By Jan TenBruggencate
Advertiser Columnist

Q. "I think I have Hawaiian koa trees around my house. Are they?"

— F.A., Puhi, Kaua'i.

A. Several koa relatives are found in the Islands, including the native Hawaiian koa and its variety, koaia, but also imported species such as Formosa koa, which is a smaller tree with bright yellow flowers.

There are several great places on the Web to look at photos of Hawaiian plants. One is the new "Meet the Plants" section on the National Tropical Botanical Garden Web site, www.ntbg.org. Another is University of Hawai'i botany professor Gerald Carr's Web site, www.botany.hawaii.edu/faculty/carr. Still another is the Hawai'i Ecosystems at Risk Web site for plants, www.hear.org/starr/hiplants.

Q. In response to a story about the environmental friendliness of various building materials, a reader e-mailed to ask, "What is the energy use of recycled steel?"

— D.H., Kapa'a, Kaua'i

A. A review of literature on the subject indicates there are significant energy savings in recycled steel as opposed to steel produced from ore, although the amount of energy used to produce virgin steel or to produce recycled steel varies fairly widely depending on the technology used — older steel plants are far less efficient than newer ones.

The Environmental Protection Agency's Industrial Technologies division estimates it takes 18 million Btu to produce a ton of steel, or about 9,000 Btu to a pound of steel. Recycled steel — steel made from scrapped cars, refrigerators and tin cans — can save as much as 5,500 Btu per pound. That represents more than half the energy cost of new steel, and many recycling and steel industry sources say the savings can be as high as 76 percent.

(A Btu, or British thermal unit, is the amount of energy needed to raise the temperature of a pound of water 1 degree Fahrenheit. The EPA says one Btu is about the amount of heat produced by lighting a single wooden kitchen match.)

For more on recycling of steel, visit the Steel Recycling Institute Web site at www.recycle-steel.org.

The Honolulu Advertiser invites readers to send in questions about Hawai'i's environment, "green" and sustainability issues, coastal pollution, weather and related matters. We'll try to respond from time to time in this column.

Drop a note to Jan TenBruggencate, The Advertiser's Kaua'i Bureau chief and its science and environment writer. Reach him via e-mail at jant@honoluluadvertiser.com, by telephone at (808) 245-3074, or by mail at P.O. Box 524, Lihu'e, HI 96766.

Please include information on how to reach you, in case we have questions about your query.