WINDS OF CHANGE

The managing director of BQ Energy, Paul Curran, 50, has overseen what he describes as the first large-scale wind project inside an American city. Earlier this summer his Putnam County-based company, working with UPC Wind of Newton, Mass., placed eight wind turbines on the site of an old Bethlehem Steel mill in Lackawanna, N.Y., a suburb south of Buffalo. With blades reaching higher than the Statue of Liberty, this wind farm can provide the power needs for about 7,000 homes, he said.

The project received tax credits for converting a brownfield site. Mr. Curran, who grew up in the Bronx and attended Columbia University, cited a few advantages of placing the wind farm on the brownfield site: There were already roads there, and the old steel mill site was already connected to the electricity grid, eliminating the need to install new power lines. He said the site was also an active port, allowing equipment to be delivered by barge. The land in Lake Erie where the windmills are placed originally did not exist, but came about when the company kept dumping slag (a by-product of smelting) there.

Mr. Curran said he wears a golf shirt with the name and logo of the wind project and it spurs conversation with people he meets in places like John F. Kennedy International Airport.

PIZZA POWER

If it is biodegradable, then a research physicist at Princeton Plasma Physics Laboratory, Stephen Paul, can turn that material into energy. This scientist, who advises graduate students at Princeton University, literally turns trash into treasure. Mr. Paul, 53, said fuel from consumer and municipal waste is uniquely suited to urban areas. “It’s a real New York fuel. It uses what we have here.” His approach uses local materials, such as pizza boxes, paper plates, ice cream containers, tissues, sawdust, or leaves, to make local fuels.

One advantage of biomass fuel is that it reduces waste in landfills, which release methane into the atmosphere, which Mr. Paul says on a unit-to-unit basis is more worrisome than carbon dioxide. He does not employ the fermentation process used for ethanol. Instead, Mr. Paul, a Cornell University and Columbia University graduate, uses hydrolysis. He likens the process to stomach acids placed in a steel pressure cooker.

Mr. Paul said the New York State Throughway Authority has tested his fuel. More than a decade ago, Marie Osmond and Farah Fawcett also tested a car with alternative fuel that he developed. He said he plans to open a plant in Trenton, N.J., to make 4 1/2 million gallons of renewable diesel annually.

GEOTHERMAL GO-TO GUY

Jeff Irish speaks proudly of working on “zero net energy” homes in the Hudson Valley — that is, homes without oil, gas or electricity bills. One component is “geothermal” heating and cooling systems. This licensed engineer said a pump transfers heat from the earth to the house in the winter and from the house to the earth in the summer. The pump circulates an environmentally friendly antifreeze solution through a plastic pipe buried in the ground, and a reversible heat pump extracts the heat from the solution. The heat pump is similar to the refrigeration loop in a room air conditioner or refrigerator.

Educated at Harvard Business School, he founded Hudson Valley Clean Energy after he put his first solar electric system on his own house in 2002 and had so many people asking him if he could do the same for them that he decided to turn it into a business.

He predicts that in 10 to 15 years, solar use could increase 100 times in the Hudson Valley. But that still will come out to only 2% overall, he said.

Adding these fuel savings to houses can add $20,000 to $30,000 more to a new home price, but can pay for itself in about five to seven years. He said he is proud that every day, his company is installing enough solar to eliminate five barrels of oil.

UNDERWATER TURBINES

In New York’s East River, Trey Taylor, 59, has set six tidal turbines that convert flowing water into electricity. He says they are the first underwater turbines to be connected to an urban grid generating electricity for American customers. In this case, the energy is delivered to a Gristedes supermarket on Roosevelt Island. According to him, the fish are not affected “a bit.” His company, Verdant Power, has spent $2 million dollars to make ultrasonic images of the fish interacting with the turbines. “It’s like a sonogram,” he said.

The local headquarters of Verdant is in the ecologically designed “Octagon” building on Roosevelt Island, not far from the water where the turbines lay. From the top of the water level to the tip of a rotor during low tide is a depth of only 6 to 8 feet. He said the blades, which run 17 hours a day, turn not by waves but by tidal currents.

Mr. Taylor said that when he first tested the turbines, the blades broke. When he made them stronger, they pulled the bolts out that were holding them in.

Mr. Taylor said that the technology of tidal energy, though considered hydro-power, is more similar to wind power.

HELPING MEXICO CITY

Roger Slotkin has trucks and buses on his mind — large ones weighing 20,000 to 80,000 pounds each. “Heavy duty. This is not Priuses, my friend,” he says. Mr. Slotkin, 55, is chairman and chief executive officer at Odyne Corporation, in Hauppauge, L.I., which develops plug in hybrid electric power and stored energy systems for heavy vehicles. His 21-person company went public in 2006.

He works with vehicles that stop and start a lot, or idle a lot, like bucket trucks that hoist power line workers in the air. He says the electric motors get their energy from a battery pack that sustains its charge from a generator on the vehicle as well as from brake systems that convert kinetic energy to electric energy.

His vehicles include a converted diesel New York City garbage truck is now a plug in hybrid truck in Hempstead, L.I. “It is quieter and cleaner than before, he said.

The Mineola-born Mr. Slotkin, who graduated from the C.W. Post campus of Long Island University, said bucket trucks equipped with plug in technology can idle all day “in zero emissions mode,” greatly reducing pollution and costs.

In Mexico City, he is participating in converting 500 conventional city-owned, governmental cars into electric vehicles.