» Does the $25,000 fully electric Nissan Leaf muddle environmental arguments in favor of transit?

Nissan’s new Leaf, expected to reach American shores this December, represents nothing less than a revolution in thinking about automobile propulsion: it is the first modern, reasonably priced, four-door car powered completely by electricity. It is the opening slide in what is likely to be an avalanche of such vehicles coming to market over the next decade — Chevrolet’s electric-for-40-miles Volt is arriving later this fall as well at a higher price point. The significance of their collective potential environmental benefits cannot be dismissed.

The immediate consequences of the replacement of at least a segment of the American vehicle fleet with electric cars will be positive: an immediate elimination of local point-source pollution, lessened street noise in the urban environment, and of course a reduction in the consumption of fossil fuels, at least by individual consumers. These are advances that must be applauded.

The widespread availability of electric cars will make one argument made by transit proponents harder to advance: that riding trains and buses is better for the environment. In cities where the electric grid is powered by renewable or nuclear energy, these vehicles will produce zero carbon — also true of electric trains, but not of diesel or even hybrid buses, which will continue spewing pollutants into the atmosphere.

But transit must continue to compete from an environmental perspective, or it will lose some of its appeal; the arrival of the electric car is a direct challenge to the claim that public transportation is greener. But it’s not too late to make that argument — there are significant ecological advantages of mass transit even if they share their propulsion technologies with some automobiles. The contention that transit is the more sustainable answer to questions of mobility has not suddenly expired.

The clearest flaw in the argument for electric cars is that the majority of electricity produced in the United States — almost 75% — comes from power plants that burn fossil fuels. This means that “clean” cars like the Nissan Leaf are simply shuffling pollution production elsewhere, not actually getting rid of it. This would not be true if American power were produced like it is in France, where about 90% of power is carbon-free, and where a switch to electric cars would mean a vast reduction in air pollution overall. At least for now, though, the widespread adoption of electric cars in the U.S. will require a large ramping-up of power generating capacity and therefore increase pollution from power plants, not necessarily generating a net benefit, even as there is a significant decrease in air pollution in congested urban areas.

If all transit vehicles switched to electric propulsion and public transportation absorbed a much larger percentage of the commute market, on the other hand, they would require less overall electricity because they’re more energy efficient per passenger. So even if everything were electrically powered, transit would still have some advantages.

Second, electric cars may be environmentally responsible in operation, but their manufacturing and disposal require a significant energy expenditure: between 10 and 20% of overall lifetime energy use. Transit vehicles last longer and are used more intensely than automobiles, meaning that their per-rider-mile manufacturing and disposal costs are significantly lower than those of cars.

But all of the discussion about the relative ecological advantages of cars and public transportation vehicles ignores their greater effects on the human environment, and that is the basis of the primary argument transit proponents must use to defend the environmental credibility of buses and trains. Transit nurtures the creation of dense urban environments in which the majority of trips are made by carbon-free walking and in which people live and work in energy-efficient multi-story buildings. A society dependent on automobiles cannot establish such sustainable communities and will ultimately always depend on energy-heavy single-family homes and private vehicles. There’s no getting around that fact, Nissan Leaf or not.

Electric vehicles could play an auxiliary role as the basis for new car-sharing efforts, but the implementation of electric chargers on the street for private users seems far off. Nissan and other auto companies are expecting most of their customers to refill their vehicles in their private garages overnight, not exactly an urban-friendly scheme.

Nevertheless, transit agencies still have an obligation to increase the efficiencies of their vehicle fleets — primarily by increasing ridership and maximizing the number of riders per bus or train. There’s nothing wrong with finding as many ways as possible to reduce energy consumption.

Image above: Nissan Leaf, from Nissan

Straight to the point: There are a panoply of choices to be made when investing in public transportation, but there is never an excuse for minimizing the negative environmental effects of a transit vehicle.

Some American public transportation agencies run bus fleets that consume on average a gasoline-equivalent 25 miles per gallon. This means — and this must be interpreted literally — that there are plenty of cars that, when driven from one point to another, are less carbon-intensive even with only one passenger than buses running the same route.

This fact is a disappointing one for transit advocates who would promote the idea that transit is, on face value, always more ecologically conscious than private transportation. It is a letdown to discover that the simple formula — more people in one vehicle = more fuel efficiency, thus public transportation > automobiles — doesn’t work out when those transit vehicles average fewer than 10 passengers at a time.

To the anti-transit zealots of the world like Wendell Cox, this fact is evidence that governments would be more likely to encourage decreases in carbon production by ridding cities of transit and instead pushing people into hybrids and other mildly polluting cars. That argument, however, completely ignores the fact that transit promotes communities that are denser, more walkable, and in general less energy consumptive — even if trains and buses sometimes feature lower fuel efficiencies than the newest Toyotas and Hondas.

To transit promoters like Jarrett Walker, this same information is indicative of the fact that transit planners must take to heart a variety of rationales when considering how to choose routes; the most ridership-heavy routes (those that would feature the highest average fuel efficiency) are not necessarily the most politically or regionally prioritized investments — which means that vehicles can often be found running with few passengers on board. Transit that runs all the time and to many places — and which therefore is frequently empty — is absolutely necessary to advance the kind of transit-dependent population that consumes less energy overall.

Nevertheless, the limited fuel efficiency of the fleets of many transit agencies is troubling because even if public transportation is effective in promoting better land uses, if buses and trains continue to spew pollutants, we’re not doing enough to address the underlying environmental consequences of transportation use. Indeed, while the adoption of hybrid-electric buses by many transit agencies is a step forward, the vehicles continue to emit carbon into the air — a problem that shouldn’t be side-stepped.

Full-scale electrification of bus routes and installation of catenary along train lines should be encouraged to further the environmental credentials of public transportation — as long as power providers increase the supply of renewables in the electricity mix. For cities, this clears the air as power is produced elsewhere (rather than in the vehicles, on the street). Overall, efficiencies are increased since centralized power production is more efficient than burning fuels vehicle-by-vehicle.

As automobiles become more and more efficient, buses and trains must be able to keep up — and the best way to do that is to go electric. To suggest that the poor fuel efficiencies of transit are merely a consequence of the realities of decision-making in the field is an attempt to make the issue go away, when in fact we should be addressing it straight-on.