Tuesday, October 27, 2009

To solve pollution problems, planners examine steam heat in Fairbanks
by Christopher Eshleman/ceshleman@newsminer.com
10.26.09 - 02:30 am
FAIRBANKS — The roots of downtown’s largest plant tunnel under much of the city, thick steel pipes twisting beneath intersections and sidewalks on their way toward the city’s biggest buildings.

Instead of absorbing water, however, these roots deliver it, and are a major unseen space heating supplier.

Private and public utility specialists have for years looked at expanding the pipe network — a district heating system that feeds the bulk of downtown’s commercial landscape with cheap heat. Any expansion would cut community-wide heating costs. Aurora Energy, which owns the network, estimates the system replaces the need for 2 million gallons of fuel oil per year, and say it could easily expand two- or three-fold.

But it could be awhile before any such expansions occur. A study early this year estimated the work needed to connect the grid to Hamilton Acres, Shannon Park, Island Homes and another neighborhood just south of Aurora’s downtown power plant could cost more than $200 million.

“It’s obviously just way too big of a project to build at once,” Buki Wright, president of Aurora Energy, said earlier this month. But Wright said the company sees potential in expanding the underground system slowly, particularly if work is coupled with nearby construction projects.

Unseen power

The report was part of a look by Aurora, which is owned by the Usibelli family — operators of the Interior’s biggest coal mine — and the borough government at how the system might grow and whether it could take a bite out of chronic wintertime air pollution. Aurora bought the district heat system and its parent power plant when city officials privatized Fairbanks’ utilities 11 years ago.

It has expanded the system significantly since then. Borough officials, who were facing federal environmental problems because of air pollution in Fairbanks, chipped in more than $20,000 last year to study expansion options.

The underground system consists of insulated steel pipes carrying hot water away from the power plant and returning cooler water to the plant.

Older pipes carry unconverted steam. Much of the system is housed in downtown’s one-story utility corridor, which offers visitors an impressive tour.

The city built the corridor, a sort of underground hallway, before the utility privatization. Aurora was able to expand district heating largely because of that investment, which eliminated the need to dig trenches.

Under the corner of Second Avenue and Lacey Street, the corridor’s floor drops, deepening the hallway to roughly two stories as the heating system’s welded steel arms and elbows bend this way and that on their way to customers’ basements.

“When they built this, it was like building a ship in a bottle,” said Steve Ferree, who manages Aurora’s power plant. “It was really tight.”

A cleaner option

The pipes originate from the coal-fed electric plant, which produces roughly 30 megawatts of electrical power. A large boiler incinerates the coal, heating water and turning it to scalding steam pressurized to more than 800 pounds per square inch. The steam powers the turbine that eventually produces electricity.

But that’s not the only usable energy. When the steam has cooled to roughly 300 degrees, less than one-half its original temperature, it leaves the turbine rooms still carrying enough energy to heat offices, homes or buildings. Much of that heat is then transferred to the insulated pipes leading to and from large customers such as the 12th Avenue federal building. During winter cold snaps, the district heat system produces about 75 million British thermal units — enough energy to heat an Olympic-sized swimming pool from 32 to 147 degrees — after electrical power generated at the plant is excluded.

The dual benefits coming from one energy generation process makes the plant a “cogenerator,” where steam, as a byproduct of electrical generation, supplies heat without producing any extra carbon emissions or air pollution. (The University of Alaska Fairbanks also heats largely through its own district heating system.)

Aurora says its heating system could expand significantly — up to another 130 million British thermal units, or 38 megawatts, of heat power — with little or no loss of electrical generation. That would be enough to heat another 1,500 to 2,000 homes in dense neighborhoods. The study, however, said such an expansion could cost $240 million to build. District heat construction is expensive because it often involves tearing up streets and sidewalks and laying two lines — a feed and a return — of welded, insulated pipe in each direction.

“It’s likely the project would need to be constructed in many phases based on available funding for a given year,” a synopsis of the study reads.

Common alternative

District steam or water systems often heat entire communities in northern climates around the world. Ferree speculated they are particularly handy where high taxes on petroleum products make district heat prices competitive. Outside the United States, governments often remain involved with operations and it can be profitable as a stand-alone enterprise. The Seattle Steam Company, which serves about 200 customers with steam heat, has burned fuel oil or natural gas to produce steam heat and recently converted a boiler to combust biomass.

Customers in downtown Fairbanks continue to sign up for hot water heat, which costs about two-thirds to three-quarters as much as fuel oil. Ferree said Mt. McKinley Bank, the Morris Thompson Center and part of the state railroad’s property have all hooked up in the past two years.

In 1982, the district heating system, then owned by the city, expanded to include its water-based lines, as a demonstration project, after a multimillion-dollar grant arrived from the state. Energy specialists reported spending more than $2 million to prepare public buildings including Ryan Middle and Lathrop High schools and the public library for hot water heat. The switch cut heating costs at those buildings by $100,000 within months, and the project was expected to pay for itself within seven or eight years, according to a 1983 Daily News-Miner article. Homeowners hooked to the project said they saw a 40 percent drop in their heating bills, an engineering report from the following year stated.

The engineers also, however, found that it could cost far more to keep expanding lines to homes — up to $50,000 per house. Ferree said changes in technology have since cut that figure in half, enough to make district heat’s large construction costs affordable to larger customers or properties near main lines.

http://newsminer.com/printer_friendly/4142937

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