April 27, 2009

JEAN SORENSEN

Vancouver’s Olympic Athlete’s Village will use heat recovered from raw sewage.

Thermal system at 2010 Olympic Village will recover heat from spent sewage

Jean Sorensen

correspondent

Vancouver’s 2010 Olympic Village will feature a unique heat recovery system from spent sewage through the use of a neighborhood energy utility (NEU), built under the south end of the Cambie Street bridge.

The system will direct the heat back into a thermal system for area condominiums.

It will be the first community energy system in North America to use heat recovered from raw sewage in an urban setting, said Chris Baber, project manager with the City of Vancouver.

“(Its) a community energy system supplying thermal energy for space heating,” he explained.

It will first supply heat and hot water to the Olympic Village site and then to all Southeast False Creek (SEFC) buildings at full project build-out.

The utility’s three main components are: the energy centre located under the bridge producing thermal energy, the hot water distribution pipes looping the site to buildings and back to the energy centre, and the energy transfer stations located in each building’s basement used to draw in heat from closed loop hot water system, explained Baber.

NEUs or district energy systems are not new.

Vancouver has several, but these are legacy systems, utilizing steam rather than hot water.

Other systems utilize heat recovered from treated sewage at sewage treatment facilities, where as the Vancouver system utilizes raw sewage upstream of the treatment facility.

Two such systems exist. One is in Oslo, Norway and another is in Tokyo, Japan.

Vancouver’s application is expected to become popular as treatment facilities are often outside major populated areas and the closer it is to the sewage source, the easier it is to capture heat.

Baber said that sewage contains significant latent heat, which is derived from a number of domestic and commercial functions.

In the False Creek system, it flows by gravity pipes to a sewage pumping station (SPS), or a lift station, which lifts it into another main towards a treatment centre.

“The SPS we currently have in the area is at the end of its life,” said Baber.

A new station must be built to service the area.

The NEU presented the opportunity to integrate the SPS into the energy centre and not only recover heat, but also share building costs.

Sandwell Engineering has designed the SEFC energy centre.

Raw sewage is first screened to remove solids, then pumped through a heat exchanger.

Sandwell’s project manager, Ray Tarnai, said heat is only drawn from liquids.

The solids go into a self-cleaning wet well, where they are rejoined with the spent liquid later and returned to the pump station.

A major concern is preventing fouling of the heat exchange surfaces in the heat pump evaporator.

The heat pump has been designed with a self-cleaning ability to ensure that any particulate in the liquid does not block heat exchange tubes or cause bio-film build up and impede transfer.

The system, Tarnai said, has the ability to effect a self-cleaning protocol such as a bar passing over a mesh filter to remove particulate build-up.

FVB Energy Inc., a Swedish company, has designed the distribution system, which will eventually serve all 18 buildings on the SEFC site.

The European-made, 10-inch pipe is jacketed, insulated and corrosion protected with an internal liner.

“It will lose very little heat,” said Baber, adding only a few degrees of heat will be lost as water loops the site.

The sewage recovery system has the ability to generate about 2.7 megawatts of energy, but will be supplemented by the energy centre’s three natural gas fired boilers. One boiler features a condensing economizer designed to reduce the operating costs.

The sewage recovery system will supply 70 per cent of the energy needs for the False Creek project.

Most of the NEU is actually below grade underneath the bridge.

Its flu stacks have been disguised; the five stacks (three for the boilers, one from an odor control system and a fifth for waste energy) extend into a sculpted stainless steel hand, reminiscent of a female athlete’s hand with long fingers.

“The fingernails are actually LED panels that can change color and are programmed to reflect the amount of green energy being produced,” said Tarnai.

“It is really a showcase building.”

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