Things I was wrong about

The delay in my posting is sufficient enough that there isn’t even much to say about it. However, this period of time has further established certain trends which to observers more savvy than I were obvious years ago, and an update to the perspectives in my previous posts is sorely needed.

We who observe and comment on the Energy Transition are no less subject to hubris than others, and as I’ve noted on here forecasting the exact details of future trends and scenarios is inherently dicey. But since previous posts made statements about technologies which no longer make sense, it’s time to update a few things, and along the way issue a few overdue mea culpa.

1) Batteries are the future

In previous posts, I emphasized other forms of energy storage such as pumped hydro and CSP with thermal storage, due to the high cost of batteries. Battery technology does not have as steep of a price decline as solar PV, and current levels of deployment are low. I will be the first to admit that the reason that I have downplayed batteries in the past is incumbency bias; in other words it is safer to talk about costs today than future projections.

However, it is clear that lithium-ion batteries are showing a similar relationship of falling costs and increased deployment to solar PV, and this makes it only a matter of time before costs are no longer a limiting factor.

Batteries address many of the short-to-mid-term problems of integrating high levels of variable renewable energy, and their ability to be used for multiple different applications and business cases is key. As has been noted in Bloomberg, lithium-ion batteries will not provide seasonal energy storage, however in the near term, and possibly over the long-term, they don’t need to.

This is for multiple reasons. First, while levels of renewables are reaching the points in some geographies where they are saturating instantaneous demand, even where there is not sufficient capacity of flexible hydro or imports there usually is still ample capacity of flexible fossil fuel generation, and given existing pipeline capacity and levels of fuel storage this can be utilized on a seasonal basis.

Once we get close to the goal of 100% renewable energy, things may look different, but as I’ve argued before, 80% is the more important goalpost.

Additionally, if the right mix of wind and solar is deployed, seasonal storage is less important. Even in Germany, which has very high seasonal variation of PV output, in 2013 the highest and lowest months for combined wind and solar output were December and February due to fluctuations in wind output (p.13), and the biggest change was not from summer to winter.

Following this logic, some resources are less suited to certain geographies. In far northern nations, such as Scandinavia, solar is ill-suited to meet electricity demand, and deployment of renewable energy should focus on wind and biomass to meet the higher wintertime electricity demand. For the rest of the world where the large majority of people live and electricity is used, solar more suitable.

Another reason that batteries are the future is the rise of electric vehicles, which I will get to later.

2) CSP is (mostly) dead in the water

In the past many of my arguments about the feasibility of high levels of renewable energy featured concentrating solar power (CSP) with thermal energy storage (TES) as an important component of high-renewable energy scenarios. This was in part because many of the scenarios created by researchers also featured CSP with TES.

Batteries and solar PV share several traits. Chiefly, they can be deployed quickly at a variety of scales most anywhere in the world and are following exponential cost and deployment patterns. CSP does not share these virtues. In order to be practical CSP must be deployed at a large scale in more limited geographies. More importantly, the relatively hard, conventional, 20th century infrastructure of plumbing and turbines on which CSP technology depends means that cost declines do not follow a pattern similar to semiconductors or solar PV.

Over the past decade, CSP in the United States fell victim to a combination of falling costs for PV and conservationists skilled in environmental law. In Europe it fell prey to the Spanish government’s fickle policies. And now, it is only being deployed in places like China, and at a smaller scale than previously.

It has become increasingly obvious that CSP is basically dead in the water, because anything CSP can do can be done with PV and batteries, in a more flexible way. It took me a while to accept this, but there it is.

3) electric vehicles are the future

I’ve been resistant to the rise of electric vehicles because I believed, and still do, that mass transit is an inherently better solution for cities. However, as anyone following PV technology should know, the theoretically “best” technologies and systems, such as those with the highest efficiencies, aren’t the ones that get deployed. Instead, it is the technologies which are able to scale easily and reduce costs.

Electric vehicles are still deployed at depressingly small scales, but they are growing quickly. And as a veteran of fights over public transit in the Boston area, at this point I have more confidence in the ability of EV makers to bring down costs (led by Tesla’s Model 3), than I am in the kind of near-term political change that would enable the massive build-out of public transit that we need to address Climate Change.

Too many social and economic trends and indicators point in the wrong direction for us to fix the mass transit problem anytime soon. Instead we have Elon Musk and Panasonic building a gigafactory. As Climate Change is an emergency, it is important to get behind not only the best solutions, but the ones most likely to get implemented on a meaningful scale.

One factor behind my faith in EVs is the synergy between EVs and battery storage to balance fluctuations in renewable energy. There are two aspects here: As we build more batteries for EVs we bring down costs not only for EVs but also grid battery storage. Second, there is the ability of parked EVs to be used as an asset to the grid, which is on the list of resources being investigated as policymakers in several states look into distributed energy resources as an increasingly important component of energy systems.


We will see what other compelling technology arises, and it will take a little while for academics and their models to catch up, but for most of the world I am betting on EVs and battery storage along with solar and wind as main components of the Energy Transition – and not CSP.



  1. Thank you for this filter. The media can describe potential like it is possible tomorrow. In this energy transition it is important to check in with the stats every so often!

  2. Tim Moore · · Reply

    These were positions you learned as the future came more into focus. I too found these positions strengthened to the point of certainty over the past 5 years – first point 3, then 2 and then 1. I’m going through many of your articles. Thank you for your hard work. Math based writing without too much math is uncommon.

  3. […] been produced by academics, it did not include technologies like concentrating solar power that are failing in the market, or insist on using today’s prices for technologies that are experiencing ongoing cost […]

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