MAN Engines

H2 blending – a good mix for the climate

Added hydrogen can make gas engines more climate-friendly
In focus:

Hydrogen is the energy source of the future. It can already be added to the natural gas network to make cogeneration units more climate-friendly. Natural gas engines from MAN Engines are prepared for this.

Hydrogen can be added to natural gas

A high-energy cocktail: up to 20 percent by volume of hydrogen can be added to natural gas. ©Shuterstock/Kamira

In the future, hydrogen will play a crucial role as an environmentally friendly energy source. However, it will be some time yet before sufficient “green” hydrogen from renewable energies is available. That being said, cogeneration units can already be made a little more climate-friendly by adding hydrogen to natural gas (“H2 blending”). This is because the natural gas network is able to transport a mix of natural gas with 20 percent by volume of hydrogen. Due to the lower density of hydrogen, its proportion in the total energy of the gas mixture is around seven percent.

Since hydrogen burns completely CO2-free, carbon dioxide emissions from cogeneration units decrease significantly thanks to H2 blending. The addition of hydrogen to natural gas can therefore act as a bridge to the future era of hydrogen. This has also been recognised through legislation that requires large cogeneration units with more than 10 megawatts (MW) of electrical output to be "H2 ready". “Cogeneration units can already handle a 10 percent H2 addition to the natural gas network,” states the Bundesverband Kraft-Wärme-Kopplung [BKWK, federal cogeneration association]. MAN Engines has even given the majority of its natural gas engines the green light for a hydrogen addition of up to 20 percent by volume.

MAN Engines has been successfully developing gas engines of various sizes for use in buses and stationary applications since the early 1990s. Over the past few decades, the company has built up a great deal of knowledge and expertise in this field. Due to these years of experience, MAN Engines can easily adapt its engines to current requirements. Thanks to special spark plugs and modified control software, they are “H2-ready” without limitations. Customer demand is already high because they want to prepare for the hydrogen future today.

All stationary MAN gas engines (supercharged lean-burn engines and lambda 1 naturally aspirated engines) are designed for the addition of up to 20 percent by volume of hydrogen when running on natural gas. With the maximum addition, they achieve an average CO2 saving of seven percent. Gas engines from MAN Engines therefore have the potential to make the operation of cogeneration units more climate-friendly. Around 10 to 20 percent of CO2 emissions could be avoided compared with diesel simply through the use of natural gas alone. The addition of green hydrogen adds a further eight percent to this figure.

20 percent by volume of hydrogen can be added to natural gas

The colours of hydrogen

Hydrogen is produced in different ways, so there is a hydrogen colour code to indicate its origin. Let us explain what the colours mean:

Green hydrogen is produced via the electrolysis of water. The electricity for this comes exclusively from renewable sources (e.g. wind or sun).

Red hydrogen is also produced via the electrolysis of water, but the electricity comes from nuclear energy.

Grey hydrogen is obtained from fossil fuels, with the generated CO2 escaping into the atmosphere. For production, natural gas is usually converted into hydrogen and CO2 using heat (steam reformation). Fossil hydrogen is occasionally produced by gasifying coal (brown hydrogen).

Blue hydrogen is grey hydrogen but the CO2 generated during its production is captured and stored (CCS). As the CO2 does not escape into the atmosphere, it also does not contribute to the greenhouse effect, meaning the process is climate neutral.

Green hydrogen is produced via the electrolysis of water. The electricity for this comes exclusively from renewable sources (e.g. wind or sun).

Turquoise hydrogen is hydrogen produced during the thermal splitting of methane (methane pyrolysis). Solid carbon is produced as a waste product. This is very easy to store underground or even use in products like lithium-ion batteries. The process is only climate neutral if the energy for splitting comes from renewable sources.

White hydrogen is hydrogen from natural sources. It often occurs together with fossil hydrocarbons and helium. White hydrogen can be extracted using various methods such as fracking.

Header image: © Adobe Stock/Viks_jin