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Looking Toward Long Duration Storage
OP: I assume that in your discussion of CSP with storage, and demand side technology, you’re talking about what is needed now to take us up to 20% intermittent renewables in the grid. Jumping up to 20 to 40%, we’re probably looking out 10 to 20 years in the future. What are you seeing in this longer time frame?
SG: Yes, what I’ve spoken about so far is looking at 6 to 12 hour storage, and making the grid more robust. These are all things that have to happen today as we’re moving in a direction of having higher renewables.
Now, regarding storage, this is where I think things get interesting. Because for storage right now, what you’re seeing is a proliferation of lithium ion technology. That’s happening because lithium ion is obviously the choice for battery storage in vehicles. The automotive sector is pulling forward a lot of the battery innovations in the lithium ion space.
But lithium ion batteries, to be quite honest, are probably going to be good for 4 to 6 hours of grid storage and up to a couple hundred megawatts in scale. When you get beyond that, the challenges of lithium ion scalability become apparent. If you think about this, with lithium ion batteries, we have battery cells arranged into battery packs that are simply multiplied in number to achieve more storage capacity. So it’s almost like a linear progression in cost, because you’re not generating any more electricity from batteries. Rather, you’re just storing it for later use. When you want to shift the use of electricity in time, you’re adding cost to achieve the flexibility. So at some point it really doesn’t make a lot of sense to go with lithium ion if you’re talking about long-term storage that needs to have some very significant economies of scale to be economical.
Moreover, taking a look at what’s happening with lithium ion today, and considering that cobalt is now a key material in advanced lithium ion technology, there’s a concern that we’re going to have a cobalt shortage given the projections for use of cobalt-based lithium ion electrodes in electric vehicles. So that may limit the deployment of lithium ion batteries, particularly for grid-scale storage.
OP: Higher shares of renewables will require longer term storage?
SG: Yes, long duration storage. Let’s say we have a couple days with limited generation from renewables but we have very high shares of renewables on the grid. We have to be able to have some way in which energy is stored and dispatched to the grid over a period of days.
This requires moving to a new class of technologies that allow you to achieve scalability for cost-effective storage when you have just a few charge and discharge cycles each year and discharges for, potentially, for very long periods.
If you look at technologies like flow batteries, you have the ability to completely decouple the power generation from energy storage and so scalability becomes more achievable. With flow batteries, you have tanks of electrolytes that run through cells with positive and negative electrodes and a membrane and allow for an ion exchange to occur in order to generate electricity. With this type of technology, you want to have very cheap tanks, electrolytes and other systems components that allow for cheaper unit production of electricity as size increases.
The challenge, though, is that today the incumbent flow battery technology is vanadium redox. It’s good except the vanadium, which is both the catholyte and the anolyte in different charge states, is expensive and energy density is modest at best. However, there’s some breakthrough research going on now, especially that’s come out of MIT, that’s looking at using sulfur-based flow batteries. The value here is that Sulphur is abundant and cheap and so can be used in large systems with improved energy density and so scale pretty well. When this happens, all of a sudden you can start talking about, 10 hours, 20 hours, 30 hours of dispatchable storage that’s very cost effective.
Now long-duration storage doesn’t always have to be via flow batteries. It can be via whatever technology you can conceive that allows you to dispatch electricity economically for long durations and with few cycles. ARPA-E has launched a new program for this kind of long-term energy storage R&D.
So in short we can have flow batteries that are working with very cheap electrolytes, or any other technology in which you don’t use expensive metals or commodities and can achieve sufficient energy density for scalability. The key is to achieve very low cost per charge and discharge cycle.
So that’s long duration storage, which is critical when you get to very high shares of renewables. Lots of research now is going toward what’s anticipated to come in 10 to 15 to 20 years.
Carrying Across Seasons
OP: And beyond 20 years?
SG: In many locations we’ll move beyond 50% renewable electricity and in most locations this much renewable energy will not be fully accommodated within a given season. You’re going to have to curtail excess energy, which means that you won’t be able to use all that you have and the economics will be negatively impacted.
What I’ve seen as far as seasonal storage interest is largely from European countries. Some studies there have focused on 50%-plus renewable electricity as the point where seasonal storage becomes very relevant. The major seasonal storage interest now is in hydrogen. Hydrogen has actually become one of the new programs of Mission Innovation, which is the major global initiative to accelerate public and private clean energy innovation. Related: Is This Europe’s Newest Oil & Gas Producer?
The question with hydrogen is whether you can take renewable energy that you can’t fully use when available and use it to affordably create hydrogen that can be stored and used across seasons. Because hydrogen storage in tanks is very scalable, such storage can be used to optimize the overall level of renewables required for meeting year round electricity needs.
Let’s say we’re in Abu Dhabi, it’s the wintertime, and we’ve got lots of PV because we need a large amount to meet peak electricity demand in the summer, but in the winter we don’t really need so much electricity. If it were not economical to curtail all of this excess PV, we could perhaps use an electrolyzer, create the hydrogen, store the hydrogen, and then use this hydrogen to produce electricity when needed, across seasons, either via a fuel cell or gas turbine retrofitted to burn the hydrogen for power. That’s a technologically feasible thing to do.
So I certainly think that hydrogen production via electrolysis and then storage is interesting. It is a particularly important topic if we’re going to achieve 85% of electricity from renewables by 2050, which is what IRENA (International Renewable Energy Agency) suggests is needed in the power sector for long-run climate change mitigation. 85% means a lot of renewable electricity and so we’re going to have to see long-duration storage and seasonal storage become a bigger part of the discussion if the majority of that electricity will be from intermittent sources.
Today you’re going to hear almost everyone talk about lithium ion batteries, which is ok, as it is an important technology. Bloomberg New Energy Finance has shown in their New Energy Outlook that you can get to very high shares of renewables in electricity, about 70%, with just lithium ion storage and balancing support from flexible demand and gas peaker plants. Some relatively significant amounts of renewable power curtailment are considered inevitable. This approach is definitely feasible given the right assumptions, but the take away should not be that you don’t have to pursue all of these other technologies we’ve discussed. If you further research and develop them and they become cost effective, some of them definitely will become a mainstream part of the electricity system of the future. Assuming that we can rely in the future only on the renewable energy technologies that are mainstream today is not, in my opinion, a wise approach.
A Few Big Players
OP: Do you see a lot of research institutes and companies anticipating this kind of long-range, 20 years out, 50%-plus renewable share, and working on new storage techniques now?
SG: Yes, I’ll give you an example. At MIT there’s something called the MIT Engine, which is an incubator for new “deep” technologies. The Engine is supporting a new company called Form Energy that is co-founded by Yet-Ming Chiang, who was one of the early pioneers of lithium ion batteries. He’s an electrochemistry expert and his company is producing a Sulphur-based flow battery, which I think can certainly be disruptive in the long-duration energy storage arena.
Another new company supported by the Engine is called Cambridge Electronics and it was co-founded by Tom Palacios at MIT. He’s developing a technology platform to produce low-cost gallium nitride devices and chips. As I mentioned, gallium nitride is one of the key materials for next-generation power electronic devices. We’re going to have to be using power electronics for the grid of the future and that’s an opportunity for Cambridge Electronics.
I also mentioned ARPA-E as an important program for stimulating energy innovation. They bring a lot of universities and a lot of companies together under their research programs. They’ve done a pretty good job recently of putting out focused research challenges to address the long duration storage question. I mentioned already the NODES program, which is trying to figure out how to leverage distributed energy resources to help manage the electrical grid. The Department of Energy and ARPA-E have further developed research programs targeting the optimal power flow challenge we discussed.
I mentioned previously Mission Innovation, in which countries globally have gotten together to try and solve the world’s greatest energy challenges. Hydrogen is a relatively new Mission Innovation program that compliments their other established programs, which include Smart Grid. Both the Hydrogen and Smart Grid programs are directly aligned with trying to push toward achieving very high shares of renewables in the electricity system.
There are several companies now which, if you look at Bloomberg New Energy Finance, or you look in the Global Cleantech 100, are repeated names that pop up. For example, Advanced Microgrid Solutions is both a Cleantech 100 company and a Bloomberg New Energy Finance New Energy Pioneer, and they’re working on the leading-edge of distributed energy resource management. They are one of the interesting companies working in the space that I mentioned already is at the forefront of where the energy sector is headed. Related: Dubai To Become Global Leader In Solar Energy
On battery storage there’s a company called Stem, which is a former Bloomberg New Energy Finance New Energy Pioneer. They’re trying to aggregate and bring together energy storage systems and manage energy storage systems for consumers and small businesses using artificial intelligence and other analytical techniques. Their business is not about one-off individual batteries for consumers or the grid, but bringing intelligence to systems of storage.
Key Concepts and Terms
OP: Is there anything you’re concerned about, where there’s not enough research going on now, either in the near term, the midterm or the long term outlook?
SG: If we’re going to get to 50% and then to 100% renewables, there’s a wide range of research going on now, and all the areas that I’ve mentioned need to be covered.
I would always start with thinking about the demand side because what you want to be able to do is produce as little electricity, whether it’s clean or fossil, as possible while still providing all needed energy services. The demand side approaches, like load shifting and profile shaping, are based on the integration of sensor data and software that interacts with hardware for action. This is an area where more and more needs to be done to leverage the current trends in the internet-of-things and the related sensor and software capabilities. You know, with high speed or next generation networks, acquiring and analyzing data for distributed resource management is a great opportunity. So I think smart systems for demand management is an area that needs to be pursued pretty aggressively in parallel to the growth in new hardware and software capabilities.
From there, I think the storage question, being able to store energy at very low cost and then dispatch it or shift it over long timescales, is important for achieving very high shares of renewables in electricity. Also, we talked about frequency and voltage control on the grid. You know there are many different ways in which at a short time scale and a long time scale we have to manage the grid when we have a very high share of renewables. Next-generation power electronics will be important for supporting grid operations at all time scales.
On the supply side, I’m not worried so much. I think we’ll continue to see aggressive pursuit of wind energy cost reduction and solar PV cost reduction. CSP is certainly very relevant given the storage opportunity but I would not prioritize it over the demand side.
Regarding lithium ion batteries, they’re going to be pulled ahead by electric vehicles. So I don’t think there’s any need for the power sector to be ultra-concerned about lithium ion developments. That said, I don’t think lithium ion is best for grid storage except for specific, relatively short duration storage applications. But lithium-ion is the incumbent technology and so it is the technology to beat for storage. I think we do, however, want to see if we can get long duration storage technologies going.
Looking further afield, I think sector coupling needs to be looked at quite aggressively. We need to start to understand how sectors – the power sector, the building sector, the transportation sector, and the industry sector – work together and synergize so that we can optimize the way in which the overall electricity system works.
Also, I’d say electric vehicles are important because a big part of the electricity equation will be electric vehicle charging. Trying to figure out how to optimize charging of a very large number of electric vehicles is going to be an extraordinarily important part of this electricity system discussion. In short, I think the systems level is where research needs to really push ahead because it’s a very challenging problem. The good news is that we’re getting more and more the technological hardware and software resources required to be able to address systems analyses in greater depth.
OP: Are there four or five key terms that people should be thinking about?
SG: I’d say distributed energy resource management, ‘derm’, is key! Also, long duration storage, such as novel flow batteries, and hydrogen for seasonal energy storage.
I would also say, power electronics, for being able to have an intelligent and efficient grid. Putting it bluntly, we want to operate the grid with the speed and efficiency of operating a computer. When you look at these power semiconductor devices, that’s kind of what we’re talking about, about having that level of control but with materials beyond silicon. So I think solid-state power electronics is a key area that people would want to be considering as we’re looking at very high shares of renewables.
OP: Steve thanks very much for sharing your thoughts.
SG: It’s my pleasure.
Part 2 of 2 - find part 1 here
By Alan Mammoser for Oilprice.com
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Alan Mammoser writes about energy, environment, cities, infrastructure and planning. He writes the weblog, www.warmearth.us