July 27th 2007
More energy is needed
to isolate hydrogen from natural
compounds than can ever be recovered from its' use
In a recent
study, fuel cell expert Ulf Bossel explains
that a hydrogen economy is a wasteful economy.
The large amount of energy required to isolate hydrogen
from natural compounds (water, natural gas, biomass),
package the
light gas by compression or liquefaction, transfer
the energy carrier to the user, plus the energy
lost when it is converted to
useful electricity with fuel cells, leaves around
25% for practical use — an unacceptable value to run
an economy in a
sustainable future.
Only niche applications like submarines and spacecraft
might use hydrogen.
“More energy is needed to isolate hydrogen from natural
compounds than can ever be recovered from its use,”
Bossel explains. “Therefore, making the new chemical
energy carrier form natural gas would not make
sense, as it would
increase the gas consumption and the emission of
CO2. Instead, the dwindling
fossil fuel reserves must be replaced by
energy from renewable sources.”
While scientists from around the world have been
piecing together the technology, Bossel has taken
a broader look at
how realistic the use of hydrogen for carrying energy
would be. His overall energy analysis of a hydrogen
economy
demonstrates that high energy losses inevitably resulting
from the laws of physics mean that a hydrogen economy
will never make sense.
“The advantages of hydrogen praised by journalists
(non-toxic, burns to water, abundance of hydrogen
in the
Universe, etc.) are misleading, because the production
of hydrogen depends on the availability of energy
and water,
both of which are increasingly rare and may become
political issues, as much as oil and natural gas
are today,”
says Bossel.
“There is a lot of money in the field now,” he continues.
“I think that it was a mistake to start with a ‘Presidential
Initiative’
rather with a thorough analysis like this one. Huge
sums of money were committed too soon, and now even
good scientists
prostitute themselves to obtain research money for
their students or laboratories—otherwise, they
risk being fired.
But the laws of physics are eternal and cannot be
changed with additional research, venture capital or
majority votes.”
Even though many scientists, including Bossel, predict
that the technology to establish a hydrogen economy
is within reach,
its implementation will never make economic sense.
“In the market place, hydrogen would have to compete
with its own source of energy, i.e. with ("green")
electricity from
the grid,” he says. “For this reason, creating a new
energy carrier is a no-win solution.
We have to solve an energy problem not an energy carrier
problem."
A wasteful process
In his study, Bossel analyzes a variety of methods
for synthesizing, storing and delivering hydrogen,
since no single method
has yet proven superior. To start, hydrogen is not
naturally occurring, but must be synthesized.
“Ultimately, hydrogen has to be made from renewable
electricity by electrolysis of water in the beginning,
and then its energy
content is converted back to electricity with fuel
cells when it’s recombined with oxygen to water.
Separating hydrogen from water by electrolysis requires
massive amounts of electrical energy and substantial
amounts of water.”
Also, hydrogen is not a source of energy, but only
a carrier of energy.
As a carrier, it plays a role similar to that of water
in a hydraulic heating system or electrons in
a copper wire.
When delivering hydrogen, whether by truck or pipeline,
the energy costs are several times that for established
energy carriers
like natural gas or gasoline.
Even the most efficient fuel cells cannot recover
these losses. For comparison, the "wind-to-wheel"
efficiency is at least three
times greater for electric cars than for hydrogen
fuel cell vehicles.
Another headache is storage. When storing liquid
hydrogen, some gas must be allowed to evaporate for
safety reasons
—meaning that after two weeks, a car would lose half
of its fuel, even when not being driven.
Also, the output-input efficiency cannot be
much above 30%, while advanced batteries have a cycle
efficiency of above 80%. In every situation, the
energy input outweighs the energy delivered by a factor
of three to four.
“About four renewable power plants have to be erected
to deliver the output of one plant to stationary
or mobile consumers via
hydrogen and fuel cells,” he writes. “Three of these
plants generate energy to cover the parasitic losses
of the hydrogen economy
while only one of them is producing useful energy.”
This fact, he shows, cannot be changed with improvements
in technology. Rather, the one-quarter efficiency
is based on necessary
processes of a hydrogen economy and the properties
of hydrogen itself, e.g. its low density and extremely
low boiling point,
which increase the energy cost of compression or
liquefaction and the investment costs of storage.
The alternative: An electron economy
Economically, the wasteful hydrogen process translates
to electricity from hydrogen and fuel cells costing
at least four times
as much as electricity from the grid. In fact, electricity
would be much more efficiently used if it were sent
directly to the appliances
instead. If the original electricity could be directly
supplied by wires, as much as 90% could be used
in applications.
“The two key issues of a secure and sustainable
energy future are harvesting energy from renewable
sources and finding the
highest energy efficiency from source to service,”
he says. “Among these possibilities, biomethane
[which is already being
used to fuel cars in some areas] is an important, but
only limited part of the energy equation.
Electricity from renewable sources will play the
dominant role.”
To Bossel, this means focusing on the establishment
of an efficient “electron economy.” In an electron
economy, most energy
would be distributed with highest efficiency by electricity
and the shortest route in an existing infrastructure
could be taken.
The efficiency of an electron economy is not affected
by any wasteful conversions from physical to chemical
and from chemical
to physical energy. In contrast, a hydrogen economy
is based on two such conversions (electrolysis and
fuel cells or hydrogen engines).
“An electron economy can offer the shortest, most
efficient and most economical way of transporting
the sustainable ‘green’
energy to the consumer,” he says. “With the exception
of biomass and some solar or geothermal heat, wind,
water, solar,
geothermal, heat from waste incineration, etc. become
available as electricity. Electricity could provide
power for cars,
comfortable temperature in buildings, heat, light,
communication, etc.
“In a sustainable energy future, electricity will
become the prime energy carrier.
We now have to focus our research on electricity
storage, electric cars and the modernization of the
existing
electricity infrastructure.”
Citation: Bossel, Ulf. “Does a Hydrogen Economy
Make Sense?”