Hydroelectricity is one of the oldest forms of cleaner sources of energy. The approach uses the kinetic energy of water to turn turbines and generate electricity and has been adopted across countries. Recent studies have, however, shown that the water stored for hydroelectric power plants is a significant source of methane, and startups are looking to tap into it as an alternative to fossil fuels.

Like carbon dioxide, methane is also a greenhouse gas known to trap heat in the atmosphere, leading to global warming. However, it is a much more potent greenhouse gas since it can trap 80 times more heat than CO2 and, therefore, needs to be tackled on priority. 

The energy sector (oil and gas) is responsible for 40% of methane emissions. The burping and ruminating animals reared as livestock make dairy the second most polluting sector, contributing 32% of global methane emissions. Human constructs like sewage treatment plants and rice fields are also sources of methane.

But now, it has emerged that even hydroelectric power plants emit methane. Estimates suggest that as much as three billion tonnes of methane comes from water used in these clean energy power plants.

How is methane released from water?

Carbon-rich water bodies where microbes decompose organic matter without oxygen also produce methane. The methane, however, stays dissolved in the water and is not released into the atmosphere. This is similar to the carbon dioxide dissolved in a capped fizzy soft drink bottle. It isn’t visible until the pressure is released.

However, suppose the soft drink bottle is shaken before releasing the cap. In that case, the gas comes out faster as a stronger effervescence when the pressure is released. A similar process occurs when water stored for a long period is sent through the turbines of a hydroelectric power plant. The agitation of the water releases methane from the water, making these clean energy structures sources of greenhouse gases. 

Startups looking to tap into this methane

Methane is a component of natural gas and is used as a fuel in many places globally. Startups such as Blue Methane are now looking for ways to trap methane from hydroelectric power and sewage treatment plants, since they can serve as a non-fossil energy source.

Wastewater companies are already generating methane as a fuel for processing waste. However, the methane dissolved in the water isn’t extracted. London-based Blue Methane has patent-pending technology that can be installed on these facilities without disturbing existing infrastructure.

Their tech is even more interesting because it relies on gravity to do the significant chunk of the work. Unlike most tech that pumps water to be processed, Blue Methane intends to maximise methane output with minimal energy input.

Currently, BlueMethane is focused on estimating how much methane is available to tap into and is conducting measurements at 20 reservoirs. In the future, hydroelectric power plants could also harvest methane from their facilities and generate additional revenues. Methane can be used as fuel in vehicles, to generate electricity, or even as a feedstock for generating hydrogen, a clean fuel source. 

The technology could help developing countries like Brazil, that have invested in hydroelectric power plants, set foot in the future. With increasing urbanisation, the wastewater systems built in the region could double up as fuel producers, too.

The report contains information that first appeared on the BBC.