Physics of the Future

by Michio Kaku

  In 2009, First Solar, the world’s largest manufacturer of solar cells, announced that it will create the world’s largest solar plant just north of the Great Wall of China. The ten-year contract, whose details are still being hammered out, envisions a huge solar complex containing 27 million thin-film solar panels that will generate 2 billion watts of power, or the equivalent of two coal-fired plants, producing enough energy to supply 3 million homes. The plant, which will cover twenty-five square miles, will be built in Inner Mongolia and is actually part of a much larger energy park. Chinese officials state that solar power is just one component of this facility, which will eventually supply 12 billion watts of power from wind, solar, biomass, and hydroelectric.

  It remains to be seen whether these ambitious projects will finally negotiate the gauntlet of environmental inspections and cost overruns, but the point is that solar economics are gradually undergoing a sea change, with large solar companies seriously viewing solar power as being competitive with fossil fuel plants.

  ELECTRIC CAR

  Since about half the world’s oil is used in cars, trucks, trains, and planes, there is enormous interest in reforming that sector of the economy. There is now a race to see who will dominate the automotive future, as nations make the historic transition from fossil fuels to electricity. There are several stages in this transition. The first is the hybrid car, already on the market, which uses a combination of electricity from a battery and gasoline. This design uses a small internal combustion engine to solve the long-standing problems with batteries: it is difficult to create a battery that can operate for long distances as well as provide instantaneous acceleration.

  But the hybrid is the first step. The plug-in hybrid car, for example, has a battery powerful enough to run the car on electrical power for the first fifty miles or so before the car has to switch to its gasoline engine. Since most people do their commuting and shopping within fifty miles, it means that these cars are powered only by electricity during that time.

  One major entry into the plug-in hybrid race is the Chevy Volt, made by General Motors. It has a range of 40 miles (using only a lithium-ion battery) and a range of 300 miles using the small gasoline engine.

  And then there is the Tesla Roadster, which has no gasoline engine at all. It is made by Tesla Motors, a Silicon Valley company that is the only one in North America selling fully electric cars in series production. The Roadster is a sleek sports car that can go head-to-head with any gasoline-fired car, putting to rest the idea that electric lithium-ion batteries cannot compete against gasoline engines.

  I had a chance to drive a two-seat Tesla, owned by John Hendricks, founder of Discovery Communications, the parent company of the Discovery Channel. As I sat in the driver’s seat, Mr. Hendricks urged me to hit the accelerator with all my might to test his car. Taking his advice, I floored the accelerator. Immediately, I could feel the sudden surge in power. My body sank into the seat as I hit 60 miles per hour in just 3.9 seconds. It is one thing to hear an engineer boast about the performance of fully electric cars; it is another thing to hit the accelerator and feel it for yourself.

  The successful marketing of the Tesla has forced mainstream automakers to play catch-up, after decades of putting down the electric car. Robert Lutz, when he was vice chairman of General Motors, said, “All the geniuses here at General Motors kept saying lithium-ion technology is ten years away, and Toyota agreed with us—and boom, along comes Tesla. So I said, ‘How come some tiny little California startup, run by guys who know nothing about the car business, can do this and we can’t?’ ”

  Nissan Motors is leading the charge to introduce the fully electric car to the average consumer. It is called the Leaf, has a range of 100 miles, a top speed of up to ninety miles per hour, and is fully electric.

  After the fully electric car, another car that will eventually hit the showrooms is the fuel cell car, sometimes called the car of the future. In June 2008, Honda Motor Company announced the debut of the world’s first commercially available fuel cell car, the FCX Clarity. It has a range of 240 miles, has a top speed of 100 miles per hour, and has all the amenities of a standard four-door sedan. Using only hydrogen as fuel, it needs no gasoline and no electric charge. However, because the infrastructure for hydrogen does not yet exist, it is available for leasing in the United States only in Southern California. Honda is also advertising a sports car version of its fuel cell car, called the FC Sport.

  Then in 2009, GM, emerging from bankruptcy after its old management was summarily fired, announced that its fuel cell car, the Chevy Equinox, had passed the million-mile mark in terms of testing. For the past twenty-five months 5,000 people have been testing 100 of these fuel cell cars. Detroit, chronically lagging behind Japan in introducing small car technology and hybrids, is trying to get a foothold in the future.

  On the surface, the fuel cell car is the perfect car. It runs by combining hydrogen and oxygen, which then turns into electrical energy, leaving only water as the waste product. It creates not an ounce of smog. It’s almost eerie looking at the tailpipe of a fuel cell car. Instead of choking on the toxic fumes billowing from the back, all you see are colorless, odorless droplets of water.

  “You put your hand over the exhaust pipe and the only thing coming out is water. That was such a cool feeling,” observed Mike Schwabl, who test-drove the Equinox for ten days.

  Fuel cell technology is nothing new. The basic principle was demonstrated as far back as 1839. NASA has used fuel cells to power its instruments in space for decades. What is new is the determination of car manufacturers to increase production and bring down costs.

  Another problem facing the fuel cell car is the same problem that dogged Henry Ford when he marketed the Model T. Critics claimed that gasoline was dangerous, that people would die in horrible car accidents, being burned alive in a crash. Also, you would have to have a gasoline pump on nearly every block. On all these points, the critics were right. People do die by the thousands every year in gruesome car accidents, and we see gasoline stations everywhere. But the convenience and utility of the car are so great that people ignore these facts.

  Now the same objections are being raised against fuel cell cars. Hydrogen fuel is volatile and explosive, and hydrogen pumps would have to be built every few blocks. Most likely, the critics are right again. But once the hydrogen infrastructure is in place, people will find pollution-free fuel cell cars to be so convenient that they will overlook these facts. Today, there are only seventy refueling stations for fuel cell cars in the entire United States. Since fuel cell cars have a range of about 170 miles per fill-up, it means you have to watch the fuel meter carefully as you drive. But this will change gradually, especially if the price of the fuel car begins to drop with mass production and advances in technology.

  But the main problem with the electric car is that the electric battery does not create energy from nothing. You have to charge the battery in the first place, and that electricity usually comes from a coal-burning plant. So even though the electric car is pollution free, ultimately the energy source for it is fossil fuels.

  Hydrogen is not a net producer of energy. Rather, it is a carrier of energy. You have to create hydrogen gas in the first place. For example, you have to use electricity to separate water into hydrogen and oxygen. So although electric and fuel cell cars give us the promise of a smog-free future, there is still the problem that the energy they use comes largely from burning coal. Ultimately, we bump up against the first law of thermodynamics: the total amount of matter and energy cannot be destroyed or created out of nothing. You can’t get something for nothing.

  This means that, as we make the transition from gasoline to electricity, we need to replace the coal-burning plants with an entirely new form of energy.

  NUCLEAR FISSION

  One possibility to create energy, rather than just transmit energy, is by splitting the uranium atom. The advantage is that nuclear energy does not produce copious quantities of greenhous
e gases, like coal-and oil-burning plants, but technical and political problems have tied nuclear power in knots for decades. The last nuclear power plant in the United States began construction in 1977, before the fateful 1979 accident at Three Mile Island, which crippled the future of commercial nuclear energy. The devastating 1986 accident at Chernobyl sealed the fate of nuclear power for a generation. Nuclear power projects dried up in the United States and Europe, and were kept on life support in France, Japan, and Russia only through generous subsidies from the government.

  The problem with nuclear energy is that when you split the uranium atom, you produce enormous quantities of nuclear waste, which is radioactive for thousands to tens of millions of years. A typical 1,000-megawatt reactor produces about thirty tons of high-level nuclear waste after one year. It is so radioactive that it literally glows in the dark, and has to be stored in special cooling ponds. With about 100 commercial reactors in the United States, this amounts to thousands of tons of high-level waste being produced per year.

  This nuclear waste causes problems for two reasons. First, it remains hot even after the reactor has been turned off. If the cooling water is accidentally shut off, as in Three Mile Island, then the core starts to melt. If this molten metal comes into contact with water, it can cause a steam explosion that can blow the reactor apart, spewing tons of high-level radioactive debris into the air. In a worst-case class-9 nuclear accident, you would have to immediately evacuate perhaps millions of people out to 10 to 50 miles from the reactor. The Indian Point reactor is just 24 miles north of New York City. One government study estimated that an accident at Indian Point could conceivably cost hundreds of billions of dollars in property damages. At Three Mile Island, the reactor came within minutes of a major catastrophe that would have crippled the Northeast. Disaster was narrowly averted when workers successfully reintroduced cooling water into the core barely thirty minutes before the core would have reached the melting point of uranium dioxide.

  At Chernobyl, outside Kiev, the situation was much worse. The safety mechanism (the control rods) were manually disabled by the workers. A small power surge occurred, which sent the reactor out of control. When cold water suddenly hit molten metal, it created a steam explosion that blew off the entire top of the reactor, releasing a large fraction of the core into the air. Many of the workers sent in to control the accident eventually died horribly of radiation burns. With the reactor fire burning out of control, eventually the Red Air Force had to be called in. Helicopters with special shielding were sent in to spray borated water onto the flaming reactor. Finally, the core had to be encased in solid concrete. Even today, the core is still unstable and continues to generate heat and radiation.

  In addition to the problems of meltdowns and explosions, there is also the problem of waste disposal. Where do we put it? Embarrassingly, fifty years into the atomic age, there is still no answer. In the past, there has been a string of costly errors with regard to the permanent disposal of the waste. Originally, some waste was simply dumped into the oceans by the United States and Russia, or buried in shallow pits. In the Ural Mountains one plutonium waste dump even exploded catastrophically in 1957, requiring a massive evacuation and causing radiological damage to a 400-square-mile area between Sverdlovsk and Chelyabinsk.

  Originally, in the 1970s the United States tried to bury the high-level waste in Lyons, Kansas, in salt mines. But later, it was discovered that the salt mines were unusable, as they already were riddled with numerous holes drilled by oil and gas explorers. The United States was forced to close the Lyons site, an embarrassing setback.

  Over the next twenty-five years, the United States spent $9 billion studying and building the giant Yucca Mountain waste-disposal center in Nevada, only to have it canceled by President Barack Obama in 2009. Geologists have testified that the Yucca Mountain site may be incapable of containing nuclear waste for 10,000 years. The Yucca Mountain site will never open, leaving commercial operators of nuclear power plants without a permanent waste-storage facility.

  At present, the future of nuclear energy is unclear. Wall Street remains skittish about investing several billion dollars in each new nuclear power plant. But the industry claims that the latest generation of plants is safer than before. The Department of Energy, meanwhile, is keeping its options open concerning nuclear energy.

  NUCLEAR PROLIFERATION

  Yet with great power also comes great danger. In Norse mythology, for example, the Vikings worshipped Odin, who ruled Asgard with wisdom and justice. Odin presided over a legion of gods, including the heroic Thor, whose honor and valor were the most cherished qualities of any warrior. However, there was also Loki, the god of mischief, who was consumed by jealousy and hate. He was always scheming and excelled in deception and deceit. Eventually, Loki conspired with the giants to bring on the final battle between darkness and light, the epic battle Ragnarok, the twilight of the gods.

  The problem today is that jealousies and hatreds between nations could unleash a nuclear Ragnarok. History has shown that when a nation masters commercial technology, it can, if it has the desire and political will, make the transition to nuclear weapons. The danger is that nuclear weapons technology will proliferate into some of the most unstable regions of the world.

  During World War II, only the greatest nations on earth had the resources, know-how, and capability to create an atomic bomb. However, in the future, the threshold could be dramatically lowered as the price of uranium enrichment plummets due to the introduction of new technologies. This is the danger we face: newer and cheaper technologies may place the atomic bomb into unstable hands.

  The key to building the atomic bomb is to secure large quantities of uranium ore and then purify it. This means separating uranium 238 (which makes up 99.3 percent of naturally occurring uranium) from uranium 235, which is suitable for an atomic bomb but makes up only .7 percent. These two isotopes are chemically identical, so the only way to reliably separate the two is to exploit the fact that uranium 235 weighs about 1 percent less than its cousin.

  During World War II, the only way of separating the two isotopes of uranium was the laborious process of gaseous diffusion: uranium was made into a gas (uranium hexafluoride) and then forced to travel down hundreds of miles of tubing and membranes. At the end of this long journey, the faster (that is, lighter) uranium 235 won the race, leaving the heavier uranium 238 behind. After the gas containing uranium 235 was extracted, the process was repeated, until the enrichment level of uranium 235 rose from .7 percent to 90 percent, which is bomb-grade uranium. But pushing the gas required vast amounts of electricity. During the war, a significant fraction of the total U.S. electrical supply was diverted to Oak Ridge National Laboratory for this purpose. The enrichment facility was gigantic, occupying 2 million square feet and employing 12,000 workers.

  After the war, only the superpowers, the United States and the Soviet Union, could amass huge stockpiles of nuclear weapons, up to 30,000 apiece, because they had mastered the art of gaseous diffusion. But today, only 33 percent of the world’s enriched uranium comes from gaseous diffusion.

  Second-generation enrichment plants use a more sophisticated, cheaper technology: ultracentrifuges, which have created a dramatic shift in world politics as a result. Ultracentrifuges can spin a capsule containing uranium to speeds of up to 100,000 revolutions per minute. This accentuates the 1 percent difference in mass between uranium 235 and uranium 238. Eventually, the uranium 238 sinks to the bottom. After many revolutions, one can remove the uranium 235 from the top of the tube.

  Ultracentrifuges are fifty times more efficient in energy than gaseous diffusion. About 54 percent of the world’s uranium is purified in this way.

  With ultracentrifuge technology, it takes only 1,000 ultracentrifuges operating continuously for one year to produce one atomic bomb’s worth of enriched uranium. Ultracentrifuge technology can easily be stolen. In one of the worst breeches of nuclear security in history, an obscure atomic engineer, A. Q. Kh
an, was able to steal blueprints for the ultracentrifuge and components of the atomic bomb and sell them for profit. In 1975, while working in Amsterdam for URENCO, which was established by the British, West Germany, and the Netherlands to supply European reactors with uranium, he gave these secret blueprints to the Pakistani government, which hailed him as a national hero, and he is also suspected of selling this classified information to Saddam Hussein and to the governments of Iran, North Korea, and Libya.

  Using this stolen technology, Pakistan was able to create a small stockpile of nuclear weapons, which it began testing in 1998. The ensuing nuclear rivalry between Pakistan and India, with each exploding a series of atomic bombs, almost led to a nuclear confrontation between these two rival nations.

  Perhaps because of the technology it purchased from A. Q. Khan, Iran reportedly accelerated its nuclear program, building 8,000 ultracentrifuges by 2010, with the intention of building 30,000 more. This put pressure on other Middle East states to create their own atomic bombs, furthering instability.

  The second reason the geopolitics of the twenty-first century might be altered is because another generation of enrichment technology—laser enrichment—is coming online, one potentially even cheaper than ultracentrifuges.

  If you examine the electron shells of these two isotopes of uranium, they are apparently the same, since the nucleus has the same charge. But if you analyze the equations for the electron shells very carefully, you find that there is a tiny separation in energy between the electron shells of uranium 235 and uranium 238. By shining a laser beam that is extremely fine-tuned, you can knock out electrons from the shell of uranium 235 but not from that of uranium 238. Once the uranium 235 atoms are ionized, they can be easily separated from uranium 238 by an electric field.