grid is unable to handle the amount of traffic, resulting in bottlenecks and making it necessary for grid operaters to re-dispatch energy to other locations. Sometimes, this also goes across borders, which has the added result of forcing Germany’s neighbors to curtail their production. To make the German grid more efficient, it is necessary to add more ultra high-voltage lines.
Therefore, the German government has set up a Grid Development Plan, to be updated every two years. The first plan released in 2013 called for 36 projects and the construction of 2,800 kilometers of new power lines. Each now plan has since called for further expansions, and the latest version contains 42 projects covering a total of 5,900 kilometers of new lines.
Putting grid expansion into perspective
To put all of this in perspective: First, Germany has gone from 3% renewable power at the beginning of the 1990s to 41.5 percent in the first half of 2018 without any major changes to its grid. After all, wind power, biomass, and solar power are largely distributed sources of energy – at least the way Germany is doing it.
Critics of renewables sometimes complain when the grid has to be expanded for renewables: The problem with wind farms is that they are built in places where there is no need for electricity. As a result, the produced electricity has to be moved elsewhere.
In fact, this describes coal power better than wind power. You can spread solar, wind power, and biomass fairly evenly across the landscape in a way that you cannot do with conventional power. In contrast, brown coal plants are never built where power is needed, but rather where the brown coal is dug out of the ground. Even power plants fired with hard coal, which is traded globally, were traditionally built close to the source of the coal, such as in Germany’s Ruhrgebiet (Ruhr Area).
Clearly, however, it is much easier and less expensive to transport large amounts of power across power lines than it is to haul loads of coal. And while one could argue that coal plants are often located close to industry (as is the case in the Ruhr Area), this description puts the cart in front of the horse. Go back some 200 years to the beginning of industrialization – most of the towns in the Ruhrgebiet were small villages. Coal plants were not built in the Ruhr because industry was there; rather, industry developed there because the area was full of coal reserves.
Furthermore, while nuclear plants are built more or less where power is needed, not where uranium is mined, all central plants are so huge that the grid is always expanded for them. In the 1960s and 70s, new nuclear power plants in Germany not only required the grid to be expanded, but also led to the installation of a large number of electric home heating systems that generated heat from power overnight so that the nuclear plants would not have to be ramped down each day. A distributed supply of renewable power is a much softer approach with a much smaller impact on the environment. Hermann Scheer, the late German expert on renewables, once compared distributed power supply to our conventional centralized power supply by saying that the latter is like “cutting butter with a chainsaw.”
Opposition to German grid expansion
These plans have been met with criticism among proponents of renewables in Germany who are proponents of distributed energy. After all, a lot of these lines would not be needed if the government promoted more energy storage, or onshore wind in the south rather than additional offshore and onshore wind in the north. In the past years, the wind industry has come up with special wind turbines with taller towers and longer blades designed especially for use in weak-wind locations, such as southern Germany. Such onshore turbines in the south would not require as many power lines, thereby reducing the overall cost of Germany’s energy transition, and provide benefits for local communities. Likewise, some proponents of solar would also like to see feed-in tariffs for photovoltaics adjusted by region (as is done in France) so that more PV is installed in the north, thereby facilitating grid integration.
In addition, grid upgrades have faced local opposition, and complicated red tape and financing also slow things down. Underground cables are an option, but they are more expensive. As of 2016, the government has decided to use underground cables over overhead power lines for the high voltage direct current lines built to connect northern Germany with southern Germany (even though this will add between 3 and 8 billion euros to the project’s price tag). For AC lines, the number of underground cables has been increased compared to earlier plants, too. As part of the revised Renewable Energy Act, it is also discussed to reduce the number of new wind energy installations that are auctioned in areas with grid bottlenecks.
Some have suggested that if the bottlenecks aren’t resolved 2025, Germany should be split into two market-power bidding zones. This could solve the imbalance between energy-hungry industries in the south, and the wind-power giants in the south. Already in 2018, a new agreement will go into effect between Germany and Austria to better manage energy flows and prevent bottlenecks.
Alternatives to grid expansion
Germany’s renewables sector is not, however, just sitting back and waiting for the government to provide a future-proof grid. Under German law, there is a regulation called “n+1”; it means that whenever a line is set up, there has to be a reserve line that can take up its capacity in case it fails. The wind sector has come up with a solution that could mean that this requirement is no longer necessary: dedicated power lines to connect renewables.
Furthermore, the European Union – as part of its Energy Union plans – is stepping up interconnections between countries to strengthen the continent’s energy security and keep costs down. By 2020, all EU countries should be able to import and export at least percent of their energy production. At the same time, however, surges in wind and solar power production in Germany are already pushing power into Poland and the Czech Republic, in particular, so further integration would be a challenge for those countries. Phase shifters, which actively control real power flows in order to enforce or block load, have been installed at the German-Polish border so the Poles can have better control of their own grid.