Overview

Air emissions from the proposed Metcalf Energy Center will be controlled through the use of the best available emissions control technology. These controls will make the Metcalf Energy Center one of the cleanest power generation facilities in the world. In addition, certain emissions will be mitigated, or offset, by reductions from other sources of air pollution in the region.

What are emission offsets?

In the early days of California's air pollution control program, companies that wanted to build a new factory or power plant would merely have to perform a modeling analysis to show that the new facility would not cause a violation of any air quality standards. However, as our urban areas became more crowded with homes and businesses, it was no longer good enough to simply say "I'm not causing the problem"; all of us, individuals and businesses, small and large, contribute to our air quality problem. That is why, in the late 1970's, California became the first state in the nation to require businesses to provide emission offsets when seeking to build new factories or plants.

The idea behind emission offsets is simple: within each air basin (such as the San Francisco Bay Area), our air quality objective is to reduce overall pollution rates to acceptable levels. The acceptable level of pollution is the one where state and federal air quality standards are achieved throughout the year.

Think of an air basin as a large mixing bowl filled with water: We want to make sure that the mixing bowl does not overflow. The problem is, how do you allow for reasonable growth (more homes, businesses, jobs) without causing water to overflow the mixing bowl? The answer is, you regularly scoop out some water (reducing air pollution). If you scoop out enough water on a regular basis, the overall water level in the bowl will go down, even if some water gets added (from new homes or factories, for example).

There are two techniques used to reduce air pollution. First, the U.S. Environmental Protection Agency, California Air Resources Board, and Bay Area Air Quality Management District adopt regulations that require car makers to reduce emissions from new cars and trucks; require oil refiners to make cleaner burning gasoline; require factory operators to invest in new pollution control technologies that reduce emissions from their plants; and even require that the paints, cleaners, and deodorants we use at home contain fewer and fewer smog forming chemicals. This is where most of the cleanup in our air comes from.

The second technique used to reduce air pollution is to require anyone who wants to build a new factory or plant to reduce emissions from within the same air basin by an amount at least as great as the amount that will be added. Want to build a new factory that adds a tablespoon of water to the mixing bowl? Fine; first scoop out a tablespoon, plus a little more. Want to add a cup of water? Then you'll have to scoop out a cup, plus a little more. This second technique is what we refer to as providing offsets-before a new factory or power plant can start operation, the owners have to reduce, or offset, emissions by an amount at least as great as the amount the new plant will add.

How are offsets created?

Emission offsets can be created when an old source of pollution is shut down; when a company chooses to curtail its operations; or when a company chooses to install new pollution control equipment that goes beyond the federal, state and local requirements.

When a company decides to create offsets, it must file a formal application with the Bay Area air quality district. The offsets must meet rigorous tests established by the district. Once these tests are met, the air district will issue certificates, known as Emission Reduction Credit (ERC) certificates. These credits can then be used to offset new sources of air emissions or can be sold to other companies.

The use of these certificates is critical to the success of the program. It isn't always possible to match up the time when one company decides to reduce emissions to create ERC's, and a second company decides to expand operations. Since the ERC's are always created before they can be used, the reductions in air emissions always precede the growth and new emissions. Thus, the water is scooped out of the mixing bowl before more water is added.

How do offsets protect my community?

Offsets are only one part of the air pollution control program. The community is protected by the entire program, which includes the following:

· Existing pollution sources are regularly reviewed to ensure that they comply with all regulations, and are periodically required to reduce their emissions to help achieve our air quality goals.

· New cars and trucks are subject to increasingly stringent standards each year and the fuels used to power them are also tightly regulated.

· New sources of air pollution are required to use the best pollution control technology available to ensure that they add the least amount of new pollution to the air.

· Some new sources of air pollution are required to provide emission offsets. These sources also have to demonstrate that they will not cause any localized air quality problems.

Thus, offsets help clean our air on a regional basis and the remainder of the air program ensures that local problems are not created.

Conclusion

The Metcalf Energy Center has been designed to have extremely low emission rates and minimal environmental impacts. It will be one of the cleanest power plants in the world, with state-of-the--art design features and emission control capabilities. Remaining increases in emissions of smog-forming pollutants, such as oxides of nitrogen (NOX) and hydrocarbons, will be offset at a ratio greater than one to one, at 115%, so that the emission reductions provided as mitigation will be greater than the project's emission increases, thus ensuring a net benefit to regional air quality.