Tiamat is a French startup developing sodium batteries. Created in 2017, it exploits work by the CEA and CNRS begun in 2012.
Tiamat technology: sodium-ion batteries
With lithium supplies under stress, more and more manufacturers are looking for alternatives to lithium-ion batteries for electricity storage. Sodium-ion batteries could be a viable substitute: not only is sodium a very common material, but these batteries would also have higher charge/discharge speeds than their competitors.(summary)
At present, the company seems to be focusing on supplying small batteries to manufacturers of hybrid cars. These would be more powerful and faster to recharge than lithium-ion batteries, which would be important for certain applications, notably acceleration assistance. In particular, it has partnered with:
- BMS PowerSafe and Neogy (Startec Group), to develop sodium-ion batteries in the “industrial design of electronic and energy storage solutions”.(source)
- Plastic Omnium to equip its hybrid cars.
History and financing of Tiamat
The research leading up to the Tiamat project began in 2012, with the creation of a “task force” between CEA, CNRS (Réseau sur le stockage électrochimique de l’énergie, RS2E) and Collège de France. The first 18650 sodium batteries (the model used I assume?) were produced by the scientists. In 2017, Tiamat won a national innovation competition, i-Lab, and the company was set up in Amiens. The founders are an entrepreneur, researchers from RS2E and CNRS Innovation.
It raises €1.6M in 2018 from Picardie Investissement and Finovam. After completing the first POCs (Proof of Concept) in 2019, in 2020 €3.5M is raised from historical investors and various local players.
Highlights:
- In 2019, the French President is said to have started up a bus using a Tiamat battery.
- Partnership with Startec Group announced: https://bmspowersafe.com/fr/actualites/tiamat-choisi-bms-powersafe-pour-la-conception-de-ses-batteries-sodium-ion/
Redflow is an Australian company developing zinc-bromide redox flow batteries. The products are based on a 10kWh module, the ZBM3.
Redflow zinc-bromide redox flow batteries
Batteries are a mode of electricity storage with several problems: they require a lot of materials, there are safety issues (risk of fire) and they are not suitable for long-term storage. A new battery technology, storing electricity in electrolytes, is currently being developed: redox flow batteries. Redflow proposes one using a zinc solution and a bromide solution to store electricity.
They offer their technology in three formats: a small module, ZBM3, a medium-sized module (the size of a small car) and a large module, the size of a container.
ZBM3 flow battery, a small module
The ZBM3 flow battery is a very small battery, weighing less than a m3 (but still 240kg with electrolyte), 3kW (with a maximum of 5kW), 10kWh capacity and a claimed efficiency of 80%. Longevity is said to be 36,500kWh stored (3650 cycles at 100%) or 10 years. They operate at room temperature (10-45°C) and at altitudes of up to 2000m.
It is these 10kWh modules of which the other modules are composed.
Previously, they marketed a small “Zcell” module for private customers, which seems to have been discontinued. This was a 10kWh battery that cost around 12600 Australian dollars.
Quadpod, a car-sized module
The Quadpod is made up of 4 ZBM batteries. They are 2.27m long, 1.15m wide and 1.25m high. They therefore have a capacity of 40kWh and a power of 12kW (which can be increased to 20kW).
Energy pod200: a battery the size of a container
This is the module for industrial storage farms. These are 6.25-tonne containers designed to hold 20 ZBM3 batteries connected in parallel. They have a capacity of 200kWh and 60kW, which can be increased to 100kW.
Financing and development of Redflow
Redflow was founded in 2005 by brothers Chris and Alex Winter. It went public in 2010. It has around 90 employees and is based in Brisbane, Australia.
They sold 2MWh of these systems in California, atAnaergia’s Rialto Bioenergy Facility, in March 2021.
In January 2023, the company announced the integration of its system with the Deye hybrid inverter.
The company was worth around $60 million in August 2022.
- Interview with the founder in 2022: https://pv-magazine-usa.com/2022/09/19/redflow-targets-us-market-with-lithium-ion-battery-alternative/
Quino Energy is a startup founded in 2021 from a Harvard laboratory, developing flowing (= redox flow) batteries whose electrolytes are said to be particularly available and low in toxicity.
Quino Energy flow batteries (redox flow)
The originality of the Quino Energy project lies in the use of quinone and ferrocyanide as electrolytes for its redox battery. These components are very easy to find: quinones are produced from wood and coal residues
They are also biodegradable and non-toxic. Quinones are found, for example, in dyes, henna and food: vitamin K1, phylloquinone, belongs to this family.
One of the problems with this technology is that quinones are not a stable storage medium, as the molecules change. In June 2022, the start-up’s researchers published a mechanism by which these molecules (2,6-dihydroxy-anthraquinone (DHAQ)) could be “regenerated”:
Jing, Y., Zhao, E.W., Goulet, MA. et al. In situ electrochemical recomposition of decomposed redox-active species in aqueous organic flow batteries. Nat. Chem. 14, 1103-1109 (2022). https://doi.org/10.1038/s41557-022-00967-4
You can find the 4 scientific articles published on this topic, which I haven’t gone into in depth, at this link: https://quinoenergy.com/technology/. The innovation seems to be at a very early stage of research.
History and financing of Quino Energy
Quino Energy’s redox flow battery was conceived at Harvard’s John A. Paulson School of Engineering and Applied Sciences, as part of research led by Michael Aziz and Roy Gordon. Together with Eugene Behet (also CEO) and Meisam Bahari, the latter two founded Quino Energy in 2021. The laboratory has given the company a license to commercially exploit the process. The company is based in San Leandro, California (USA).
In 2022, the company received a grant of $4.58 million from the US Department of Energy (DOE) and raised $3.3 million from ANRI and TechEnegy Ventures.
FAQ
How much funding does Quino Energy have?
Quino Energy is still at a very early stage and has only raised $3.4 million.
What is Quino Energy’s innovation?
Quino Energy is one of a number of startups developing redox flow batteries, which have the particularity of being able to store electricity for a long time without degradation, and of having a high storage capacity for relatively few materials. Their solution is based on quinone and ferrocyanide electrolytes.
- A comprehensive presentation (Oct. 2022): https://www.chemeurope.com/fr/news/1178206/une-batterie-redox-flow-innovante.html
Research into nanomaterials at the CEA led to the creation of a spin-off company in 2013: NawaTechnologies. Founded by Pascal Boulanger, who chairs the board of directors, the startup develops solutions around the “Vertically Aligned Carbon Nanotubes (VACNT)” technology.
Its situation is rather unusual: placed in receivership, two offers have been made by its current shareholders. One wonders whether this is not simply the result of internal discord.
Nawacap Power
Nawa Technologie is based on the use of vertically aligned carbon nanotubes (5nm/100µm). (5) It does not use rare metals such as cobalt.
Nawacap Power is a supercapacitor available in 3 cell sizes:
- 30x40x0.5, with a power density of 54kW/kg and a capacity to absorb 2.7J for 1.2g
- 30x40x11, with a power density of 141kW/kg and a capacity to absorb 82J for 14.4g
- 100x120x5, with a power density of 171kW/kg and capable of absorbing 273J for 38g
They could last a million charge/discharge cycles and 15 years under ordinary conditions. (1) According to Pascal Boulanger, founder and COO/CTO, Nawacap Power“provides a power density 10 to 100 times greater than traditional supercapacitors“
Their added value would include high energy density and rapid recharging, which is a considerable asset for the electric vehicle market.
NAWAStitch
Nawa Technologie has created a subsidiary in the United States, in Dayton, Ohio, “Nawa america”, from the acquisition of the assets of N12 Technologies, a company marketing aligned nanotube mats for composite applications.
This subsidiary is developing a new material concept: a thin film of hundreds of billions of vertically aligned carbon nanotubes, serving “as an interface between the plies of composite materials” and “mechanically reinforcing the interface between carbon-fiber fabrics”, rather like a kind of “nano-velcro”. This would make the materials more resistant to fatigue and damage, and better electrical and thermal conductors. NECSTLAB has signed an exclusive licensing agreement with the Massachusetts Institute of Technology (MIT). (2)
Applications for this new material include aerospace, wind turbine blades, sports equipment, medical devices and robotics.
About NawaTechnologies
NawaTechnologies is a public limited company registered with the Aix-En-Provence Trade Registry under SIREN number 792701518, with APE code 7490B (Specialized, scientific and technical activities). Its registered office is at STMicroelectronics Rousset, 190 avenue Louis Philibert, Aix-En-Provence (13100).
The Managing Director was initially Ulrik Grape, who had long worked in the lithium-ion battery sector. In January, he became Antoine Saucier. Ludovic Eveillard is Deputy Managing Director. Henri Levebvre is Chief Financial Officer. Stéphane Coletti is Industrial Director.
The company has had several rounds of financing:
- 4.1 million euros in 2014
- 9 million euros in 2019
- 13 million euros in 2020 from “Bpifrance, Kouros SA, Crédit Agricole Alpes Provences Création and EIT Innoenergy”.
The startup has several investors: CEA Investissement, Demeter Partners, Davanière Capital Partenaire, the Paca Investissement fund, OPUS SAS, Groupe Kouros, EIT InnoEnergy, Crédit Agricole Alpes Provence, Conseil Plus Gestion and BPI France.
The company was placed in receivership in October 2023. There are two takeover bids:
- One by the Kouros group
- One by Altya Invest, BPI (via its Ecotechnologies 2 fund), the company’s CEO (Antoine Saucier), and its CFO. (4)
- (1) http://www.nawatechnologies.com/technologie/(archive)
- (2) http://www.nawatechnologies.com/nawa-america/(archive)
- (3) https://sciencebusiness.net/news/southern-france-startup-chases-global-battery-market
- (4) https://www.lefigaro.fr/secteur/high-tech/nawa-technologies-cette-pepite-de-la-french-tech-brusquement-tombee-en-redressement-judiciaire-20231018
- (5) https://solarimpulse.com/solutions-explorer-fr/nawacap-high-energy-high-power-ultracapacitors
Kemiwatt is a French startup founded in 2014 that develops redox flow batteries with organic electrolytes.
Kemiwatt battery technology
Batteries are a mode of electricity storage that has several problems: they need a lot of materials, there are safety issues (risk of fire) and they are not suitable for long-term storage.
Redox flow batteries solve these problems. Electricity is stored in solutions, so their storage capacity depends on the size of their reservoirs. There are no (or few?) fire hazards, and electricity can be stored for a long time without being lost. One of their current problems is the nature of these solutions. In particular, they use vanadium, an unusual metal, in an acid electrolyte.
Kemiwatt’s innovation consists in using electrolytes that are biodegradable: a solution of aluminum ions (Al2 / Al3 couple) and one of carbon ions (C3 /C2 ).
The reaction takes place inside graphite felts separated by a proton exchange membrane.
This battery could last more than 10,000 cycles, would require little maintenance and would have a long service life of over 20 years(source)
Progress and funding
The technology was initially developed by Didier Floner and Florence Geneste at the University of Rennes 1 laboratory. In 2014, they teamed up with François Huber to create Ionwatt and raised €1.4m through Demeter Partner and GO Capital. The company develops a 10-20kW prototype in 2016 and raises €1.2m from the same investors. In 2017, it renamed itself Kemiwatt [rq: obviously there was a float on the name, which is displayed as “Kemwatt” in several media] and developed a demonstrator of up to 30kW.(source) They raised €2M, again from the same investors, in 2018, bringing the total to €4.4M.(source)
They would have been backed by Demeter Ventures, GO CAPITAL, Pierre-Yves Divet [presents himself as “non-executive director” since 2018 on Linkedin] and SATT Ouest Valorisation.
Since 2018, the company’s president is Guillaume Chazalet.
- Interview with F.Huber in 2017 on the interest of redox flow batteries: https://lenergeek.com/2017/08/04/stockage-energie-batteries-redox-flow-kemwatt/
- A comprehensive presentation of the project: https://www.energystream-wavestone.com/2018/10/interview-rencontre-avec-kemiwatt-une-startup-qui-fabrique-des-batteries-a-electrolytes-biodegradables/
Form Energy has developed iron-air batteries that are 10 times cheaper than lithium-ion batteries for large-scale electricity storage. The startup has raised over $800 million from prestigious investors such as Breakthrough Energy Ventures and the venture capital funds ofArcelorMittal and ENI.
Iron-air battery technology
Form Energy uses iron-air batteries: when they charge, the iron oxide reduces (= deoxidizes), with oxygen leaving the “air” electrode side (in reality, this happens in an electrolyte). Then, when the battery discharges, the electrons are released and the iron oxidizes again. The big advantage of this method is the extremely low cost of materials: iron is one of the cheapest metals available.
The disadvantage of iron-air batteries is their reactivity: they would have difficulty with high currents. However, this is not a problem: you just need to couple them with a small, more reactive storage, such as lithium-ion batteries or mechanical storage.
The company seems to be highlighting the fact that the battery would be“capable of supplying electricity for 100 hours“. This is a bit disturbing, since I don’t see how it makes sense: basically you can probably last for weeks on any battery if the flow rate is low enough …
According to Form Energy, large-scale batteries could cost as little as 10% of the LCOS price of their lithium-ion equivalents.
Form Energy history and progress
Form Energy’s progress
Form Energy was founded in 2017 by Mateo Jaramillo (former head of Tesla’s battery department), Yet Ming Chiang (MIT professor), Ted Wiley, William Woodford and Marco Ferrara.
A 300MW pilot project is planned in Minnesota for 2024.
On January 23, 2023, Xcel announced the installation of a very large Form Energy battery farm, one of the largest in the world.
Financing Form Energy
The company’s financing is quite extraordinary, both in terms of its amount ($818Mn) and the identity of its investors (Breakthrough Energy Ventures, ArcelorMittal, Energy Impact Partners, Capricorn Investment Groupe, Prelude Venture…). It breaks down as follows:
- The Series A round closed in June 2018 at $9M. Breakthrough Energy Ventures (BEV), Prelude Ventures, The Engine (MIT) and Macquarie Capital invested.
- The Series B round was announced at $40M on August 19, 2019 and was led by ENI’s venture capital firm, Eni Next LLC. It includes Capricorn Investment Group and investors from the first round.
- The Series C round was announced on November 30, 2020 at $76M. Joining historic investors Coatue, NGP Energy Technology Partners III, Energy Impact Partners and Temasek.
- The Series D round in 2021 amounted to $240M, including $25M fromArcelorMittal. At the same time, the two companies signed an agreement under which ArcelorMittal would supply direct reduced iron for the batteries.
- Former Energy announces the closing of its $450 million Series E financing round on October 4, 2022, led by investment platform TPG Rise. Joining historical investors (ArcelorMittal, Breakthrough Energy Ventures (BEV), Capricorn Investment Group, Coatue, Energy Impact Partners (EIP), MIT’s The Engine, NGP ETP, Temasek, Prelude Ventures, and VamosVentures) GIC and Canada Pension Plan Investment Board.
FAQ
How much money has Form Energy raised?
Form Energy has raised $818.8 million.
Who are Form Energy’s main investors?
From the very first investment round, Form Energy mobilized a number of major innovation players, including Breakthrough Energy Ventures and The Engine (MIT). They were subsequently joined by other major players, such as ArcelorMittal.
What is Form Energy’s innovation?
Form Energy is developing iron-air batteries, which would use very common materials (iron) and would be suitable for long-term stationary storage of electricity, which is one of the major challenges of the energy transition, to stabilize the electrical grid in the face of intermittent energies.
Who are the founders of Form Energy?
Form Energy was founded in 2017 by Mateo Jaramillo (former head of Tesla’s battery department), Yet Ming Chiang (MIT professor), Ted Wiley, William Woodford and Marco Ferrara.
Who is the head of Form Energy?
Mateo Jaramillo is both co-founder and CEO (Chief Executive Officer) of Form Energy.
- A study by the Franhaufer Institute: https://www.umsicht.fraunhofer.de/en/projects/iron-air-battery.html
Enairys Powertec is a small company based in Vaud (Switzerland) which has been developing a compressed air energy storage system (CAES) since 2008.
The Enairys Powertech compressed air storage system
Enairys Powertech’s compressed-air energy storage system, HyPES for Hydro-Pneumatic Energy Storage System, is based on an original system: it doesn’t use a mechanical piston compressor, but a system based on the “liquid piston” principle. During charging, the injection of (cold) water acts as a piston, compressing the air under relatively isothermal conditions. This process consumes less energy than a mechanical piston. The opposite occurs when the device needs to be unloaded. In this case, the role of the water is to heat (if I’ve understood correctly) the air. The process is presented here: https://www.enairys.com/overview-technology/
It mobilizes several elements presented as original:
- A rotating module for low-pressure compression-expansion: https://www.enairys.com/low-pressure-air-compression-expansion/
- The liquid piston system for water compression (liquid piston): https://www.enairys.com/high-pressure-air-compression-expansion/
The company is said to be developing 2 products:
- HyPES-R, for “Renewable energy sources support
- HyPES-G for “Grid support”.
The system would be made up of at least “98% easy-to-recycle, non-toxic metals” and would make it possible to combine electrical and thermal load sources, or even “create synergies between them to maximize overall efficiency”.
I have no information on the viability of this system.
History and financing of Enairys Powertech
Enairys Powertech was founded in 2008 by engineer Sylvain LEMOFOUET. It appears to be a spin-off from the École polytechnique fédérale de Lausanne (EPFL). Traces of the manager’s activities can be found on Linkedin (e.g.: training in Africa), but they do not concern the company, and nothing on the website.
The only source comes from a CleantechAlps post published around August 2022: they would have tested a first prototype in 2018 and, since then, have been working to optimize and validate HyPES systems in real-life conditions. This stage should be completed in 2023. I have no information on funding.
It is located at the EPFL-PSE D Science Park, in Lausanne (Switzerland).
- The cleantech Alp post: https://www.linkedin.com/posts/cleantechalps_enairys-portrait-activity-6972466976858210304-DnG4
- The site (in noindex): https://www.enairys.com/
- https://fr.wikipedia.org/wiki/Enairys_Powertech
- https://www.polymedia.ch/fr/un-systeme-original-de-stockage-denergie/
Many of us have heard of large concrete block towers to store electricity. Kinetic energy is stored when the blocks are raised to the top of the tower, and released when they are lowered. This is the Energy Vault project, which we present here.
The technology proposed by Energy Vault
Energy Vault offers two types of product: long-term storage using concrete blocks and gravity energy, and more conventional products, short-term storage (apparently mainly battery-based) and a charge management software suite.
Long-term storage
This is the company’s main focus: long-term energy storage using concrete blocks. While the idea is appealing, I haven’t found an independent source to support its viability.
The Energy Vault concrete tower
Initially, Energy Vault made a name for itself with a project involving giant cranes to move concrete blocks upwards (to store energy) or downwards (to release it). In this way, they built immense towers. The company claimed an efficiency of 90% and could reach maximum power in 2.9s.(source) A 120-meter tower could store 20MWh. The cost would be between $280-350/kWh and could go down, according to Robert Piconi, head of the startup, to $150/kWh. (Combier 2018) In 2019, they announced a capacity of 35 MWh, a maximum output of 4 MW and an LCOS of $0.05/kWh compared with “$0.17 per kWh for STEPs”. (Colas des Francs 2019) The company was still announcing a LCOS of €0.042/kWh in 2021. I have not heard of any confirmation of this. These LCOS claims leave me rather suspicious.
This model has made the headlines, claiming great performance and being scalable in principle. Nevertheless, it has been widely criticized, not least for the risk of mechanical wear and tear and of being caught in the wind. A working prototype, 120m high and named “EV1”, was built in Switzerland’s Ticino region. This version appeared to be a success, with the company reportedly selling 3 projects totalling 1.6 GWh of storage for 520 million euros by 2021.
It clearly failed to convince, and the company moved on to another model.
The new model
Following Energy Vault’s IPO, another sustainable storage solution was designed, called the “Energy Vault Resiliency Center” (EVRC). This time, it takes the form of a large warehouse-type building, with the blocks stored on metal frames.
While this solves the problem of wind load, it raises the question of the quantity of resources required.
An agreement had been signed with Atlas Renewable for an installation in China. Construction of a 100MWh facility is due to start in March 2022. An agreement was signed in September for a 2GWh global installation.
Short-term energy storage and software
Energy Vault also markets “short duration energy storage” (SDES) systems (<4h), including lithium-ion batteries. 500MWh of this system has reportedly been purchased for the 330MW Meadow Creek solar park, near Melbourne (Australia).
The company also markets a charge management software suite.
A criticized technology
A report from a rather special organization (they do negative reports and bet on the stock going down, if I understand correctly) points out anomalies:“Energy Vault (NRGV): New Evidence Leads Us To Downgrade This Company To A Middle-School Science Fair Project“. Energy Vault responded in a press release.
The company’s communication leaves a bad impression. I couldn’t find anything to explain the decision to change the model. Above all, the claim of a system 3 times cheaper in LCOS than STEP makes me frown. What’s more, while the executive had announced several contracts in 2019, I didn’t see any echoes afterwards … Ditto in 2021 ..
Progress and news
Energy Vault is a spin-off from the stuatup studio Idealab. It was founded in 2017 in Switzerland. It had a first large investment round in May 2019, with Cemex and $110 million from Softbank Vision Fund. A second round of $100 million brings together Aramco Energy and the previous investors in August 2021.
In February 2022, the startup’s holding company is listed on the New York Stock Exchange. Sales in 2022 are estimated at between $142 and $152 million.
- Combier E., “Quand le béton fait office de batterie”, Les Echos, August 26, 2018
- Colas des Francs O., “Quand le mouvement sert à stocker l’energie”, Les Echos, October 23, 2019
Airthium is a greentech – deeptech startup developing three solutions revolving around a Stirling engine, a kind of reversible heat pump:
- The production of process heat up to 550°C from electricity, at a price that will eventually be competitive with natural gas.
- A seasonal electricity storage system to bridge off-peak periods in wind and solar production, combining
- short-term storage of electricity in molten salts (in the form of heat) which, thanks to the Stirling engine, would enable storage using common materials with an efficiency of 70%.
- the production of ammonia, which can then be converted into heat using a burner, and then into electricity using the Stirling engine.
The Stirling engine makes a wind- and solar-powered electricity system more reliable.
The Airthium company
Airthium was founded in March 2016 by Andreï Klochko and Franck Lahaye. The birth of Airthium is recounted in the interview given by Andreï Klochko for École polytechnique:
” The idea for Airthium germinated in 2008 when I became aware of a technology at the crossroads of fluid mechanics and electromagnetism, but it wasn’t until I had completed my thesis at the Plasma Physics Laboratory at X that I was able to apply it to energy storage by working on the design of a new type of gas compressor. In 2014, when we won the Gérondeau – Safran prize and the Concours mondial de l’innovation de Bpifrance, I realized that our project had convinced people and I realized its full potential. I then devoted myself to it full-time, and Airthium was officially created in March 2016.”
https://www.polytechnique.edu/fondation/actualites/toutes-les-actualites/airthium-la-start-qui-revolutionne-le-stockage-de-lenergie
The company was incubated by the prestigious Y Combinator in 2017. It raised €500k from several investors, including Y Combinator.
Housed atÉcole Polytechnique until 2019, the startup was until recently based at Air Liquide’s Innovation Campus, before moving this October to dedicated premises in Villebon-sur-Yvette (91).
It raised ~1.3 million euros in crowdfunding in 2021 and is currently raising a second round, again in crowdfunding (source: interview).
On the industrial front, they are planning a 1kW prototype in 2023, a heat pump demonstrator the following year and a 1MW industrial model in 2025. (https://airthium.com/about_us)
Then, larger-scale heat pumps (20MW) would be available in 2028. Seasonal energy storage is planned for 2030 on a small scale (50MW) and 2035 on a large scale (1GW).
Questions and answers
– On the principle of the Airthium solution
- Discover The Greentech (DTG): If I’ve understood correctly, you’re proposing an industrial heat pump capable of capturing heat between 100 and 500°C or atmospheric heat from -50°C and delivering it at the desired temperature, is that correct? What’s the difference between heat you can only capture at 100°C and atmospheric heat?
- Airthium: Yes, our heat pump can capture waste heat (heat produced by a process but not recovered) or atmospheric heat and deliver it at the desired temperature (up to 550°C). We are able to collect heat from -50°C up to 550°C, so there’s no fundamental difference between atmospheric and 550°C heat.
Depending on the temperature at which the heat is collected and released, the heat pump operates differently: the working fluid may change (water between 20°C and 80°C, oil up to 250°C and molten salts to reach 550°C), but it’s above all the COP (coefficient of performance) that is affected.
A resistance has a COP of 1 (1 joule of electricity = 1 joule of heat), but the advantage of the heat pump is that it has a COP greater than 1. In our case, going from 20°C to 200°C we have a COP of 1.9, but if we go from 100°C to 200°C our COP is 2.7.
- DTG: Can you explain in a few words how a heat pump works? How is it more efficient than a resistance heater? A layman would think that 1 joule of electrical energy would give 1 joule of heat. Is it more complicated than that?
- Airthium: The greater-than-1 efficiency of the heat pump may seem surprising, but it’s based on thermodynamic principles. The heat pump’s job is to move calories from the cold source to the hot source. Electricity is therefore not used directly to create heat, but to move calories. In this way, it can be more efficient than resistance heating. In fact, they are already widely used in homes and industry.
- DTG: How is heat transmitted? Air, liquid, metal?
- Airthium: Heat is captured in the cold process by a heat exchanger, which transmits it to a fluid (water, oil, molten salts) which is then sent to our heat pump. Inside, it interacts with helium gas, which transfers calories from the cold source to the hot source. We then recover another fluid (water, oil, molten salts) that has been heated by the heat pump, which is sent to the heat exchanger on the hot side to reheat the hot process.
– On uses :
- DTG: I see you’re talking about using your heat for cement. However, it seemed to me that, to remove the carbon from limestone, it had to be heated to extremely high temperatures (>1450°C). Do you go that high? The same question applies to glass and metal. For what processes and how can your process be used?
- Airthium: Our heat pump can be used in the cement, metal and glass industries, but that doesn’t mean it’s used directly in the main process (metal or glass melting, for example). These industries require moderately high temperatures for other applications, such as drying, heat treatment, temperature maintenance… This is the kind of process we can help with.
– On the energy storage system:
[Here we’ll be discussing the schematic of their seasonal storage system in particular]
- DTG: I’m having a bit of trouble understanding your diagram: why produce ammonia? Take heat from water? Is the “Airthium Stirling Engine” dependent on these two specific processes? Or are they examples of use?
- Airthium: The Airthium Stirling Engine is the machine we build, which can be used both as a heat pump and as a Stirling engine. The Stirling engine is a thermal machine that can produce heat from electricity (heat pump mode, COP up to 3.5) or electricity from heat (engine mode, thermal>electric efficiency up to 50%). We plan to start by producing heat pumps to develop our technology and make the system more reliable, before entering the energy storage market (which requires a substantial capital investment).
Our storage system works in a hybrid way: for daily storage we use molten salts or sand as purely thermal storage, but our main advantage is seasonal storage (very long duration), for which we need ammonia (NH3).
With an energy mix based on renewables, there is a risk (a few times a year) of a major drop in production (more or less sun and wind at the same time). We therefore need to compensate for this shortfall with storage capacity.
Ammonia is a synthetic fuel whose combustion generates no CO2, and is fifteen times cheaper to store than hydrogen. When there is a surplus of renewable energy production, we produce ammonia from electricity, then store it in large-capacity tanks in liquid form (it is easy to store, and there is already a whole industry that has mastered this technology). The parallel can be drawn with the natural gas reserves that are in use today. When demand exceeds production, the ammonia is burned (in a burner developed to limit NOx emissions) to heat the molten salts, which are then sent to the Stirling engine to generate electricity.
- DTG: Can you give us an outline of this system? How efficient would it be? What would be the storage medium (liquid, gas, etc.)? Does the system’s stability require any special maintenance (maintaining temperature/pressure/other conditions)?
- Airthium: The round-trip efficiency of thermal daily storage will be around 70% (compared with 80-90% for lithium-ion batteries, which discharge more quickly, use rare earths, are expensive and present a risk of thermal runaway). The fluid (molten salt or sand) is stored in thermally insulated tanks to minimize heat loss. Molten salt needs to be kept at a minimum temperature to prevent it from solidifying. This will be guaranteed by the minimum temperature of the tanks, which will be much higher than the solidification temperature, and when solar and wind power are lacking, by the combustion of ammonia.
As mentioned above, the seasonal storage medium is liquid ammonia (-33°C under 1atm), with a return electrical efficiency of close to 30%. Its storage conditions are very similar to those of propane. Ammonia storage is already an established and mature industry, which we can build on.
Discussion with CEO Andrey Klochko
I then chatted with Airthium’s CEO, Andrey Klochko, to discuss a few points in greater depth, mainly around the energy storage solution. I’ve noted in [ ] the passages I’ve taken up or summarized.
The principle of the long-term energy storage system
- DTG: So the daily storage solution would use highly available materials with an efficiency of 70%? What’s stopping this solution from being more sustainable?
- Andrei Klochko: That is, to store for more than 40 hours?
- DTG: Yes.
- Andrei Klochko: It’s just too expensive. […] Seasonal energy storage compensates for a lack of solar and wind power, which […], 2 to 4 weeks a year, […] can drop significantly over very large territories at the same time. Whether it’s the whole of France or the whole of Europe. For those times, we’ll have to keep power plants [, currently mainly gas-fired, which will also] have to recoup their fixed costs with just 1 month’s energy sales. So either they sell their energy at a very high price, or they are subsidized. [For storage], it’s all a question of price per kWh. [Lithium-ion batteries cost $200 per kWh in capital […], with molten salt it’s $60 per kWh and for ammonia, it’s something like $2 per kWh. The problem is that $2 is an optimum. If you only use ammonia, then the ammonia production equipment is too expensive and, because of the yield (30%), you’ll need a solar [or wind] field that’s too big; if you only use molten salt, […] it’s too expensive. The optimum, to reach $2, is to use a mix of the two.
In other words, molten salt storage would make it possible to smooth out electricity production in the short term to limit the power requirements of ammonia production. The great advantage of ammonia is that it’s cheap to store. When production drops, the ammonia is burned and transformed into electricity using their Stirling engine, in a process that limits nitrogen oxide (NOx) emissions.
Then there’s the question of the power of the Stirling engine. Indeed, it will be used to smooth out the production of electricity for ammonia production throughout the year, and then, one month in the year, will have to burn all or a large part of the stored ammonia.
“Ammonia is produced in dribs and drabs all year round and burned one month of the year. So there’s a power asymmetry. If we ever have 1GW of power output, then the solar field will make 3 to 5 GW peak […] and the burner will make something like 2GW thermal, but the Haber-Bosch power plants the electrolysers will make something like 600 MW. [By way of comparison, if we depended solely on ammonia, we’d need at least 3 GW of electrolysers, plus a solar field more than twice as big. All these numbers depend, of course, very much on the case under consideration].”
Limiting NOx
Using a combination of burner and Stirling engine at the end of the chain is also an advantage in terms of limiting NOx:
- DTG: In your interview for X, you talked about converting renewable fuels into electricity. Is your solution more efficient in this respect than a conventional (turbine) system?
- Andrei Klochko: The advantage is that it’s mutualized [=the Stirling engine is used both for short-term storage by heat pumping, and for seasonal storage by ammonia]. [A strength of our solution] is that there is a combination of small advantages [which add up to one big advantage]. We could have burned the ammonia in a turbine, but that [isn’t interesting], because it produces lots of NOx. We compensate for this by using an external burner [equipment that can be optimized to emit less NOx natively (before filtration), which facilitates filtration].
The trade-off between fertilizer and electricity
- DTG: What is the trade-off between using the ammonia produced to regenerate electricity and using it to make fertilizer?
- Andrei Klochko: Both work. The first few times the system is installed, it will still be expensive, so it will be installed on islands or in Alaska [for example], in [remote] places. The more we install, the lower the unit costs will be, and eventually we’ll be pretty cheap to produce fertilizer too. […] That’s why we have the heat pump value proposition in the first place, to get the cost of the Stirling engine down to a minimum and industrialize it [following the example of the automotive industry].
Water supply
Andrei also explained a little about the bottom of the Airthium storage system diagram. The energy storage system uses water in a closed cycle and is exposed to freezing if it uses air/water that is too cold (which can be problematic in very cold countries). To counter this, water is stored for cooling purposes. There would also be cooling towers, as the system would still radiate heat, especially in hot weather. As regards the need for water for ammonia synthesis, a large proportion is recovered during ammonia combustion, by condensation of the water contained in the burner exhaust stream.