Composition, not consumption - why we can’t learn from Costa Rica

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In 2016 Costa Rica ran on 100% renewables for 76 straight days.  Science Alert claims this is possible due to the small size of Costa Rica’s electricity demand. This is only partly true.

The table below shows the composition of Costa Rica’s electricity supply over this period.  The large penetration of hydro is what allowed Costa Rica to operate with 100% renewables.

Table 1 - Costa Rica’s electricity supply composition (June - August 2016)  
Hydro 80.27 %
Geothermal 12.62 %
Wind 7.1 %
Solar 0.01 %

Hydro power allows high renewables penetrations because hydro comes with energy storage for free. The storage allows hydro to be dispatched to support the grid, independent of the weather.

This allows hydro power to act in the same role that fossil fuels do in other countries.  Dispatchable generation is crucial for electricity as supply must always match demand.

A larger electricity demand with the same penetration of hydro would likely find it as easy to run fossil fuel free as Costa Rica.  The same sized demand with hydro replaced with wind or solar would need fossil fuels, demand flexibility or storage to keep the grid stable.

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