Today, there are 600 million automobiles on the road worldwide, and that number is forecast to double to 1.2 billion in the next 30 years. The environmental impact of those 600 million vehicles greatly exceeds the impact of the world's 22,000 airliners. Consequently, one of the most promising technologies for the future is that of hybrid electric power for automobiles. The first hybrids became available a decade ago and hybrid models are now offered by most major auto manufacturers. Early hybrids added electric motor-generators to existing internal combustion (IC) based drive trains. The electric motors boosted performance by allowing the use of smaller IC engines. The generator function allowed energy to be recovered when breaking or slowing down—called regenerative braking. These features greatly enhanced mileage in stop and go driving.
Unfortunately, none of the early or existing hybrid models allowed their battery packs to be recharged from external sources. All the energy to drive the vehicles still had to come from their IC engines. Also, some hybrids only use electric motors to assist their IC engine and could not run on electric power alone. These vehicles are called power assist hybrids. Honda's hybrids, including the Insight, use this type of design. However, starting with the 2006 Civic, some newer model Honda's can run on electricity alone.
Other models, such as the Toyota Prius, are full hybrids. This means that the car can move under electric power when it is going slowly, but when speed or acceleration increases, the gasoline motor kicks in automatically. A full hybrid, sometimes called a strong hybrid, is a vehicle that can run on just the IC engine, just the batteries, or a combination of both. A number of enterprising, and ecology-minded hobbyists have taken full hybrid models, expanded their battery capacity and added external recharges—creating plugin hybrids. We think that plugin hybrids are the future of the automobile.
The primary advantage of being able to plug in a hybrid is that some of the vehicle's power can come from sources other than oil. A plugin hybrid can be powered by wind, solar, hydro or nuclear power, reducing a portion of its emissions to zero. Another advantage is that, at least for full hybrids, short trips at moderate speeds can be accomplished without ever turning on the IC engine. This would enable many people to effectively drive fully electric vehicles, particularly in large cities and urban areas where air pollution is heavily concentrated. The drawback with electric cars has always been their short range due to limited battery capacity. Plugin hybrids overcome that disadvantage by also having an IC engine ready to kick in whenever needed. They can be electric for local trips and gas powered for long trips.
The Chevrolet Volt, from General Motors (GM), is a hybrid car but it is radically different than any on the road today. While current hybrids, such as the Prius, are parallel hybrids—meaning they have a small electric motor that moves the car when it is going slowly, but when speed or acceleration increases, a gasoline motor kicks in—the Volt is a series hybrid. It has a powerful 161 horsepower (16 kWh) electric motor that is the only engine that powers the car. This engine is capable of moving the car from 0 to 60 in 8 seconds, and reaching a top speed of 120 mph.
The electric engine gets its energy from a powerful high-voltage battery pack that can store enough energy to drive the car up to 40 miles under standard driving conditions. That battery pack is recharged by plugging the car into a standard home wall outlet. A full-charge cycle takes about 6 hours. Based on current prices, electricity costs should amount to a gas equivalent price of 50 cents per gallon. Studies suggest that 78% of drivers travel less than 40 miles (65 km) per day, making it possible for many people to use no fossil fuel at all. Imagine such a car charging its batteries with electricity generated by nuclear power. We would have a vehicle that leaves a zero carbon footprint.
General Motors is still in the early stages of production planning for this car and the official release date is expected to be late 2010. As of now, GM is not soliciting customers, but an activist web site, GM-Volt.com, is asking people to join a waiting list to help ensure that the Volt makes it to production. But even if this particular car never gets produced, interest in hybrids is strong and growing stronger around the world.
In Europe, at the Frankfurt Motor Show, Volvo unveiled a concept car called the ReCharge. Based on their existing C30 model, the ReCharge is a series hybrid like the Volt. Volvo claims an all-electric range of up to 65 miles. Power is stored in a lithium-polymer battery pack and the car can drive up to 30 miles on a one hour charge. There is an electric motor at each wheel providing all-wheel-drive (AWD) and enhanced traction. An electrical generating unit called an auxiliary power unit (APU) provides power when the batteries run low. The APU, a 1.6 liter gas engine driving an electric generator, is not directly connected to the wheels.
Operating costs for the ReCharge are estimated to be 80% lower than a similar gas-powered vehicle when using battery power alone. For a 90 mile (150 km) drive starting with a full charge, the car will require less than 0.75 gallons of fuel, giving the car an effective fuel economy of 124 mpg. At least on the automotive front the future looks bright, even exciting.
There are two main obstacles to full hybrid production; the high cost of batteries and battery life. The familiar 12 volt lead-acid batteries found in cars cost $40 to $50 per kWh (one gallon of gasoline is equivalent to 8.8 kWh of stored electricity). Nickel-metal-hydride batteries, used in portable electronics, cost $350 per kWh. Newer lithium-ion cells used in the same application cost around $450/kWh. For automotive applications, nickel-metal-hydride batteries cost $700/kWh. Several companies around the world are working on building less expensive lithium-based batteries that will last for 10 years and cost under $300/kWh. Prices are expected to drop dramatically when the batteries enter mass production.551
From a technological point of view, the move to full series hybrids means that auto manufacturers will be well-positioned to take advantage of future breakthroughs. This is because the APU can be easily replaced with any other source of electrical power. If fuel-cells become reliable and cost effective, the IC engine can be swapped for a fuel-cell-based power pack. If battery technology advances to the point where energy density and fast recharge time make gas engines obsolete, the APU can be replaced with more battery storage. From a development point of view, the change to hybrid technology allows manufacturers to refine electrical drive trains while awaiting future APU advances. Who knows, in the future we may be driving hybrid cars powered by “mister fusion” generators, like in the movie Back To The Future II.
Other modes of transportation need to be improved as well. Trucks are moving to so-called clean diesel, but that is only a small improvement. Both trucks and trains can benefit from hybrid technology. The main obstacle to developing hybrid trains, trucks, and buses is the significantly higher energy levels required. The amount of electrical power generated when decelerating a train or large truck can exceed current battery's recharge capacity. Some companies are developing super capacitors that can handle the high regenerative braking currents, allowing batteries to be charged at a more leisurely pace.
Another developing technology that could replace chemical batteries in hybrid trains or trucks is based on an old idea—flywheels. Not heavy wheels of metal spinning at a few thousand rpm, but high tech carbon composite flywheels, suspended in vacuum by magnetic fields whirling at 50,000 rpm. Some day, departing trains could get their initial energy for free, each time saving the equivalent of several days' worth of electricity usage by an average US household.
Engineers at the University of Texas at Austin are developing an improved flywheel that can store enough energy to accelerate a passenger train up to cruise speed. Such a locomotive flywheel could weigh 5,000 pounds and, when fully charged, its rim may move at the speed of sound.552 The researchers' experimental flywheel is a cylinder 4.9 ft (1.5 m) in diameter and 4.2 ft (1.2 m) tall. When spinning at full speed, it is designed to store 133 kWh of energy. Flywheel systems can pack more energy than batteries of comparable weight. They can also last decades with little
or no maintenance and do not degrade over time as chemical batteries can. It is estimated that a flywheel-based hybrid locomotive could attain a 15% increase in efficiency on a route such as New York to Boston. Light rail commuter trains, which stop and start frequently, could save even more.
Flywheels can provide a boost for smaller vehicles as well. A Dutch company, called Centre for Concepts in Mechatronics (CCM), has developed and tested a flywheel-powered hybrid bus. The prototype bus incorporated a small car engine to keep the flywheel spinning. Running at constant speed, the engine's fuel efficiency was maximized. The flywheel stored up to 3 kWh, running on conventional ball bearings in a vacuum. When needed, the flywheel could supply bursts of 300 kilowatts, the equivalent of about 400 horsepower. According to the developers, the bus “ran like a Porsche,” and had 35% better mileage than a comparable-size conventional bus.553
CCM's flywheel technology is currently used in a tram from Fraunhofer Gesellshaft, and a light rail vehicle from Siemens. The company has also contracted with French engineering giant Alstom to develop a wireless tram that would recharge its flywheel at passenger stops. But flywheels are not limited to mobile applications.
One of the impediments to wider use of intermittent electrical power sources, such as wind and solar, is that power availability cannot be matched with demand. With solar power, energy for nighttime use must be stored during the day, and with wind power, if there is more energy available than is needed, excess energy is wasted without storage. Several countries have built energy storage facilities, mostly to cushion peak demand spikes. The conventional way this is done is to use excess power to pump water back upstream, into a dam's reservoir. When more power is needed later, the water flows back through the dam's hydroelectric generators. Unfortunately, this technology can only be used where geography allows.
Flywheels have no such geographic restrictions. Flywheels are one type of storage device, collectively known as power-quality units. These devices are used to dampen fluctuations in the power grid's frequency, current or voltage. With the addition of wind and solar generation, the role for such technology becomes even more important. In the US, several companies are already producing commercial flywheels for power-quality applications. Beacon Power, based in Wilmington, Massachusetts, manufactures 9-kWh units used by telecommunications companies to stabilize power in remote locations. Beacon is developing larger, 25-kWh flywheels meant to be installed in arrays of as many as 200. Such arrays could provide 20-megawatt bursts of power to stabilize a grid or store excess energy for later use.
Beyond adding new forms of green power, and storage devices to make the most of their spotty power output, national power grids will need a major overhaul. In Europe, there is already talk of linking the output of wind generators, scattered about the continent, to the huge hydroelectric reservoirs in Norway's fjords.554 But moving huge amounts of power over long distances raises another problem, transmission loss.
Most existing long distance power lines are based on alternating current (AC). This is because AC is more efficient than the alternative, direct current (DC), over short to medium distances. On average, transmission and distribution (T&D) losses between 6% and 8% are considered normal. According to data from the Energy Information Administration, net generation in the US came to over 3.9 billion megawatt hours (MWh) in 2005 while retail power sales during that year were about 3.6 billion MWh. T&D losses amounted to 239 million MWh, or 6.1% of net generation. Using the national average retail price of electricity for 2005, T&D losses cost the US economy around $19.5 billion.
Over long distances, losses are even higher, sparking new interest in DC power transmission. Most of the transmission lines that make up the North American transmission grid are high-voltage alternating current (HVAC) lines. DC transmission offers great advantages over HVAC, as much as 25% lower line losses. DC is also capable of two to five times the capacity of an AC line at similar voltage, with improved ability to control the flow of power. Any nation or group of nations that wishes to take full advantage of renewable energy in the future needs to plan their power grid on continent-spanning scales. The power grid is not glamorous, usually only attracting attention when it fails, but politicians must start paying attention to power infrastructure, or the future will be filled with brown-outs and rolling power failures across wide regions.
Building for the Long Run
To fully replace older vehicles with new, more efficient ones will take some time. In the US, the average car has a median lifetime of 17 years and Boeing expects 21.4% of the aircraft in service by 2025 to be “holdovers” from today.555 Other parts of the world's energy-consuming infrastructure last even longer. The average lifetime of a detached house in Japan is 40 years, in the US, it is around 100 years, and even higher in Europe.556 New solar cells have been developed that look similar to traditional shingles, so retrofitting a house doesn't mean adding a large, ugly solar panel to the roof. Of course, existing structures can be made more efficient by adding insulation and upgrading heating and air conditioning equipment, but sizable savings are best found in new commercial buildings.
New office buildings are being constructed that use zero net energy from the commercial power grid, yet provide normal office lighting levels with comfortable heating and cooling. These so-called z-squared buildings are just now starting to appear on the city skyline. One such building is the new San Jose headquarters of Integrated Design Associates (IDeAs). The IDeAs building, designed by Scott Shell of EHDD Architecture, makes innovative use of natural lighting and generates more electricity than it uses during the day from an array of solar cells on its roof.557 It is one of a handful of buildings that meet the platinum energy rating of the US Green Building Council (USGBC).
To promote more efficient building design, the USGBC has developed the Leadership in Energy and Environmental Design (LEED) Green Building Rating System,TM a nationally accepted benchmark for the design, construction, and operation of high performance green buildings. LEED promotes a whole-building approach to sustainability by recognizing performance in five key areas of human and environmental health: sustainable site development, water savings, energy efficiency, materials selection, and indoor environmental quality. Depending on location, the payback period for a building with built-in solar power ranges between 20 and 35 years. While it used to cost 15% more to construct a green building, today the added cost is only 1-3%.558 With buildings accounting for 18% of US energy consumption, we need to build more efficient commercial structures as well as more clean power plants.
Another change in building practices that can benefit the environment seems counter-intuitive at first glance—using more wood. Cutting down trees for building material seems anything but green, but it can be. When trees are turned into lumber, the carbon stored in the wood is taken out of circulation unless the wood decays or is burned. If the wood comes from a managed forest, where new trees are planted to replace the ones harvested for building materials, more and more CO2 is removed from the atmosphere. This is a better use of forest material than cellulosic ethanol, which returns the carbon in the wood back to the atmosphere when the fuel is burned. It is also far better than using concrete. The production of cement, the primary component of concrete, accounts for 5 to 10 percent of the world's total CO2 emissions.559 The warm, natural look of wood is better for the environment than cold concrete and steel.
The New Nuclear Age
A major non-polluting energy source that we have not discussed is also mentioned as a mitigating technology in the IPCC report discussed in the previous chapter. Because this clean, carbon-free technology is proven, readily available, and can make the greatest immediate contribution to reducing GHG emissions, we include it here in our road map for the future. Much to the displeasure of the neo-Luddite wing of the ecology movement, the technology that has the greatest potential to free the planet from fossil fuels—a technology recommended by the IPCC—is nuclear power.
Nuclear power has long been
the favorite whipping boy of the ecology movement. An irrational fear of all things nuclear firmly took root in the US in the late 1960s—but the event that shut down the American nuclear power industry was the 1979 reactor accident at Three Mile Island.
Around 4 am, on March 28, through a series of errors—including a valve that was supposed to close but didn't, and a known leak that led operators to conclude high temperatures readings were false—water escaped from the reactor core. Without a way to remove the heat, reactor temperature began to rise. Within a matter of minutes, the operators, believing that water was still circulating through the core, concluded they had a “bottled-up system.”
Unable to deal with the unfolding events, by 7 am the operators called a site emergency. By 7:30 am, amid concerns that a hydrogen bubble had formed in the reactor core, a general emergency was declared. No bubble had formed, although months later cleanup crews were astonished to see how much of the core had actually melted. But the melted nuclear core had been contained and the radiation released was minimal. The plant design and safety protocols had worked, despite numerous operator mistakes.
Before the Three Mile Island incident, the United States had 104 nuclear reactors generating electricity—the most of any country in the world. After the accident at Three Mile Island and the anti-nuclear propaganda film, The China Syndrome, the country turned its back on nuclear power. A new reactor hasn't been built in the US since. Public opinion forced power utilities to cancel 96 new nuclear projects. If those 96 plants have been built on schedule, along with additional ones that would surely have been ordered over the past 30 years, more than half of US electrical generating capacity would produce no greenhouse gases. Instead, the last nuclear power plant built in the US was started in 1973 and America's existing plants are starting to show their age. Jane Fonda, the star of The China Syndrome, has done more to cause global warming than all the people driving SUVs.
The Resilient Earth: Science, Global Warming and the Fate of Humanity Page 38