By Bronwen Parsons
Storing Power at Bella CoolaEngineering
This is kind of the Holy Grail for a lot of renewable power advocates," says Allan Grant, B. Sc., head of the alternative energy group at Powertech Labs in Surrey, B. C. "They would like to find a cos...
This is kind of the Holy Grail for a lot of renewable power advocates,” says Allan Grant, B. Sc., head of the alternative energy group at Powertech Labs in Surrey, B. C. “They would like to find a cost effective way to be able to store the renewable power produced when it is surplus to what is required on the grid.” Grant thinks the holy grail is within sight at a pilot project in Bella Coola, 400 kilometres up the B. C. Central Coast. Powertech is doing the project for its parent organization, BC Hydro. The challenge with renewable power sources, Grant explains, is that the supply is intermittent. The sun doesn’t always shine, the wind doesn’t always blow. And especially in the winter, small run-of-river hydroelectric power stations don’t run at capacity because most of the water is trapped in the snow pack. Run-of-river generating stations don’t have reservoirs behind their dams and so cause less disruption to the environment. But with no means of storing water, it means the plants cannot guarantee a steady power supply. Bella Coola is a remote community of approximately 1,800 people situated at the end of a steep valley in the Coast Mountains. This is magnificent country, habitat of bald eagles, grizzly bears, and heli-skiers. Industries include farming, fish processing and recreation. The town’s peak power demand is about 3.8 MW, which occurs in the winter. The run-of-river hydroelectric plant called Clayton Falls can produce about 2 MW. In addition, diesel generators can supply about 7 MW as back-up. To help the community become less reliant on diesel power, Powertech’s Hydrogen Assisted Renewable Power (HARP) project will tie two new technologies into the hydroelectric station. One involves a Vanadium Redox Battery to store surplus power for use when it’s needed. The other is an electrolyzer to produce hydrogen to feed a fuel cell.
Vanadium Redox Battery and Electrolyzer The vanadium redox battery, or VRB, was invented in Australia, but there is a manufacturer in Richmond, B. C. “The VRB is basically two tanks of solutions of dilute sulphuric acid with vanadium,” Grant explains. “The solution is pumped through a membrane, and when electricity is added, it charges the solution. Then when you want to extract the electricity, you pump it the other way past the membrane and it discharges the electrons out of it.” As for the electrolyzer, Grant explains: “Figuratively, it’s like a bucket of water with two electrodes in it, although it’s much more complex than that. You pass an electrical current through and it breaks the bonds in the H2O and changes it into hydrogen and oxygen. The oxygen is released into the atmosphere, and the hydrogen is compressed and stored. “When we need electricity we’re going to take the stored hydrogen and put it through a fuel cell to generate power,” Grant continues. “It’s a proton exchange membrane (PEM) fuel cell, which is the type that Ballard makes. What happens in the fuel cell is the hydrogen ion comes in contact with a membrane coated with platinum, which is a catalyst. The platinum encourages the hydrogen to split into a proton and an electron. The electron goes up through an electrical circuit — that’s electricity — and the proton goes through the membrane. Hence the name.” The only emission from a fuel cell is water.
At Bella Coola they will generate hydroelectric power at off-peak times and feed it into the electrolyzer to make hydrogen. “We then compress the hydrogen and store it in compressed gas cylinders on site until such time as we need it for the fuel cell, such as during times of peak electricity demand,” Grant explains.
The VRB battery should provide about 125 kW, and the fuel cell will give about 200 kW. “We won’t be able to eliminate the use of diesel,” says Grant, “but we can reduce it.
First a fuelling station
To start things rolling, this summer Powertech is to ship a mobile hydrogen fuelling station it has built up to Bella Coola. The station will be used to fuel a 4 x 4 pick-up truck whose engine has been converted to run on gaseous hydrogen. This way the local operators will become familiar with handling compressed hydrogen and they will have an emis- sions-free maintenance vehicle to take them up the winding road to the generating station at Clayton Falls.
Meanwhile, responses to requests for proposals are due in this spring for the vanadium redox battery, the fuel cell and the electrolyzer. Powertech will be setting up and testing the equipment at their labs over next winter, and then shipping it in 20-foot containers to Bella Coola. They plan to commission the system in the fall of 2009.
Project managers on the HARP project are the Vancouver Consulting Group (Bruce Henry and David Minocola). Grant thinks that later on the project will also require consulting civil engineers for preparing the site at Bella Coola.
Another important piece of the puzzle, says Grant, is the development of a control system software or “smart grid” that will coordinate all the generating equipment at Bella Coola. GE Digital Energy of Mississauga and GE Global Research of New York State are creating the software program.
BC Hydro is hoping that the lessons from the HARP project in Bella Coola might be used at 30 or 40 other remote communities, helping to reduce the communities’ carbon footprint as well as easing their vulnerability to volatile fuel prices.