This trend - in which cheaper renewables are outpaced by even cheaper fossil fuels - portends drastic climate problems. (Representational Image)
Technology-driven cost reductions in fossil fuels will lead us to continue using all the oil, gas and coal, instead of choosing renewable energy, unless governments pass new taxes on carbon emissions, according to a new study.
"If we don't adopt new policies, we're not going to be leaving fossil fuels in the ground," said Christopher Knittel, from the Massachusetts Institute of Technology (MIT).
While renewable energy has made promising gains in just the last few years - the cost of solar dropped by about two-thirds from 2009 to 2014 - new drilling and extraction techniques have made fossil fuels cheaper and markedly increased the amount of oil and gas we can tap into.
In the US alone, oil reserves have expanded 59 per cent between 2000 and 2014, and natural gas reserves have expanded 94 per cent in the same time.
This trend - in which cheaper renewables are outpaced by even cheaper fossil fuels - portends drastic climate problems, since fossil fuel use has helped produce record warm temperatures worldwide.
The study concludes that burning all available fossil fuels would raise global average temperatures 10 to 15 degrees Fahrenheit by the year 2100; burning oil shale and methane hydrates, two more potential sources of copious fossil fuels, would add another 1.5 to 6.2 degrees Fahrenheit to that.
"Such scenarios imply difficult-to-imagine change in the planet and dramatic threats to human well-being in many parts of the world," researchers said.
They examined costs over a time frame of five to 10 years, stating that further forecasts would be quite speculative, although the trend of cheaper fossil fuels could continue.
Some energy analysts once thought the limited amount of oil reserves would make the price of oil unfeasibly high at some point, that dynamic seems less likely now.
As a result of improved oil and gas extraction techniques, we have consistently had about 50 years' worth of accessible oil and natural gas reserves in the ground over the last 30 years, the researchers said.
Renewable energy has seen decline in its prices within the last decade. But looking at the "levelised" cost of energy (which accounts for its long-term production and costs), solar is still about twice as expensive as natural gas.
The development of better battery technology, for storing electricity, is vital for increased use of renewables in both electricity and transportation, where electric vehicles can be plugged into the grid for charging.
New solar techniques - such as thin-film layers that integrate solar arrays into windows - may lead to even steeper reductions in the price of renewables, especially as they could help reduce installation costs, a significant part of the solar price tag.
Still, the immediate problem of accumulating carbon emissions means some form of carbon tax is necessary, especially given what we now know about declining fossil fuel costs, Mr Knittel said.
The study was published in the Journal of Economic Perspectives.