Biogas
Biogas is produced from biomass such as agricultural waste, liquid manure or renewable resources. A large number of biogas plants are already connected to the gas network, currently replacing some 1% of fossil natural gas.
Green Gases
Towards a carbon-neutral energy system
Sources, recycling, transport and use of green gases
The energy industry is changing, with a growing number of initiatives underway to reduce carbon emissions. As a traditional gas transmission system operator, OGE is committed to actively supporting the energy transition by combining years of experience with innovative technologies. Everyone is talking about green gases in combination with renewable electricity and many other technical terms. But what are so-called “green gases” anyway, where do they come from or how are they produced, and what can they be used for?
The situation:
Natural gas
Transporting natural gas across Germany — that’s OGE’s core business. The fossil fuel is imported from natural gas-producing countries such as Norway or Russia via transmission pipelines, transferred to downstream networks and ultimately serves a wide variety of end users such as households, industry or the mobility sector.
Naturalgas
Naturalgas
Natural gas pipeline
CO2
Biogas plant
Treated
Biogas
Biogas
Biogas
Natural gas pipeline
Decarbonised
(blue and turquoise)
hydrogen
Whilst hydrogen is the most abundant element in the universe, it hardly occurs in its pure form on our planet. Two common processes for producing hydrogen from natural gas are steam reforming and natural gas pyrolysis.
Decarbonised
(blue and turquoise)
hydrogen
Steam reforming involves the capture of CO2, which can then be stored (CCS) or reused (CCU). This reduces CO2 emissions. Carbon is obtained as a by-product of pyrolysis. The solid granules can be safely stored and later reused as raw material.
Steam reforming
Pyrolysis
CO2
C
H2
CCS — Carbon Capture and Storage
Ship
Storage
CCU — Carbon Capture and Usage
Industry
Natural gas pipeline
Hydrogen pipeline
Power-to-gas: renewable (green) hydrogen
Power-to-gas refers to the generation of synthetic gases from electricity. The process used is electrolysis of water. If electricity from renewable energy sources is used for this purpose, hydrogen is produced without any emissions. Power-to-gas can thus make an important contribution to climate protection and to the success of an integrated energy transition.
If electricity from renewable energy sources is used for this purpose, hydrogen is produced without any emissions.
Power-to-gas can thus make an important contribution to climate protection and to the success of an integrated energy transition.
Electricity from
renewable energies
renewable energies
H2O
Electrolysis
O2
H2
Blending
Methanisation
+
CO2
SNG
Natural gas pipeline
Hydrogen pipeline
What can green gases be used for?
As an energy carrier of the future, hydrogen will play a crucial role, especially in the energy mix. It is therefore important to make the best possible use of existing infrastructure and to develop it further as required so that hydrogen can be used as an energy carrier in a wide variety of areas.
Mobility
Households/heat
Industry
Power stations/
power generation
power generation
Natural gas pipeline
Hydrogen pipeline
Glossary
Biomethane/biogas
Biomethane, also known as biogas, is a gas produced by fermentation of biomass. After treatment (drying, CO2 removal and desulphurisation), the chemical and combustion properties of biomethane are comparable to natural gas, allowing it to be fed into the public gas grid as a substitute for natural gas.
Blending
The term blending is used to describe the mixing of different liquids or gases. In the context of green gases, it refers to the mixture of natural gas and alternative fuel gases such as hydrogen.
Carbon (C)
Carbon is a chemical element which exists in the solid state under standard conditions. During pyrolysis, carbon is deposited in the form of soot.
Carbon dioxide (CO2)
Carbon dioxide is a compound of carbon and oxygen. Under standard conditions it is a colourless and incombustible gas. CO2 is the most widely known greenhouse gas. The so-called CO2 equivalent is a measure of how harmful a greenhouse gas is to the climate.
CCS
Carbon Capture and Storage is a method used to reduce CO2 emissions in technical processes. The CO2 is removed from the exhaust gas of a technical plant and stored in underground reservoirs.
CCU
Carbon Capture and Utilization refers to the removal of CO2 from the exhaust gases of technical plants and subsequent further use in chemical processes. In contrast to CCS, the captured CO2 is not stored but reused. CO2 consumers include the food industry (mineral water) and fire extinguisher manufacturers.
CNG
Compressed Natural Gas is used as a fuel in mobility.
Electrolysis
A method of separating chemical compounds using electrical energy. In the context of green gases, it refers to the decomposition of water into hydrogen and oxygen.
Existing infrastructure
Existing natural gas pipelines can in principle also be used for transporting hydrogen. It is therefore possible to develop a hydrogen network largely by converting natural gas pipelines to carry hydrogen. Using rededicated pipelines alongside new hydrogen pipelines can help save both time and money.
Hydrogen (H2)
Hydrogen is the most abundant chemical element in the universe and the first element in the periodic table. Under standard conditions, it is a colourless and odourless gas. Hydrogen has a lower energy density than methane; in terms of volume, it has only about one third of the chemical energy of natural gas. Hydrogen can be used both as an energy carrier and as a raw material for the chemical industry. Fuel cells running on hydrogen produce no harmful emissions (only water). The majority of today’s global hydrogen production is based on fossil fuels (see steam reforming and pyrolysis). A small proportion of hydrogen is produced by electrolysis.
Grey hydrogen
Hydrogen produced from fossil energy sources, the production of which releases CO2 into the atmosphere.
Decarbonised (blue) hydrogen
Hydrogen produced by steam reforming. The CO2 generated is captured and stored/used.
Decarbonised (turquoise) hydrogen
Hydrogen produced by pyrolysis. The elemental carbon produced is either stored or used.
Renewable (green) hydrogen
Hydrogen produced from electrolysis using electricity generated from renewable sources.
LNG
Liquefied natural gas is natural gas that is liquefied through cooling to below -160 °C, which shrinks its volume by a factor of about 600. Due to its small volume, it can be transported by ship over long distances in thermally insulated tanks.
Methanisation
Methanisation is a chemical process involving the use of carbon monoxide (CO) or carbon dioxide (CO2) to produce synthetic methane. The process can be carried out either with the aid of a catalyst or with the use of microorganisms.
Natural gas
Natural gas is a combustible, naturally occurring gas mixture that is found in underground reservoirs. The main component of natural gas is methane (CH4).
Power-to-Gas
The conversion of electric current into other energy sources is referred to as power-to-x. One form of power-to-x is power-to-gas, which refers to the conversion of electrical current into combustible gases (e.g. hydrogen or methane) by means of electrolysis. Compared to electricity, gases can be better stored and transported in the existing gas network.
Pyrolysis
Pyrolysis is a chemical process in which carbon compounds are split into their constituent parts at high temperatures and in the absence of oxygen. In the pyrolysis of natural gas, the methane (CH4) contained in the gas is split into hydrogen (H2) and elemental carbon (C).
Sector coupling
Sector coupling refers to the integration of different networks (electricity, heat, gas, mobility) and industries to create synergy effects between the different sectors. A concrete example of sector coupling at OGE is the use of surplus electricity to drive compressors.
SNG
Synthetic natural gas is a type of gas produced from fossil fuels or biofuels (see methanization).
Steam reforming
Steam reforming is a process used to produce hydrogen from carbonaceous raw materials, mainly natural gas. In a multi-stage process, the methane (CH4) contained in natural gas is split into carbon monoxide (CO) and hydrogen (H2) at high temperatures through the injection of steam (H2O). Using a catalyst, the majority of the CO is converted to CO2. The CO2 released in the process can be captured for storage or further use (see CCS and CCU).