By Joe Wiesenfelder, Cars.com
Today’s cars are greener than ever, if you define greenness by conventional standards. Since the industrial revolution, calling vehicles or industries "dirty" has meant they emitted excessive levels of traditional pollutants — things like oxides of nitrogen and particulates, or soot. In this regard, cars have only improved over time. In the past decade, though, we’ve come to regard carbon dioxide as a harmful emission because it’s a greenhouse gas implicated in global warming. Carbon dioxide is an unavoidable byproduct when you burn anything, and the amount is proportional to the fuel burned. A car that uses twice as much gasoline as another releases twice as much CO2. There’s no such direct connection to the level of pollutants; an efficient car can be dirty, and a gas guzzler can be relatively clean. So our constantly growing use of fossil fuels means we’re less green than ever in terms of greenhouse gases.
Alternative fuels, such as ethanol, and alternative propulsion systems, like hybrid or electric, vary in what they accomplish. Too often they’re lumped together into one green category, when their greenness is open to debate, particularly when you consider life-cycle analyses of the energy used — the so-called "well-to-wheel" approach — and not just what the car itself gives off. Also in question is the cars’ ability to achieve other goals, including saving money, emitting less pollution, producing less greenhouse gas, relying less on foreign sources of oil and allowing their manufacturers to profit on them as products. There’s a balance, and all these things must be considered, so here’s a rundown on some of the current and planned alternatives and what promise they hold for car shoppers.
Ethanol/E85
Ethyl alcohol, or ethanol, holds a great deal of promise, but the current source of the ethanol that’s mixed with gasoline to form E85 (85 percent ethanol) is corn, which is a relatively expensive source. The money and energy that goes into its production results in only a slight improvement in pollutants and greenhouse gases and — at this point — no significant financial savings for owners of flex-fuel vehicles, which can burn E85 or gasoline or any mix thereof. Because the cars use more E85 than gas to travel the same distance, its lower per-gallon prices are usually negated. There’s reason for optimism, however, because it’s relatively inexpensive for automakers to produce flex-fuel cars, which means they’re inexpensive to buy. Even though filling stations require new pumps to dispense E85, the infrastructure costs are also low compared to some alternatives. The key to ethanol as a renewable, cleaner and domestically produced alternative to gasoline is the use of simpler sources — basically, cellulose, in the form of plant waste or simple grasses rather than crops. With this expected change will come lower prices and a possible life-cycle greenhouse-gas improvement of more than 90 percent, as opposed to corn-based ethanol’s 22 percent.
Diesel
Though diesel cars have historically been so dirty as to be banned from sale in California and other states, the introduction in 2006 of ultra-low-sulfur fuel has reduced emissions and allowed the use of exhaust aftertreatments that will, within the next year, make diesel passenger vehicles as clean as gasoline ones. What makes diesels still greener is that they’re roughly 25 percent more efficient than equivalent gas engines. That means less fuel burned and less CO2 released. The main problems are cost: Diesel drivetrains have always cost more to build, and thus to buy, than gas versions, and that’s unlikely to change. Where buyers once could justify the premium because they’d make it up in the long run, diesel fuel is now often more expensive than gasoline — enough so that owners might only break even with each tankful due to the vehicle’s better mileage. Petroleum diesel’s greenhouse gas advantage over gasoline is incremental — proportional to the fuel burned.
Biodiesel
Another promising renewable fuel that doesn’t come from outside the United States is biodiesel, which isn’t vegetable oil but is made from it in a relatively simple process for use in any diesel engine, without modifications. As with ethanol, the current leading source is a food crop, soybeans, which makes for expensive fuel. The best-case scenario is the use of used cooking oil or some other less expensive source, such as algae, for biodiesel that costs less and delivers a theoretical 68 percent improvement on the greenhouse gas that comes from gasoline. (Optimally, biofuels reduce the carbon footprint because the source material — such as a plant — removes CO2 from the air as it grows, and then re-releases it when the fuel is burned. Fossil fuels, on the other hand, free carbon that’s been trapped underground for millions of years, effectively adding it to our ecosystem.) Unfortunately, biodiesel stations are rare and, though it comes pure (B100) or mixed 20 percent with petroleum diesel (B20), automaker warranties allow no more than 5 percent biodiesel to be used in their new diesel cars. Inconsistent quality, they say, is the reason. Higher concentrations are mostly used in vehicles that are out of warranty.
Battery-Electric
The electric-car movement suffered a setback in 2003 when the California Air Resources Board repealed the state’s Zero Emission Vehicle mandate. There is currently no mass-market electric car, though Tesla Motors gets a lot of attention for its low-volume roadster. Now the rules of the game, if not the legislation, have changed as fuel prices have soared, the geopolitical consequences of foreign oil have taken center stage and the environmental effect of greenhouse gases has surpassed concern over traditional pollutants that are responsible for illness, as well as smog.
The cost of electricity used in an electric car is claimed to be as cents on the dollar when compared to gasoline. Though the cars themselves produce no emissions, the environmental footprint of the electric power used to charge the batteries can’t be ignored. More than half of U.S. electricity comes from pollution and carbon-intensive coal, with most of the balance from nuclear and natural gas, each with its own environmental tradeoffs. Still, based on the current mix, life-cycle analyses of electrical generation suggest a greenhouse gas reduction of 47 percent over the equivalent amount of gasoline.
The challenges are the same now as they’ve always been: battery performance and range. Affordable versions of lightweight, energy-dense lithium-ion batteries are the holy grail expected to open up the world of both battery- and hybrid-electric cars as early as 2010. The movement will be furthered by a willingness among motorists to accept a shorter-range car for commuting, given that overnight recharging can be done simply at home. Though it’s an entirely different way of building cars, the purely battery-electric vehicle has one powertrain — not the two found in current hybrids — and thus has the potential for reasonable production costs, vehicle prices and manufacturer profits. All of these factors matter in the long run.
Common hybrids
Today’s hybrids team an electric motor and battery pack with a gasoline engine that would have to be larger — or at least would have to work harder — without it. From the driver’s perspective they drive like any other car; they get filled with gas and off they go. Some systems are more elaborate than others, with the most complex typically delivering better mileage and costing more than the modest type. With more than a dozen gasoline/electric hybrids now on the market, and as many to come within a year, it would seem that there are more ways than ever before to save money on gas. Maybe not. Even with the rise in gas prices, the premium price of hybrids means it could take years — possibly more than you’re willing to invest — just to break even on fuel savings. It depends on what you pay for the car, minus any federal or regional incentives you’re able to exploit, and what you’re comparing the hybrid against. The most favorable calculation puts the hybrid up against a comparably equipped model. However, most hybrids are the equivalent of well-equipped, higher trim levels, so if you compare them to a more modest gas-only version, you’ll find the long-term payback elusive.
Hybrids aren’t by nature clean, in the pollution sense, but their manufacturers have made a point of marketing models that are among the cleanest cars on the road, with pollution scores as high as 9.5 or 10 on the EPA’s Green Vehicle scale, where 10 is cleanest. The less sophisticated hybrids typically aren’t as clean, and the larger models pay a price for their higher overall emissions. The Chevy Tahoe Hybrid is no cleaner than the non-hybrid in terms of pollutants, despite being markedly more efficient. The decrease in greenhouse gas again is proportional to the decrease in gasoline burned.
The biggest long-term problem for the current type of hybrid is cost. Automakers don’t discuss it freely, but most hybrids are sold at a loss, and the increase in volume won’t account for the cost of two drivetrains in one car. That doesn’t mean you should avoid them yourself. They’ve been more trouble-free than expected — above average, actually. Concerns and rumors about battery death and replacement costs have been greatly overestimated and are largely unsubstantiated in our experience.
Plug-In hybrids
The next thing in hybrids is exactly what potential buyers cited as a disincentive to purchasing such technology when the concept was new: plugging the hybrid in and charging its battery. Today’s hybrids charge their own batteries using the gas engine, or by recapturing the energy of momentum in braking, which turns the drive motor and generates electricity, recharging the battery pack. The reuse of this power is one source of fuel savings. Plug-ins, which are coming from Toyota and Saturn, to name two, add more battery capacity and allow you to charge them overnight so you start out the morning without wasting gas topping-off the charge. Household electricity comes from domestic and potentially renewable sources, is cheaper and is at least potentially cleaner and less carbon-intensive than gas, depending on the source. These cars will operate like normal hybrids with even more generous ranges per tankful if trips are short between charging.
Series hybrids
Unlike parallel hybrids, which propel the car with electric or gasoline power, or the two in tandem, series hybrids such as the upcoming Chevrolet Volt are basically battery-electric cars. They simply supplement their limited range with the help of an onboard generator (driven by a fuel-needing engine) that can recharge the battery or extend the range indefinitely once the initial charge is depleted. Unlike the plug-in hybrids soon to come, they’ll run as electric-only initially, meaning the car itself will burn zero fuel if it’s operated within its electric range. (Chevrolet says a 40-mile range will handle more than 75 percent of Americans’ daily round-trip commutes.) The answer for people who would otherwise consider an electric car but fear becoming stranded with run-down batteries, series hybrids have great potential, with all the benefits of battery-electrics. Their generators can be driven by gasoline, diesel, E85 or whatever else, using engines that are only as large as necessary. The benefits of this include low cost, low emissions and any advantage of the fuel type used. Similar to battery-electric cars, series hybrids will be a new animal in terms of manufacturing, and will be expensive initially, but they theoretically will become more affordable than current, parallel hybrids are. That will be good for automakers and buyers alike.
Compressed natural gas
Compressed natural gas meets such a broad range of alt-fuel objectives it’s surprising that only one model — the Honda Civic GX — is available for personal purchase, and only in California and New York. The GX sacrifices some trunk space to accommodate the natural-gas tank, and it’s less powerful than the gasoline and hybrid Civics. It’s also the most expensive trim level, with a price tag of more than $24,000 (excluding the ultra-high-performance Civic Si Mugen). But it’s eligible for the highest federal tax credit, $4,000, because it’s the cleanest vehicle sold, in terms of emissions. It’s also eligible for thousands of dollars of state and regional incentives too numerous to list. Even when carrying the driver alone, the GX can use high-occupancy-vehicle lanes in Arizona, California, Colorado, Florida, Georgia, New Jersey, Utah, Virginia and the District of Columbia. It even gets free metered parking in Los Angeles, San Jose and Santa Monica.
The life-cycle decrease in greenhouse gas versus the gasoline equivalent is 28.5 percent, and natural gas is a North American resource, which means CNG cars use almost no foreign oil (life-cycle analyses account for fuel used in the production and distribution of the natural gas). So why only California and New York? Mainly because they have the most developed refueling infrastructure. All the same, GX owners can lease or buy a home refueling machine called Phill, which fills the car overnight from a home’s natural gas line. Its price and installation also enjoy government subsidies. According to Honda, a home-fueled GX costs 50 percent less than a gasoline Civic to operate, or 30 percent less when using a filling station.
High-Mileage
Now that you’ve amassed the above knowledge, the best thing you can do when looking for a green car is ignore what’s under the hood and look at the bottom line. That’s the EPA Green Vehicle Guide’s fuel economy estimates and pollution and greenhouse gas ratings. Not surprisingly, smaller and lighter vehicles get better mileage, as do ones that accelerate less quickly. The secret to buying as efficient a car as possible is to rethink what you really need. How large a car and how much power can you live with? Are you currently driving a pickup or SUV when you could borrow or rent one on the rare occasion that you need it? The fuel and money savings can be huge.
Hydrogen
You’ll hear hydrogen discussed both as a fuel for use in internal-combustion engines and as a source of electricity in fuel cells. The dangers of hydrogen gas aren’t what people assume; the industry considers the safety risks different but no greater than those of gasoline. This isn’t a large hurdle, but there are many others associated with the prospect of hydrogen cars. As an actual fuel, hydrogen leaves a lot to be desired. Its energy content is low compared to conventional fuels, and it is most often suggested as a bridge solution to encourage formation of a hydrogen fueling infrastructure for ultimate use by fuel-cell cars. The biggest player in this arena is BMW, whose Hydrogen 7 version of the 7 Series luxury sedan gets a fair share of attention. However, the H7 has an enormous engine and a cryogenic liquid-hydrogen tank (not compressed gas) to improve range, yet it still has modest acceleration and range and maintains a gasoline fuel source as a backup. The cost of the liquid hydrogen aspect alone is ridiculous, as is the prospect of having two different fuel systems. Speaking of money, ours isn’t on this technology.
Still experimental and extremely expensive — regardless of the 100 copies each hitting the streets from GM and Honda — fuel-cell cars convert hydrogen gas into electricity using a component that emits only water vapor. As such, it’s a zero-emissions vehicle, though hydrogen gas in this usage isn’t a fuel so much as a means of storing and transferring electricity. Electricity must go in at the start of the chain, so the same tradeoffs of electrical generation apply here as they do in battery and plug-in electric cars. Using natural gas as a relatively clean and efficient source of hydrogen gas nets a theoretical greenhouse gas advantage of 41 percent over gasoline.
Getting the components down to a reasonable price and creating an infrastructure for hydrogen production and distribution are herculean endeavors a‚Ǩ" ones whose payoff will be determined against a backdrop of improving battery-electric and other alternative fuel and propulsion types. The positive aspect is that fuel-cell cars are basically electric vehicles, as are the promising series hybrid designs. Presumably a fuel cell could take the place of a generator in a car like the Chevy Volt. We’re already heading in that direction, and if a time comes when fuel cells are abandoned, no harm will have been done (with the possible exception of tax dollars being spent on fuel cell research and development). Though it’s fielded fewer experimental cars, Toyota is perhaps most bullish on fuel-cells, promising a viable — if not cheap — product within a few years. It’s also the company that has suggested all its models will someday offer hybrid drivetrains, even when competitors deem the current type financially unfeasible. Toyota could very well know something we don’t, and we’ll be sure to keep an eye on it for you.
