PROJECT
08
Reclaimed Wastewater for Power Generation
The ENMAX Shepard Energy Centre is an 860 MW natural gas-fired combined cycle power generating facility, located at the east end of Calgary. Shepard was built with the goal of providing safe, reliable electricity to Albertans long into the future, with a simultaneous commitment to reducing emissions and using resources responsibly. Shepard uses reclaimed wastewater from The City of Calgary’s Bonnybrook Wastewater Treatment Facility for all its power generation needs – a first in Alberta. This design feature prevents from having to draw nearly 6 million cubic meters of fresh water from the Bow River every year.
After nearly three years of research, observation and lab testing, the team at Shepard was able to pinpoint the optimal operating efficiency of the cooling towers while still maintaining all cooling water chemistry parameters within their required concentration limits. This perfect balance has reduced the plant’s annual wastewater volume by 25-30 per cent – saving nearly 500 million litres per year with a related annual cost savings of more than $1.5 million. Now into the third year of the initiative, the process has been continuously improving. As of the third quarter of 2020, Shepard has already saved $1.7 million while still increasing the megawatt output being produced.
Reclaimed water is far more variable than fresh water and contains a large proportion of inorganic and organic compounds that must be kept within strict concentration limits for health and environmental reasons. In the cooling water cycle, every pass through the cooling towers increases the concentration of these dissolved substances.
CoE 2020: Electricity Innovation • Canadian Electricity association 19
