How battery storage contributes to the decarbonization of the power supply

How battery storage contributes to the decarbonization of the power supply
Germany's decarbonization targets

To prevent the worst consequences of the climate crisis, most countries have set themselves the goal of radically reducing their greenhouse gas emissions. The German government has also further tightened its binding climate protection targets. Last year, for example, the Bundestag passed a new Federal Climate Protection Act (KSG). Also included in it - Germany's decarbonization targets.
The aim is now to reduce greenhouse gases to minus 65 percent by 2030 compared with 1990 levels, and to achieve greenhouse gas neutrality by 2045.  

Energy-related emissions, i.e. emissions resulting from the conversion of energy sources, for example into electricity and heat, accounted for 83% of German greenhouse gases in 2020. The main source of these energy-related emissions was the energy industry, with a total share of 36%. Therefore, the power sector is also particularly important for achieving the decarbonization targets, as it is Germany's largest producer of greenhouse gases. In the electricity market, complete decarbonization is therefore already targeted by 2035.

This is mainly due to the fact that Germany relied mainly on fossil energy sources for a very long time. Due to the progressive expansion of renewables, a downward trend inCO2 production has also been observed in the energy sector over the last thirty years. However, due to the energy crisis, this trend has (temporarily) reversed and a slight increase in emissions has been seen over the last two years. In 2020 alone, the energy industry emitted 212 million metric tons of carbon equivalents.

So what does it take to achieve these ambitious goals?

The most obvious measure for achieving the decarbonization targets in the energy sector is to accelerate the shutdown of conventional power plants and the more rapid expansion of renewable energies. This is because the burning of fossil fuels, which are also largely imported, produces the majority of all greenhouse gases. A switch to renewable energies is indispensable. At the same time, the electricity market must be comprehensively modernized, made more flexible and digitized in order to keep pace with the expansion of renewables. To this end, energy storage systems of all kinds must also become an integral part of the grid.

How do battery storage systems contribute to savingCO2 contribute?

Decarbonization in the energy sector aims to feed a greater amount of renewables into the grid and thus reduce dependence on fossil fuel generation. However, the electricity infrastructure in Germany is not designed for the high volatilities and grid expansion is lagging behind the accelerated expansion of renewables. This is already resulting in increased grid congestion, shutdowns of renewable energy plants (Read more in our article: Why around 3% of all renewables are shut down annually) and the discourse around security of supply.  

In this public discourse, the question is often asked to what extent the energy supply is ensured when the wind does not blow or the sun does not shine. On the other hand, however, there will be very many times with significant surpluses from these forms of generation. Energy storage is increasingly recognized as a critical element in integrating renewables into power systems and in achieving widespread decarbonization. As part of congestion management, battery storage can be used selectively to avoid overloading the nationwide power grid. In doing so, they are available to transmission system operators for redispatch measures, just as other generation plants are. By being strategically placed at grid nodes where grid congestion is particularly frequent, battery storage systems can even be particularly effective in preventing congestion. In addition to normal redispatch measures, i.e. throttling the output of the large-scale battery storage systems, the storage systems can optionally also act as consumers and thus reinforce their positive effect. Large-scale battery storage systems can not only be throttled to zero before bottlenecks like generation plants, but can also be used to absorb and store excess capacity in the grid that would otherwise be lost unused. By storing excess energy, they can balance volatility while integrating more renewables into the power grids. Once the bottleneck has been avoided, the storage facilities can feed this electricity back into the grid on a time-delayed basis. This is particularly useful at times of high demand, when generation from renewables is low and conventional power plants would have to be called upon to cover the load. The additional share oflow-CO2 electricity that can be provided by battery storage during these periods then displaces theCO2 -intensive power plants, accelerating the achievement of decarbonization targets. By improving the integration of renewable energies, creating flexibilities in the power grid and thus increasingly displacing conventional power plants, battery storage makes a decisive contribution to decarbonizing the power supply.

The expansion of renewables reduces the C02 intensity of the electricity mix enormously

An analysis of theCO2 intensity of the German electricity mix clearly shows the effect that battery storage can have onCO2 savings. This shows how much greenhouse gas emissions inCO2 equivalents are emitted per kilowatt hour of electricity produced. According to the Federal Environment Agency, greenhouse gas emissions averaged 438gCO2 per KWh of electricity produced in 2020, rising to 485g/KWh in 2021 (when upstream emissions are included).
A comparison of emissions from individual energy sources reveals major differences. This is because the production of renewable electricity produces on average only 10% of the greenhouse gases that fossil energy sources would cause.

This is illustrated by an example of the dailyCO2 emission factor.  

TheCO2 emission factor peaks in the early morning or late evening. Due to the volatility of renewable energies, conventional energy sources must be increasingly used for power supply. On this example day, up to 580gCO2 per kilowatt hour of electricity are emitted. By contrast, as solar output increases, especially around midday, i.e. between 11 a.m. and 2 p.m., there is a rapid decline in greenhouse gas emissions to just under 310g/KWh. During this time, the low-GHG renewable energy sources increasingly displace fossil fuel generators, thus reducingCO2 emissions enormously. In total,CO2 emissions at peak times can be reduced by 270g/KWh in this exemplary daily course. The positive contribution of renewable energies can be clearly seen. If more electricity from renewable energy sources is integrated into the electricity mix through the addition of battery storage and more conventional power plants are displaced accordingly,CO2 emissions in Germany will also fall.


In order to master the energy transition in Germany and decarbonize our power supply, a fundamental restructuring of the energy supply and, above all, a massive expansion of renewables is required. A switch from fossil fuels to sustainable energy sources could save up to 90% of greenhouse gas emissions in the energy sector. At the same time, a switch will also change the demands on our power supply. Battery storage is a critical building block for decarbonizing the energy supply. By balancing volatilities and storing excess electricity, they can integrate more renewables into the power grids overall. At the same time, by shiftinglow-CO2 electricity, they also make more clean electricity available to the grid. This increasingly displaces or replacesCO2 -intensive power plants and avoids enormous amounts of greenhouse gases. In order to achieve climate neutrality in the German energy industry by 2035, many structures will have to change rapidly in the coming years. Thus, the Federal Network Agency has also made adjustments and increased forecasts within its scenario framework for the 2037/2045 network development plan. The demand for large-scale battery storage was increased 14-fold to 54.5 GW by 2045. The Fraunhofer Institute ISE even forecasts a demand for 104GWh by 2030 with an upward trend. It is clear that battery storage will play a decisive role in decarbonization.

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