Ten Technologies to Save the Planet

Energy Options for a Low-Carbon Future

Chris Goodall

• Publisher: Greystone Books
• Year: 2010
• ISBN:
  9781553656241
• Topic: Biological Sciences
• Subtopic: Environmental Science
• Index: Biological Sciences

Respected, authoritative, award-winning author Chris Goodall tackles global warming reversal in this engaging and balanced book. Ten Technologies to Save the Planet — popular science writing at its most crucial — is arguably the most readable and comprehensive overview of large-scale solutions to climate change available. Goodall profiles ten technologies with the potential to slash global greenhouse emissions, explaining how they work and telling the stories of the inventors, scientists, and entrepreneurs who are driving them forward. Some of Goodall's selections, such as the electric car, are familiar. Others, like algae and charcoal, are more surprising. Illustrated with black-and-white photos and simple charts, Ten Technologies to Save the Planet combines cutting-edge analysis with straightforward explanations about pros and cons, and debunks myths along the way.

1

CAPTURING THE WIND

Clean power that’s more reliable than you’d think

WIND TURBINES are now almost a routine sight in some parts of the world. On hills in western Spain, on Danish islands, on New Zealand’s moorlands, and in the Atlantic provinces of Canada, hundreds of thousands of turbines now provide power to national electricity grids. The U.S. and China were relative latecomers to the wind business, but much of the growth in wind-generated electricity now comes from these countries. All the U.S. wind farms are on land, but developers are sizing up the coastlines for the big opportunity presented by offshore turbines. A few miles offshore, and winds are generally faster and more consistent, and the lack of ground obstructions means the flow of air is less turbulent. But offshore wind power is more expensive to develop. The turbines have to withstand twenty-five years of pounding by waves and salt spray that could corrode the electrical components. So even though the same turbine might generate 20 percent more electricity offshore than it would on a nearby hill, only brave and well-financed investors will back large wind farms in coastal waters.

Everybody is watching Cape Wind, sited in shallow water off Cape Cod, which promises to be the first offshore wind farm in the U.S. The developers struggled for nearly ten years to get the necessary permits to construct 130 large turbines that would provide enough electricity for the needs of most of the communities of Cape Cod and the islands off the southern coast of Massachusetts. When constructed, the farm will produce power that would otherwise take half a million tons of coal to generate. The proposed site is one of the best in U.S. coastal waters; wind speeds are relatively high, but the area is well protected from the worst of the Atlantic waves. The environmental consequences of installing the turbines seem likely to be relatively benign, and organizations like the Sierra Club have supported the scheme. In 2006, the Sierra Club said it “has tentatively concluded that the project does not pose a significant ecological threat to birds, marine animals, and marine habitat.” Even with the support of environmental activists, the Cape Wind project has struggled against hostility from many people whose ocean views and sailing routes would be affected by the banks of turbines. Although the wind farm will be several miles offshore, a determined and effective group has fought every inch to prevent the construction of even one steel tower. Since Cape Cod was once the home to over a thousand working windmills providing mechanical power to small communities, the opposition to a field of turbines scarcely visible from the shore seems somewhat eccentric.

In late 2009, the Cape Wind organization jumped the final hurdle and was granted approval by the U.S. Department of the Interior. The business now faces the task of raising the money—an amount those spearheading the project described to me as a “ten-figure sum”—to build the farm and link it to the existing NSTAR electricity network. Raising money for projects of this size and unusualness is far from easy in today’s risk-averse financial markets. Banks and investors have to take a gamble—will future electricity prices be high enough to repay the capital? One particular advantage of the Cape Wind location is that the offshore breezes characteristic of the hot summer afternoons will turn the turbines at times when electricity is at its most valuable. Mark Rodgers, Cape Wind’s communications director, told me that he felt confident that the project would be financed by the end of 2010 and would ship its first electricity two or three years later. This huge scheme demonstrates both the importance of wind power and the serious obstacles that it faces in many parts of the world.

Adam Twine tends an organic farm not far from Oxford in southern England. The surrounding areas are flat and low lying, but Twine’s land occupies a small and windswept plateau. Down below, in the far distance, the cooling towers of Didcot power station are the most visible marks on the landscape. Didcot is a decaying coal-fired generator due to close in a few years because it cannot meet the latest European emissions regulations. Twine’s fields are not ideal for wind power—central England has far lower speeds than the western coasts and many other regions around the world—but he decided in the mid-1990s that he wanted to build a wind farm owned by the local community, sited as a perfect contrast to Didcot, the single largest source of carbon dioxide in the prosperous southern heartland of England.

As with the Cape Wind project, the struggle to get the turbines constructed was a long one. Just getting planning permission took the better part of a decade. Although Didcot’s six huge cooling towers and the multiple power lines trailing away from the station have already had a huge impact on the landscape, local resistance to the visual effect of the turbines was fierce. When Twine finally obtained approval, a protracted process of fundraising began. By the time the capital was raised, a worldwide shortage of components had pushed the prices of turbines up 30 percent, so more cash was needed. With a few grumbles and support from Britain’s Cooperative Bank, the shareholders obliged, raising the final installment with a few days to spare in spring 2007.

In February 2008, the wind farm started producing electricity. Five 1.3-megawatt turbines now rotate sedately (and very quietly) whenever the wind blows. Over two thousand people own shares in the development. Some invested because of a passionate belief in renewable energy; others because the venture promised good financial returns. So far, Adam Twine says that the output from the wind farm has more than delivered on the promises made, and its investors have already received their first dividend payment.

As Twine’s farm shows, new wind farms are already good investments in many parts of the world. The best returns come from buying the largest possible turbines, all from a single manufacturer, and installing as many as possible in the local area. This approach reduces the costs of connecting the wind farm to the electricity grid and minimizes the amount paid for yearly maintenance. In countries such as Portugal, the largest wind developments are now obviously competitive with fossil fuel sources of electricity. BT , the U.K.’s largest telecommunications company and the user of more than half a percent of the country’s electricity, says that its wind turbine construction program, planned to provide a quarter of its needs, is easily justified to its shareholders as making good financial sense.

The years 2006–2008 saw a sharp rise in the price of turbines as the steel for the supporting column and copper for the turbine wiring suddenly cost far more than ever before. The rapid growth in demand for turbines also caused production bottlenecks for some of the eight thousand components in a typical turbine. The shortages have now eased and costs have fallen, a downward trend predicted to continue, with expected costs falling from about $1,200 per kilowatt of generating capacity down to perhaps $800 by 2013—roughly equivalent to the capital cost of a new gas-fired power station. The full cost of Adam Twine’s wind farm came to almost twice today’s average, inflated by the relatively small size of the development and the expensive struggle to get permission to build it. Cape Wind—because it is offshore—will also be far more expensive to install.

As the critics of wind power never tire of pointing out, turbines do not generate their maximum power all the time. They only produce their full output when the wind is blowing strongly. But not too strongly: above a certain wind speed, the machines shut down to prevent the blades from rotating too fast and damaging the turbine. Averaged across the year, a 2-megawatt turbine in a reasonable location will typically produce only about a third of this figure—about two-thirds of a megawatt. The wind farm on Twine’s land will probably generate about 13 gigawatt-hours in its first year. This figure sounds impressive, but the old dinosaur of a coal-fired power station down the road at Didcot will produce the same amount of electricity in a busy afternoon. It would take nearly a thousand wind farms the size of Adam Twine’s to replace just one power station of Didcot’s size. The huge Cape Wind field will only replace about 10 percent of the output of one of the largest U.S. coal-fired plants.

Given their relatively small output and inconsistent performance, are wind turbines a genuinely useful tool in the fight against climate change? The answer t0 that question is an emphatic yes, and this chapter explains why.

THE POWER OF THE WIND

Wind arises from variations in atmospheric pressure between different parts of the world. Air tends to flow from high-to low-pressure areas, with the speed of the wind depending on the gradient between the wind cells. The ultimate cause of these pressure differences is the differential amounts of solar heating across the globe. We can therefore think of wind as an indirect form of solar energy. A small fraction of 1 percent of the light and heat energy that the earth receives gets turned into the moving, or “kinetic,” energy of the wind. We can capture this energy using windmills or wind turbines that slow down the speed of the air, transferring power to the rotation of the blades.

A wind turbine can be thought of as the opposite of an electric fan. A fan uses an electric motor to turn the blades when the electricity is turned on; a turbine does the reverse. The rotating arms turn gears, which then rapidly rotate an electrical conductor, usually a dense mesh of copper wire, inside a powerful magnetic field, inducing electricity to flow.

A wind turbine cannot capture the full power of the wind. The theoretical limit is just under 60 percent of the energy in the flow of air. And the amount of electricity generated by the rotation of the blades is only equivalent to about 70 percent of the energy captured, even in an efficient new turbine. Even with these disadvantages, wind is still a very productive source of electric power, comparing favorably with solar photovoltaic panels, which turn less than a fifth of the energy they receive into electricity.

The secret of wind’s success is the sheer mass of moving air that passes through the rotating blades of a turbine. Air may seem almost weightless to humans, but each cubic yard actually weighs almost two pounds. A strong gust consists of air moving at perhaps 40 miles an hour, or 55 feet per second. This means that every second, over 37 pounds of air pass through each vertical square yard. This motion contains a substantial amount of energy, with the power in the wind proportional to the cube of the speed of the air. In other words, a wind turbine in a 14-mile-per-hour air flow will generate almost 60 percent more power than one in a breeze of 12 miles per hour. (This is why it is so important to choose windy sites for turbine locations.) At 14 miles per hour, which is little more than a gentle breeze, the motion of the wind contains about 18 watts of power per square foot. This is less than the full power of the midday tropical sun, which delivers more than a thousand watts in the same area, but wind is easier to convert to electricity and will often blow for the full twenty-four hours in the day, not just during daylight hours.

Of course, the amount of power that a wind turbine can capture is also linked to the area of the circle swept by its blades. The very biggest new turbines have arms that are 200 feet long: in a 40 mile-per-hour wind, about 200 tons of air will pass through the blades’ circle every second, with a usable energy of more than 2 million watts. By comparison, a tiny domestic wind turbine with blades just over 3 feet long covers a little more than 30 square feet, capturing up to 600 watts. Somewhat counterintuitively, the large turbine doesn’t sweep sixty times the area of the domestic turbine; it covers over three thousand times as much.

Wind turbines will probably stop increasing in size soon. There’s talk of giant 7-megawatt turbines for offshore installations, but the limit may be 5 megawatts. The problem is that longer turbine arms, while providing more power, are also subjected to more stress. As an arm swings downward, it stretches under its own weight; as it swings upward, it becomes fractionally compressed. Repeated millions of times a week, this stress will destroy all but the strongest and most flexible materials—and the longer and heavier the blades, the greater the forces they need to withstand.

WIND’S GROWING IMPORTANCE

Only about 1 percent of world electricity demand today is met by wind, but the figure varies enormously around the world. Some areas of Germany generate more wind energy than their total power needs. Almost 20 percent of Danish electricity comes from wind, and the figure is similar in Prince Edward Island. The local electricity companies can accommodate these high levels of wind power because they have the freedom to export excess power when the wind is blowing hard and import electricity when the air is calm. Denmark’s access to Norwegian hydroelectric power is particularly important.

The U.S. and Spain are adding the largest amounts of new generating capacity every year. Wind energy in India and China is also becoming increasingly important: in China, the amount of wind generation has doubled every year over the last three years. By 2015, China may have 50 gigawatts of wind capacity, or about half today’s global total. In developing countries without a national electricity grid, wind power combined with large batteries will often represent the cheapest reasonably reliable way of generating power for small communities.

There’s no shortage of windy sites left to exploit. One study put the average power in the global winds at any one moment as about 72 terawatts—around thirty times the world’s electricity requirements, or ten thousand times the wind power we currently generate. And this estimate only includes sites with average wind speeds above 15 miles per hour, a level usually only met at coastlines or on the tops of hills. No one pretends that we can capture this entire potential, but we will be able to use wind to provide a good fraction of total world energy needs, and we can expect the rapid growth of the industry to continue for several decades.

Some of wind’s growth is being pushed by subsidy schemes. Spain’s 30-percent annual increase in wind power is propelled by price guarantees for the electricity that the turbines generate. But most experts now think that onshore wind turbines are close to competitive with traditional forms of electricity generation, at least in windy locations. Fairly assessing whether wind is cheaper or more expensive than gas turbines or coal-fired stations is surprisingly difficult. The assessment critically depends on assumptions about inflation, interest rates, and how long the turbines will last. And, of course, it depends on the price of fossil fuels. Nevertheless, the trend is unambiguous: wind is going to become a relatively inexpensive provider of power, and if fossil fuels continue to increase in price, this advantage will become more pronounced. Wind generation has its problems and complexities, some of which are discussed later in this chapter, but it provides us with the best possible example that technological progress, heavy investment, and government help can push a new technology forward. The cost of wind power has probably fallen by a factor of ten in the last twenty-five years, and we can reasonably hope that some of the other infant technologies in this book will improve to a similar degree.

Wind provides a little less than 4 percent of the European Union’s electricity today, four times the average for the world as a whole. The trade body for European wind thinks that this figure will rise to about 13 percent in 2020 and continue to increase rapidly thereafter. This increase would mean installing around 10 gigawatts of wind capacity each year over the next decade or so, which equates to thousands of new turbines annually, but since the new capacity installed in 2008 alone was almost 9 gigawatts, the target seems to be well within reach.

Getting to this level will require capital expenditure of almost $15 billion per year, even if turbine prices fall as expected. For this money, AREVA , the main European nuclear construction company, says that the continent could have two or three atomic power plants, although the final pages of this book cast some doubt on whether nuclear power can be delivered at this price. Three nuclear stations would have a capacity of almost 5 gigawatts, and typically, they would operate at full power more than 90 percent of the time. Even in windy offshore locations, wind turbines with a total maximum power of 10 gigawatts will provide at most 40 percent of their rated power, or just 4 gigawatts. So the math is quite simple: capital investment of $15 billion a year would buy Europe more low-carbon energy if invested in nuclear power than in wind.

However, once the infrastructure is constructed, wind energy is close to free—the cost of annual maintenance is usually a small percentage of the value of the electricity generated. Nuclear fuel is not very expensive, but nevertheless, its costs help equalize the price of the two forms of electricity generation. Add in the unknown costs of indefinite safe storage of nuclear waste, and wind seems only a little more expensive than nuclear energy. It will eventually be cheaper, particularly for turbines on windy coastlines.

So why do the big power companies in many countries still hanker after more nuclear plants? The reason is probably that nuclear plants are large and centralized, and they work around the clock. A big corporation can manage a small fleet of nuclear plants far more easily than it can control a network of thousands, perhaps tens of thousands, of turbines spread across large numbers of sites. The nuclear option also simplifies matching electricity supply with customer demand; if the company relies on erratic wind supplies, it will frequently be forced to buy power from alternative sources at unpredictable prices. In other words, nuclear generation works well for the big companies that dominate power generation in most countries, even though it will probably not deliver lower costs than power generated from large land-based wind farms.

Low and predictable running costs also help wind compare well with fossil fuels. Once the turbine is placed on top of its tower, virtually free electricity will be generated for the next twenty-five years or so. By contrast, the world now assumes that coal, gas, and oil are going to get increasingly expensive. So investing in wind mitigates the burden from increasing prices of other fuels. Wind has an additional advantage, too. Because its fuel is free, the turbine owners will generally always be able to sell their electricity at a profit. By contrast, the main fuels for power stations—gas and coal—can swiftly vary in price in relation to each other. The hundreds of millions of dollars invested in a coal-fired generator may produce nothing for months if the price of coal rises too high compared with the cost of gas. Didcot coal-fired power station, a few miles from Adam Twine’s wind farm, sat idle over much of the winter of 2008 because an unpredicted spike in the price of coal meant that it was uneconomical to run the plant.

Reliance on fossil fuels has a real cost to the economy if consumers and manufacturers can’t guess ...

Table of contents

• COVER PAGE
• TITLE PAGE
• COPYRIGHT PAGE
• DEDICATION
• CONTENTS
• AUTHOR’S NOTE
• INTRODUCTION
• 1 CAPTURING THE WIND: CLEAN POWER THAT’S MORE RELIABLE THAN YOU’D THINK
• 2 SOLAR ENERGY: ENOUGH TO POWER THE WORLD MANY TIMES OVER
• 3 ELECTRICITY FROM THE OCEANS: TAPPING TIDES, WAVES, AND CURRENTS
• 4 COMBINED HEAT AND POWER: FUEL CELLS AND DISTRICT HEATING
• 5 SUPER-EFFICIENT HOMES: PASSIVHAUS AND ECO-RENOVATIONS
• 6 ELECTRIC CARS: THE INEVITABLE SWITCH TO BATTERY PROPULSION
• 7 MOTOR FUELS FROM CELLULOSE: SECOND-GENERATION BIOFUELS
• 8 CAPTURING CARBON: CLEAN COAL, ALGAE, AND AMBIENT SCRUBBERS
• 9 BIOCHAR: SEQUESTERING CARBON AS CHARCOAL
• 10 SOILS AND FORESTS: IMPROVING THE PLANET’S CARBON SINKS
• PUTTING IT ALL TOGETHER: ARE THE TEN TECHNOLOGIES ENOUGH TO SAVE THE PLANET?
• EPILOGUE
• NOTES