In a sustainable future, solar energy, wind, running water, geothermal heat, and biomass will become the only viable energy sources. Energy will become a precious commodity that will have to be distributed to consumers with the highest efficiency, and used intelligently to provide maximum comfort and services from every energy unit harvested and delivered. The efficient use of energy and its conservation will become the cornerstones of this sustainable energy future.
However, there seems to be no clear
picture of the sustainable economic mix
of energy sources, energy
distribution, and energy demand. The future will most likely not be
based on a one-to-one replacement of fossil fuels by renewables, but
will rely on a more complex substitution of processes involving physical
and chemical energy carriers.
Renewable energy will be harvested mainly in the form of electricity-direct current (DC) from photovoltaic arrays, and alternating current (AC) from rotating generators powered by wind and water, or steam turbines that convert geologic or solar heat into electricity. Solar heat will also be used for water and space heating. Biomass from plants and organic refuse will become feedstock for liquid biofuels. So how does hydrogen fit into this energy equation?
Just as it was in the 1920s, the '50s, and again in the '70s, a hydrogen energy future is offered as a solution. But today's hydrogen promoters have joined journalists and lobby groups to convince politicians to fund extensive programs-at the expense of ignoring other readily available and proven renewable energy (RE) technologies.
is not a new energy source,
but rather an energy carrier-like
in a hydronic heating system or electrons in a copper wire. And this
energy has to come from somewhere. In a sustainable energy future,
hydrogen will be produced mainly by the electrolysis of water. But
to carry the energy equivalent of 1 gallon (3.8 1) of gasoline, 2.4
gallons (9 1) of water are needed to yield 2.2 pounds (1 kg) of
To satisfy all present transportation energy needs of the city of
Los Angeles with hydrogen would double the water consumption rate
of the city and require the continuous output of the equivalent of
about 100 nuclear power plants.
All energy conversion processes are associated with energy losses. The highest losses occur when chemical energy (coal, oil, natural gas, or hydrogen) is converted to physical energy (electricity, motion, pressure) in power plants or internal combustion engines. Those efficiencies can be far below 50 percent.
Promoters of a hydrogen economy argue that hydrogen also can be produced from natural gas or biomass. In both cases, chemical energy is converted into hydrogen energy with the help of heat obtained by burning fuels. But again, when the original energy content of the fuels is considered, hydrogen carries much less energy, compared to what was required for its production. The high losses of hydrogen production might be tolerable if the distribution of the energy carrier was much more efficient than energy distribution by electricity. However, this isn't the case.
Hydrogen is not a good
energy carrier, mainly as a result of its unique physical properties
of being the lightest of all elements and having an extremely low
boiling point. Because of its low density, it must be compressed or
liquefied for transport. Both of these processes require energy. Compression
requires about 10 percent of hydrogen's energy content; liquefaction
consumes about 30 to 40 percent. Twenty-two tube trailers loaded with
hydrogen at 3,500 psi would be needed to match the energy contained
in a single gasoline tanker truck.
About half of the original electrical
energy is lost between the power plant and the hydrogen outlet at
filling stations or homes. If hydrogen is reconverted to electricity
with 50 percent efficient fuel cells, about three-quarters of the
original electrical energy is lost. The point is that our energy problem
certainly will not be solved by wasting energy.
Because of this, promoters of "green" hydrogen should be aware that nuclear energy may be the only practical energy source for the inflated energy demand a hydrogen economy requires.
Sustainable Structures & Costs
Wind can already be harvested profitably along the coasts and in many other areas throughout the country. It is estimated that only 0.16 percent of the U.S. land mass would be required to generate 300 gigawatts of continuous wind energy-enough to meet the entire electricity demand of the United States.
These wind farms could be installed on farm and grazing lands, far away from population centers. Coupled with energy efficiency measures and photovoltaic arrays on most southfacing roofs, this energy mix could provide enough energy to meet our demands.
Before a sustainable energy economy is established, the costs for natural gas and heating oil will have reached levels that make energy conservation by using thermal insulation, better glazing, and appropriate architecture economically attractive. By implementing these measures, the heating and cooling demands of residential buildings could easily be halved. Electric heat pumps will replace fossil fuel based central heating systems, and heating oil will be rerouted to fuel vehicles. Building energy conservation may act to extend the fossil era in the transportation sector, making the early establishment of a hydrogen infrastructure less likely.
The transition from today's energy economy to a sustainable energy economy will also affect the energy cost structure. Because of the inherent losses directly associated with hydrogen production and distribution, hydrogen energy will cost at least twice as much as electrical energy, and hydrogen derived electricity will be four times as costly as electric power from a wall socket. This will result in a complete reversal of the entire energy market. Energy prices will no longer be set by oil or gas, but by the cost of renewable electricity.
An analysis of the energetics of a sustainable energy economy indicate that hydrogen's role will be limited to applications like space flight or submarines, or for storing electric energy from intermittent sources. Hydrogen may also provide energy for portable systems, or serve as clean energy applications for mining or in places where equally clean renewable energy solutions, like wind or PV, cannot be implemented. But because of the high losses associated with hydrogen's production, packaging, and distribution, hydrogen will likely remain an expensive luxury fuel.
But what about the future role of fuel cells? We need fuel cells now for the efficient and clean conversion of natural gas and liquid hydrocarbons like oil and gasoline. They have the potential to be more efficient and less polluting than internal combustion engines and gas turbines. Fuel cells with internal reforming (the ability to chemically convert hydrocarbons into hydrogen and carbon monoxide) offer inherent advantages over hydrogen-only systems. Even in a distant future,
fuel flexible cells will be used to convert synthetic hydrocarbons into electricity.
However, fuel cells shouldn't serve as a justification for a premature and hasty change of our energy system. A hydrogen economy should only be established if it makes economic and environmental sense, not because there are fuel cells waiting for hydrogen. Introducing a new energy carrier will not solve our energy problem, and it makes no sense to develop and introduce technologies to prepare for a "transition" to an energy future that cannot meet our future needs.
Because of its low energy efficiency, a hydrogen economy cannot be sustainable. However, a sustainable energy future can certainly be realized with energy conservation, efficient energy distribution, and the intelligent use of energy from renewable sources. With respect to overall efficiency and environmental friendliness, and by the fundamental laws of physics, hydrogen can never compete with its own source of energy.
Effects on Transportation
As RE-generated electricity from the grid will cost only half as much as the hydrogen energy offered by filling stations, electric cars-not hydrogen fuel cell vehicles-may become the preferred option for commuters. The
power plant to wheel efficiency of electric cars approaches 60 to 70 percent, compared to fuel cell vehicles, which have "wind-to-wheel" efficiencies between 17 and 23 percent when energized with liquid or gaseous hydrogen derived from renewable sources.
In a sustainable energy future, millions of electric vehicles
may be in daily use for local driving. Unlike the hydrogen infrastructure, which has yet to be developed, the energy infrastructure to support "fueling" these vehicles already exists, or could be easily implemented.
With all-electric commuter cars and automatic battery
chargers in every garage, bigger vehicles will most likely be hybrid
electric, operating on batteries for short trips and burning liquid
hydrocarbon fuels like methanol or biodiesel on longer hauls. Many
hydrocarbon fuels are as universal as elemental hydrogen. Biomethane
carries 3.5 times more energy per volume than hydrogen gas at the
same pressure. It is very unlikely that synthetic hydrogen will be
derived from biomethane, because it is much more difficult to distribute
and store onboard in sufficient quantities and over longer periods.
Also, most liquid hydrocarbons contain more hydrogen per volume than
liquid hydrogen. This suggests that hydrogen should be packaged in
synthetic hydrocarbon carriers rather than be distributed in its elemental
When physical energy is stored in a chemical energy carrier, the losses are equally significant. The electrolysis of water is a good example. The hydrogen produced carries much less energy than the
energy required to separate it from water.
Global warming and dwindling oil and gas reserves remind us that we
are approaching the end of the fossil energy road. But how can we
prepare for the unavoidable end of the fossil fuel era and meet our
energy needs sustainably, without using more energy than nature can
provide indefinitely, and without leaving waste that nature cannot
The Hydrogen Myth