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Sector coupling technologies

Introduction

Take a look at how to achieve an integrated energy system. Power, heat and mobility need to be combined in a way that is both intelligent and sustainable.

Image Copyright: The Linde Group

© The Linde Group

Renewable energy is set to gradually replace fossil fuels – not only in the electricity sector, but also in the heat, industry and transport sectors. What are known as sector coupling technologies may prove beneficial in this regard. In most cases, these are used to convert electricity from renewable sources like wind and solar power into heat or into fuels in gas or liquid form, which can then be used in other sectors.

Power-to-heat technology uses power to generate heat. For example, a geothermal heat pump uses electricity to extract heat from the earth, increases the temperature level and transfers the heat energy to building heating systems. Water is heated by electricity in electrode boilers, e.g. for industrial operations or district heating. Power-to-gas applications produce hydrogen and methane using electrical power from renewable energy. In this way, renewable energy can be stored long-term in the natural gas grid and used as fuel or to generate electricity and heat. The gases from power-to-gas processes can also be processed into liquid fuels (power-to-liquid). Synthetically produced fuels currently offer the best option for utilising renewable energy, in particular in the areas of heavy goods transport, aviation and shipping.

In Germany, demand for sector coupling technologies has grown considerably in connection with the rise of renewable energy. As a result, German companies have already gained a wealth of experience in this area.

Using power-to-heat technologies, electricity is converted into heat and used to supply heat. This technological solution is applied in conventional electrical heat and in heat pumps. Many everyday household appliances such as electric kettles and hot water boilers are also based on the technological concept of power-to-heat. In addition, power-to-heat technologies are also used in commercial supplies of negative control energy, process heat and local and district heating for water heating and the operation of heating systems.

Conversely, the power-to-heat technological process can also take the form of conversion of heat to electricity, such as the use of waste heat in gas-steam power plants. In these cases, the waste heat from the gas power plant process is used to operate the steam power plant and thereby converted into electricity.

With power-to-gas technology, electricity is converted to hydrogen or, in an additional step, to a synthetic gas.

The two gases can be used either in the energy or mobility sector. Hydrogen may be used as an alternative fuel to generate electricity and heat within a fuel cell and thus drive, for example, an electric motor in a fuel cell vehicle or a hydrogen heater. Synthetic methane, on the other hand, can be used as an alternative fuel for the propulsion of natural gas vehicles in the mobility sector and to operate CHP plants or block-type thermal power stations and gas heating systems.

Power-to-gas technology also enables hydrogen and synthetic methane to be used as a power storage medium and stored in gas storage tanks. At the end of the desired storage period, the hydrogen or synthetic methane is, for example, converted back into electricity by a block-type thermal power station.

The production of liquid fuel from electricity is also known as power-to-liquid. The power-to-liquid process is based on the power-to-gas process, but with the addition of another conversion process. Power-to-liquid technology is used to liquefy the gases generated from the power-to-gas process, making them easier to transport far away from piping systems.

Various methods are available for the liquefaction of hydrogen or synthetic methane. Both gases can be liquefied by means of compression and cooling to extremely low temperatures.

Alternatively, the recovered hydrogen can be mixed with carbon monoxide or carbon dioxide and converted in a synthesis process to liquid hydrocarbons. Synthetic gasoline can be obtained, for example, from the hydrocarbons in another processing step.

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