October 8, 2018

Future heat storage technology: Interview with Nobel laureate R. Laughlin

  • Heat storage will play a central role in the sustainable energy system of the future.
  • For this reason, DLR intends to intensify its research in this area together with the Karlsruhe Institute of Technology (KIT) and the University of Stuttgart.
  • The partners have signed an agreement to build a research facility to develop highly efficient and cost-effective energy storage.
  • Guest speaker, Nobel Laureate for Physics and Stanford Professor Robert B. Laughlin, explained why he also considers heat storage as one of the key technologies of the future. More about this in the interview.
  • Focus: energy, energy storage, climate change

Energy storage plays a key role in the sustainable energy system of the future, which is based on renewable resources. But until now, location-independent and cost-effective solutions for energy storage systems on a power plant scale have been missing. The German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt; DLR), together with the Karlsruhe Institute of Technology (KIT) and the University of Stuttgart, intends to build a research facility to research and develop technologies for highly efficient and cost-effective energy storage systems. The agreement for the NADINE (National Demonstrator for IseNtropic Energy Storage) project was signed on 8 October 2018 in Stuttgart. At the signing ceremony, 1998 Nobel Laureate in Physics, author and professor at Stanford University Robert B. Laughlin outlined his ideas for a reliable and sustainable energy strategy.

Heat storage plays a central role in this. Laughlin is also the initiator of the Google X energy storage project MALTA, which explores molten salt heat storage. For him, one of the major technical challenges of the 21st century is the safe storage of large amounts of energy over a long period of time and its recall when needed. In the interview, Laughlin describes why he relies on heat storage, the technical and economic challenges he is facing and what he wants from leading energy politicians.

Prof Laughlin, you are a quantum physicist. How come you are now working on heat-based energy storage systems, such as the Google X project Malta?

Laughlin: Well, one answer is that good physicists have many interests, and I am an extremely good physicist.

The more careful answer is that it came about through a book I wrote back in 2011, upon request of several senior members of the American Physical Society (Powering the Future, 2011; Der Letzte macht das Licht aus, 2012). What I discovered during my research for the book was that the energy storage problem was central – together with the associated cost issue. Whilst writing about the history of the Andasol 1, 2 and 3 Spanish solar power plants, which use molten salt to store energy, I was getting more and more depressed about the fact that this concept would not work for storing wind energy. These plants have known, controlled costs and are proliferating in many countries around the world – a sure sign that the economic calculus works. Then it suddenly hit me that a minor modification of the concept would enable it to store wind energy as well. One thing led to another and I have now become a supporter of pumped thermal storage using molten nitrate salt. The concept has recently been published. Note that the time delay between 2011 and 2017 is due to my economic partners, who forbade me from talking about these ideas in public for four years.

Do you think heat storage can develop from a niche application into the limelight of future energy technologies?

Laughlin: Yes. I think this is a ‘global’ solution to the entire problem. The record also shows that I backed up this assessment by placing an economic ‘bet’ with the chief asset I had: my time. It's one thing to make armchair conversations about these issues, quite another to actually act on them.

Are energy systems that are largely based on renewables inextricably linked with the rise of energy storage technology?

Laughlin: Yes. The electricity industry is all about timing. When you flip on a light switch, a signal travels backward along the electricity cables at the speed of light and tells the generator that it must work a little harder. In modern times, these generators are usually powered by natural gas or hydropower. In contrast, generators powered by the wind and sun do not have this ability to respond to demand. They simply deliver power when the wind blows and the sun shines. This terrible ‘dispatchability’ problem forces utility companies to have non-renewable electricity generation capacity standing by as a back-up, ready to be turned on when the wind and sun fail to deliver. Utility companies do not like this, because it forces them to pay twice for the same, very expensive generation capacity. There is much evidence now to suggest that the economic facts of life linked to this ‘non-dispatchability’ issue prevents the wind and sun from supplying more than about 30% of the grid's energy needs. It also commonly happens in many places in the world that the wholesale price of electricity generated from wind becomes negative – meaning that the owner of the wind farm has to PAY the utility company to take its electricity.

Which technological challenges need to be addressed before we are able to realise heat-based energy storage systems on a large scale?

Laughlin: That's the beauty of it. There are no technological challenges. The secret is that there is no secret. Any good turbine engineer responds to a discussion about the details of this technology by saying: "Oh, I can do that!" Energy storage is all about controlling costs, not about leveraging new laboratory discoveries. All of the scientific principles involved were already worked out in the 19th century and have long been in display cases at the Deutsches Museum in Munich. The key thing that has happened since then is the invention of the jet engine and the steady improvement in its performance. One could refer to this problem as ‘rocket science’ – doing something you already know how to do – just with extreme excellence and careful attention to detail. In practice, that means the problem is mainly how to allocate flows of money properly. I view this as the ‘Moon shot’ problem of the 21st century.

When will they become an economically interesting option, and who will profit?

Laughlin: The market issues for storage are complex and not something I can distil into a couple of sentences. In short, I think the technology will have great market power and there will be lots of buyers from the moment it is created. The reason why it does not have market power right now is that there are simply no such machines to buy! They do not exist!

The important market niche for thermal energy storage is presently occupied by ‘pumped hydro’ storage – the pumping of water uphill into reservoirs at night for the purpose of letting the water down again during the day when the energy is needed. Pumped hydro technology is excellent, but it has issues of land use and is also somewhat dangerous. For pumped thermal storage to succeed, its associated costs must be less than that of pumped hydro storage – preferably much lower.

In the United States and Great Britain, pumped hydro storage is much loved by governments, but less so by the electric power industry. The reason is that natural gas ‘peaking plants’ can serve the same delivery needs at lower cost. This calculation is more complicated in countries with poor domestic natural gas supplies, but even there it is difficult to beat natural gas at present world prices.

In matters of money, everything is uncertain until a sales transaction actually takes place and an enterprise makes enough profit from such sales to sustain itself. Before that happens, nobody's opinion about the cost of this technology can be completely trusted – including opinions of Nobel laureates. As I said, I have demonstrated my own confidence by wagering the assets that I had. Other people are free to join or walk away as they see fit.

The usual rule is that the person who profits is the person who takes on the risk. However, in most countries, the energy industry is private. As a practical matter, this means that using public money to develop technologies of this nature is politically problematic. Any such public expenditure would compete with private industry and/or subsidise it. For this reason, I have been working chiefly with potential private sector investors rather than with government. But the entire situation is quite maddening, because governments of major countries have enough power in their little fingers to get this done.

There is also, of course, a national security issue in most countries. The benefit calculus therefore has a national security component.

If you had one wish to ask from leading energy politicians, what would it be?

It would be to "Please watch what I do." Most energy politicians I know are very good people who are doing what they can, but are limited by the realities of politics and economics. Indeed this is arguably also the case with many ordinary citizens. One cannot do anything because the cost is prohibitive and the risk of failure is too great. It is the way of this world that a ‘crazy person’ is often required for lowering the risk barriers for everyone else. In science we like to say that there are three stages of any important new idea:

1. That is crazy.
2. That is not crazy, but it will never work in practice.
3. I thought of it first.


Denise Nüssle

German Aerospace Center (DLR)
Corporate Communications
Pfaffenwaldring 38-40, 70569 Stuttgart
Tel: +49 711 6862-8086

Dorothee Bürkle

German Aerospace Center (DLR)
Media Relations, Energy and Transport Research