Article

PSNH's wood-burning plant makes power practical

A lot of regulatory issues had to be settled, including the decision by Connecticut, Massachusetts and New Hampshire that the switch to wood counted as a renewable energy project. This was vital because it allows the Northern Wood Project to earn Renewable Energy Certificates, or RECs. Those certificates can be bought and sold like shares, and are a major incentive for alternative energy projects, such as the proposed Lempster Wind Farm north of Keene. “We probably would not have proposed, nor won approval for this, unless the REC market existed,” said Martin Murray, PSNH spokesman.

Depending on how you look at it, PSNH’s new wood-burning boiler at the venerable Schiller Station power plant in Portsmouth is either enormous or tiny.

“As wood plants go, it’s large – very large,” said Fred Mayes, who oversees renewable energy statistics for the U.S. Department of Energy’s data group, called EIA.

At the power plant, which earlier this month finished converting one of its three 50-megawatt boilers from burning coal and oil to burning wood, that size is clear. Among other things, it has massive hydraulic rams that lift tractor-trailers like they were toys, dumping their load of wood chips, while the new boiler house is so big that elevator buttons are marked in feet above sea level rather than floors.

“This is a very practical operation here. It’s not some sort of scheme that looks good just on paper,” said Dick Despins, plant manager. “It’s about as big as a wood plant can be, just from the logistics.”

In fact, PSNH says it thinks the Schiller Station conversion, called the Northern Wood Power Project, may be the biggest such biomass project in the country at the moment.

Then Mayes adds the proviso: “But as power plants go, it’s small.”... more [truncated due to possible copyright]  

Depending on how you look at it, PSNH’s new wood-burning boiler at the venerable Schiller Station power plant in Portsmouth is either enormous or tiny.

“As wood plants go, it’s large – very large,” said Fred Mayes, who oversees renewable energy statistics for the U.S. Department of Energy’s data group, called EIA.

At the power plant, which earlier this month finished converting one of its three 50-megawatt boilers from burning coal and oil to burning wood, that size is clear. Among other things, it has massive hydraulic rams that lift tractor-trailers like they were toys, dumping their load of wood chips, while the new boiler house is so big that elevator buttons are marked in feet above sea level rather than floors.

“This is a very practical operation here. It’s not some sort of scheme that looks good just on paper,” said Dick Despins, plant manager. “It’s about as big as a wood plant can be, just from the logistics.”

In fact, PSNH says it thinks the Schiller Station conversion, called the Northern Wood Power Project, may be the biggest such biomass project in the country at the moment.

Then Mayes adds the proviso: “But as power plants go, it’s small.”

Despins agrees: “It’s big for renewables, small for the industry.”

Indeed, compare this project with the state’s most famous power plant, the Seabrook nuclear power station. Seabrook can generate 1,200 megawatts at a time – 24 times as much as the Schiller wood boiler. The Granite Ridge natural gas plant in Londonderry is 15 times as powerful, and even the Wood Power Project’s neighbor, PSNH’s aging oil-fired Newington Station, has eight times as much output.

The fact that a $70 million plant capable of making electricity for at least 40,000 homes is considered “small” shows the size of the nation’s power market and the amount of work needed to be done for America to wean itself from foreign oil and polluting coal, or make any dent in greenhouse gas emissions.

But we have to start somewhere, and a visit to this project on the banks of the Piscataqua River shows it’s as good as any.

Is it or isn’t it?

The Northern Wood Power Project was born more than three years ago, when PSNH applied to the state Public Utilities Commission to make big changes to one of the three 50-megawatt boilers at the Schiller Station. As a regulated utility, PSNH isn’t allowed to build more power plants because of concern that those costs will lead to higher rates, but it can modify existing plants.

A lot of regulatory issues had to be settled, including the decision by Connecticut, Massachusetts and New Hampshire that the switch to wood counted as a renewable energy project.

This was vital because it allows the Northern Wood Project to earn Renewable Energy Certificates, or RECs. Those certificates can be bought and sold like shares, and are a major incentive for alternative energy projects, such as the proposed Lempster Wind Farm north of Keene.

“We probably would not have proposed, nor won approval for this, unless the REC market existed,” said Martin Murray, PSNH spokesman.

PSNH anticipates between 300,000 and 400,000 RECs will be generated each year by the wood project, bringing in at least $15 million at their current value. Murray said the REC income is expected to pay off the cost of building the new boiler and the associated wood yard, and is a big part of the reason the company could pursue the project without increasing rates.

“We have to answer to our shareholders; it has to make sense from a business perspective to do this,” Murray said.

Another part of the appeal for PSNH is keeping Schiller Station relevant. The oil- and coal-burning plant, named after a former PSNH chairman, was built a half-century ago, and time isn’t a generating facility’s friend.

But now it’s modernized again, using a technology known as fluidized bed combustion that cuts emissions of such things as “nox,” the shorthand for nitrous oxide pollutants.

“Being an older facility has always been a concern,” Despins, the plant manager, said during a recent tour. “It’s important to provide something that will be some semblance of an operation for years to come.”

Local impact

There’s one more benefit from a wood-burning plant: The fuel is bought locally.

“It’s good for us. A lot of guys are using it,” said Reggie Sweet, owner of Sweet’s Logging of Strafford, as he held down the switch that caused his tractor-trailer to be raised to a 70-degree angle, dumping its 25 tons of wood chips into the massive processing shed.

Loggers such as Sweet take trees or portions of trees that aren’t good enough for sawmills or the cordwood market and run them through huge chippers on site, then haul the resulting chips to Portsmouth, where they’re currently worth about $25 to $30 a ton.

The Wood Power Project buys its fuel from about 60 logging operations of all sizes, said Richard Roy, a University of New Hampshire graduate who is its wood-chip buyer. (It signs contracts with them, however; you can’t show up with a load of wood and sell it.)

Buying wood is a lot different than buying coal because of the exponential increase in the number of suppliers and deliveries needed. There are also other problems PSNH isn’t used to facing; the warm December has made it tough for logging machines, which work better on frozen ground. “It’s like an early mud season for them,” Roy said.

The plant’s Seacoast location, far from New Hampshire’ north woods, isn’t the drawback in finding suppliers that it might seem, since the region’s development displaces a lot of nearby trees.

“These guys like not having to go as far,” Roy said. “It all comes down to transportation costs.”

New Hampshire has a half-dozen other wood-burning power plants in the North Country. All of them are half the size of Schiller or less.

“Yeah, we hope it does well,” Sweet said. “This is a lot closer than Ossipee.”

Overwhelming tour

The low power density of wood might make it something of a pain as a fuel, but it makes a tour of the Wood Power Project something to see. To keep up to nine days of fuel, PSNH can store as much as 14,000 tons of wood chips at a time on the former coal yard, piled in mountains big enough to ski down.

The chips are handled inside an 85-foot-tall metal shed by a massive automated system – “basically, it’s run by PCs,” Despins said – built by the French company Ameco.

As chips travel on reams of conveyer belts, they pass huge magnets designed to keep bits of metal from sneaking into the boiler and specialized screens to reduce oversized chunks before making a half-mile trip on a belt that rises higher in the air than most bridges; its a terrific place for a view of the river, for those who can get past the PSNH security.

The new boiler house is tucked between railroad tracks and the river – “it was quite an engineering feat to fit it here,” Despins said – and created about two-thirds of the total cost of the project. It uses fluidized bed combustion, a method developed to burn coal more cleanly; in fact, the boiler can switch back to using coal without shutting down if financial or other concerns arise with the wood supply.

The system uses huge air drafts to keep the fuel floating in mid-air, allowing a more complete burning at a relatively low 1,400-1,700 degrees and creating a swirling mix of gases and solids that improves many chemical reactions, reducing emissions, and improves heat transfer.

Floating solid particles are snagged by big filters, called bags, and the energy created by the burning wood is carried by steam to turbines, which spin and create electricity at 13,800 volts, just as they have done for decades.

To the visitor, ducking under pipes carefully labeled “no asbestos” and trying to talk over the roar of fans and the six “cyclones” that use centrifugal force to separate floating matter, it’s a huge, overwhelming machine that’s a world away from tree-hugging ecologists. But to those in the industry, it’s trying to be a mix.

“We have to serve our customers, but this is a better way to do it,” Despins said.

David Brooks can be reached at 594-5831 or dbrooks@nashuatelegraph.com.


Source: http://www.nashuatelegraph....

DEC 31 2006
https://www.windaction.org/posts/6564-psnh-s-wood-burning-plant-makes-power-practical
back to top