Hydrogen as a Source of Clean Energy

By Paul Stockes

First, organizations like 350nm.org and the Sierra Club have shown that it is almost certain that the hydrogen extracted from natural gas (blue hydrogen) cannot generate clean energy as the extraction process generates significant amounts of greenhouse gases.  Some proponents of blue hydrogen count on greenhouse gas sequestration (i.e. burying it) to eliminate its emission into the atmosphere, but that has been tried by the US and Australia and maybe others, and has been abandoned as economically infeasible.

Hydrogen produced by the electrolysis of water (green hydrogen) using energy from renewable sources does produce clean energy, but electrolysis is not very efficient, so it is far better simply to use the renewable energy to produce electricity.

There are, however, at least two contributions that green hydrogen could make to a fully clean energy economy:

  • Producing hydrogen as a fuel for commercial transportation, which could be needed if batteries turn out to be impractical for large, heavy vehicles (e.g., tractor-trailer rigs) 
  • Providing a back-up source of energy for the electrical grid when there are long-term, usually weather related, outages of solar and/or wind.  Outages of several days or weeks of solar and/or wind do occur, even in sunny New Mexico (think of the Texas disaster of a few years ago), and some way will be needed to provide electricity during those periods as the transition from fossil fuel energy sources to renewable energy is completed.  Batteries can probably supply sufficient back-up power for several hours or even overnight, but not much more.

A potential concern regarding green hydrogen is that its source is water, a commodity in short supply in New Mexico.  In light of that concern, I analyzed how much of our valuable water would be used if our electricity needs during long-term outages were supplied by green hydrogen.  I was pleasantly surprised to find that the water consumption to supply all the electricity for the state by green hydrogen during, say, a five day solar and wind lapse would only use a tiny, 0.002% of average annual water consumption in New Mexico (For the stout-hearted, see the analysis below).

As renewable energy becomes the dominant source of electricity, peak power production (e.g., during the middle of sunny days) will usually be significantly greater than the power being used.  This is already happening in California.  The current practice is to shut down some of the production, or dump the excess power, so the supplied power matches the power being used.  Thus, this excess power could be used to produce hydrogen, essentially for free.  That free hydrogen could be stored for use when there are long-term outages.

In sum, the governor’s hydrogen project that includes green hydrogen should be supported, but the rest, being dependent on blue hydrogen, should not be supported, as has been said by most, if not all, of the organizations that are concerned about the climate crisis.

The Governor’s vetoes

While it is regrettable that the governor has vetoed the tax rebates for electric vehicles and geothermal energy development, there is an argument that the rebate for electric vehicle purchases would have been unwise.  That is because 1) we are in a sellers market regarding electric vehicles, 2) and related to that, most buyers in the price ranges that apply to electric vehicles will buy the electric vehicles whether or not there is a rebate, 3) and also related to item 1, car companies are simply adding the amount of the federal rebate to the price of the vehicle.  Moreover, there is an odd provision (e.g., see section 12F of HB 547) in the state EV rebate program that allows the buyer to “sell or transfer” the rebate, and for convenience, the buyer may choose to transfer it to the car dealer.  Item 3 and this odd provision has the effect of enriching the car companies with money that could otherwise be used by the state for worthy projects.  As well, most buyers of electric vehicles are, for now, probably well-off and don’t need rebates.  So the rebates cost the state money that could otherwise be used for people in need.

I don’t know if that argument is supported by data, but there it is for your consideration.

Analysis to determine how much water would be used supply the hydrogen needed to cover the state’s electricity needs during long-term outages

The values of variables in the calculation:

  • New Mexico uses about 3×10**6 acre-feet of water per year
  • one kilo of hydrogen produces about 33 kWhrs of usable electrical energy (e.g., produced by fuel cells)
  • New Mexico consumes about 23×10**9 kWhr/year or 63×10**6 kWhr/day of electrical energy
  • There is about one kilo of hydrogen per nine kilos of water

For a simplified example, assume that a long-term outage is rarely longer than 5 days.  Then, (5 days)(63×10**6 kWhr/day) = 300×10**6 kWhr of backup electrical energy would be needed for each 5 day outage.  Then, (300×10**6 kWhr)/(33kWhr/kilo of hydrogen) = 10**7 kilos of hydrogen needed for each 5 day outage.

At 9 kilos of water per kilo of hydrogen, 9×10**7 kilos of water is required for each 5 day outage.

There are 1,233,482 kilos of water in one acre-foot of water.   So, (9×10**7 kilos of water)/(1,233,482 kilos of water/acre-foot of water) for each 5 day outage = 73 acre-feet of water for each 5 day outage.

(73 acre-feet of water for each 5 day outage)/(3×10**6 acre-feet of water used/year) = 0.002% of total water used in a year for each 5 day outage.

If any of you see flaws in the analysis, I would appreciate it if you would so inform us.


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