I just read your article on the engineers who face hazards every day at Ground Zero (ENR 12/24/01 p. 27). It's a great piece. It gave me a small taste of what it must be like to be working at the site. After reading so much about what emergency workers are going through, I needed a reminder of how many other people are stepping up to the plate as well. Major news outlet coverage seems to have dwindled to a predictable cycle of the same four or five stories. Not being in New York, I've wondered if I'm getting the full picture.

This article really struck a chord with me. Thanks for shining a light on a different angle.

JENNIFER E. GROVER
Manager, Media Relations
Portland Cement Associations
Skokie, Ill.

Clean And Efficient

Your recent article by Robert Swanekamp entitled, "Plentiful, 'Green' Resources Seen As Dream Energies of the Future" is a nice overview, but is misleading in two respects (ENR 12/3 p. 53). First, many people talk about wind power and the enormous amount of energy to be expected on an annual basis. On its face that is a true statement. However, you cannot expect the 2,000 Mw of new U.S. wind power capacity in 2001 to be available every day all year long or on a base load basis. In most cases, windmill generated power has a fairly low availability, about 3,000 hours per year.

Second, Swanekamp talks about gasification technology co-firing biomass with coal, but the focus is on syn gas from fluidized-bed boilers. He also states that more work needs to be done on exhaust-gas cleanup and actual firing in a gas turbine. But there are environmentally benign and safe gasifiers that are being built around the world, such as those by the Solena Group. Many of them are endorsed by "green" groups in the European Union. Other such plants are under development in the U.S., and are supported as much as possible by the U.S. Environmental Protection Agency.

Solena's Integrated Plasma Gasification Combined Cycle plants use renewable products, such as municipal solid waste, biomass, industrial wastes and waste coal. They produce four times as much electricity as they consume. The net power generated is sold to the grid. Solena's plants operate 8,000 hours per year and have about an 85% availability.

As in a standard IGCC facility, the syn gas, which has about one-half the thermal content as natural gas, is cleaned and sent to a turbine. All inorganic material melts into a vitrified slag, which meets all EPA requirements. Gaseous emissions from the plants are similar to or less than those from a natural gas-fired powerplant. Most importantly, it does not produce ash, dioxins, furans or add any contaminants to the water or ground media as do fluidized bed burners.

DENNIS F. MILLER
Chief Scientist and Vice President for
North America
Solena Group
Washington, D.C.