Wind and solar advocates are constantly looking for ways to store electricity for use when the wind stops blowing or the sun stops shining.
Pumped storage is the traditional method for storing large amounts of energy that can be converted to electricity. Batteries and all the other methods are too expensive or can’t store and release the energy economically.
Periodically, a new method is touted as the answer.
The latest such proposal comes from the Netherlands and Germany, where EU policies are forcing the adoption of renewables, no matter what the cost and no matter how much they harm the economy and the standard of living of Europeans.
The latest proposal is termed Power to Gas, or PtG. It uses hydrolysis to convert unneeded electricity, from wind and solar, to hydrogen.
It has already been tried in Germany, where excess electricity was converted to hydrogen and injected into natural gas pipelines, but the PtG approach has a few new wrinkles.
There are several safety concerns with adding hydrogen to natural gas pipelines.
These concerns vary between countries, due to the composition and design of pipelines and appliances.
In the United States, there are three basic concerns over the concentration of hydrogen being transported or distributed by natural gas pipelines.
- Concentration of hydrogen in natural gas that can safely be used by appliances.
- Concentration of hydrogen that can safely be in transmission lines.
- Concentration of hydrogen that can safely be in distribution and service lines.
The assessments referenced here are from The National Renewable Energy Laboratory (NREL) and apply to the United States. Conditions in Europe and elsewhere may vary.
The effect of hydrogen mixed with natural gas varies with the age and type of home appliance. Acceptable concentrations of hydrogen for use by appliances have ranged between 5% and 20%.
For industrial applications, each installation will have to be evaluated separately.
Most transmission lines are made of steel and can usually accommodate hydrogen, though some lines may be susceptible to hydrogen embrittlement.
Mixing hydrogen would require a mandatory assessment of all U.S. transmission pipelines. Concentrations above 50% are ruled out.
Distribution and service lines
Safety concerns are magnified due to distribution lines being in close proximity to populated areas, and for service lines being inside buildings and homes.
All piping will have very small amounts of leakage, either through the wall of polymer piping or though the threads of black iron or other metal piping. Leakage of hydrogen is up to five times greater than with natural gas alone. Leakage of hydrogen can be especially dangerous in confined spaces in homes and other buildings.
Overall, the NREL report indicates that it’s reasonably safe to mix hydrogen with natural gas in pipelines, if the mixture contains less than 20% hydrogen, and if all the piping systems and appliances have been assessed as being of the types that can accept up to a 20% concentration of hydrogen.
The NREL report’s Appendix, prepared by the Gas Technology Institute (GTI), says the risk of using a 20% mixture of hydrogen in service lines is approximately 25% greater than for natural gas alone.
Adding hydrogen to natural gas pipelines, therefore, results in some added risk and increased cost.
There will be energy losses from converting electricity, generated by wind and solar, to hydrogen.
Not discussed here are the added costs of extracting hydrogen from the mixture of hydrogen and natural gas if the hydrogen is to be used for purposes other than burning in gas turbines to generate electricity.
Adding equipment to a wind farm to convert electricity to hydrogen, increases the total investment. The value of the hydrogen can’t be great since natural gas which the hydrogen is replacing, only costs $4 per million BTUs. ( Currently closer to $3 per million BTUs)
There are 30 PtG demonstration plants installed in the EU, mostly in Germany, with a few in surrounding countries. Concentrations of hydrogen have mostly been around 5%. These are experimental installations. One experiment is to make methane by combining hydrogen with CO2, referred to as eGas, which is far more expensive than natural gas in the United States.
While European countries must adopt expensive technologies to meet the CO2 reduction mandates established for Europe, PtG is inappropriate for the United States: PtG merely increases costs, making electricity generated by wind and solar even more expensive than it already is … which would further hurt American consumers and industry.
There is no valid reason to reduce safety and increase costs by adding hydrogen to natural gas pipelines, other than as part of a regimen for reducing CO2 emissions. See The Great Divide.
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