Portugal demonstrated its commitment to the environment over the weekend by shutting down the country's last coal-fired power plant, thereby cutting its use of the pollutant for electricity production. With the action, it will become the fourth country to stop using coal for electricity production. Belgium, Austria and Sweden are the other three European countries that have already abandoned the pollutant to generate energy.

The environmental group Zero said in a statement that the Pego plant, in central Portugal, is the country's second largest emitter of carbon dioxide, adding that "freeing ourselves from the largest source of greenhouse gases was an important day for Portugal.

The move comes nine years before Portugal sets a goal of using fossil fuels by 2030.

Portugal still relies heavily on imported fossil fuels to meet global energy needs, but is already on an advanced path as about 70% of its electricity comes from renewable sources.

However, there is concern that the private Tejo Energia group's Pego plant will now be converted to burn wood pellets.

According to Europe Beyond Coal's campaign director Kathrin Gutmann, another point to care about, so as not to reduce Portugal's efforts to nothing, is the possibility of utilities replacing coal with unsustainable fossil gas or biomass, which is now the "big challenge."

"Getting rid of coal only to switch to the next worst fuel is clearly not an answer," said Zero's president Francisco Ferreira. "Instead, the focus should be on rapidly increasing our renewable energy capacity in wind and solar power."

The EU is evaluating the rules on whether energy obtained from burning wood should be classified as renewable or not.