The Ecological Footprint of Energy

Local opportunities for a responsible energy policy

Urbanist Article August 1, 2003

Perhaps the most challenging environmental issue facing humankind over the next century will be global climate change. There is growing evidence that burning fossil fuels such as coal, oil, and natural gas is altering the earth's climate by increasing the concentration of carbon dioxide in the atmosphere. Scientists have observed that the earth's surface has warmed by one degree Fahrenheit during the 20th century. The scientific advisory committee created by the United Nations to analyze the science of climate change has estimated that global temperatures could rise by as much as another six degrees Fahrenheit by the year 2010.

There is a strong scientific case that global climate change will have devastating impacts on both nature and human beings. Agriculture would be disrupted by changes in rainfall and temperature, posing a problem in meeting food needs in some parts of the world. As global temperatures rise, sea levels are also likely to rise, affecting the large portion of the world's population living at or close to sea level. Climate change also threatens to reduce biodiversity since some species will be unable to adapt to changing conditions.

The generations living on the planet today--especially those in the developed world, with abundant wealth, resources, and technology--must find a way to change this course of events.

And while the United States continues to capitulate to the narrowest of economic interests, namely the corporations that make their money from petroleum, the interests of humanity lie elsewhere.

This is the reason for the political momentum behind the alternative energy movement in San Francisco: we have the ability to make a real difference on a local level by becoming national leaders for renewable energy. San Francisco has the opportunity not only to close its older power plants but to reduce the risk of climate change by making more efficient use of fossil fuels, using fossil fuels with the lowest carbon content, and, most importantly, promoting the development of renewable energy technologies.

There are two ethical imperatives that must drive energy policy in San Francisco:

  • first, we have to reduce the immediate health impacts of locally-generated power on the people who live near power plants. This is a major environmental justice issue, as the power the city relies on is all produced in the southeast part of the city, where poor and African American residents are concentrated
  • second, we have to reduce the overall "ecological footprint" of the energy we consume. In other words, we need to reduce the contribution to pollution and global warming that comes from the energy we use in San Francisco, regardless of where the energy is produced. Because of this second imperative, it is not acceptable to simply move production out of the city to somewhere "out of sight, out of mind."

Ecological footprint analysis tries to measure the impact that our technological and lifestyle choices have on the planet, by expressing them in terms of acres of land that are appropriated to support a given activity. Redefining Progress, the Oakland-based policy organization, estimates that the average American uses 24 acres to support his or her current lifestyle, while the average Canadian lives on a 17-acre footprint, and the average Italian lives on a 9-acre footprint. In other words, the amount of land on the planet that is necessary to support the lifestyle of an average American is almost three times the amount of land needed to support the lifestyle of the average Italian. The American energy system is one major reason.

The most recent data show the U.S. electricity industry was responsible for:

  • 67 percent of sulfur dioxide emissions that contribute to acid rain
  • 25 percent of nitrogen oxide emissions that contribute to urban smog
  • 40 percent of carbon dioxide emissions that contribute to global climate change

And these figures do not even account for the water pollution and solid wastes that come from electricity generation!

It's not surprising that electric power generation produces more pollution than any other single industry in the United States, given that electricity is an intermediate "input" into so many other processes. But this is precisely why the electricity industry is such an important leverage point for dealing with our contributions to global climate change.

Almost all sulfur dioxide emissions come from the burning of coal to produce electricity. While there are no coal-burning facilities in California, the state does import considerable quantities of power from other parts of the western United States. Coal-fired power plants account for about 16 percent of the power used in California. Increasing the use of cost-effective renewable technologies such as wind and geothermal throughout the West can displace the need for coal generation.

Power plants that rely on high-temperature combustion processes produce significant quantities of nitrogen oxides (NOx). In the presence of sunlight, NOx reacts with organic compounds to form smog (ozone--a molecule comprised of three oxygen atoms). Ozone irritates membranes lining the lungs' air passages as well as the eyes. Mounting scientific evidence links ozone to a number of short and long-term respiratory and visual problems. Nitrogen oxides (NOx) can be reduced substantially by the installation of power plant emission-control technologies.

In addition to NOx, power plants that burn fossil fuels also produce particulates. Particulates are airborne solid or liquid droplets. Commonly called soot or smoke, they are referred to by regulators as PM-10, since they measure 10 microns in size or larger. Most PM-10 comes from roads (asphalt, tires, and brake linings), materials handling, and crushing and grinding operations. Often new power plant developers are required to reduce these other sources of PM-10 as a condition for their license.

In terms of the impact on the health of people adjacent to a power plant, small particulates are also of special concern since they can become lodged deep into the lungs and often contain greater amounts of toxic materials than larger particulates. Burning fossil fuels such as coal, oil, diesel fuel, and gasoline is the primary source of fine particulates. The quantity of particulates can be reduced by using more efficient combustion processes so that less fuel is used, and by using natural gas rather than liquid or solid fossil fuels that contain greater quantities of impurities like sulfur, mercury and cadmium.

This is an turbulent time. As the federal government seems to have renewed its commitment to petroleum and failed to develop a future-oriented energy policy for the United States, the burden of developing a responsible energy policy rests at the state and local level. Fortunately, there are not (yet) laws preventing San Francisco from walking down a different energy path than the rest of the country. We have the ability to produce our own energy from renewable sources. The city's Public Utilities Commission is making real progress toward this goal.Spur logo

About the Authors: 

Gabriel Metcalf is deputy director of SPUR.

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