Costa Rica has achieved 150 days of electricity production entirely through renewable energy sources this year.

The Central American country was powered on carbon-free electricity for 76 days straight from June 17, according to the Costa Rica Electricity Institute (ICE).

In August, just over 80 per cent of their electricity came from hydro sources, while geothermal power contributed nearly 13 per cent of electrical power.

"According to our projections, we will close 2016 with only 2 per cent of thermal production, which will give us a key to fulfill the commitment rate stability support," ICE chief executive Carlos Manuel Obregon said.

The tropical nation is aiming for carbon neutrality by 2021 and its size, available natural resources and electricity consumption all help achieve this goal.

Costa Rica's heavy tropical rainfalls and volcanoes provide a big source of energy, helping power the country's four hydroelectric plants as well as their geothermic energy production.

The country is also only 51,100 square kilometres in size — smaller than Tasmania, which is 68,401 square kilometres.

And its lack of major energy-intensive industry and relatively small population of 4.9 million people means the country consumes less energy overall than bigger countries.

Could a bigger country also have carbon-free success? Possibly, but it would require reliable renewable resources, better energy storage and tailored electricity needs, Hanley Sustainability Institute research director Robert Brecha told Mic.

In Australia last year, 14.6 per cent of electricity was renewable — up from 13.5 per cent the year before, according to the Clean Energy Council.