by David VonSeggern, Sierra Club Maine Volunteer
Hydrogen as a fuel is being mentioned more often in the media these days, including as
a visionary hydrogen “Earthshot” by the US Department of Energy. Several decades
ago, we started to hear of hydrogen as a fuel for motor vehicles using fuel cells.
Emitting only water vapor at the point of use, hydrogen-powered vehicles were touted
by several car companies, non-profit organizations, and the US government. Today,
hydrogen fuel-cell vehicles have lost the race for pollution-free transportation to
battery-powered EVs, with only Toyota having any significant sales of fuel-cell vehicles,
and then only in California. The reasons are many, but the cost of fuel is probably the
most compelling in the buyer market.
Hydrogen is not a primary energy source. Though it is the most abundant element in the
universe, it is not readily available by itself because it easily and quickly forms
molecules with many other elements. It is an energy carrier, much like a battery. It
takes a significant amount of existing energy to create hydrogen in sufficient quantities
to power anything. Remember this when evaluating hydrogen as an alternative fuel:
How did it get made? And at what cost?
To assess this, there has been an informative classification devised to describe
hydrogen: the hydrogen color spectrum. Ranging from green (made from renewable
energy) to black (made by coal burning), produced hydrogen may be environmentally
friendly or, on this scale, all the way to gravely environmentally damaging. In the case of
the latter, it would be far better to actually burn coal to make electricity to power an EV
than to convert the coal energy to a hydrogen carrier that was then “burned” again in the
fuel cell. Even at the other end of the spectrum, with so-called “green hydrogen”, it
usually makes sense just to put the renewable energy on the grid, let it charge EV
batteries, and then run vehicles on battery energy. The direct use of electricity (rather
than using it to make hydrogen and then passing that through fuel cells) is vastly more
efficient. This process is more technically elaborated in my white paper on hydrogen
(Sierra Club Maine, Nov. 2022)
So what’s with all the renewed interest in hydrogen? This has emerged in several
analyses of needs for 1) heavy-duty trucking, 2) home and business heating, 3)
high-temperature industrial processes, 4) ammonia production, 5) energy storage, and
for some lesser needs. Let’s look at them briefly.
Heavy-duty trucking. Today, the trucks that transport goods across the US roadways
are almost all running on diesel fuel refined from oil. Battery and fuel-cells can replace
fossil-fuel engines in the future, and it remains to be seen which technology will dominate. We must keep in mind the overall efficiency of batteries versus fuel cells — this favors batteries. If fuel cells become dominant, we must ensure that the hydrogen is indeed green.
Home and business heating. The natural gas industry would like us to believe that
hydrogen can partially replace natural gas and that, if we were to use “green” hydrogen,
it would reduce harmful CO2 emissions from using gas for heating. We need to
remember the inefficiency of creating and using hydrogen as a fuel, when compared to
the simplicity of heat pumps using electricity to move heat from outside to inside, and
vice versa. The Sierra Club has issued an explainer on the misguided use of hydrogen
for building heat.
High-temperature industrial processes. This may be the most challenging area to
which electrification can be applied. Electricity cannot readily create the high
temperatures required for some industrial processes, and some of these processes will
depend on combustion of hydrogen as an alternative fuel.
Ammonia production. Ammonia is used in vast amounts to fertilize crops world-wide.
It is largely made with hydrogen and nitrogen feedstocks. As with other uses of
hydrogen, the conversion to green hydrogen would greatly reduce the global-warming
impact of fertilizer production.
Energy storage. For energy storage, hydrogen has been suggested as a competitor
for batteries. Again, this confronts the physical principle that using electricity directly is
more efficient than passing it through hydrogen production and combustion. The
throughput efficiency of hydrogen energy storage may be only 30% while that of battery
storage is around 85%. That difference in efficiency translates directly into a difference
in true cost for end use of the electricity.
In Maine we have recently seen that the Governor’s Energy Office has applied, along
with other New England states, for a Regional Clean Energy Hub in which hydrogen
plays a role. Also, the Maine Policy Institute is promoting the use of Maine’s abundant
biomass (forests) to produce hydrogen and other biofuels. Do we wish our forest
reserves to be utilized for energy production which can be much better met with
onshore and offshore wind generation and with solar generation? We anticipate that
some legislation will be introduced in Maine to further the aims of the hydrogen
proponents, and we will be vigilant in assessing it.