17.3 The Electric Vehicle
In a bid to lower air pollution in big cities, much emphasis has been placed on the electric car. The notion of driving a clean, quiet and light vehicle appeals to many city dwellers. Being able to charge the car at home for only a dollar a day and escape heavy fuel taxes (at least for the time being) makes the electric car even more attractive.
The battery is still the main challenge in the development of the electric car. Distance traveled between recharge, charge time and the limited cycle count of the battery continue to pose major concerns. Unless the cycle life of the battery can be increased significantly, the cost per mile will be substantially higher than that of a fuel-powered vehicle. The added expense is the need to replace the battery after a given number of recharges. This could offset any advantage of lower energy costs or the absence of fuel taxes. Disposing the spent batteries also adds to the expenditure.
Another challenge associated with the electric vehicle is the high power demand that would be placed on the electric grid if too many cars were charged at a certain time. Each recharge consumes between 15 to 20kW of power, an amount that is almost as much as the daily power requirement of a smaller household. By adding one electric car per family, the amount of electric power a residence requires would almost double. Delayed charging could ease this problem by only drawing power during the night when the consumption is low.
A rapid shift to the electric car could create shortages of electric power. With the move to reduce the generation of electricity due environmental concerns, electricity would need to be imported at high costs. This would make the electric car less attractive.
If the electricity was generated with renewable energy such as hydroelectric generators and windmills, the electric vehicle would truly clear the air in big cities. The generation of electricity by means of nuclear power or fossil fuels simply shifts the pollution problem elsewhere. However, a central source of pollution is easier to contain than many polluting objects in a metropolitan area.
A hybrid car is an alternative to vehicles running solely on battery power. Here, a small combustion engine works in unison with an electric motor. During acceleration, both the electric and combustion engines are engaged. Because of superior torque, the electric motor takes precedence during acceleration. Once cruising, the combustion engine maintains the speed and keeps the batteries charged. Hybrid cars achieve fuel savings of 30 percent or better compared to the combustion engine alone.
A hybrid car is less strenuous on a battery than a conventional electric car because the battery is not being deeply discharged during regular use. A deep discharge only occurs on a long mountain climb where the small combustion engine could not sustain the load and would need assistance from the electric motor and its battery bank. Driving habits would, to a large extent, determine the service life of the battery. A light foot on the pedal will help the pocket book also with the hybrid car.
Another alternative to powering cars is the fuel cell. Although much cleaner running than the combustion engine, the fuel cell must solve a number of critical problems before the product can be offered to the consumer as an economical alternative. The major challenge is cost reduction. If fossil fuel remains as low-priced is it is today, many drivers owning high-powered cars, SUVs and trucks would be reluctant to switch to a new technology. Concerns over pollution only persuade a limited number of drivers to switch to a cleaner-running vehicle. With the slow and gradual progress in the fuel cell, it will be some time before this technology renders the combustion engine obsolete.
Europe is talking about the three-liter motor, an internal combustion engine running on gasoline or diesel fuel. Remarkably, ‘three’ does not denote the engine displacement but stands for liters of fuel consumed per 100 km traveled. There is talk about the one-liter engine also. Major car manufacturers are divided on the fuel that will power our cars in the future. Within one large auto manufacturer in Europe, opinions regarding the fuel cell and an economical three-liter engine are divided fifty-fifty.
17.4 Strengthening the Weakest Link
The speed at which mobility can advance hinges much on the battery. So important is this portable energy that engineers design handheld devices around the battery, rather than the other way around. With each incremental improvement of the battery, the doors swing open for new products and applications. It is the virtue of the battery that provides us the freedom to move around and stay in touch. The better the battery, the greater the freedom we can enjoy.
The longer runtime of newer portable devices is not only credited to higher energy-dense batteries. Much improvement has been made in reducing the power consumption of portable equipment. These advancements are, however, counteracted with the demand for more features and faster processing time. In mobile computing, for example, high speed CPUs, large screens and wireless interface are a prerequisite. These features eat up the reserve energy that the more efficient circuits save and the improved battery provides. The result is similar runtime to an older system, but with increased performance. It is predicted that the improvements in battery technology will keep par with better performance.
Wide-band mobile phones, dubbed G3 for third generation, are being offered as replacements for the digital voice phone. There is public demand for Internet access in a tiny handset that connects to the world by the push of a few buttons, twenty-four hours a day. But these devices require many times the power compared to voice only when operating on wideband. Higher capacity batteries are needed, preferably without added size and weight. In fact, the success of the G3 system could hinge on the future performance of the battery. G3 technology may be ready but the battery lags behind.
The battery has not leap-frogged at the same speed as microelectronics. Only 5 to 10 percent gains in capacity per year have been achieved during the last decades and the ultimate miracle battery is still nowhere in sight. As long as the battery is based on an electro-chemical process, limitations of power density and life expectancy must be taken into account.
The battery remains the ‘weak link’ for the foreseeable future. A radical turn will be needed to satisfy the unquenchable thirst for mobile power. What people want is an inexhaustible pool of energy in a small package. It is anyone’s guess whether the electro-chemical battery of the future, the fuel cell or some groundbreaking new energy storage device will fulfill this dream.