When 23 percent of BC Hydro’s hydroelectric power is being supplied by the largest dam in British Columbia, shutting down even one turbine for the six to seven months required to replace it requires extensive planning and coordination.

It is that type of coordination with BC Hydro on which Voith Hydro – which is manufacturing and replacing five of the oldest 10 turbines in the G.M. Shrum Generating Station in the W.A.C. Bennett Dam – is relying.

Voith Hydro’s first turbine was produced in 1870 in Germany. It is continuing its tradition of workmanship and reliability by manufacturing new turbines for the Bennett dam and installing them one at a time while the dam continues producing power. The amount of time required to refurbish and install each new turbine varies.

“There’s always slight changes in each unit – they’re not identical – so there’s a little bit of variation,” says Lawson Crichton, Voith Hydro western Canada business development manager. “BC Hydro will have other units down for shorter periods of time. We worked out a very innovative schedule for installing these turbines to minimize the effect on BC Hydro.” The need for this refurbishment was identified 15 years ago. Bids were put out in 2010, and refurbishment of the first unit began in April 2012. All five turbines are scheduled to be installed by 2015. 

Because the powerhouse at the dam is underground, Voith has to follow safety rules for confined spaces. Complicating that is the required removal of lead-based paint. “We have to have special safety training for the workers and confined-space access dealing with the removal of the hazardous material – the lead paint – being sandblasted away,” Crichton says. Approximately 14 subcontractors are being used on the project, many of them local. 

From the 1960s

The Bennett dam is located on the Peace River. “It’s in northeast British Columbia just outside a small village called Hudson’s Hope,” Crichton says. “It’s a historic old crossing point of the Peace River with narrow canyon walls.” Construction of the original dam began in 1960, and it was commissioned in 1968 with the five turbines now being replaced. 

Five more turbines were added throughout the late 1970s. Crichton expects the new turbines to last at least 50 years. “Hydroelectric turbines run forever,” he maintains. “They are some of the most reliable machines in the world.” Approximately 95 percent of British Columbia’s electrical power is supplied by 39 dams throughout the province that are operated by BC Hydro, a public utility.

Turbine Design

Each of the five new turbines is expected to generate approximately 3 percent more electrical power than the one it is replacing. That improvement is gained by computational fluid dynamics programs used to design the new highly efficient turbine blades.

“These programs allow us to make a better turbine blade profile to capture the energy in the water, and material and manufacturing has improved over the last 40 years,” Crichton points out. “We can make blades stronger and in a more dynamic shape with the five-axis CNC machining to actually make the blades in the more complicated shape to capture the energy.”

Laser measurement techniques are used to ensure that the turbines are installed to the correct tolerances for long life. Part of the installation procedure is modifying the water flow passages in the existing water passageway components to allow greater energy to be obtained from the fluid dynamics of the water.

“If we were designing the turbines from a clean sheet of paper, they would be a different kind of design,” Crichton concedes. “With utilizing the existing civil structures, the restraints of the existing machines and the massive cost of replacing all that, we manufacture a new turbine within the existing water passageways and dimensions to get the best out of the modern technology.”

An environmental improvement with the new turbines is that they do not require the grease the old ones did, which eliminates the possible release of that grease into the Peace River. The new turbines’ improved design also allows for an improved fish survival rate in the river for spawning.

Up from Brazil

The stainless steel turbines – each of which is 6.7 meters in diameter – are manufactured in Voith Hydro’s factory in Sao Paulo, Brazil, and shipped in one piece by boat to Houston. Then they are trucked as oversized loads 1,200 kilometers to Alberta, 800 kilometers through Alberta and approximately 250 kilometers to the Bennett Dam.

Houston was chosen to receive the turbines because it is on the same side of the Rocky Mountains as the dam. Shipping the turbines to Vancouver would have reduced the trucking distance but required crossing the Rocky Mountains with the turbines, which are longer than the originals to achieve their added efficiency.

“The collaboration between BC Hydro and Voith Hydro has been great,” Crichton declares. “We continue to work very well together to meet all the project deadlines and minimize the impact of energy loss to the province of British Columbia. One of the amazing things about this project is we have this great team working together collaboratively and pulling toward the same goals. That is a great bonus for us.”