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As ozone levels in the U.S. remain at unhealthy levels, researches and government officials continue to study alternatives to reduce air pollution from gasoline-powered cars.
Among the alternatives are ultra-low emission vehicles (ULEVs) and zero-emission vehicles (ZEVs). ULEVs are equipped with emission controls that release only 45 pounds of carbon monoxide per 12,000 miles. ZEVs produce no tailpipe emissions at all. ZEVs include vehicles powered by electricity, flywheels, hydrogen fuel cells, and other zero emission energy sources. Although some ZEVs are still in the experimental stage, electric vehicles (EVs) are available today. In fact, more EVs roamed the nation's roads in the early 1900's than did gas-powered cars.
Unlike a gasoline car that is powered by an internal combustion engine (ICE), an EV uses electricity stored in batteries to power one or more electric motors. When the batteries need recharging, you simply plug in from the convenience of your home. EVs have no tailpipe or evaporative emissions, because they have no fuel, combustion, of exhaust systems. In fact, EVs are virtually maintenance-free because they never need oil changes, air filters, tune-ups, mufflers, timing belts, or emission tests.
One of the most common issues surrounding EVs today is their status as ZEVs. Critics proclaim that EVs are simply "elsewhere emission vehicles" because they transfer emissions from the tailpipe to the smokestack. Although there are emissions associated with coal- and oil-fired power plants, smokestack emissions associated with charging EVs are extremely low (3). In fact, EVs can charge from zero emission sources such as nuclear, hydroelectric, solar, and wind power.
The purpose of this paper is to prove that EVs recharging from today's power plants are substantially cleaner than even the most efficient ICE vehicles. The myth that EVs are "elsewhere emission vehicles" will be put to the test with facts that clearly show EVs and power plants are cleaner, more efficient and more reliable than the infrastructure that supports ICE vehicles.
The golden age of the automobile has lasted more than 50 years. However, the golden haze cause by our love affair with the ICE car will have long-lasting effects. Despite stringent standards to improve tailpipe emissions, the number of vehicles and miles traveled are increasing every year. Scientists predict that our increased reliance on the automobile could increase pollution levels 40 percent by the year 2010 (4). In California, where the automobile is considered a necessity, ICE vehicles account for 90 percent of the carbon monoxide, 77 percent of nitrous oxides, and 55 percent of reactive organic gases (5). In addition, greenhouse gases such as carbon dioxide are expected to increase approximately 33 percent by the year 2010.
Continual exposure to these pollutants can cause a variety of symptoms and aggravate existing medical conditions. The elderly and the young are more susceptible to the risks imposed by air pollution. Children in the Los Angeles area have 10 to 15 percent less lung capacity than children in cleaner cities such as Houston, Texas.
The following list describes the potential health risks associated with these emissions.
EVs have the unique advantage of using electricity generated from a variety of fuels and renewable resources. The overall mix of power plants in the U.S. is 55 percent coal, 9 percent natural gas, and 4 percent oil (9). The other 32 percent include nuclear power and renewable energy sources such as hydroelectric, solar, wind, and geothermal.
Many EVs critics point out that charging thousands of EVs from aging coal plants will increase greenhouse gases such as CO2 significantly. Although half the country uses coal-fired plants, EVs recharging from these facilities are predicted to produce less CO2 than ICE vehicles. According to the World Resources Institute, EVs recharging from coal-fired plants will reduce CO2 emissions in the country from 17 to 22 percent.
Reductions in pollutants such as HCs, CO, NOx, SO2, and particulates vary according to a region's power plant mix. If EVs were introduced on a global scale, urban pollution would improve significantly. (See Table 1) In France, where most of the power comes from nuclear energy, emissions produced to charge EVs would be cut across the board. Countries such as the U.S. and the U.K. use a mix of coal- and oil-fired facilities that produce an elevated level of SO2 and particulates. However, levels of HC, CO and NOx would decrease significantly.
| HCs | CO | NOx | SO2 | Particulates | |
|---|---|---|---|---|---|
| France | -99 | -99 | -91 | -58 | -59 |
| Germany | -98 | -99 | -66 | +98 | -96 |
| Japan | -99 | -99 | -66 | -40 | +10 |
| U.K. | -98 | -99 | -34 | +407 | +165 |
| U.S. | -96 | -99 | -67 | +203 | +122 |
| California | -96 | -97 | -75 | -24 | +15 |
Although half the electricity generated in the U.S. comes from coal-fired plats, larger regions of the country such as California and the Northeast are turning toward cleaner fuels such as natural gas.
In California, where over half of the state's pollution comes from ICE vehicles, the overall mix of power plants is one of the cleanest in the country. (See Table 2) Power plants burning cleaner fuels, such as natural gas, account for a major share of the state's electricity. In fact, natural gas facilities in California emit 40 times less NOx than existing coal plants in the Northeast (2). Renewable sources such as hydro, solar, wind, and geothermal produce a respectable share of the electricity generated in California.
| Power Plant | Percent |
|---|---|
| Natural Gas | 33 |
| Hydroelectric | 20 |
| Coal | 16 |
| Nuclear | 15 |
| Solar and Wind | 6 |
| Geothermal | 6 |
Taking advantage of California's abundance of sunlight, several utilities are using Solar Charge Ports to charge EVs. Charge Ports are facilities that have an array of solar panels placed strategically on the roof of the structure. The solar panels convert sunlight into electricity where it is distributed to the vehicles or the adjacent building's power supply. On cloudy days, the building supplies the electricity to charge the EVs. Charge Ports are in operation in several cities in California including Diamond Bar, Azusa, and Santa Monica.
Because California has a mix of cleaner fuels and renewable sources, several studies have concluded that improvements in air quality can be achieved easily by plugging in to EVs.
The California Air Resources Board (CARB) estimates that EVs operating in the Los Angeles Basin would produce 98 percent fewer hydrocarbons, 89 percent fewer oxides of nitrogen, and 99 percent less carbon monoxide than ICE vehicles.
In a study conducted by the Los Angeles Department of Water and Power, EVs were significantly cleaner over the course of 100,000 miles than ICE cars. The electricity generation process produces less than 100 pounds of pollutants for EVs compared to 3000 pounds for ICE vehicles. (See Table 3)
| Engine Type | CO | ROG | NOx | Total |
|---|---|---|---|---|
| Gasoline | 2574 | 262 | 172 | 3008 lb. |
| Diesel | 216 | 73 | 246 | 835 lb. |
| Electric | 9 | 5 | 61 | 75 lb. |
CO2 emissions are also significantly lower. Over the course of 100,000 miles, CO2 emissions from EVs are projected to be 10 tons versus 35 tons for ICE vehicles (5).
Many EV critics remain skeptical of such findings because California's mix of power plants is relatively clean compared to that in the rest of the country. However, in Arizona where 67 percent of power plants are coal-fired, a study concluded that EVs would reduce greenhouse gases such as CO2 by 71 percent (6).
Similar comparisons to those in California and Arizona can be found in the northeastern part of the country where the majority of power plants are coal-fired.
A study conducted by the Union of Concerned Scientists found that EVs in the Northeast would reduce CO emissions by 99.8 percent, volatile organic compounds (VOC) by 90 percent, NOx by 80 percent, and CO2 by as much as 60 percent (7).
According to the Northeast States for Coordinated Air Use Management (NESCAUM) study, use of EVs results in significant reductions of carbon monoxide, greenhouse gases, and ground level ozone in the region, with magnitudes cleaner than even the cleanest ULEV.
In the future, EVs in the Northeast will reap the benefits of switching to cleaner fuels such as natural gas. In the next 15 years, aging coal plants will be replaced by modern natural gas fired plants. This improvement alone will reduce power plant emissions significantly.
Several northeastern states are also exploring renewable sources such as solar energy to generate electricity for EVs. The EVermont Project is using a successful solar-powered system to charge a mail delivery truck used at the General Services Center in Middlesex, Vermont. A solar array was installed and wired into the system's power grid. The solar array generates electricity during the day and the truck charges at night. Overall, the solar panels put out more power than the truck uses on its daily rounds.
EVs recharging from fossil-fueled power plants such as coal and oil have unique efficiency advantages over ICE vehicles. As a system, EVs and power plants are twice as efficient as ICE vehicles and the system that refines gasoline (See Table 4). Although there are losses associated with generating electricity from fossil-based fuels, EVs are significantly more efficient in converting their energy into mechanical power.
| EVs & Power Plants | ICE & Fuel Refining | |
|---|---|---|
| Processing | 39% (Electricity Generation) | 92% (Fuel Refining) |
| Transmission Lines | 95% | - |
| Charging | 88% | - |
| Vehicle Efficiency | 88% | 15% |
| Overall Efficiency | 28% | 14% |
Since EVs operate more efficiently than their ICE-powered counterparts, overall fuel economy is higher. However, making a direct comparison between the fuel efficiencies of both vehicles is difficult. By applying a common unit of energy, such as British Thermal Units (BTUs), we can get a fair comparison between the two.
For the following example we will compare the fuel efficiencies of a 1995 Acura 3.2 TL and GM's new electric vehicle: the EV1. See Table 5. Both cost about $34,000 and can accelerate from 0 to 60 mph in 8.5 seconds.
| Electric-Powered GM EV1 | Gasoline-Powered Acura .2TL |
|---|
| Start with | 1 million BTUs | Start with | >1 million BTUs |
| Energy left after generation (39% efficiency) | 390,000 BTUs | Energy left after refining (92% efficiency) | 920,000 BTUs |
| Energy left after charging losses (88% efficiency) | >343,000 BTUs | Energy left after transport (95% efficiency) | 874,000 BTUs |
| BTUs per kilowatt-hour | 3412 BTUs | BTUs per gallon of gasoline | 115,400 BTUs |
| Electricity available | 100.6 kWhr | Gallons available | 7.6 gallons |
| Energy efficiency | 0.19 kWhr/mile | Fuel economy> | 24 mpg |
| Miles per million BTUs | 529.5 miles | Miles per million BTUs | 182.5 miles |
| Equivalent mpg | 69 mpg | Equivalent mpg | 24 mpg |
Even though the GM EV1 has 43 percent fewer BTUs after electricity generation, it can be driven almost 350 miles farther because the vehicle is more efficient than the Acura. In fact, the GM EV1 has the gasoline equivalency of 69 mpg (23) even after factoring in losses from electricity generation and charging!
We've discussed how the system of power plants and EVs can improve air quality, improve operating efficiencies, and save fuel, but just how efficient are power plant emissions controls?
Controlling emissions from several hundred power plants is much easier than controlling the emissions from 187 million ICE vehicles. In fact, electric utilities go through considerable efforts to monitor and remove emissions from their facilities. Teams of engineers carefully maintain the plants at peak operating efficiency. State-of-the-art equipment such as scrubbers are installed to remove emissions. Electrostatic precipitators (ESPs) between the boilers and smokestacks remove up to 9g - 75 percent of the ash emitted by power plants. Coal-fired plants in Texas using ESPs remove up to 13.4 million tons of ash each year, releasing only 3000 tons into the atmosphere (24). The amount released falls below U.S. EPA regulations for ash emissions.
Over the next seven years, electric utilities in the Northeast are committed to reducing NOx emissions by 55 to 70 percent (25). When one power plant upgrades its emission controls, thousands of EVs immediately reap the benefits from this improvement.
Upgrading and maintaining emissions for ICE vehicles is a different story. According to Drew Kodjak, a lawyer from NESCAUM, ICE vehicles pollute more over time while power plants tend to pollute less over time. Over the course of its lifetime, a gasoline car will spew out 60 times more CO, 30 times more VOC, and twice as much CO2 as an electric power plant.
The U.S. Environmental Protection Agency estimates that tailpipe emissions increase 25 percent for every 10,000 miles traveled (26). As gasoline cars age, their engines, catalytic converters, and other emission control devices become less efficient. The cleanest a gasoline car ever will be is the day it rolls off the assembly line.
The deterioration of emission control systems on ICE vehicles can increase emissions up to 90 percent. To deal with increased emissions, state governments have adopted emission inspection programs with varied degrees of success. Many of these programs have been delayed due to public concern for the cost of repairing emission components. In Maryland, drivers can receive a waiver if they document attempts to repair their ICE cars even though the cars continue to fail emission tests.
Newer cars entering the market are not necessarily the cleanest either. The hottest vehicles on the market today are sport utility vehicles (SUVs) which now account for 40 percent of all new car sales. These gas guzzlers are driving up this country's demand for imported oil, decreasing overall fuel efficiency, and increasing emissions.
Many critics ask how this country could possibly support millions of EVs on today's existing power grid. The Electric Power Resource Institute (EPRI) estimates that this country has the ability to support 50 million EVs without building any more power plants. Another study puts this number closer to 20 million (27). Even so, 20 million EVs is only 10 percent of today's fleet of 187 million cars. Thousands more could be added if they are charged at night during off-peak hours. Twenty million EVs, each with 100,000 miles on the odometer, would reduce CO2 emissions in this country by 500 million tons without building more power plants.
Southern California Edison (SCE) estimates that it has enough off-peak capacity to refuel up to 2 million cars, 25 percent of the area's automobiles. SCE estimates it will only need to add 200 megawatts of capacity by 2008 to accommodate EVs.
In conclusion, EVs will have a considerable impact on reducing air pollution, improving fuel efficiency, and reducing our overall dependence on foreign oil. As power plants improve efficiency and turn to cleaner fuels such as natural gas and zero-emission renewable sources, EVs will continue to be the best solution towards attaining clean air.
Kevin Conners, Advocacy Institute; Kyle Davis, Southern California Edison; Hilton Dier III, VT Electric Car Co.; Dave Goldstein President EVA/DC; Monica Gribben, EVA/DC; Jane Hathaway, NRDC; Jason Marks, Union of Concerned Scientists; and David Rezachek, Ph.D., P.E.