Hybrid Cars

Today, hybrid automobiles are used more to make political or cultural statements than because their mileage is much superior to that of conventional automobiles. Almost all manufacturers are in the process of developing hybrids. They include Cadillac's Provoq, Chevrolet's Volt; Chyrsler's EcoVoyager; Dodge's ZEO; Fisker Automotive's Karma; Ford Escape; GMC Yukon; Honda Civic; Jeep's Renegade; Mazda Tribute; Mercedes-Benz's S 300 BlueTec; Mercury Mariner; Nissan Altima; Saturn's Flextreme; Tesla's Roadster; and Toyota's Camry, Highlander and Prius.

Toyota's Prius uses the heavy, range-limited nickel-metal hydride battery, basically because it is safe. The Prius recaptures the braking energy (instead of wasting it in friction) and runs on electric power in stop-and-start traffic, but its all-electric mode of operation is limited. Toyota's Prius is also available in a version that has been converted to hydrogen by Quantum Fuel Systems. Toyota is planning to have a hybrid version of all its 2010 models.

GM plans to increase the electric mode of operation of the Chevrolet Volt, which is designed as a "plug-in hybrid" that can be recharged overnight. This manufacturer plans to use high-energy-density lithium-ion batteries to obtain an all-electric range of 40 mi, and hopes that these batteries will be safe and reliable by 2010. This car is claimed to provide 150 mi/gal and is expected to be available by 2010.

Honda has dropped the hybrid versions of its Insight and Accord, but (in addition to its hybrid Civic) is working on a completely new hybrid car. Conversion kits are also available* to add extra batteries and convert the Prius and Ford's Escape into plug-in hybrids that provide up to 75 mi/gal.

In order to reduce peak demand on power plants, it has been suggested that stored electricity in the batteries of plug-in hybrid cars could be used during peak periods. The contract between the owner of the car and the

* From A123 Systems of Watertown, Massachusetts.

utility that operates the grid would stipulate that at night, when electricity is inexpensive, the owner would charge the batteries, and during the peak periods of the day, if the car is not in use, it would be left plugged in and the charge in the batteries would be available to the utility. Naturally, controls would be provided to always leave enough power to start the gasoline engine until recharged.

1.2.8.3 Electric Cars

In the past, electric vehicles (EVs) were thought of as glorified golf carts. That is no longer the case. Today, about ten electric car designs are in production, including the Tesla Roadster, GM's Sequel, Chevrolet Volt, Electrum Spyder, Phoenix SUT, Tango, Think City, Venturi Fetish, Wrightspeed X1, and Zap-X, and more from Nissan, Mitsubishi Motors, Fuji Heavy Industries, Renault, Project Better Place, and Bajaj Auto are on the way.

Their advantages and limitations are multiple. From the American perspective, energy independence and the EV's operating cost are the main advantages of replacing the internal combustion (IC) engines with batteries: energy independence, because electricity is made mostly from American coal, and operating cost, because the price of a gallon of gasoline can pay for the electric energy used to drive 100 mi. When compared with hydrogen fuel cells, another advantage is that the electric "fuel" distribution infrastructure already exists, as only an electric plug is needed to refill the batteries.

The main disadvantage is cost: the purchase price of an EV today is still around $100,000. This will drop drastically when Nissan American comes out with its electric vehicle in 2010 and Bajaj Auto starts producing its $2,500 car in 2011. Other disadvantages include the limited driving range of the electric cars, long charging time, short battery life, and the small cargo space because of the weight and size of the batteries. To overcome the charging time, there are some high-voltage charger designs (Altair Nanotechnologies) that claim to reduce the normally required time from several hours to about 10 minutes.

Ideas to overcome the charging-time problem include the introduction of new types of "filling stations" where all the batteries as a single pack would be replaced in a couple of minutes with already charged ones. These electric filling stations could also offer multiple fuels. Yet another design variation being experimented with is to add solar collectors to the roof of the car and use the electricity generated to recharge the batteries.*

As to past history, during the last 25 years the cost of batteries has been reduced by a factor of 12, and according to some estimates (California Air Resources Board), if lithium-ion packs were mass produced, their unit cost would be between $3,000 and $4,000.

A few years ago Ford Motor Company leased some 300 electric cars in California. Later, although their owners were satisfied, the cars were recalled and sold in Norway, without a clear explanation of the reason for this recall.

* From solar electric vehicles in California.

1.2.8.4 Fuel Cells vs. Batteries

Until new batteries that can provide much higher energy densities without compromising safety are discovered, fuel cells will continue to outperform today's heavy and large storage batteries. On the other hand, it is less expensive to build electric cars with batteries than with fuel cells. Today's batteries are less expensive than fuel cells, but their energy density is insufficient, and their weight and size are too high to provide the required driving range. The final outcome of the battery-versus-fuel cell race cannot be predicted. All that is obvious right now is that there are substantial developments in both fields.

In the area of fuel cells, reliability and availability have much improved. Recent U.S. military experience with phosphoric acid fuel cells found that the mean time between failure (MTBF) was almost 1,800 h and the availability was 67%. This is comparable with the MTBF service intervals for diesel generators. These fuel cells also favorably compare with the service interval needed for a typical gas turbine generation set. Still, much more development is required to obtain a commercially viable product. Today, the typical fuel cell system still requires servicing every 3-4 days to replace its scrubber packs.

The early electric cars used the old lead-acid batteries. Today's hybrids are provided with more robust nickel-metal units. The EVs of the future are likely to be provided with lithium-iron batteries, found in today's laptops and cell phones. Much work remains to be done in this area to increase safety and life span (to 100,000 mi of driving), while reducing their cost. Nissan and Mitsubishi are both making major investments in building lithium-ion battery mass production plants.

New battery developments include the ultracapacitor hybrid barium titan-ate powder design (EEStors). These devices can absorb and release charges much faster than electrochemical batteries. They weigh less, and some projections suggest that in electric cars they might provide 500 mi of travel at a cost of $9 in electricity. But these are only the projections of researchers.

Another direction of battery development involves high temperature and larger units. NGK Insulators, Ltd., in Japan uses sodium-sulfur batteries operating at 427°C (800°F) that are able to deliver 1 mW for 7 hours from a battery unit. The size of these units is about the size of a bus. Such units could be used at electric filling stations that are not connected to the grid.

1.2.8.5 Hydrogen Fuel Cell Cars

Hydrogen fuel cells are widely used in forklift trucks and for power backup in data centers. The reason for their popularity, in contrast to lead-acid batteries is that they last longer (8 hours instead of 2 hours), require no recharging, can discharge energy faster, and their price is becoming competitive.

In June 2008, Honda started the production of its FCX Clarity (a sleeker version of its Accord) which runs on hydrogen and provides a driving range of 280 miles, a mileage of 78 mpg of gasoline-equivalent hydrogen, and an

Hydrogen is supplied in the fuel cells

Hydrogen is supplied in the fuel cells

Oxygen from the air and hydrogen combine in the fuel cells to generate electricity that is sent to the traction invertor module

Fuel

Hydrogen

Cells

Tank

Chemical Energy (gaseous flow)

The traction invertor module converts the electricity for use by the electric motor/transaxle

Oxygen from the air and hydrogen combine in the fuel cells to generate electricity that is sent to the traction invertor module

The traction invertor module converts the electricity for use by the electric motor/transaxle

The electric motor/ transaxle converts the electric energy into the mechanical energy which turns the wheels

The electric motor/ transaxle converts the electric energy into the mechanical energy which turns the wheels

Electrical Energy Mechanical Energy figure 1.17

The hydrogen fuel cell car causes zero emissions of greenhouse gases or pollutants. (Courtesy of H2Gen Innovations, Inc.)

ability to accelerate from 0 to 60 mph in 9 seconds. Honda is going to lease the vehicle for $600/month; although the car itself cost several hundred thousand dollars to produce in 2008, the price is predicted to drop drastically as mass production starts. The FCX Clarity is driven by a 100 kW fuel cell, which is the size of a desktop PC.

In the cars with high-efficiency hydrogen fuel cells, the motor is electric. Fuel cell efficiency is about 60%, whereas the efficiency of gasoline IC engines is only 25%. It is this high efficiency of the fuel cells that makes them prime candidates to provide electricity for the electric cars of the future (Figure 1.17). As of today, the fuel cell-based electric vehicles (FCEVs) are the best long-term options for the zero emission vehicles (ZEVs) of the future. Assuming that the fuel cell efficiency is 2.5 times that of a gasoline engine, and assuming that gasoline costs $3.50/gallon and hydrogen is $5/kg, their fuel cost will be about half the standard rate, or about 10i/mile.

The newer fuel cell-based automobile designs include Honda's "FCX Clarity," Volkswagen's "space up! Blue" and "Touran"; BMW's "Hydrogen 7"; Toyota's "FCHV SUV and Highlander"; Nissan's "X Trail"; Hyundai's "i/Blue"; GM's "Volt, E-Flex, Hydrogen3, and Sequel"; Mercedes/Benz's "F/Cell"; Ford's "Edge, Daygo, and Focus"; Cadillac's "Provoc"; and Chevrolet's "Equinox SUV and ecoVoyager." At the end of 2007, the only hydrogen fuel cell vehicle that is certified by the American IRS, EPA, and CARB as a zero emission vehicle (ZEV) is Honda's "FCX" which qualifies for a $12,000 federal tax credit.

Their fuel tanks contain either high pressure gas or liquid hydrogen. High pressure gas units operate at pressures from 150 to 700 bar (2,200 to 10,000 psig). GM's 100 HP Hydrogen3 model wagons can store hydrogen in either gas or liquid form. One version of the hydrogen fuel tanks, Quantum Technologies'

LH2 _ Tank System super-insulation level probe filling line — gas extraction liquid extraction filling port inner vessel outer vessel

LH2 _ Tank System super-insulation level probe filling line — gas extraction liquid extraction filling port electrical heater reversing valve (gaseous/liquid)

suspension liquid hydrogen (-253°C)

safety valve gaseous hydrogen (+20°C up to +80°C)

shut-off valve cooling water heat exchanger figure 1.18

Hydrogen fuel tanks hold 3 kg or more of hydrogen, which, due to the high efficiency of a fuel cell car provides a driving range of 150 miles or more. (Courtesy of EERE/DOE). (Top) High pressure hydrogen fuel cylinders. (Courtesy of Quantum Technologies.) (Bottom) Liquid hydrogen fuel tank. (Courtesy of Linde.)

inner vessel outer vessel suspension liquid hydrogen (-253°C)

safety valve gaseous hydrogen (+20°C up to +80°C)

shut-off valve cooling water heat exchanger figure 1.18

Hydrogen fuel tanks hold 3 kg or more of hydrogen, which, due to the high efficiency of a fuel cell car provides a driving range of 150 miles or more. (Courtesy of EERE/DOE). (Top) High pressure hydrogen fuel cylinders. (Courtesy of Quantum Technologies.) (Bottom) Liquid hydrogen fuel tank. (Courtesy of Linde.)

TriShield composite cylinders, are shown in Figure 1.18. They can hold up to 3 kg of hydrogen at 350 bar (5,000 psig), which is sufficient for a 200-km journey in a standard sedan. The Lawrence Livermore National Laboratory designed a tank for BMW to hold liquid hydrogen and found that it held the cryogenic liquid for 6 days without venting. Their goal is extending the "no-vent storage period" to 15 days. For more details on hydrogen storage refer to Section 1.5.8.

These cars provide a range of up to about 300 miles and an acceleration of 8 to 10 seconds from 0 to 60 mph. Their mileage is from 50 to 60 miles per kilogram of hydrogen. The fuel cells usually are PEM units and range from 40 to 80 kW in size. The lithium-ion battery sizes range from 8 to 20 kWh. BMW's Hydrogen 7 model burns hydrogen in its fuel cell up to a range of 200 kilometers (125 miles) and when that range is exceeded it can be switched to burn gasoline. GM's "Volt" and Ford's "Dayglo" and "Edge" have fuel cell hybrids that operate with lithium-ion batteries. Mazda is working on a dual mode, gasoline/hydrogen rotary engine to be used in its Premacy Hydrogen RE Hybrid with 346 volt lithium batteries.

In the United Kingdom, Lotus Engineering Ltd. will be converting the black cabs of London by installing 25 kW hydrogen PEM fuel cells made by Intelligent Energy for the 2012 Olympics. In the United States, the largest fuel cell order for public transport to date (mid-2008) has been the eight 120 kW PureMotion fuel cells ordered by California's AC Transit from UTC Power. In Germany, the aerospace agency DLR and Lange Aviation are planning to convert the Antares 20E glider to hydrogen fuel cells as well.

1.2.8.6 Hydrogen ¡C Engine

The volumetric energy density of H2 is less than that of gasoline. Therefore, to provide the same driving range, the hydrogen fuel tank needs to be three times the size of a gasoline tank. Today, a typical passenger car has a range of 575 miles and is provided with an 18-gallon tank, whereas an 18-wheeled semitruck has a 750 miles driving range and requires two 90-gallon tanks. Actually, the volume of the hydrogen tanks can be somewhat smaller than three times because the efficiencies of hydrogen IC and fuel cell engines are better than the efficiency of gasoline engines (gasoline, 25%; hydrogen IC, 38%; and hydrogen fuel cell, 45-60%).

BMW, DaimlerChrysler, GM, Honda, and Toyota are in the process of placing both IC and fuel cell units into the hands of ordinary drivers to gain experience and to collect data. Their prototype units cost about $1 million each. The manufacturers aim for a "pilot commercialization phase" by 2010-2012 at a unit cost of $250,000. They expect full production by 2013 at a unit cost of $50,000, and this cost will drop as the volume of production increases.

The list of vehicles that can run on H2 is constantly growing. Quantum Fuel Technologies Worldwide converted Toyota Priuses to hydrogen fuel. BMW is marketing its 7 Series, 12-cylinder, 260-horsepower car with an IC engine that can burn liquid hydrogen or run on gasoline, whereas the BMW 750hL is designed to burn liquid hydrogen. The IC engine of the Ford E-450 shuttle bus burns 5,000 psig hydrogen gas.

In connection with using H2 as a fuel for transportation, there is a lot of activity, but no firm direction or conclusion yet. In Iceland, one can rent a hydrogen-fueled car from Hertz. In Japan, as part of its national hydrogen program, a 200,000 m3 tanker ship has been designed for transporting H2. Also in Japan, an H2-fueled commuter train is in operation, using H2 at 35 mPa (5,000 psig or 350 bar) to fuel a 125 kW "Forza" proton exchange membrane (PEM) fuel cell by Nuvera (http://www.rtri.or.jp).

Hydrogen buses operate in Montreal and Bavaria, an H2-powered passenger ship sails in Italy, and the 2008 Olympics in Beijing featured hydrogen vehicles. Russia has flown a jet, fueled partly by hydrogen. In the United States, the Defense Advanced Research Project Agency (DARPA), NASA, and the Air Force are jointly developing an Earth-orbit airplane fueled by

H2. Two teams (in Turin and Madrid) are converting two light planes so that they can use hybrid fuel cell-battery electric engines.

1.2.8.7 Hydrogen Filling Stations

As of this writing, there are some 160 hydrogen fuel stations worldwide, for a list of hydrogen fueling stations, see http://www.fu elcells.org/info/charts/ h2fuelingstations.pdf or http://www.naftc.wvu.edu/naftc/data/refueling/ h2fuelingstations.pdf.

In the United States, there are 170,000 gas stations. In terms of infrastructure during the transition from oil to hydrogen, 12,000 filling stations would be needed to provide access to 70% of the population.

Hydrogen tanks for high-pressure gas are made of carbon fiber. Cryogenic (liquid) hydrogen tanks are double-walled with the space between the walls evacuated to provide good thermal insulation. The Lawrence Livermore National Laboratory also designed small fuel tanks for cars holding liquid hydrogen and found that they held the cryogenic liquid for 6 days without venting. Their goal is extending "no-vent storage" to 15 days.

Hydrogen filling stations are already in operation in Japan and Germany, and in the United States in Vermont, Florida, and California. Some of these stations dispense both gas and liquid hydrogen such as the one designed by Air Products at the University of California in Irvine. In 2008, Air Products also started up a new solar-powered hydrogen fueling station at the Sacramento Municipal Utility District. In Burlington, Vermont, the Department of Public Works' hydrogen fuel station uses wind energy to produce 12 kg/d of H2. Air Products and Chemicals participated in the design of this wind-to-hydrogen generator. Figure 1.19 illustrates some of the hydrogen handling facilities that are already in operation.

In Orlando, Florida, Ford airport buses are served at a Chevron energy station, where 115 kg/d of H2 is generated by H2Gen Innovation units. In Munich, a fuel station designed by Linde can dispense both liquid and gas. At that fuel station, H2 is stored above ground in a 17,600 liter tank and is

figure 1.19

The technology for hydrogen storage, transportation, and dispensing at regular filling stations already exists. (Courtesy of the US Department of Energy's "Hydrogen Fuel Initiative.")

figure 1.19

The technology for hydrogen storage, transportation, and dispensing at regular filling stations already exists. (Courtesy of the US Department of Energy's "Hydrogen Fuel Initiative.")

dispensed at a rate of 50 L/min. GH2 is produced from LH2 by evaporation followed by two steps of compression reaching 350 bar (5,000 psig) at 15°C.

1.3 Non-Solar Renewable Technologies

The energy consulting firm Cambridge Energy Research Associates estimates that the combined investment to date in renewable energy, and carbon capture technologies has been $125 billion and that it could surpass $7 trillion by 2030. The renewable energy sources include hydroelectric dams; wind turbines; solar cells; geothermal, wave, or tidal power; biofuel; and methane obtained from rotting trash, manure, or landfills. The term renewable is used in the sense of "not exhaustible," because when biofuels, methanol, or methane are burned, they do emit CO2. Nuclear power is not renewable, and it is estimated that the uranium-235 deposits, if used at the present rate, will be exhausted in about 60 to 70 years.

Some of the available renewable energy sources are also limited. Much of the available hydropower has already been utilized during the last century, the availability of new sites is limited, and resistance against flooding large areas is increasing. The availability of geothermal energy is also limited to certain locations on the planet. Solar energy is intermittent, and the generated electricity is still somewhat expensive; in most areas it is competitive only with electricity generated during peak periods. Solar storage (in areas where the grid is unavailable) is also expensive. It should be noted that new technologies are available to solve both the cost (mass production, thin film, etc.) and the storage (grid, hydrogen, and thermal) problems. Ocean power (thermal, wave, and tide) availability is limited to certain areas and requires further development. Yet technological advances and the increase in the cost of fossil and nuclear energy are making these forms of energy (particularly wind, geothermal, and solar-hydrogen) more competitive.

1.3.1 Ethanol, Biofuels, Biodiesel, and Bioplastics

Biofuels have triggered a "food versus fuel debate." A few years ago turning farms into fuel factories appeared to be a good idea and both Europe and the United States supported it. For example, the American Congress mandated a fivefold increase in the use of biofuels. Today these views and policies are being reconsidered because they drive up food prices, which in turn contribute to starvation.

Biofuels and bioplastics are renewable; they reduce the need for oil imports, but some of them cause more greenhouse gas emissions than do regular fossil fuels and others such as biodiesel plants also cause water pollution. When forests are cut, they not only stop absorbing CO2, but the destroyed vegetation will release staggering amounts of greenhouse gases as they are burned. Therefore the production of biofuels from most sources can actually exacerbate global warming.

On the other hand, if these fuels are made from sources that do not cause deforestation and do not compete with food supplies, such as agricultural waste, algae, coconut and babassu nut, and if their refining meets pollution standards, they can be useful. One of the most promising biofuel source is algae because it can be produced in large quantities. Cellulose- or sugarcane-based fuels are less desirable because the clearing of land for their production can cause deforestation, but they are superior to corn-based ethanol. Similarly, non-food grasses and reeds can also be harmful because they can overrun adjacent farms or natural lands, or drain wetlands and clog drainage systems. Therefore, the sources of cellulosic biofuels should be used only selectively and after careful analysis.

The Agriculture Secretary of the United States, Edward T. Schafer, said in May 2008 that biofuel production was responsible for only 2% to 3% of the global increase in food prices while it reduced crude oil consumption by 1 million barrels per day. Others suggest a much higher impact on food prices, but nobody disputes that biofuel production, particularly if speeded by government subsidies, does increase food prices. The UN Food and Agricultural Organization reported in 2008 that wheat prices increased by 80% in 2007, and the cost of corn doubled in 2 years, both occurred because a rising proportion of the crop is used for biofuel production. Today, a Nigerian family spends 75% of its income on food and 33 nations are at risk for social unrest because of rising food prices.

Biofuels are being used both directly by burning and indirectly by first being converted to liquid fuels. This conversion is an energy-intensive process. In many parts of the world, wood, sugarcane, animal wastes, etc., are still being burned as fuel. New biomass facilities, such as the world's largest biomass plant (350 mW costing $830 million) in England, are also being built. This plant will burn some 3 million tons of wood per year.

Elsewhere, wood chips, sugarcane, switchgrass (also called Miscanthus), corn husks, prairie grass, or soybean and corn are being converted into liquid biofuels. Various waste materials are also used to make ethanol, butanol, biodiesel, and other substitutes for gasoline.

The DOE also supports research to develop genetically engineered trees. The goal of this effort is to reduce the amount of lignin in the wood, making it easier to break down its cellulose into sugar, which then can be converted into ethanol. This approach does not seem to be a good idea because, although saving on acid and steam in the processing of the wood, the reduction in lignin will make the trees structurally weaker and less resistant to pests. Therefore, the use of switchgrass for cellulose and the direct use of sugar are better options.

By 2020 the EU wants to replace 10% of its transportation fuel with biofuels, while China is aiming for at least 15%. In the United States, 6 billion gallons of ethanol were produced in 2006, 15 billion is projected by 2012, and 36 billion by 2020. In 2006, in the United States 250 million gallons of biodiesel, were also produced, and in 2008 the production is expected to reach 2 billion gallons. In Europe, in 2005, biofuels accounted for about 1% of the fuel used.

In 2008 Virgin Atlantic Airlines successfully tested a 25% biofuel mixture in a flight without passengers between London and Amsterdam. The goal was to show that the coconut- and babassu nut-based fuel would not freeze at 30,000 feet (10,000 meters) altitude.

Bioplastics can be made by fermentating corn sugar (propaneidol-based Cerenol by DuPont), starch and cellulose can be used to make nylon (Michigan State University), or propaneidol can be used to produce stain-resistant textiles (DuPont).

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