by Alice Friedemann - September 2004
Renewables 2004: conference
More alternative energy articles:
Fuel Cell Technology
By Alice Friedemann
The energy literate scoff at perpetual motion, free
energy, and cold fusion, but what about the hydrogen economy? Before we invest trillions of dollars, let’s take a
hydrogen car out for a spin.
Hydrogen isn’t an energy source – it’s an energy
carrier, like a battery. You have
to make it and put energy into it, both of which take energy.
Ninety-six percent is made from fossil fuels, mainly for oil refining
and partially hydrogenated oil--the kind that gives you heart attacks (1).
In the United States, ninety percent is made from natural gas, with an
efficiency of 72% (2), which means you've just lost 28% of the energy
contained in the natural gas to make it (and that doesn’t count the energy
it took to extract and deliver the natural gas to the hydrogen plant).
Only four percent of hydrogen is made from water via
electrolysis. It’s done when the
hydrogen must be extremely pure. Since
most electricity comes from fossil fuels in plants that are 30% efficient, and
electrolysis is 70% efficient, you end up using four units of energy to create
one unit of hydrogen energy: 70% * 30% = 20% efficiency (3).
Getting hydrogen using fossil fuels as a feedstock or an
energy source is a bit perverse, since the whole point is to get away from them.
The goal is to use renewable energy to make hydrogen from water via
electrolysis. When the wind is blowing, current wind turbines can perform
at 30-40% efficiency, producing hydrogen at an overall 25% efficiency, or 3
units of wind energy to get 1 unit of hydrogen energy. The best solar cells available on a large scale have an
efficiency of ten percent, or 9 units of energy to get 1 hydrogen unit of
energy. If you use algae making
hydrogen as a byproduct, the efficiency is about .1% (4).
No matter how you look at it, producing hydrogen from water
is an energy sink. If you don't
understand this concept, please mail me ten dollars and I'll send you back a
Hydrogen can be made from biomass, but then these problems
arise: 1) it’s very seasonal, 2) contains a lot of moisture, requiring energy
to store and dry it before gasification, 3)
there are limited supplies, 4) the
quantities are not large or consistent enough for large-scale hydrogen
production, 5) a huge amount of
land would be required, because even cultivated biomass in good soil has a low
yield -- 10 tons per 2.4 acres, 6)
the soil will be degraded from erosion and loss of fertility if stripped of
biomass, 7) any energy put into the
land to grow the biomass, such as fertilizer and planting / harvesting will add
to the energy costs, 8) delivery costs to the central power plant,
and 9) it’s not suitable for pure hydrogen production (5).
One of the main reasons for switching to hydrogen is to
prevent global warming caused by fossil fuels.
When it’s made from natural gas, nitrogen oxides are released, which
are 58 times more effective in trapping heat than carbon dioxide (6).
Coal releases large amounts of CO2 and mercury. Oil is too powerful and
useful to waste on hydrogen–it’s concentrated sunshine brewed over hundreds
of millions of years. A gallon of gas represents about 196,000 pounds of fossil
plants, the amount in 40 acres of wheat (7).
Natural gas is too valuable to make hydrogen with. It is used to create fertilizer (as both feedstock and energy source). This has led to a many-fold increase in crop production, allowing an additional 4 billion people to exist who otherwise wouldn’t be here (8, 9).
We also don’t have enough natural gas left to make a
hydrogen economy happen. Extraction of natural gas is declining in North America
(10). It will take at least a decade to even begin replacing natural gas with
imported LNG (liquid natural gas). Making
LNG is so energy intensive that it would be economically and environmentally
insane to use it as a source of hydrogen (3).
Putting energy into hydrogen
No matter how it’s been made, hydrogen has no energy in
it. It is the lowest energy dense
fuel on earth (5). At room temperature and pressure, hydrogen takes up three
thousand more times space than gasoline containing an equivalent amount of
energy (3). To put energy
into hydrogen, it must be compressed or liquefied. To compress hydrogen to
10,000 psi is a multi-stage process that will lose an additional 15% of the
energy contained in the hydrogen.
If you liquefy it, you will be able to get more hydrogen
energy into a smaller container, but you will lose 30-40% of the energy in the
process. Handling it requires
extreme precautions because it's so cold – minus 423 F. Fueling is typically done mechanically with a robot arm (3).
On a vehicle you’d need to have a heavy cryogenic support
system if you use liquid hydrogen. The
tank is cold enough to cause plugged valves and other problems.
If you add insulation to prevent this, you will increase the weight of an
already very heavy storage tank (11).
Let’s assume that a hydrogen car can go 55 miles per kg
(5). A tank that can hold 3
kg of compressed gas, will go 165 miles and weigh
400 kg / 882 lbs (12). Compare
that with a Honda Accord fuel tank that weighs 11 kg / 25 lbs, costs $100, and
holds 17 gallons of gas. The
overall weight is 73 kg / 161 lbs (8 lbs per gallon). The driving range is 493
miles at 29 mpg.
According to the National Highway Safety Traffic
Administration (NHTSA), "Vehicle weight reduction is probably the most
powerful technique for improving fuel economy. Each 10 percent reduction in
weight improves the fuel economy of a new vehicle design by approximately eight
The more you compress hydrogen, the smaller the tank can
be. But as you increase the
pressure, you also have to increase the thickness of the steel wall, and hence
the weight of the tank. Cost
increases with pressure. At 2000
psi, it’s $400 per kg. At 8000 psi, it’s $2100 per kg (5). And the tank will
be huge -- at 5000 psi, the tank could take up ten times the volume of a
gasoline tank containing the same energy content.
Fuel cells are also heavy: "A metal hydride storage system that can hold 5 kg of hydrogen, including the alloy, container, and heat exchangers, would weigh
approximately 300 kg (661 lbs), which would lower the fuel
efficiency of the vehicle," according to Rosa Young, a physicist and vice
president of advanced materials development at Energy Conversion Devices in
Troy, Michigan (12).
Fuel cells are expensive.
In 2003, they cost $1 million or more. At this stage, they have low
reliability, need a much less expensive catalyst than platinum, can clog and
lose power if there are impurities in the hydrogen, don’t last more than 1000
hours, have yet to achieve a driving range of more than 100 miles, and can’t
compete with electric hybrids like the Toyota Prius, which is already more
energy efficient and low in CO2 generation than projected fuel cells. (3)
Hydrogen is the Houdini of elements.
As soon as you’ve gotten it into a container, it wants to get out, and
since it’s the lightest of all gases, it takes a lot of effort to keep it from
escaping. Storage devices need a complex set of seals, gaskets, and
valves. Liquid hydrogen tanks for
vehicles boil off at 3-4% per day (3, 13).
Hydrogen also tends to make metal brittle (14). Embrittled
metal can create leaks. In a pipeline, it can cause cracking or fissuring, which
can result in potentially catastrophic failure (3).
Making metal strong enough to withstand hydrogen adds weight and cost.
Leaks also become more likely as the pressure grows higher.
It can leak from un-welded connections, fuel lines, and non-metal seals
such as gaskets, O-rings, pipe thread compounds, and packings.
A heavy-duty fuel cell engine may have thousands of seals (15).
Hydrogen has the lowest ignition point of any fuel, 20 times less than
gasoline. So if there’s a leak,
it can be ignited by a cell phone, a storm miles away (16), or the static from
sliding on a car seat.
Leaks and the fires that might result are invisible.
Unless you walk into a hydrogen flame, sometimes the only way to know
there’s a leak is poor performance.
Canister trucks ($250,000 each) can carry enough fuel for
60 cars (3, 13). These trucks
weight 40,000 kg but deliver only 400 kg of hydrogen. For a delivery distance of 150 miles, the delivery
energy used is nearly 20% of the usable energy in the hydrogen delivered. At 300
miles 40%. The same size truck carrying gasoline delivers 10,000 gallons of
fuel, enough to fill about 800 cars (3).
Another alternative is pipelines. The average cost of a natural gas pipeline is one million per
mile, and we have 200,000 miles of natural gas pipeline, which we can’t re-use
because they are composed of metal that would become brittle and leak, as well
as the incorrect diameter to maximize hydrogen throughput. If we were to build a
similar infrastructure to deliver hydrogen it would cost $200 trillion. The
major operating cost of hydrogen pipelines is compressor power and maintenance
(3). Compressors in the pipeline
keep the gas moving, using hydrogen energy to push the gas forward. After 620
miles, 8% of the hydrogen has been used to move it through the pipeline (17).
At some point along the chain of making, putting energy in,
storing, and delivering the hydrogen, you’ve used more energy than you get
back, and this doesn’t count the energy used to make fuel cells, storage
tanks, delivery systems, and vehicles (17).
When fusion can make cheap hydrogen, reliable long-lasting nanotube fuel
cells exist, and light-weight leak-proof carbon-fiber polymer-lined storage
tanks / pipelines can be made inexpensively, then let’s consider building the
hydrogen economy infrastructure. Until
then, it’s vaporware. All of the
technical obstacles must be overcome for any of this to happen (18).
Meanwhile, we should stop the FreedomCAR and start setting higher CAFE
Some time in the future, the price of oil and natural gas will go up relentlessly due to geological depletion and political crises in extracting countries. Since the hydrogen infrastructure will be built using the existing oil-based infrastructure (i.e. internal combustion engine vehicles, power plants and factories, plastics, etc), the price of hydrogen will go up as well -- it will never be cheaper than fossil fuels. As depletion continues, factories will be driven out of business by high fuel costs (20, 21, 22) and the parts necessary to build the extremely complex storage tanks and fuel cells might become unavailable. In a society that’s looking more and more like Terry Gilliam’s “Brazil”, hydrogen will be too leaky and explosive to handle.
The laws of physics mean the hydrogen economy will always
be an energy sink. Hydrogen’s
properties require energy to overcome waters’ hydrogen-oxygen bond, to move
heavy cars, to prevent leaks and brittle metals, to transport to the
Any diversion of declining fossil fuels to a hydrogen economy subtracts that energy from other possible uses, such as planting, harvesting, delivering, and cooking food, heating homes, and other essential activities. According to Joseph Romm “The energy and environmental problems facing the nation and the world, especially global warming, are far too serious to risk making major policy mistakes that misallocate scarce resources (3).
(1) Michael F.
Jacobson Waiter, please hold the