More than 750 people came to the Rock Financial Showplace Tuesday to learn how to make green by going green.

The event was the 12th annual Energy Conference and Exhibition, cosponsored by DTE Energy and the Engineering Society of Detroit.

The event is a hard-core, highly technical event on saving energy in business and industry. Breakout sessions featured titles like "Emerging Technology that Reduces Energy Conumption in Automotive Metal Forming and General Stamping" and "Catalysts for Improving Energy Efficiency in Regenerative Oxidizers."

But it also featured a more generalist keynote speech from James R. Scapa, CEO of Troy-based Altair Engineering Inc.

In introducing Scapa, DTE Energy vice president Trevor F. Lauer said the prospects for those working in energy efficiency are bright -- since current power demand trends will require building dozens of new nuclear plants and hundreds of new coal-fired plants, yet few plants are being built.

Scapa outlined the ways Altair is helping produce a more energy-efficient future.

Started in 1985 as a three-man product design consulting company tied to the auto industry, today's Altair is a $175 million-a-year company with most of its business in HyperWorks design software and PBS Professional grid computing management software. The company also has a new product in business intelligence, and a new subsidiary, Ilumisys, in efficient lighting.

Scapa said today's biggest business focus is energy efficiency and sustainability. But he said sustainability often gets complicated -- mentioning reports that the energy it takes to ship a Toyota Prius to the United States outstrips the environmental benefit of the more efficient car.

HyperWorks software has helped companies like Unilever use less material in their packaging, and companies like Airbus and Boeing shave weight off their next-generation jets.

But it's in lighting where Altair's green future really shines.

Scapa said Altair began exploring the use of LEDs to replace flourescent lighting tubes while spending $3 million on research toward a more efficient city bus. Buses vibrate so badly that flourescent tubes don't last, so Altair engineers looked at replacing them with a series of LEDs that would fit inside a standard 48-inch tube.

The cost of that replacement tube has fallen fourfold since then, but it's still around $100, Scapa said. But he's predicting it's going to fall still further, to less than $20, by 2012.

The first Ilumisys installations have already taken place -- 100 tubes at a state office building in Escanaba, and eight tubes at Ann Arbor city hall.

The LED flourescent tube replacements offer several advantages over flourescents. They use less electricity -- current models about 10 percent, a next generation coming out later this year 40 percent. They perform better in cold weather. They stand up to vibration better. They offer reusable components. They offer lighting that can be programmed with smart building systems.

But most importantly, they're mercury-free. Scapa said a typical flourescent tube contains 10 to 15 milligrams of mercury, and those little compact flourescent light bulbs people are putting in their houses four to six mg. And four mg of mercury is enough to contaminate 6,000 gallons of fresh water.

More about Ilumisys technology at www.ilumisys.com. More about Altair at www.altair.com.