What happens after your country runs on 99 percent renewable electricity?

While most of the world still runs on dirty fossil fuels, Costa Rica has generated nearly all of its electricity from renewable sources of energy for nearly a decade. For comparison, the US generates just over 20 percent of its electricity from renewable sources.

Costa Rica made global headlines in 2015 for generating 100 percent of its electricity from renewable energy for 75 days in a row. Today, it consistently gets around 99 percent of its electricity from renewables. Even so, it’s not a perfect system. Climate change poses new risks to the power grid, and Costa Rica has a lot of work left to do to get more solar and wind farms online. 

The Verge spoke with Kenneth Lobo Méndez, director of planning and sustainability in electricity management, and Marco Jiménez Chavez, an engineer who works on generation expansion planning at the state-run electricity utility Instituto Costarricense de Electricidad (ICE). We wanted to know what’s led to the country’s success with renewable energy and what problems it has to troubleshoot now in a warming world.

This interview has been edited for length and clarity, and most of the conversation was interpreted from Spanish to English.

Costa Rica generates around 99 percent of its electricity from renewable sources. How was the country able to accomplish that?

Kenneth Lobo Méndez: The secret of this achievement is mainly planning. 

Identify the capacity of the different energy sources so you can get the big picture about how different resources can work together to get a renewable system. In the winter, like a six-month period from June to December, many of the hydropower plants get surplus flows. That’s when we have low wind, but we have more hydropower. And then in the summer, like from December to May perhaps, we get low hydropower, so the other sources of energy complement that electricity supply — mainly wind power, biomass, and geothermal.

Why does Costa Rica rely so heavily on hydropower, which makes up 73 percent of electricity generation? 

KLB: There are two main reasons why hydropower is so important in the country. The first one is because there’s plenty of hydropower resources. Costa Rica lies in a tropical zone with heavy rainfall. And also we have good topography [and] elevation difference for producing power. 

The other one is that the founders of this utility had the vision. There was a law in 1949 [which established ICE] that states that the country should develop its natural resources for electricity supply. Hydropower was the only source or the only technology that was available at the time.

With any energy project, even with clean energy, there can still be damage. There has been opposition to large hydroelectric dams because they harm river ecosystems and displace people from their homes. How do you think about those risks? 

KLB: Planning needs social and environmental aspects, it’s very important. From the start of the project, we get the communities and all the stakeholders involved in the project. We know that perhaps this will be a little more expensive. However, with this perspective the project will be held with lower risk and we can fulfill our environmental and social requirements.

How is climate change affecting electricity generation?

KLB: That’s a big challenge, how to manage the hydropower resource in the future.

Our own studies have shown that in the short term, we won’t see a significant impact. In the mid term, like in 2030, in the north of the country, there will be a decrease in rainfall. Most of the country’s hydropower capacity is in the north. So, it will be affected. 

In the long term, what we see is an increase in hydropower production — but in the west and south of the country, mainly because rains will get heavier, more intense in that region.

Marco Jiménez Chavez: There’s a hydroelectric plant called Arenal. It’s one of the most important plants in the country, and it’s in the zone where we expect lower precipitation due to climate change. In the south of the country, we will get heavier rainfall. However, we can’t get that rainfall into our system; our plants are not ready to harness that amount of water. 

So how will you prepare for that?

The thing with a renewable energy system is that you also need to diversify so that you won’t be subjected to only the availability of water. You can avoid that risk and share the risk with the other energy sources. Hydropower will still be a great percentage of the country’s energy mix, but new energy sources will be added to the system, for example: solar power and wind. Another important source is geothermal because it’s the only renewable energy source that does not depend on climate variability.

We’ve got a problem because hydropower does not have the same variability as solar wind. So, if we get more solar and more wind, our system will have more variability. So, we need to get back up to that variability. And that’s where batteries are also important.

What effects did El Niño and drought have in 2023?

KLB: There are two effects that El Nino has on the country. The first one is on the demand side because the climate is hotter, so everybody is using the air conditioners and the electricity demand gets higher. 

The other effect is a significant reduction in hydropower not only in Arenal but also in other power plants across the country. We got a 16 percent reduction in inflow to our hydropower reservoirs.

In the rainy season, our reservoirs normally recover. However, they’ve been extremely low in 2023. So, our main concern is that the hot season in 2024 will be a little bit complicated. 

Does drought lead to burning more fossil fuels?

KLB: We need to have insurance for the period when we don’t have green power, we don’t have hydropower. So, we get a small percentage of electricity from diesel thermal power plants, but only as a backup.

It’s suspected that diesel thermal power plant use will increase in 2024 because of low hydropower. Another resource that we can tap is electricity from the regional electricity market with Central American countries. However, because we are in the same region, they also have the same problems. They’ve also got low hydropower; there’s not a lot of resources in the region to share.

In the US, we’re used to many smaller private electric utilities. Does having a national energy company like ICE make it easier to adopt renewable energy?

KLB: In our perspective, yes, it’s an advantage that the planning is held by a government state company. It can make a plan for the country according to the government’s vision. We only sell what we need, and there’s no interference from different stakeholders. It makes the planning process more simple.

Photography by Justine Calma / The Verge

The International Center for Journalists supported this reporting, and Punto y Aparte contributed to the report.