TransAlta Corporation (formerly Calgary Power) is an electricity power generator and wholesale marketing company headquartered in Calgary, Alberta. It is a privately owned corporation and its shares are traded publicly. It operates over 70 power plants in Canada, the United States and Australia. TransAlta operates geothermal, wind, hydro, natural gas and coal power generation facilities. The company has been recognized for its leadership on sustainability by the Dow Jones Sustainability North America Index, the FTSE4Good Index and the Jantzi Social Index. TransAlta is Canada's largest investor-owned renewable energy provider. TransAlta, on several occasions, illegally manipulated the energy market to drive up power prices.

In 1909, the company began the planning and construction of the Horseshoe Falls Hydro Plant in Seebe. Two years later, Calgary Power Company, Limited was born.

That first dam was built by a crew of about 200 with primitive tools, such as picks and wheelbarrows. It initially had a 10 MW capacity (13,500 horsepower). Its second dam was commissioned in 1913 at Kananaskis Falls and was built by close to 500 workers.

At the time, streetcars were responsible for a significant share of Calgary’s electrical load. Residential power was just being introduced, and many homes were lit for the first time with electrical lamps because of Calgary Power. Calgary Power's cheap power is credited with Canadian Pacific Railway's decision to locate its regional engine repair shop in Ogden, Calgary spurring Calgary's economic development.

Notable leaders from the company’s early years included W. Max Aitken, eventually Lord Beaverbrook, and R.B. Bennett, who went on to become Canada’s Prime Minister from 1930 to 1935.

Its monopoly position and behavior made its status as a private corporation unpopular among rural customers and some Calgary residents and a move to nationalize it was converted to a province-wide referendum in 1948, which came down very narrowly on the side of maintaining its private ownership.

In 1981, the company changed its name to its current name of TransAlta Corporation.

Generation summary:

Net Capacity Owned by Fuel Type
(in operation and in development)

Net Capacity Owned by Geography
(in operation and development)

At the end of 2010, TransAlta became the first company to own and operate more than 1,000 MW of installed wind capacity in Canada - almost 30 per cent of the country's total.

After the 2013 Alberta floods, as a temporary partial solution to mitigate flood damage, during those months when there is a greater risk of rising water that might cause flooding, the government pays TransAlta Corporation $2 million to lower the level of water on its Ghost Reservoir.

"A temporary deal between the government and TransAlta Corp that pays the utility 2M to lower water levels on its Ghost Reservoir for two months this year when the risk of rising water looms largest offers a partial solution

In 2010 and 2011, TransAlta timed their power outages so as to drive up prices of electricity and increase their revenues. The Alberta Utilities Commission declared these acts illegal in their review, concluded on July 27, 2015. The commission has yet to determine penalties for this manipulation of the energy markets.

Upper Mamquam built by Canadian Hydro Developers and operational in 2005, it is a run-of-the-river hydroelectric plant 5 km northeast of Squamish, BC. The penstock is 1.6 km long, dropping 120 meters to the powerhouse containing two 12.5 MW Pelton wheel generators.

Bone Creek flows into the North Thompson River, the hydroelectric plant constructed in 2011, has a 5 km penstock dropping 148 meters to a powerhouse with two 9.5GW Francis turbines. It is located 90 km south of Valemount, BC Operating as Valisa Energy Inc., approximately 72 GWh of power annually is sold to BC Hydro.

Akolkolex was built by Canadian Hydro Developers and operational in 1995, it uses two Francis turbines in a 10 MW run-of-river hydroelectric plant discharging into Arrow Lakes, it is located 25 km SE of Revelstoke, B.C. The plant produces approximately 37 GWh of electricity annually.

Pingston Creek has a 12 meter high sheetpile rock fill dam which diverts water to the western shore of Arrow Lakes, it was built by Canadian Hydro Developers and Brascan Power and began operation as Pingston Power Inc. in 2003. A 4 km tunnel achieves a huge drop of 557 meters to three 15 MW Pelton wheels to generate about 200 GWh annually. The project is 53 km south of Revelstoke, BC. 50°33′00″N 117°56′54″W / 50.55°N 117.9484°W / 50.55; -117.9484