Sector coupling

Author: Kerstin Gemmer-Berkbilek, AREVA GmbH Date: February 2017 The "Rio Conference" in 1992 marked the start of climate protection on a political level. The "Kyoto Protocol" of 1997 made the reduction of greenhouse gases a major goal and finally during the "World Climate Conference" in Paris in 2015 (see "Related Links") 195 countries agreed on the goal to limit global warming to below 2°C. Net emissions are to be reduced to zero in the second half of the century - Germany is aiming for a completely carbon dioxide-free energy supply between 2040 and 2050. In perspective, this means ending the use of fossil fuels such as oil, coal and natural gas. The energy turnaround, which in Germany to date has mainly referred to the generation of electricity from renewable energy sources, must also include the heat supply and transport sectors. The transition from a fuel-based energy economy to an electricity-based energy economy, as well as the integration of the increasing share of renewable energies, requires the coupling and joint optimization of the sectors. A number of application-ready technologies such as power-to-heat (e.g. heat pumps) or power-to-mobility (e.g. electric vehicles) are available for this purpose. In the following, the coupling of the electricity sector to the transport sector via power-to-gas, i.e. hydrogen generation from (renewable) electricity, will be discussed. 

Functional principle and state of the art

If one assumes that renewable and thus also fluctuating generated electricity will be the primary energy source in the future, the coupling of the energy networks electricity and gas will be of particular importance. Requirements for future-proof energy generation such as flexibility, long-term storage and a variety of uses must be met. Hydrogen from renewable electricity, produced via electrolysis, has these diverse uses. The principle of electrolysis is used to produce hydrogen. Electricity from renewable sources, such as solar parks or wind turbines, is used to split water into its basic components. These are oxygen (O2) and hydrogen (H2). The chemical reaction equation for this is described as follows. From water (H2O) and the addition of energy .

The gases obtained from electrolysis can now be stored and used in many different applications as needed, as shown in the figure below. In addition to reverse power generation or heat recovery, the use as fuel in the mobility sector is gaining more and more importance, thus opening up an economically higher value use.

The technical and commercial key data mentioned below refer to PEM (=Proton Exchange Membrane) electrolyser systems as they are available today. PEM electrolyzers allow high dynamics in operating performance, are emission-free, allow high outlet pressure and require relatively small footprints. For these reasons, they have some advantages over alkaline electrolyzers for the aforementioned applications.

PEM electrosyleur:

Cost reduction programs, which are expected to halve the investment costs for PEM electrolyzers by 2025, have been launched by manufacturers.

State of Commercialization

Hydrogen technology may not be the latest feat of engineering, but it now seems to be really taking off in the wake of zero-emissions efforts and the rising share of renewables. As a result, most premium OEMs have launched hydrogen and fuel cell powertrains to complement their e-mobility strategy. Asian manufacturers in particular have embraced fuel cell technology and are market leaders in the automotive sector. Toyota with the "Mirai" or Hyundai with the "ix35 Fuel Cell" are already making market-ready hydrogen cars available for sale. Daimler has announced the production of larger batches from 2018, Audi and BMW will follow in 2020. The train sector is also focusing on hydrogen propulsion. On non-electrified lines, the old diesel locomotives will soon be replaced by hydrogen trains. The world's first train models of this type will roll over the tracks on selected lines in Lower Saxony at the end of 2017 (Alstom H2 train Coradia Lint, Innotrans 2016, see "Related links"). A suitable hydrogen refueling infrastructure in Germany is under construction:

• by 2017, however, there should already be 50 hydrogen refueling stations
• by 2019 80 to 100, by 2023 400, and by 2030 up to 1000 hydrogen refueling stations

Support programs for H2 activities

At the political level, the topic of "hydrogen" has long been actively discussed. The German Federal Ministries of Transport, Building and Urban Affairs (BMVBS), Economics and Technology (BMWi), Education and Research (BMBF) and the Environment (BMU) launched a program back in 2007 to further develop and promote hydrogen technology, known as the "Hydrogen and Fuel Cell Technology Innovation Program" (NIP). The NIPI, which expires in 2016, was recently extended by the NIPII until 2026 and provides a total of €1.4 billion in funding, particularly for market activation of existing hydrogen and fuel cell technologies. In addition, there are numerous internationally funded projects aimed at reducing emissions in inner cities and testing the everyday suitability of hydrogen  in road transport. The "Clean Hydrogen in European Cities" (CHIC) project is already delivering some positive results in this regard (see "Related Links"). With a total of 90 fuel cell buses in Europe, e.g. at Regionalverkehr Köln GmbH, in Hamburg, London  or in Stuttgart, proof has already been provided that fuel cell buses and, above all, the infrastructure for small vehicle fleets work and are close to conventional solutions in terms of availability and reliability. Further major EU funding programs for the use of fuel cell buses in major European cities under  the HORIZON 2020 program are in preparation for 2017 and 2018.

Conclusion

In the medium and long term, hydrogen is a promising substitute for fossil fuels that can be used to achieve zero emissions targets in the transport sector without sacrificing functionality (refueling times, ranges). However, in order to make the technology also economically interesting, some efforts must still be made on the part of the market players and also on the part of politics. So one can follow the developments of the future with excitement.

Further reading:

• BMUB/Paris Climate Agreement/02.01.2017 
• Handelsblatt/Hydrogen Cars/12/19/2016 
• ndr/Hydrogen Train/22.12.2016
• BMVI/NIPII/02.01.2017 
• CHIC/Clean Hydrogen in European Cities/02.01.2017