How to gauge a clean city

At the recent climate conference, cities played a big role, as they should. They are part of the solution but, as we have seen with recent air pollution problems in Delhi and Beijing, they can also be the problems. Conrad de Aenlle provides a good article in the New York Times about the difficulty in comparing cities. You should enjoy this. Please send us your views.

 

The Cleanest Cities? It’s Not So Simple

Some cities consume energy with admirable efficiency. Others are more profligate. Gauging which is which involves more than just reading a meter. And it depends who’s doing the judging.

Various lists of winners and sinners tend to contain the same names. The usual winners include wealthy, white-collar American cities, such as San Francisco and Seattle, and Nordic ones like Copenhagen and Oslo.

The two European capitals held prominent positions within the region on the Siemens Green City index, a compilation of cities lauded for using innovative methods to minimize their impact on the environment. Singapore and, perhaps surprisingly, the Brazilian city of Curitiba were the leaders for Asia and Latin America.

San Francisco and Seattle, along with New York and Los Angeles, ranked among the top 10 in a 2008 Brookings Institution study of the 100 largest American cities with the lowest carbon emissions per resident. Seattle was the only one of these four cities that did not also finish in the top 10 in the latest annual ranking of energy efficiency compiled by the United States Environmental Protection Agency.

Some of these cities deserve their praise, such as Copenhagen, with its offshore wind turbines and ubiquitous bicycles, and Curitiba, which has implemented conservation and sustainability programs since the 1970s in a part of the world where environmental concerns often get short shrift in the quest to lift economic growth. Other cities are often beneficiaries of accidents of geography or history.

San Francisco, for instance, sits on a small peninsula in a prime location, ensuring that its population would be packed tightly together and be amenable to using public transportation. It also catches a break because it developed as a center of finance and other service industries for people in urban centers that are somewhat messier than San Francisco, but support the city in its cushy, albeit energy-efficient, lifestyle.

Experts in urban planning and related fields acknowledge that there are many ways to measure energy efficiency — or energy intensity, an idea that encompasses the quantity and quality of energy consumed — and that any assessment must include a degree of subjectivity. Some surveys adjust the measurement of a city’s energy intensity to include not just how much its residents consume but also how much others consume on their behalf.

“It’s awfully hard to find one metric to declare who’s the winner,” said Clinton Andrews, a professor of urban planning and policy development at Rutgers University.

“One way is to count all greenhouse emissions within your city boundaries, from car exhausts, chimneys, power plants, industrial facilities,” he said. “A lot of people think that’s not a good accounting scheme and propose that wherever electricity is generated, you’re responsible for those emissions.”

That includes fuel burned to transport food to the table or to take residents to far-flung locales for vacations or business meetings. They also get the bill for energy spent elsewhere to make goods that are consumed in some cities.

“It can add up to a much larger carbon footprint,” Mr. Andrews said. “If you’re a rich city, you’re going to be responsible for a lot of consumption. San Francisco and New York start to not look so good.”

New York looks considerably worse in a study released this spring in the Proceedings of the National Academy of Sciences that assessed the world’s 27 largest metropolitan areas, or “megacities,” on energy, water use and solid waste production per capita. New York was the worst in all three categories.

Evaluations of energy intensity often adjust for differences in economic development, industrial bases, climates, population density and other factors to make a more equal comparison.

The drawback then is that “every city ends up being the same,” said Christopher Kennedy, a professor of civil engineering at the University of Toronto and the lead author on the megacities study.

Another way to compare cities is one economic or social segment at a time, such as transportation or industry, said Anu Ramaswami, a professor of science, technology and public policy at the Humphrey School of Public Affairs of the University of Minnesota.

“It’s better to talk about energy intensity by sector — how much is used per household or to produce so much” economic output “or industrial goods or to move people,” Ms. Ramaswami said. Taking such an approach, she added, “New York consistently comes out as more efficient on all measures.”

Among the 27 megacities, Mr. Kennedy admires Paris and Rio de Janeiro. Both cities have little heavy industry and use electricity from cleaner sources: nuclear in Paris and hydroelectric and ethanol from sugar cane in Rio.

“One way to reduce pollution is to reduce use of energy,” he said. “Another is to reduce the carbon intensity of the electricity you use. I think that’s the easier way.”

Shanghai is at the other end of the spectrum. It burns a lot of a coal for residential and industrial consumption. In Mr. Kennedy’s view, it’s a city that “needs a lot of work.”

An inefficient city that is not “mega” is Denver. It derives electricity from high-carbon sources, is spread over a wide area and has cold winters, Mr. Kennedy said.

Mr. Andrews tends to find greater energy efficiency among “modest-sized cities that still have crops growing nearby and where you can walk to school or work,” such as San Luis Obispo, Calif., Saratoga Springs, N.Y., and the Dutch town of Delft.

A larger city that fits the bill for him is Philadelphia, with its pedestrian-friendly downtown, well-functioning mass transit and nearby farms.

It also has chemical plants in the vicinity, Mr. Andrews said. “They’re living with their industrial past and present,” he said. “But they’re finding ways to make the city livable and perform well, even if it’s not the most economically vibrant city.”

His candidates for least energy-efficient locales include Guangzhou, the southeast Chinese industrial city where coal generates much of the power and where buildings and road systems are poorly designed. He offered similar criticism of Lagos, the Nigerian capital. “They have achieved all the costs of agglomeration without all the benefits of it,” he said.

Two inefficient American cities that he highlighted are Houston, where downtown high-rises are hard to air-condition and where driving is essential for work or recreation, and San Jose, about which he said: “It’s all there. Just try to get to any of it.”

What many efficient, low-energy-intensity cities have in common is that the factors contributing to their benign profiles produce other benefits, making the cities pleasant places to live, Mr. Andrews said.

“If you stop burning coal in inefficient power plants, you’re going to improve air quality, and if you do urban design so you can walk places, you’re going to be healthier and you won’t burn lots of gas,” he said. “A lot of what improves energy efficiency improves quality of life.”

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