Modelers take another look at Chesapeake Bay nutrient sources New computer modeling results by EPA researchers will provide policy makers with a blueprint for further reducing nitrogen loadings in the Chesapeake Bay. The latest cross-media computer models show that contributions from individual sources have changed, but overall estimates of nitrogen input are consistent with projections EPA first made in 1985. "The loadings are virtually the same. It's the same pie, we are just slicing it differentiy," said Lewis Linker, coordinator of EPA's Chesapeake Bay modeling effort. Earlier, scientists had predicted that total nitrogen loadings from water and airborne sources in die bay watershed were about 365 million pounds annually. But fine-tuning of the watershed models also turned up higher than expected contributions from numerous watershed sources, including sewage treatment plants and farm runoff. Also, for the first
time the modelers estimated the contribution from leaking septic systems. "This is something we never had data on before," said EPA scientist Rich Batiuk. In the new results, the septic tank contribution, now estimated to be 12 million pounds annually, was offset by earlier "overcalibration of other sources," including organic nitrogen, Linker said. Scientists also made adjustments after studies showed that forests had higher retention rates for absorbing atmospheric nitrogen. Although overall totals were consistent, the increases in waterborne nitrogen sources suggested that earlier Chesapeake Bay cleanup goals may prove to be elusive. The results also indicated the need for new control programs to address leaking septic systems and other nonpoint sources. A 1983 agreement among EPA, Maryland, Virginia, Pennsylvania, and the District of Colum-
bia called for a 40% reduction in nitrogen and phosphorus loadings by the year 2000. However, the reductions were based on estimates that roughly 185 million pounds annually from point and nonpoint sources were potentially controllable; the revised estimate is now 226 million pounds. That difference means that control programs designed to cut 74 million pounds of nitrogen annually will now have to cut 90 million pounds to reach the 40% goal. "This is certainly going to create some turmoil for the policy folks," added Batiuk. The parties to the Chesapeake Bay agreement were scheduled to meet on Oct. 30 to discuss the findings and review their cleanup strategy. One option is to abandon the 40% goal and replace it with a cap of about 230 million pounds annually. —RAE TYSON
DOE pushes energy technologies to reduce U.S. greenhouse gases A Department of Energy (DOE) analysis of energy technologies concludes that a strong national commitment to renewable and energy-efficient technologies, including a government-sponsored program and participation from the private sector, can curb the growth in U.S. carbon emissions while keeping consumer energy bills down. The analysis, a year-long peerreviewed study done by five DOE labs, reviews 200 technologies in the manufacturing, building, transportation, and electric utility sectors that reduce carbon dioxide (C02) emissions. The report also takes a long-term look at research and development advances that promise to generate significant energy savings by 2020. An increased market penetration of renewable energy technologies, such as wind power, solar energy, and biofuels, as well as energy-efficient technologies that are readily available or in the works, could help the United States comply with an international agreement to reduce C0 2 emissions to 1990 levels by 2010, ac-
cording to Joseph Romm, DOE acting assistant secretary for energy efficiency and renewable energy. The United States must reduce its carbon emissions by 390 million tons to meet 1990 levels by 2010, DOE says. The use of energy-
"Solar will become an increasingly useful and strategic part of the energy mix." —John Browne, CEO, British Petroleum efficient and low-carbon technologies could cut carbon emissions from 390 to 270 million tons, bringing emissions to 20% above 1990 levels, the report found. Biomass fuels could also help cut carbon emissions. Almost all of the current coal power plants can combust up to 10% of their fuel with biomass without disrupting the current infrastructure, said Romm, reducing not only C0 2 emissions but also sulfur dioxide (S02) emissions. "Technologies
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that can make a contribution [to reducing emissions] by 2010 of 5% to 10% are, in our minds, major areas that we are going to look at seriously," said Romm. To support its conclusion that technologies can hold down the costs of controlling greenhouse gases, the study estimates the costs of emission reductions at $50 billion to $90 billion annually. These costs include "incremental investments" by businesses and consumers to deploy existing technologies. The estimated savings through 2010 from the use of these technologies ranges from $70 billion to $90 billion a year, the researchers found. The report indicates that renewable energy sources can probably be used effectively to bring down carbon emissions after 2010, said Romm. But to get there, widespread use of renewable energy will need a strong push from the government and the private sector, he said. To reduce emissions by the full 390 million tons by 2010, the study models a scenario that includes a national program to pro-
