Is investment in energy storage worth the effort? Didn’t we find out last week that our industry is going nowhere because of the fundamental constraint of its energy return on investment (EROI)? Perhaps we had better take another look, just to be on the safe side.
First off: let’s not panic. While EROI studies point to a possibly critical problem in relying too heavily on energy storage for renewable power generation, the effects, if real, are presumably only likely to kick in at relatively high levels of penetration.
We are a long way off that yet. Meanwhile, there is the fact that the science around EROI, while apparently robust, is still relatively immature and clearly evolving, as indeed are the technologies and manufacturing processes being described.
This potentially implies uncertainty around current EROI assertions and predictions.
Certainly, most sector professionals consulted by Energy Storage Report had few qualms about dismissing the research: “BS” and “hokum” were among the terms used by knowledgeable industry insiders.
Some observers question the impartiality of parts of the research to date.
In particular, it is noteworthy that the authors of the important Weißbach paper, which gives nuclear power a clear EROI advantage over other energy sources, are all members of the German Institute for Solid-State Nuclear Physics.
Biases in data
Among other activities, the Institute is promoting a new nuclear reactor model. In theory, of course, any biases in the authors’ data and analysis will have been picked up during the paper’s peer-review process prior to publication.
Nevertheless, even if biases were not consciously introduced there is clearly scope for errors arising from a lack of knowledge of generation technologies outside of nuclear.
Weißbach admits to Energy Storage Report that all technologies should experience improvements over time and “the errors of our data could be in the order of 10%.”
But while Weißbach et al calculate an EROI of 3.9 for solar PV, Josefin Berg, a solar power analyst with IHS, reports: “Colleagues here say that it takes one year of a module’s electricity production to pay back the electricity spent on manufacturing.”
She cautions: “I don’t have any hard evidence. And like everything, it depends on how you look at it.”
The net result
He also says: “Of course, storage doesn’t produce energy at all. But neither do substations or power lines. Storage is just part of the grid. You need to add it all together and then see if the net result is positive, which it is.
“There is just so much renewable energy on this planet that as long as their net energy is just a little positive we can just ‘overbuild’ to cover all of our needs.”
Giw Zanganeh, head of Energy Storage Technologies at Airlight Energy, contends that the comparison between emerging renewable energy sources and established generation industries such as gas and nuclear is not really fair.
Renewable power generation and storage “might be energy intensive right now,” he says.
“But once you have had an initial investment, just like there has been for nuclear and fossil, the energy that you need to create all these facilities per kilowatt-hour will go down. It’s like comparing a toddler with an adult.”
Another point Zanganeh raises is that even a nuclear-only power supply would in practice require some form of storage since reactors cannot easily be ramped up or down to meet demand.
Pumped hydro stores
For instance, he says, Switzerland currently benefits from cheap night-time nuclear offloads from France to create pumped hydro stores that can later be sold to Italy or Austria.
Zanganeh also takes issue with studies selecting renewable energy installations in less-than-optimal locations, as is the case with PV in Germany.
While this may be representative of current market dynamics, it is far from clear how improved localisation will affect renewable energy cost and EROI in future.
This week, for example, news emerged of a proposal to ship concentrated solar power with thermal energy storage from Tunisia to the UK.
While the EROI for this project is unknown, it will be “cheaper than nuclear, applying a lot of the same terms and conditions,” says Daniel Rich, chief operating officer at Nur Energie, the developer.
Where does all this leave us? For a start, while it seems likely the gloomy EROI figures emerging from current studies could improve significantly over time, it still makes sense to treat this work seriously.
In particular, the limited lifetime and cycling characteristics of today’s battery technologies clearly raise doubts over their large-scale viability not just from an EROI perspective but also commercially.
Given their cost (in financial terms), commentators such as former Axion Power director John Petersen have questioned whether batteries should be used for anything other than high-value power applications such as frequency regulation.
In contrast, energy storage systems with favourable EROIs, such as pumped hydro, look likely to offer better financial returns for grid-scale ‘heavy lifting’ duties such as load shifting (assuming the grid model survives in its present form into the future, of course).
And Zanganeh believes the compressed air energy storage systems that his company, the Airlight subsidiary Alacaes, is working on could even outgun pumped hydro on EROI and economics.
What this hints at, unsurprisingly, is the need for a balanced approach to low-carbon power generation.
“You will be looking at a portfolio solution,” believes Richard Heap, executive analyst at the Energy Research Partnership in the UK, “so some carbon measures may be a bit more challenging energy-wise.”
A portfolio of measures
He continues: “I also think that energy storage is just part of a portfolio of measures to manage variability.
All these options would need further analysis, Heap says. And that is arguably the main value of EROI studies at the moment.
Given the vast array of new renewable and storage technologies currently under development, it is only right and proper that all future energy routes are examined exhaustively, and not just from a strictly commercial perspective.
So who knows whether there may be unforeseen consequences in our current attempts to build a carbon-free future?
Says Zanganeh: “In markets like energy storage, where there is a lot of hype, you need to have the kind of inputs that make everybody think. It’s good to create this kind of controversy, to make people think about it a bit more.”
Written by Jason Deign
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