Despite covering only a fraction of the lands surface, Costa Rica is doing more than its fair share in trying to tackle climate change. The jewel of a nation in Central America produced almost all of its electricity from renewable sources in 2016, continuing its push to become one of the "greenest" nations on Earth.
By using a mixture of hydroelectricity, solar, wind, biomass, and hydrothermal power, the nation managed to generate carbon-free electricity for 250 days last year, including an impressive 110-day stretch before they needed to turn to fossil fuel power plants for a fraction of time. This meant that in total roughly 98.1 percent of their electricity generation came from renewables for the entire year.
While the news is undoubtedly brilliant, it does hide another aspect. The vast majority of the electricity is produced via hydroelectric dams. For a start, this is unachievable for many other countries, meaning that Costa Rica’s success cannot really be used as a model for others. But more importantly, there are serious questions about exactly how “green” hydropower is.
In order to generate hydroelectricity, it is often necessary to produce vast reservoirs of water behind the dam. These in turn produce massive amounts of greenhouse gasses, mainly in the form of methane. While the lifespan of methane may not be as long as that of the more abundant carbon dioxide, it is a lot more efficient at trapping heat, with some estimates putting it at 28 to 36 times more potent.
A previous study has found that all of the world’s hydroelectric dams produce the equivalent of 907 million tonnes (1 billion tons) of carbon dioxide per year. This is not an insignificant amount. In fact, it is more than the amount of greenhouse gasses produced by Saudi Arabia, Germany, or Canada. Not only that, but they have been found to drastically reduce biodiversity.
The main reason is that to produce the reservoirs that power the turbines, large tracts of land must be flooded. As the plant material that is now at the bottom of the massive lakes rot, the bacteria responsible releases methane. As the rivers that flow into the reservoirs continue to replenish the levels of phosphorous and nitrogen, the bacteria continues to pump out greenhouse gases.
Not only that, but while 98 percent of Costa Rica’s electricity may have come from (dubiously) “green” sources, this only accounts for a small slice of their total energy consumption. Over 70 percent of the country’s energy consumption is actually oil, as it is used to heat homes and power cars and other transport.
While this is a fantastic move in the right direction, perhaps a little more caution needs to be taken.