The Renewable Energy Revolution

Transforming the world’s energy supply will take decades. It is a very tall order. But it’s starting. The price of renewables – and energy storage – continues to plunge, putting them on a path to being cheaper than any other form of energy within the coming decade. And they continue to grow exponentially – albeit it from a low baseline – spreading out into the market.


Wind, more established than solar, has seen it’s price decline by a factor of more than 20 over the last 30 years. The average wind power purchase agreement signed in 2013 was priced at 2.5 cents per kwh.

In many parts of the US and the world, wind power is now the cheapest source of new power.

In scale, the amount of wind power around the world has grown by an astounding 10x (1000%) over the last 11 years. Incredible.


Solar makes wind look slow and sedate. Solar PV module prices have dropped an astounding 150x since 1977.

Of course, module costs are not the whole cost.  Even so, fully system cost continues on an impressive decline of its own, having fallen by a factor of three in just the last 10 years – a more rapid decline than any other energy source.

And the solar market, in response to plunging prices and market and regulatory incentives, has exploded, surging by an incredible 100 times (10,000%) in just 13 years.  A few years ago the total solar installed base was just 1/10th that of the wind power installed base. Now it is almost half the size of the wind installed base, and poised to overtake it in the next 4-5 years.


The growth of solar and wind has been staggering. It has also consistently outpaced the projections of the International Energy Agency, the US Department of Energy, and virtually all other traditional energy forecasters. The graph below shows how the IEA, in particular, has had to raise their forecasts of future solar and wind growth every year to keep up with actual growth rates.

And in fact, the IEA predicts that new installations of solar and wind will stay flat or decline over time, despite all evidence to the contrary.

Here’s a fuller analysis of IEA’s continual under-estimation of renewables.  Bear this trend in under-estimating new technologies in mind when reading forecasts from traditional energy forecasters.


Finally, while the battery storage technology for the grid is, IMHO, unlikely to be lithium-ion, and is more likely to be flow batteries, it’s instructive to look at the price history of lithium-ion batteries to see what’s possible.

Between 1990 and 2005, the price per unit of energy stored in lithium-ion batteries dropped by a factor of 10, and the amount of energy that could be stored per unit weight nearly tripled.

That’s instructive, as flow batteries appear to be nearly at the price to make them viable for grid storage. If they have similar price trajectories as they scale, renewables will see one of their most formidable obstacles to adoption removed.

We shouldn’t trivialize the challenges ahead. It took decades, if not a century, to build the modern energy system. We still lack solutions for the nearly 1 billion internal combustion vehicles on the road, for the manufacture of steel and concrete, for growing meat without methane release, and for numerous other issues. This transition will be long. But the trends in the core technologies for electricity are extremely promising.

There’s more about the exponential pace of renewables in my book on innovating to beat climate change and resource scarcity and continue economic growth: The Infinite Resource: The Power of Ideas on a Finite Planet.


Solar Power Prices Dropping Faster Than Ever

In 2011, I wrote a piece for Scientific American on the exponential price decline in solar power.

I haven't had a chance to fully update that piece, but two quick notes.   First, the price decline in solar cost per watt has, if anything, accelerated since then.  

The above is on a log scale. The Y-axis is price per watt of solar modules.  And you can see that since 2010, prices have plunged.  Over the last 30 years, in total, solar module prices have dropped by a stunning 95%.  You can now buy literally 20x as much wattage of solar power for a dollar as you could when Ronald Reagan started his presidency.  And the trend shows every sign of continuing.

Second, since many have asked about storage costs, I'd note that there is a long term exponential decline in the cost of energy storage as well.  Energy storage is still far too expensive to be used to store substantial amounts of wind or solar energy, but the price decline, if anything, is steeper than the price decline in solar power itself.

Here's the original piece on the exponential decline in the price of solar power.

I write much more about solar, wind, energy storage, and why the pace of innovation in them is critical – and hopeful – for both fighting climate change and for long term economic growth in the book I originally did this research for, The Infinite Resouce: The Power of Ideas on a Finite Planet 

Energy Storage Gets Exponentially Cheaper Too

At MIT Technology Review today was an article on Sun Catalytix’s new flow battery intended for grid-scale storage, which Sun Catalytix believes will drop grid-scale storage prices in half.  As the article notes, several other storage technology companies are also working on driving down the cost of energy storage:

Sun Catalytix is also competing with companies making compressed-air storage machines and batteries with their own novel chemistries, such as a zinc-air battery from Eos Energy Storage and a liquid-metal battery from Ambri. (See “Cheap Batteries for Backup Renewable Energy” and “Ambri’s Better Battery.”)

Which brought to mind a fact that many still don’t realize.  There is a fairly well established exponential price reduction in the cost of energy storage.  This is not quite as well established as the exponential decline in solar power price per watt but it has a more than 20 year history.

As exhibit 1, here’s the trend of lithium ion batteries, on a log scale, between 1991 and 2005.  I’ve inverted the scale here. Instead of showing cost per unit of storage, I’m showing how much energy you can store for $100 worth of batteries.  And again, this is a logarithmic scale – so a straight line means an exponential rate of change.  And over this 15 year period, the amount of energy you could store for $100 went up by a factor of 11. 

The source of that data is a 2009 Duke study you can find here.


Here’s an alternate version of the above graphic that adds energy density, too.  (Energy density is the amount of energy that can be stored per unit mass or volume – in this case, mass.)  The scale here is still logarithmic, but the downward arrow in price indicates prices going down.


Nor do we have any reason to believe the pace of battery price innovation has slowed since then.

For instance, Michael Liebrich at Bloomberg New Energy Finance reports that electric vehicle battery prices fell 40% between 2010 and early 2013.  And Bloomberg NEF sees an exponential experience curve for lithium-ion batteries of the same sort that exists for solar photovoltaic.  What does that mean?  The experience curve is a sort of generalization of a trend like Moore’s Law.  It’s the general observation that as an industry scales and builds more of something, prices drop.  And in batteries, as in solar, there is one.

A back-of-envelope says we need to bring the cost of energy storage down by another factor of 10 in order to make grid-scale storage cheap enough to displace most fossil use for electricity.  On current trend, it looks like we’ll be there in the next 15-20 years.


Arguably, with flow batteries like Sun Catalytix, this may be much faster. Grid storage is likely to diverge from mobile and transportation batteries. Lithium-ion batteries are dense and compact. Flow batteries are bulky and heavy. You wouldn’t want them for your car or your mobile device, but they hold the promise of being even cheaper. If they fulfill that promise, we may achieve grid-viable batteries far sooner than the 15-20 year timeframe.

Ultimately, there’s more than enough clean energy to power the world with zero carbon emissions. And it sure looks like we’ll be able to store it.

I talk much more about renewables, energy storage, and how to accelerate progress in them in my book on innovating to beat climate change and other resource and environmental challenges: The Infinite Resouce: The Power of Ideas on a Finite Planet