A four-year drought, the worst since records began, has had a dramatic effect on California’s power system and specifically on its portfolio of major hydropower projects. Indeed, such is the scale of the drought that a lack of water is preventing hydropower plants from running at anything like full capacity. The effective result of the drought has been to roughly half the hydropower capacity available within the state over a period of a few years.
A new study by the Pacific Institute NGO recently concluded that there is evidence of growing adverse impacts for communities, ecosystems, and the economy include on all water users, including farmers, industry, cities, and natural ecosystems. The Pacific Institute analysis finds that during the three years ending in October 2014, the “cost” to California ratepayers of reduced hydroelectricity production and the use of additional natural gas was approximately US$1.4 billion while additional combustion of fossil fuels for electric generation caused an 8% increase in carbon dioxide emissions from California power plants. That the drought has not yet ended suggests these costs will rise given that electricity generated at the hundreds of major hydropower stations in California is relatively inexpensive compared to almost every other form of electricity generation and is low emissions too.
And it’s not just in the south western US that the impacts of drought on hydroelectric power generation may be felt.
Recently Brazil reported that hydroelectric capacity for its most populous city of Sao Paulo was at near zero following a prolonged drought that is apparently the worst since records began in the 1930s.
According to the federal government, hydroelectric power facilities in the country’s south eastern region that supply power to close to 20 million people in the metropolitan region of Sao Paulo (MRSP) are being ‘deactivated’ as a result of the drought that has reservoir levels fall to record lows at a number of hydropower projects – this is in a country which typically generates some 70% of its power from hydro.
Brazil too can expect emissions of carbon dioxide and other products of combustion to ramp up as fossil fuel use rises to meet the shortfall presented by a lack of hydropower.
And, although the Pacific Institute stops short of citing anthropogenic global warming as a factor in the changing outcomes for hydropower assets in California it is nonetheless evident that a changing climate can and does have an impact on catchment hydrology and that impact may be negative.
With hydropower central as a key enabler of other types of variable output renewable sources, such as wind and solar, this presents a number of additional challenges in the development and use of hydro resources, particularly over the century and more time frames that such assets are in operation for.
No-one quite knows the climate scenario a century from now but it is clear that hydropower has a major role to play in delivering clean and sustainable energy to the growing global population. It is equally clear that if hydropower is to achieve that goal then the impact of changing water flows must be considered extremely carefully and far into the future.