Power shock: the next energy revolution.

We live in a futuristic world of cyberspace, genetic engineering and other mind-boggling technologies. Yet when it comes to energy, most experts seem to think that our decades-old oil- and coal-based energy systems will barely change. Developments around the world are already proving them wrong, however. We may soon witness the most dramatic changes in the world energy economy in a hundred years.

At a small news conference in Landover, Maryland last October, two major U.S. corporations made an announcement that may one day be seen as a big step in launching the energy systems of the twenty-first century. Bechtel Enterprises Inc., once a leading builder of nuclear power plants, and PacifiCorp, a giant utility that operates several huge coal-fired generators in the northwestern United States, announced that they were teaming up to invest in solar energy and other "human-scale energy systems."

The new joint venture, called EnergyWorks, will pursue projects around the world based on wind turbines, biomass generators, industrial energy efficiency, and other technologies that most large energy firms have spurned as puny systems that cannot possibly meet the expanding energy needs of close to six billion people.

But those energy executives who still cast their lot with large oil refineries, nuclear reactors, and the like would do well to remember the lessons of IBM, which discovered too late that personal computers were more than a boutique industry that could never challenge the dominance of mainframes. Once technological change gathers momentum, it can move at lightning speed.

In fact, historians of technology may one day argue that by the mid-1990s, the world energy, economy was already in the early stages of a major transition. One sign, for example, is that relatively small, efficient jet engines are coming to dominate the power industry, sweeping aside less efficient coal-fired models. Another is that advanced electronics have improved the efficiency of lighting by as much as four-fold. Meanwhile, the fastest growing energy market in the early 1990s isn't oil, coal, or even natural gas - it is wind power, which expanded from 2,000 megawatts in 1990 to 4,500 megawatts in 1995.

Around the world, advanced electronics, new kinds of synthetic materials, and the techniques of mass production are allowing engineers to substitute clever technologies for brute force. The result is a variety of new modular, mass-produced energy systems that have the potential to be more economical and flexible than the traditional energy systems they replace.

Here, as in the mercurial worlds of computers and telecommunications, it is impossible to predict the future. But the broad outlines of a new energy economy are beginning to emerge. Its chief feature is likely to be a radical decentralization, akin to the computer industry's shift from mainframes to PCs. The new technologies will make it possible to decentralize power generation, even down to the household level, harness the world's most abundant energy resources - solar energy and wind power - and greatly reduce the burden that current energy systems place on the world's atmosphere.

But these changes may add up to more than the sum of their parts. Using technologies such as fuel cells and mass-produced solar generators, it should be possible in the long run to replace virtually all fossil fuels with a hydrogen-based energy system, something that author Jules Verne dreamed of more than a century ago. The hydrogen would be produced using sunlight harnessed on rooftops as well as in remote desert collectors, and would be conveyed to homes and industries via pipeline. Although this vision may sound futuristic, most of the inventions needed to make it real have already been made.

PUNCTUATED EQUILIBRIUM 

Technological change has been compared to the evolutionary development that occurs in nature, and the similarities are not all coincidental. Technology is, after all, a systematic extension of human biological capability - an increased capacity to use available energy to do the things that eyes, hands, and legs do, only on a vastly magnified scale. It's not surprising, then, that if there have been longstanding misconceptions about the nature of evolution, the same misconceptions have distorted our vision of technological change.

For nearly a century after Charles Darwin wrote Origin of Species, biologists thought of evolution as an exceedingly gradual process, with an almost infinite number of incremental stages between one species and its successor. During the 1970s, Harvard biologist Stephen Jay Gould proposed an alternative theory: that most evolutionary change occurs in sudden bursts - driven in part by changing climates and other environmental influences that force species to change rapidly in order to survive. According to Gould, these bursts may be preceded by long periods of stasis - giving the impression that evolution is glacially slow. Gould's theory, known as "punctuated equilibrium," has since earned broad acceptance among biologists.

In the evolution of technology, the same pattern of punctuated progress can be seen. The telephone, for example, developed rapidly in the late nineteenth century and then changed very little through the middle decades of the twentieth century. Now the telephone is again in a period of explosive transition - simultaneously becoming digital, wireless, and portable, while also becoming a carrier not only of voices but of a wide variety of other kinds of communications - from facsimile pages to debit card transactions.

To those who make a living out of projecting future energy trends, the current system appears close to immutable. For more than 70 years it has been dominated by big oil refineries, internal combustion engines, and steam-cycle power plants, devices that have become more efficient and larger, but have never been displaced. It is no wonder that these analysts see the future as marked by increasingly small refinements to the existing system.

Reflecting this bias, official energy projections published by the International Energy Agency, the World Energy Council, and various national governments conclude that future energy systems will merely be more efficient versions of the current one. Their studies suggest that our grandchildren will still be driving automobiles powered by internal combustion engines - and using electricity generated by power plants that waste two-thirds of the coal they consume - well into the 21st century.

These prognosticators are mesmerized by how little energy systems have changed in recent decades, but ignore the fact that in the more distant past, energy systems have changed rapidly. The energy economy we have today was created in an explosion of invention between 1890 and 1910. During that short period, many cities were dramatically transformed, with horse-drawn carriages replaced by automobiles, and gas lamps by electric lights.

The carriages and gas lamps had prevailed for centuries, but once the conditions for rapid change were present, the old technologies were replaced with breathtaking speed. Today, we may be at a similar turning point, as revolutionary new energy technologies emerge at the same time that consumers demand a cleaner environment and more flexible, less costly ways of meeting their energy needs. The technological upheavals sweeping so many other industries are unlikely to leave the old energy system intact.

Today, even the conservative business press is beginning to take such ideas seriously. In its October 7 issue, The Economist magazine stated: "Once [renewable energy] was the province of mad scientists and dreamers. . . No longer. Little noticed, the costs of many renewables have recently been tumbling. Fossil fuels are still almost always cheaper, but a battle has begun on the fringes of the mighty $1-trillion-a-year fossil-fuel industry that could force it into retreat early in the coming century."

ROOFTOP POWER

One of the most neglected "fringes" of the world energy economy is made up of thousands of rural villages that are home to some 2 billion people who lack access to electricity or other modern fuels. Yet these villages are now at the center of one of the most revolutionary new developments: during the past ten years, silicon cells that turn sunlight directly into electricity have been installed on or adjacent to at least 250,000 homes, mostly in remote areas of countries such as Sri Lanka, China, and Mexico.

In Kenya, in 1993, more homes were electrified using solar cells than by extending the grid. In Brazil, utility companies are starting to support solar electrification in the Amazon and other areas where it is impractical to extend power lines. (See photo, page 40.) In South Africa, the government has launched a major effort to provide solar power to millions of people. And in Vietnam, where only 14 million of the country's 72 million people currently have electricity, the Vietnam Women's Union has launched a solar electrification program.

Solar electric systems are also beginning to appear on the roofs of posh suburban homes in industrial countries. In Sacramento, California, for example, the municipal utility is putting shiny blue solar electric panels on 100 homes each year; their rooftop systems are connected to the utility's electric grid, so that power not needed within the home can be sold to other consumers. Consumers pay for the systems via their monthly power bill, at a rate that is only slightly higher than their neighbors'.

In Switzerland and Germany, more than 1,000 buildings have been outfitted with solar power systems in recent years, with government funding. Thousands more are planned. The Japanese government plans to install some 62,000 building-integrated solar generators by the end of the decade. Although such systems must be subsidized to be affordable today, they could become fully competitive with traditional power sources as large-scale production brings manufacturing costs down.

A product of the electronic revolution, solar cells bypass the mechanical generators now used by virtually all power plants, whether they run on fossil fuels, hydropower, or nuclear energy. First used to power orbiting satellites in the U.S. space program in the 1960s, solar cells are a close relative of the microprocessors that make today's computers possible. The cells consist of semiconductors - usually made of silicon - that emit electrons when struck by sunlight, thereby producing an electric current.

Japanese, Swiss, and U.S. manufacturers have designed experimental "solar tiles" that shelter occupants while also powering their appliances. In Europe, Flachglas, a leading producer of architectural glass, has developed a semi-transparent "curtain wall" that provides filtered light as well as electricity. In a joint venture in the United States, Corning Glass and Siemens Solar are developing a similar product.

The cost of solar cells has declined from more than $70 per watt in the 1970s (in 1994 dollars) to $4 per watt today, and is expected to drop to between $1 and $2 per watt within a decade, according to the National Renewable Energy Laboratory in Colorado. As a result, the potential applications have multiplied. The world market went from 34 megawatts in 1988 to an estimated 90 megawatts in 1995.

Aerial photographs show that even in the cloudy climate of the British Isles, putting solar cells on all the country's existing flat roofs could generate 68,000 megawatts of power on a bright day - about half the United Kingdom's current peak power demand. With a strong push by governments and private investors, it is possible that rooftops alone could provide as much as a quarter of the world's electricity by the middle of the next century.

POWER FROM THE BASEMENT 

Another technology that may soon allow individual buildings to produce their own power is the fuel cell. First used to provide electricity for orbiting U.S. spacecraft in the 1960s, fuel cells are battery-like devices that efficiently convert a fuel - usually hydrogen - to electricity. Compared to today's generators, which are mechanical devices, fuel cells produce minimal air pollution and virtually no noise. And because they are small and can be located inside buildings, their waste heat can be productively used, rather than vented to the atmosphere as occurs in most of today's power plants.

The hydrogen that powers fuel cells can easily be obtained by splitting the methane found in natural gas - the most common heating fuel in American and European homes - into hydrogen and carbon dioxide. A number of types of fuel cells are now under development, some with government support.

During the past five years, the imperative to improve urban air quality has produced a surge of investment in fuel cells. Several companies have successfully demonstrated the pollution avoidance benefits of fuel-cell generators by installing them in hospitals and other buildings. Typically, such fuel cells are used to provide around-the-clock electricity, with waste heat captured for water and space heating.

In the United States, the race is on. Last September, ONSI Corporation, a division of United Technologies, launched the world's first commercial fuel cell factory, which will initially turn out some 50 fuel cells each year, at less than half the cost of earlier fuel cells. Meanwhile, Allied Signal has been working on a 5- to 10-kilowatt fuel cell for home-scale use, relying on technologies it developed in its aerospace business. And IBM announced last summer that it is applying its expertise in multi-layer ceramic substrates to make less-expensive fuel cells in a joint venture with the Dow Chemical Company. In Canada, Ballard Power Systems has developed a fuel cell that is designed specifically for use as a bus engine.

Such commitments suggest that a commercial takeoff for fuel cells is likely within the next decade. And as the volume of production grows, costs are expected to plummet. If this technology flourishes, we may soon approach the day when a city that is now served by three or four power plants may have thousands of small networked generators connected to it. In a sign of things to come, the Netherlands already gets one-third of its power from industrial and commercial co-generators. Low cost fuel cells could one day push that figure to two-thirds or more.

STORING POWER

Just as buildings of the future are likely to generate their own electricity, they may also be able to store it. During the past five years, at least five companies have begun developing flywheels, which function like mechanical batteries. Operating on the same principle as a potter's wheel, a flywheel disc is set to spinning at high speed by an integrated electric motor/generator. It is contained inside an airless case, almost eliminating resistance so that the ensuing long duration of the spin serves as a means of storing kinetic energy - which can then be converted to electricity by the generator as needed.

Although it was invented over a century ago, the flywheel only became practical with the development of strong, lightweight composite materials in the 1970s and 1980s. Modern composites can spin in a vacuum at up to 200,000 revolutions per minute, with the potential to store and release energy at an efficiency of more than 90 percent. Because they have virtually frictionless electromagnetic bearings, flywheels can store electricity for weeks, and last years before wearing out.

At the Lawrence Livermore Laboratory in California, scientists and engineers are developing a mass-produced device half the size of a clothes washer that could sit in a building's basement, storing cheap electricity at night (or solar energy during the day) and releasing it to the grid when needed.

Several large and small companies are developing similar devices.

Flywheels would last much longer than chemical batteries, and would not require toxic substances. The materials needed to manufacture them are not expensive, and their design readily lends them to mass production, which will yield much lower costs. Because they could be used as storage devices in electric cars as well as in buildings, the ultimate market for flywheels could add up to millions of units. It will probably be 10 to 15 years before flywheels are widely available commercially, but after that, their use could grow as fast as that of cellular phones has in the early 1990s.

WINDS OF CHANGE

Another modular power technology, the wind turbine, has begun to change the electric power landscape from the northern coasts of Europe to the plains of southern India. The world had more than 25,000 wind turbines operating at the end of 1995, producing nearly 5,000 megawatts of power. California has 1,700 megawatts, generating enough electricity to supply all of San Francisco's residents, and Germany has more than 1,000 megawatts, supplying over 5 percent of the electricity in the state of Schleswig-Holstein.

After a slow period in the late 1980s, the world market for wind turbines has exploded since 1990. Following the laws of technological progress and large-scale manufacturing, the cost of wind-generated electricity has fallen by more than two-thirds over the past decade, to the point where it is lower than that of new coal plants in many regions. Within the next decade, it is projected to fall to 3 to 4 cents per kilowatt-hour, making wind the least expensive power source that can be developed on a large scale worldwide.

The new wind turbines aren't the quaint old "wind mills" we remember from past generations; they are sleek, high-tech fiberglass models with gearless, variable speed transmissions and advanced electronic controls. The larger machines have blade spans of 50 meters (160 feet) and more. Unlike large conventional power plants, new wind turbine models enter the market as frequently as new laptop computers do. And, like laptops, they deliver services in small units; the latest wind machines generate 300 to 750 kilowatts per turbine - one-thousandth the size of a typical coal plant.

Europe is now the world's hottest wind power market. Its wind boom is led by Germany, which now has thousands of gleaming white wind turbines sprinkled across the flat farmland of Lower Saxony and other coastal states. The tenfold rise in wind power in Germany since 1990 resulted from an investment boom stirred up by generous tax credits and the 1991 "electricity infeed law" for renewables.

Not far behind are several other European nations, including Denmark, Great Britain, the Netherlands, and Spain. If development continues at the recent frenzied pace, wind power could become a major source of European electricity within the next decade.

In India, a wind energy rush began in 1994 as the government opened up the power grid to independent developers and offered tax incentives for renewable energy development. Indeed, India is now second only to Germany in the number of annual wind power installations. By early 1995, some 300 megawatts of wind power were in place, much of it resulting from joint ventures with European and U.S. manufacturers, some of whom are building assembly plants in India. Already, land values in windy regions have jumped dramatically. Other countries with sizable wind power projects underway include Brazil, China, Greece, and Mexico.

Although wind power provides less than 0.1 percent of the world's electricity today, it is fast becoming a proven power option that is reliable enough for routine use by electric utilities. It is not inconceivable that two decades from now, millions of turbines will be spread across windy areas of the world, providing 20 or 30 percent of the electricity in some areas. In the United States, three Great Plains states could in theory supply all the country's electricity, and for China, the same can be said of Inner Mongolia, which is located within a few hundred kilometers of Beijing.

The formula used for wind energy - independent developers installing collections of small generators in resource-rich areas - is proving viable for solar energy as well. In the Mojave Desert, some 350 megawatts of parabolic dish solar collectors already provide power for Southern California Edison's power grid, and similar projects are being eyed in Australia and the Middle East. Similarly, the Houston-based Enron Corporation announced in late 1994 that it plans to build large collections of grid-connected solar photovoltaic generators in the desert regions of China, India, and the United States. As costs fall, these could become a leading source of electricity.

SMART ENERGY?

As regional power systems go from relying on 10 or 20 power plants to networking thousands of small generators, broader changes in the energy system are likely to follow. Recent advances in two-way communications make it possible to precisely monitor and control the power system using microprocessors. With such controls, each solar rooftop, fuel cell, and air conditioner can be linked to a utility's computers via copper or fiber optic lines so that the grid operates as a single "smart" system, turning various devices on and off as needed.

In an experiment in the Chenal Valley neighborhood of Little Rock, Arkansas, the local electric utility, Entergy, has installed unobtrusive, wall-mounted computers that look like fancy thermostats. They provide two-way communication between home and utility and permit on-site optimization of energy use. As demand fluctuates, the utility can provide "real time" pricing to customers, who can program their appliances to turn on when demand is low and electricity is available at less expensive rates. For example, a house can be cooled down just before a period of peak temperatures - and peak power prices.

Entergy projects that real-time pricing, combined with electronic controls, will increase the efficiency of the system by reducing peak power demand and, with it, the need for spare generating capacity. For each new household Entergy hooks up in Chenal Valley, at a cost of $1,050, the utility estimates that it avoids $1,757 worth of power supply costs over the next 20 years. Globally, such systems could eliminate the need to build hundreds of large power plants over the next few decades.

Micro-generators can also be programmed to respond to price signals automatically, so that they provide power to the grid when demand is high, and store it in devices such as flywheels when it is not. A "smart" power system can use price information to balance electricity supply and demand, limit the need for more distribution lines, and thereby reduce costs throughout the electric power system. These advances will greatly facilitate the integration of intermittent wind and solar generators, since they will facilitate the economical deployment of backup generating capacity.

Because energy management typically requires no more than 5 percent of the capacity of a fiber optic cable, energy management systems can be integrated into the high-speed information networks that telecommunications companies are now hooking up to millions of homes and businesses. Alternatively, a utility could install such a line itself and lease excess capacity to companies that provide other information services such as home shopping, travel reservations, and stock quotes. This could give electric utilities a major role in developing the fast-evolving information superhighway.

Last September, an unusual joint-venture between an electric power company, St. Louis-based UtiliCorp, and the Utah-based software firm Novell announced plans to develop and market an electronic system that allows consumers to optimize the timing of their use of electricity. Unlike the energy management systems being developed by other companies such as Microsoft and TCI, the Novell technology uses existing power lines to transfer data at speeds up to 2 megabits per second while making two-way network communications as simple as plugging a toaster into an electric wall outlet.

The dramatic changes now in prospect for the power industry were acknowledged in last September's Financial Times Energy Economist. "Just as the networking personal computer has replaced the mainframe in the office, so we may be seeing a trend towards the imploding of the centralised, integrated utility in sophisticated economies. . . In short we are at the beginnings of a revolution in power supply."

FORCES OF CHANGE

From some perspectives, the mid-1990s are a dark time for the world energy system. Oil consumption is approaching the record levels of the late 1970s, with demand in some countries growing at rates as high as 10 percent per year. Even the use of coal is still expanding in many nations, pushing emissions of carbon dioxide, the leading greenhouse gas, to more than 6 billion tons per year. Emissions are growing particularly rapidly in China and India, but even the United States and Canada are failing to hold carbon dioxide emissions steady as they are supposed to under the Rio climate convention.

Although most energy analysts view such trends as convincing evidence that the world energy system won't change anytime soon, the reverse may be true. As Stephen Jay Gould's theory suggests, evolutionary bursts are usually precipitated by strong pressures. Today, three major forces of change are bearing down on the world energy economy - new technologies, industry restructuring, and tougher environmental policies - all of which are likely to be intensified by incipient climate change.

New technologies are the most obvious. As noted earlier, advanced electronics, new materials, and biotechnology are now being put to use in energy systems. The modern automobile, for example, has become virtually a computer on wheels, with electronic controls that provide not only easier steering and breaking but improved fuel economy and lower emissions. Thanks to such developments, spurred by two decades of strong government support for R&D on new energy technologies, it will soon be possible to harness solar and wind energy on a much larger scale.

Industry restructuring is also spurring change. In the past, most electric power systems have been operated as government-owned or controlled monopolies that manage everything from constructing power plants to reading the meters attached to customers' homes. These monopolies have been drawn to giant plants and inefficient, entrenched technologies, and have had little incentive to pursue innovation.

But today, all that is changing. In Brazil, India, Poland, Great Britain, Japan, and the United States, utility systems are being broken up and sold to private investors. In many nations, the generation of electricity is increasingly provided by independent power producers that have no monopoly franchise on the business. Local distribution utilities and industrial users buy power from those producers, using the electricity transmission system as a common carrier, in the same way that railroads and telephone lines are used.

This restructuring has led to an unprecedented wave of innovation, as independent producers find that in order to be competitive, they have to build ever more efficient and less expensive plants. Such producers are pursuing smaller and less environmentally damaging energy sources than did their utility brethren. In the United States, for example, a power plant built in the early 1990s has a capacity of 100 megawatts on average, compared to 600 megawatts less than a decade earlier. Most of the latest plants now are fueled with natural gas rather than coal or nuclear power.

India provides a particularly strong example of the impact of restructuring. As the state utility monopolies were broken in the early 1990s, independent power generation blossomed. Scores of projects are now underway, in a competitive rush to reduce the country's chronic power shortages. Although many of the new plants are coal- and gas-fired, dozens of wind and solar energy projects are also underway, attracting foreign investment and creating a manufacturing boom.

The third force driving rapid change is the growing reach of policies intended to protect the earth's embattled environment. In many countries, emissions and waste-disposal laws have greatly added to the cost of building coal-fired power plants, and nuclear generators have essentially been ruled out as having unacceptably high costs and risks. These changes have boosted the market prospects for efficient natural gas and renewable energy generators.

To help protect the environment, some governments have changed tax and utility laws to level the playing field between dirty and clean technologies. India, for example, allows a full income tax deduction for renewable energy investments, and the United States offers a 1.5 cents per kilowatt-hour subsidy to renewable power. In Germany, renewable power generators have been granted the right to sell power to utilities at a rate of 0.17 DM (12 cents) per kilowatt-hour - about what Germans pay for coal and nuclear power, but well above current prices for the latest natural gas-based power systems - thereby priming the pump for renewables.

As more countries enact similar changes, the boom in renewable energy development now taking place in Germany and India is likely to spread. Japan, for example, has just opened its power grid to independent generators, with special incentives for renewables. Brazil is opening the gates to independents as well, and renewable energy developers are reported to be exploring the coasts and deserts of the country's northeast, which has prime wind and solar sites.

THE HYDROGEN AGE

In elaborate studies churned out by governments and corporations each year, powerful computers are used to project future energy trends. Although the results of such studies are received by many policymakers as gospel, they are generally based on a narrow band of oil price and economic growth assumptions. Indeed, what passes for energy analysis today is dominated by a preoccupation with econometrics and the geopolitics of the Persian Gulf, leaving unquestioned the assumption that we will stay hooked on oil until it is gone, and that coal's role must expand simply because coal is abundant.

Economists who conduct such studies often ignore ongoing technological trends, let alone the broader policy environment. If earlier forecasters had used similar techniques, they would have concluded that we - in the 1990s - would still be driving around in horse-drawn carriages and writing on typewriters. After all, we never ran out of either hay or paper. Rather, people found ways of meeting their needs more conveniently and economically.

What was true for transportation toward the end of the 19th century and for communications toward the end of the 20th will be no less true for energy at the start of the 21st: when breakthroughs alter the relative competitiveness of a long-dominant resource, its continued abundance becomes suddenly irrelevant. The age of oil, for example, was ushered in not by the discovery of petroleum, which had been found much earlier, but by the development of an internal combustion engine that made oil much more useful. Overnight, 25 million horses were rendered obsolete.

Just as our forefathers at the turn of the last century had a hard time envisioning what was to come, so we now have a hard time seeing what lies beyond the age of fossil fuels. Do all of the changes described above add up to more than an efficient version of the current system? The answer appears to be yes. A number of scientists and other experts have been able to offer at least a glimpse of what we are moving toward: a solar hydrogen economy.

Hydrogen is the simplest of the chemical fuels, and unlike methane, the cleanest fuel used today, is entirely carbon-free. Hydrogen is the lightest of the elements as well as the most abundant. Three-quarters of the mass of the universe consists of hydrogen, which of course is also a principal constituent of water. When the time comes to use the hydrogen as fuel, it is combined with oxygen to produce water, releasing energy but no pollution.

Scientists have foreseen the possibility of a transition to hydrogen for more than a century, and today it is seen as the logical "third wave" fuel - hydrogen gas following liquid oil, just as oil replaced coal decades earlier. The required technology - using electricity to split water molecules through electrolysis - is already being used commercially. (All the world's current energy needs could be met with less than 1 percent of today's fresh water supply, and hydrogen can also be produced from seawater.) Although many people worry that hydrogen is dangerous, if properly handled, it will probably be safer than fuels like gasoline that are widely used today.

The challenge now holding up the transition to hydrogen is finding inexpensive sources of energy to split water. This may seem circular - the need to find cheap energy in order to produce an affordable fuel. But the key to the puzzle lies in the possibility of storage and transportation. Wind and solar energy are often found in the wrong place at the wrong time, but those energy sources can be used to feed the electricity grid when power demand is high, and to produce storable hydrogen when it is not.

In fact, hydrogen may provide the ideal means of storing and distributing these intermittent power sources. Additional hydrogen can be produced in homes and commercial buildings using rooftop solar cells. The hydrogen can then either be stored in a basement tank for later use in a fuel cell or conventional boiler, or be piped into a local hydrogen distribution system.

In either case, a decade or two from now, hydrogen could begin to enter the markets now dominated by oil and natural gas - including home heating, cooking, industrial heat, and transportation. In fact, scientists, have determined that in the early stages, hydrogen fuel can be derived from natural gas, and that during the transition, consumers may use a mixture of hydrogen and methane gas. Experimental hydrogen-powered cars have already been developed by Mazda and Mercedes. With the advent of small fuel cells, such cars may become highly efficient and affordable. By the middle of the next century, oil and coal could be phased out.

Although renewable energy sources are more abundant in some areas than others, they are far less concentrated than oil, since two-thirds of proven petroleum reserves are in the Persian Gulf. Moreover, the coming solar-hydrogen economy is likely to be based on a diverse array of renewable resources, with the mix varying by region. The hydrogen can be carried to where it is needed through pipelines similar to those used to carry natural gas.

Over time, solar- and wind-derived hydrogen could transform the way energy is produced and used virtually everywhere. All of the world's major population centers are within reach of sunny and wind-rich areas. The Great Plains of North America, for instance, could supply much of Canada and the United States with electricity and hydrogen fuel. For Europe, solar power plants could be built in North Africa, with hydrogen transported along existing gas pipeline routes. In China, hydrogen could be produced in the country's vast western deserts and shipped to population centers on the coastal plain.

Many people assume that producing sufficient hydrogen from solar and wind energy requires huge swaths of land, but these technologies actually use less than one-fifth as much land to produce a given amount of energy as does hydropower, which now supplies nearly a third of the world's electricity. Moreover, while much of the land used for hydropower has to be condemned for flooding (often of prime cropland), the tracts used for wind farms can still be used for crops and grazing.

What then would a solar-hydrogen energy system look like? One of its chief advantages is that it would be largely invisible. Fuel cells and flywheels would be hidden in peoples' basements; solar rooftops would be nearly indistinguishable from conventional rooftops; and hydrogen pipelines would be buried underground, as are today's natural gas pipelines. Some rural farming areas may be sprinkled with wind turbines, but most of the larger wind and solar power plants are likely to be located in remote areas such as India's Thar Desert or Mexico's La Ventosa, where people rarely visit.

On first reflection, such an energy system may seem fanciful. But two decades ago, the idea of desktop computers and information superhighways would have seemed equally far-fetched. And arguably, what is most inconceivable is that an information-age economy will be powered by a primitive industrial age energy system.

As corporate and government decision makers begin to understand just how economical and practical a zero-emission, carbon-free energy system can be, and just how inefficient and dirty the current system is, they may finally summon the sort of effort that made the last great energy transition possible - a hundred years ago.

Christopher Flavin is Vice-President for Research at Worldwatch Institute and co-author with Nicholas Lenssen of Power Surge: Guide to the Coming Energy Revolution (W.W. Norton: 1994), on which this article is based.