The Dawn of
Micropower
Much of the world gets its electricity
from big, inefficient and dirty power plants situated
far from consumers. That will soon change...
THOMAS EDISON was a man of great
foresight, but who would have thought he could have been
more than 100 years ahead of his time? When he set up
his first heat-and-electricity plant near Wall Street in
1882, he imagined a world of micropower. Edison thought
the best way to meet customers’ needs would be with
networks of nimble, decentralized power plants in or
near homes and offices. What goes around, comes around.
After a century that seemed to prove Edison wrong—with
power stations getting ever bigger, and the transmission
grids needed to distribute their product ranging ever
wider—local generation for local consumption is back
in fashion.
There are several reasons for this.
One is market liberalization. About half of America’s
state governments have now forced their erstwhile
electricity monopolies to face competition. In the
European Union, a directive that took effect in 1999
ordered member governments to open up part of their
wholesale market for electricity. Many developing
countries, too, from India to Argentina, have embraced
deregulation and privatization.
Small, local power plants offer a
cheap way into such markets. Even if the power they
produce is more costly at source—which it often
is—they do not suffer huge transmission losses when
sending it to consumers. On top of that, the surplus
heat they generate can be employed for useful purposes,
such as warming buildings, whereas that from big
generators located in the middle of the countryside is
usually wasted. The result is that local power
generation has now become economically competitive.
A second reason for the rise of
micropower is environmentalism. Ever-higher emission
standards have made it unattractive to build new
coal-fired plants in the rich world. America still gets
more than half of its electricity from coal, but only
because many older plants have been “grand fathered”,
and so do not have to meet strict new emissions
standards—a derogation that is almost certain to be
struck down at some point. Europe has been even more
aggressive than America in pushing industry to adopt
cleaner forms of power generation. And microgenerators
are exceedingly clean. The worst of them burn natural
gas—a reasonably benign fuel. Others use hydrogen and
sunlight, both environmentalists’ dreams.
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A
third, increasingly important reason is the demand for
reliable, uninterrupted power. Karl Stahlkoph, the head
of the Electric Power Research Institute (EPRI), an
industry-financed American research body, reckons that
micropower will take off in America, where brownouts and
blackouts are an ever-increasing problem, as much
because it is under its owners’ control as for any
other reason.
These three things have stimulated the
search for small, clean, reliable and above all cheap
generating technologies. And such technologies are now
emerging, fuelled by a surge in venture-capital
investment (see chart) and the prediction that, within a
decade, the market for such equipment may be more than
$60 billion a year.
Powerful choices
The most dramatic breakthroughs are
taking place in the field of fuel cells. These devices,
which work by combining hydrogen with oxygen from the
air to produce electricity, are popular candidates to
replace internal-combustion engines in road vehicles.
But they look increasingly plausible as replacements for
power stations, too.
There are several sorts of fuel cell,
but all consist of two electrodes (an anode and a
cathode) separated by a material called an electrolyte.
In most fuel cells hydrogen is fed to the anode, where
it is ionized into a proton and an electron. The proton
makes its way to the cathode through the electrolyte,
while the electron goes there the long way round—via a
wire that leads into whatever the fuel cell is powering,
and back again. At the cathode, the protons and the
electrons react with oxygen from the air to make water
which, to the joy of environmentalists, is the only
waste product of such a cell.
The leading fuel-cell technology at
the moment is generally reckoned to be the
proton-exchange membrane (PEM) cell. In this, the
electrolyte is a polymer membrane coated with platinum,
a metal that acts as a catalyst for the chemistry
involved.
Ballard Power Systems, a Canadian
firm, is the leading proponent of PEM technology. Firoz
Rasul, its boss, says he expects his firm’s first
commercial product to reach the market next year. This
will be a 1kW generator, to be marketed by Coleman, an
American outdoor-goods firm, for household use. Ballard
is also developing a power unit with Tokyo Gas, a
utility that supplies Japanese homes with natural gas.
That version would “reform” the natural gas first,
by reacting it with steam to release the hydrogen in it.
This means the exhaust will include carbon dioxide. But
reformation eliminates the need to supply the cell with
pure hydrogen, making the whole process cheaper.
A rival to PEMs is the solid-oxide
fuel cell. A leading SOFC design arranges an electrolyte
and two electrode layers in a tube. Air flows through
the inside of this cell and hydrogen past the outside.
In this case it is the oxygen that is ionized (by
heating the air up to 1,000°C), and thus supplies the
electrons. Although SOFC units have to operate at higher
temperatures than PEM cells, they can achieve levels of
efficiency much greater than is now possible with PEMs.
Siemens Westinghouse, a big
power-equipment firm, expects to bring SOFCs to market
in 2004, at a price of $1,500 per kW, dropping quickly
to the $1,000 threshold that is currently achieved by
coal-fired power stations. And, unlike Ballard with its
1kW units, Siemens is building generators capable of
producing between 0.3MW and 10MW. These are aimed at
industrial customers.
A third variation on the fuel-cell
theme is the alkaline fuel cell. This requires two
porous electrodes, separated by an electrolyte composed
of potassium hydroxide. ZeTek Power, a British firm that
is due to go public early next year, is leading the
development of this technology. Nicholas Abson, the
firm’s chief executive, insists that his technology is
cheaper, easier to make and more practical than either
SOFC or PEM cells. Unlike SOFC, alkaline cells work at
relatively low temperatures. Unlike PEM cells, they do
not rely on platinum catalysts. ZeTek, according to Mr.
Abson, has perfected the use of cheap metal-oxide
catalysts that will help to bring the cost of its
stationary fuel-cell systems below $500 per kW within 18
months.
Less is more
Fuel cells are a nifty idea, but they
suffer from one serious disadvantage: that the world is
not set up to deliver hydrogen cheaply. Technologists
are working on this problem. Hydrogen for Ballard’s
cells is stored in substances called metal hydrides,
which can absorb large quantities of the gas. But
systems that can make use of existing fuel-delivery
infrastructures are likely to have a head start—as
Ballard has conceded in its deal with Tokyo Gas.
A second novel micropower technology,
however, is ideally suited to natural gas. This is the
microturbine. The clever thing about a microturbine—as
opposed to the big, clunky sort of turbine that is used
in traditional power stations—is that it has only one
moving part. This is a high-speed compressor-cum-rotor
that spins at up to 100,000 revolutions a minute.
The near-absence of moving parts means
that microturbines are cheap to operate and
maintain—costing as little as a third of the running
costs of a comparable diesel generator. Even the problem
of lubricating the one part that does move seems to have
been solved. Capstone Turbine, a small American firm,
has developed a version of the device that uses
sophisticated “air bearings” which require no liquid
lubrication. Capstone, unlike many other companies in
the microturbine market, is already selling its
products—shipping several thousand a year, ranging in
size from 25kW up to 500kW, to a number of commercial
clients.
The third aspirant micropower
technology is solar energy. Like fuel cells, which were
first dreamed up in the 1830s, photovoltaic solar cells
have been a long time coming as an everyday means of
power generation. But they are almost there.
Solar cells are composed of a
semiconductor such as silicon. When the sun’s rays hit
a cell’s surface, some of the semiconductor’s
electrons absorb enough energy to rush off towards the
other side of the cell, where a lattice of delicate
wires embedded in the surface gathers them up and feeds
them into a cable.
The advantages of small solar-power
plants are that they are clean, reliable and, of course,
that the fuel comes free. The snag, however, is that the
equipment does not. The energy from such plants costs
between 22 cents and 36 cents per kW-hour, twice the
expected cost for fuel cells.
Those costs, however, are a quarter of
their level two decades ago, and look likely to fall
further thanks to breakthroughs in the manufacture of
the silicon wafers from which solar cells are cut.
AstroPower, the only integrated solar-energy firm to be
traded publicly, has come up with a very-high-speed
manufacturing process which it calls “silicon-film”
making, and which is akin to the “float glass”
method used to make window panes. This should halve the
cost of wafers, bringing the technology’s price within
spitting distance of its rivals.
Back to the future?
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The
new micropower technology is undeniably impressive. But
the big question is whether the market for distributed
generation will take off this time—over a century
after its first bloom. One reason to think it might is
that its costs have come down to economic levels (see
chart). The trends suggest they will fall still further
over the coming decade, making micropower attractive to
the ordinary consumer in the rich world.
The greatest potential for micropower,
however, may lie in helping the 3 billion people in the
poor world who have no reliable access to electricity.
Gary Mittleman, the boss of Plug Power (a firm which, in
collaboration with GE, a big American electrical
company, is one of Ballard’s rivals in the PEM
market), reckons that it costs between $1,000 and $1,500
per kW to build or replace electricity grids in
developing countries. In such places, micropower is
already an attractive option. International agencies
such as the World Bank, as well as private-sector
operators and non-governmental groups, are devising
“microfinance” schemes to help bring electricity to
the poor in such countries as Mongolia and India.
In time, micropower may also change
the way electricity grids themselves operate—turning
them from dictatorial monopolies into democratic
marketplaces. Add a bit of information technology to a
microgenerator and it will be able both to monitor
itself and to talk to other plants on the grid.
Visionaries see a future in which dozens, even hundreds,
of disparate micropower units are linked together in
so-called “microgrids”. These networks could be made
up of all sorts of power units, from solar cells to
microturbines to fuel cells, depending on the needs of
individual users. EPRI has feasibility studies under way
to develop a microprocessor-based converter that will
enable “plug and play” connection of any micropower
device to the power grid.
As energy markets liberalize, online
energy-trading spot markets develop, and individual
consumers win the right to select their energy
suppliers, some even see the emergence of “virtual
utilities”. Microgrids would allow such firms to
combine the individual efficiency of micropower plants
with the market power that is gained by bundling
together their collective generating capacity. Whether
run in competition with established utilities, or by
them, such virtual utilities would, according to Goran
Lindahl, head of ABB, a large European
generating-equipment company, result in “greater
system reliability, lower operating costs, reduced
environmental impact and improved overall business.”
ABB is now building microgrids that should be up and
running by 2001 in both Europe and America.
Much as with the Internet, the
companies that develop the technology to allow the
electricity grid to perform intelligent metering and
switching, and that position themselves as
“air-traffic controllers” for these streams of
electrons, will lead the industry. It is a heady vision
for what many think of as a dull commodity business.
Edison would surely be proud of the role that micropower
looks likely to play in the third century of the
electricity age.
