L R AS Published on Sunday 6 December 2020 - n° 343 - Categories:hydrogen

How much hydrogen in natural gas pipelines?

Can carbon-free hydrogen replace (and in what proportion?) the fossil natural gas that circulates in pipelines to power furnaces, boilers, stoves and various building applications today?

All utilities are testing the effects of increasing the share of green hydrogen in gas pipelines.

The arrival of hydrogen creates challenges in terms of engineering, energy density and supply.

Twenty percent hydrogen has been introduced into a very small network in the UK. Consumers say they have not noticed any difference in the performance of gas appliances, says the British National Grid. Some gas companies are hoping to include 100% hydrogen to replace natural gas. In Europe, a number of pilot projects are exploring the impacts of blending hydrogen.

In the United States, some companies want to use existing natural gas pipes from the oil industry to transport hydrogen. The New York network has launched a study to determine how much hydrogen can be introduced into its gas infrastructure.

Hydrogen has drawbacks

Replacing natural gas with hydrogen has its drawbacks, starting with the way it affects the pipelines in which it circulates and the appliances that use it. Hydrogen in pipelines can weaken metal or polyethylene pipes, creating the risk of leaks, especially in high-pressure pipes, according to the 2013 NREL study: "Hydrogen can attack the metal structure under certain circumstances, at certain pressures, at certain concentrations."The HyBlend project aims to identify materials capable of resisting the corrosion of hydrogen.

Hydrogen "also burns very differently from methane. It burns almost like an explosion. This poses safety and engineering problems. Once you exceed 25% hydrogen in the fuel, you can no longer use the same equipment. There must be no sparks because hydrogen ignites with almost any air-to-fuel ratio".

Hydrogen is also three times less energy dense than methane.

Producing green hydrogen from carbon-free electricity also costs four to six times more than producing hydrogen from fossil fuels. These costs are expected to fall as a result of advances in electrolysis efficiency, lower costs of renewable energy to power them, and the economies of scale of industrial centres being built around the world.

The combination of low energy density and high cost in gas pipelines could make it a difficult commodity to sell compared to electric heating and typical uses of natural gas in homes and businesses.

The Rocky Mountain Institute's think tank supports green hydrogen for power generation and decarbonization in challenging sectors such as steel production, shipping and long-distance trucking. But it advocates electrification as being more efficient for most building uses.

The carbon reductions that will result from blending 15-20% hydrogen into natural gas could be relatively small.

https://www.greentechmedia.com/articles/read/green-hydrogen-in-natural-gas-pipelines-decarbonization-solution-or-pipe-dream

GreenTech Media of November 30

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