The Central American country of Costa Rica has successfully transitioned to a grid powered by nearly 100% renewable resources, according to the Costa Rican Electricity Institute (ICE). The primary sources of Costa Rica's power are  hydro, goethermal, wind, biomass, and solar. Fossil fuels function as backup energy generation source, accounting for less than 2% of generation.

In 2016, Costa Rica relied on renewable sources for 98.12% of its electricity, an impressive achievement and consistent with the 2015 total of 98.99%. Costa Rica further reported that in 2016 it went 250 days using only renewable power sources. With the ability to maintain high levels of renewable electricity for two years, Costa Rica's electricity sector is a world leader in clean energy.

It should be noted, however, that Costa Rica's Reventazon Hydroelectric Project, the largest hydroelectric dam in Central America, has generated concerns due to its environmental impacts on river ecosystems and migrating wildlife, including jaguars. Accordingly, it is to be hoped that Costa Rica continues to invest in non-hydro sources of clean energy, such as wind and solar, which also offer the benefit of operating during the dry season, when hydroelectric production is less reliable.

Brazil postponed an auction to sell rights to build a controversial 8,000-MW hydroelectric dam on the Sao Luiz do Tapajos River in the lower Amazon Basin, Reuters reports. The $13 billion project had outraged environmentalists and indigenous rights groups. "The dam on Sao Luiz do Tapajos that was planned for auction this year will be pushed back until next year," Altino Ventura, the Energy Ministry's secretary for development, told reporters in Sao Paulo. The Energy Ministry said that the consortium of companies planning the project had not fully addressed the concerns of nearby indigenous communities. Recently auctioned mega-dams in the Brazilian Amazon have fallen far behind schedule due to delays in environmental approval, labor protests and occupations of the dams' sites by indigenous groups.

In a detailed study of 245 dams in 65 countries, researchers with the University of Oxford found that cost overruns averaged 96% and schedule slippage averaged 44%. The study found overwhelming evidence that energy planners systematically underestimate the actual costs and implementation schedules of large hydropower dams. The larger the dam, the longer the implementation schedule and the higher the cost overrun. As a result, even before accounting for negative impacts on human society and environment, and without including the effects of inflation and debt servicing, the actual construction costs of large dams are too high to yield a positive return; including these items, costs and cost overruns are much higher. Since large dams take inordinately long periods of time to build, they are ineffective in resolving urgent energy crisis. Applying this forecasting analysis to large dam projects in the planning and construction stages, such as Brazil's Belo Monte, the authors warn that such projects are likely to face large cost and schedule overruns that seriously undermine their economic viability. The study was published in the March 2014 issue of Energy Policy.