India still plans to double coal output by 2020 and rely on the resource for decades afterwards, a senior official said on Monday, days after rich and poor countries agreed in Paris to curb carbon emissions that cause global warming.

India, the world’s third-largest carbon emitter, is dependent on coal for about two-thirds of its energy needs and has pledged to mine more of the fuel to power its resource-hungry economy while also promising to increase clean energy generation.

“The environment is non-negotiable and we are extremely careful about it,” Anil Swarup, the top bureaucrat in the coal ministry, told Reuters. “(But) our dependence on coal will continue. There are no other alternatives available.”

While India has plans to add 30 times more solar-powered generation capacity by 2022, there were limitations to clean energy and coal would remain the most efficient energy source for decades, he said.

Minister for power, coal and renewable energy, Piyush Goyal, said India’s contribution to global greenhouse gases emissions was just 2.5% with 17% of the world’s population, while developed countries contributed a fifth of emissions with just 5% of the world’s population.

While contributing to growth of renewable energy, energy conservation & efficiency, we'll make sure our development process not get hampered — Piyush Goyal (@PiyushGoyal) December 14, 2015

Even though many international lenders are turning their backs on financing new coal projects in favour of gas and renewable energy, India should have few difficulties in financing dozens more new mines.

State-owned producer Coal India, for example, has enough internal cash resources to drive more production, Swarup said.

At the global climate summit in Paris, nations forged a landmark agreement on Saturday to set the course for an historic transformation of the world’s fossil fuel-driven economy within decades, including eliminating net man-made greenhouse gas emissions.

Environmentalists worry that despite India’s commitment to renewable energy, its rising use of coal at a time when many Western nations are rejecting the dirty fossil fuel will hamper the world’s fight against climate change.

India, which is targeting to more than double coal output to 1.5bn tonnes this decade, says coal provides the cheapest energy for rapid industrialisation that would lift millions out of poverty.