How rapidly will renewable energy be adopted?
This article was originally published in 2015, in the ten years since, not only has its projection been correct -- that renewables would grow much faster than did coal, oil or natural gas, but the actual rate of adoption has even outpaced the "aggressive" adoption curve depicted below. At the time, we took issue with pieces written by Vaclav Smil that suggested, per the four graphs directly below, that, as the latest to arrive, renewable energy's growth would be even slower than coal, oil and gas before it, and would ultimately only reach a fairly small share of generation. We posited that he was ignoring the adoption curves of other new late 1900's and early 2000's technologies and we projected a far more aggressive rate of adoption shown on the second set of adoption curves below. As it turned out, even our "aggressive" projections were too conservative.
How large a role will wind and solar play in our emerging energy landscape? At the heart of that debate lies the question as to whether these renewable technologies (whose fuel is free unlike the extractive fuels costs of both fossils and nuclear power) will expand the way other extractive energy sources have, or the way that other new technologies have.
Consider these three factual statements side by side: 1) wind and solar in 2015 represented less than 5% of the energy the world then consumed; 2) wind and solar in 2015 represented roughly 50% of the new energy capacity being built each year (today that number is up to over 90% of new electricity capacity additions in the U.S. and many global markets); and 3) a growing number of consumers have purchased enough wind and solar to cover 100% of their annual energy consumption. Together, wind and solar surpassed coal in U.S. electricity generation in early 2025.
Our key question in 2015 was: Absent government intervention (or, more recently, even with positive and negative government interventions), which growth curve do you think renewables will follow?
Over the last hundred and fifty years, we have introduced a new form of primary energy (one that represents roughly 75% of our energy mix) roughly every 50 years.
Coal's key adoption period was the 1700s–1900s; its growth was a dominant factor in the Industrial Revolution, especially in England in the mid 1700's. It became the U.S. primary energy source in the late 1800s, peaking around 2005. From an adoption curve perspective, coal took about 200 years to become globally dominant. Today, it is in decline due to emissions, economics, and competition from renewables.
Oil's key adoption period was between the 1850's and the 1970's. First drilled in 1859, its growth scaled with the rise of cars and aviation. By the 1970's it had not only become central in global energy circles, but also in geopolitics. From an adoption curve perspective, oil took about 50-70 years to dominate. In many regards it is still dominant today, but far more so in transport than in powering industry, commerce and homes.
Natural Gas' key adoption period was from the early 1900's through 2000. It originally gained traction in the mid-20th Century and overtook coal by 1958. From an adoption curve perspective, it took gas about 60-80 years to scale. Today, while it is still growing in some regions, it is increasingly challenged by renewables and storage.
Nuclear energy arrived in the mid 1900's and is still coming into its own. It has been slow at replacing the fossil incumbents, with nuclear plant building peaking in the 1970's and 1980's, but then slowing due to cost, safety concerns and regulatory hurdles. It today generates about 20% of U.S. electricity. More recently, small modular reactors have led to a renaissance in nuclear power, driven in part to increasing energy demands from data centers.
In this mix, wind and solar represent the newest kids on the block with what was in 2015, a then still very small market share. In fact, history would suggest that our future is likely to be characterized by a blend of several different energy forms each holding a sub 25% market share. Without a carbon problem, one might well assume a fairly gradual progression for nuclear and renewables, tied directly to their ability to be the lowest cost provider and gain market share (which could look much like the slower growth curve for renewables in the chart above) and lead to a diversified market. That is largely what we projected in 2015, taking a conservative approach aligned with the thinking of Vaclav Smil (whose view is that these energy transitions take many decades) and comparing it to a more agggressive approach that took into account how rapidly other new technologies have become dominant in the last 50 years.
Interestingly, ten years later, even our most aggressive projections turned out to be far to conservative. It has basically taken wind and solar 20 years to scale (1/3rd to 1/5th the time it took for conventional energy sources). Renewables have recently seen annual growth rates of 20-30%, with battery storage as much as doubling year-to-year. Renewables now account for over 90% of new electricity capacity additions in the U.S. and many global markets. Battery storage capacity surged to 42 GW globally in 2023, with projections of 1,200 GW by 2030. Significant drivers of these growth rates were that the cost of solar came down 90% since 2010; with cost of batteries down 99% since 1990.