The Anonymous Widower

So, What Exactly Is Long-Duration Energy Storage?

The title of this post is the same as that of this article on Greentech Media.

This is the sub-title.

Everyone’s talking about it, and Californians are buying in. Here’s what you need to know about this emerging grid sector.

It describes what California is doing and the sector, with particular reference to Hydrostor, Form Energy and Highview Power.

The article finishes with a section entitled What’s The Catch?

This is the first two paragraphs.

The obvious barrier to a thriving long-duration storage industry is convincing generally conservative power plant customers that emerging technologies quite unlike anything the grid currently uses are safe bets for decades of operation.

Lab tests can reduce the risk, but nothing beats operational, megawatt-scale installations for proving that something works. That’s why the Form deal with Great River Energy is so crucial, as are early projects by Highview Power and Hydrostor. The big exception to technology risk is pumped hydro, which has been used at scale for decades. Those projects grapple instead with high capital expense and environmental concerns.

The article is a must-read and hopefully, this and more articles like it, will convince conservative energy company owners, regulators and governments, that long duration energy storage is the missing link between renewable power and electricity consumers.

At least, the current UK Government has backed two of the most promising British long duration energy storage companies; Gravitricity and Highview Power.

October 27, 2020 Posted by | Energy, Energy Storage | , , , , | Leave a comment

Zinc8 Seem To Be A Surprisingly Open Company

Several energy storage companies, that I have looked at for this blog are secretive companies.

In The Mysterious 150-hour Battery That Can Guarantee Renewables Output During Extreme Weather, where I pointed at an online article of the same name, the secrecy is in the headline. Look at the web site of the company involved; Form Energy and it reminds me of a term used in the 1970s and 1980s to refer to non-existent software – vapourware. Or one of my older favourite phrases – All fur coat and no knickers.

I have developed disruptively innovative software and other products and understand, the need for secrecy. But there is a need for a balance between secrecy and information.

As an example, one of the products, I have highlighted here, could be ideal for one of the followers of this blog. They will be investigating the product, as I have found enough information to enable them to decide, that contacting the company will not be a waste of time.

Some companies in innovative energy storage development like Highview Power and Hydrostor have posted informative YouTube videos about their technology, but others just rely on the same endlessly repeated phrases.

When I looked at the Zinc8 web site, I thought they were another company dealing in the same phrases, as there are two on the home page.

  • Zinc8 is redefining long-duration energy storage.
  • The leader in zinc-air battery technology.

But they are a lot more open, than the home page might suggest.

Looking up zinc-air battery on Wikipedia, gives a lot of information, that is understandable. This is the introductory paragraph.

Zinc–air batteries (non-rechargeable), and zinc–air fuel cells (mechanically rechargeable) are metal–air batteries powered by oxidizing zinc with oxygen from the air. These batteries have high energy densities and are relatively inexpensive to produce. Sizes range from very small button cells for hearing aids, larger batteries used in film cameras that previously used mercury batteries, to very large batteries used for electric vehicle propulsion and grid-scale energy storage.

I instantly thought, if a technology can be both non-rechargeable and rechargeable and useable in applications from hearing aids to vehicle propulsion and grid-scale energy storage, the technology must have something. I also worked in a non-ferrous metals factory as a teenager and know that zinc is easy to handle.

I then looked at their technology page

  • There is a detailed explanation of the technology.
  • They stress their patents and certification.
  • They show how a system can be expanded.
  • They list the major technological advantages of the system. Robust, safe, scalable etc.
  • They claim 20,000 operating life hours and 8+ operating hours.

They also finish off by giving an energy capacity cost of $45 per kWh.

I tend to think, that they have found a quirk in zinc-air technology, that they are exploiting, by some good old-fashioned innovative engineering.

I shall be watching Zinc8 and the other zinc-air battery start-ups.

May 16, 2020 Posted by | Energy Storage | , , , | 1 Comment

Hydrostor Announces Australia’s First CompressedAir Energy Storage Project Secures Funding From Arena And South Australia Renewable Technology Fund

The title of this post, is the same as that of this article on the Australian Energy Storage Alliance.

This is the introductory paragraph.

Hydrostor Inc., a leader in Advanced Compressed Air Energy Storage (A-CAES), is pleased to announce that its subsidiary, Hydrostor Australia Pty Ltd, has been awarded a combined total of $9 million of grant funding from the Australian Renewable Energy Agency (ARENA) and the Government of South Australia Renewable Technology Fund for Australia’s first A-CAES project, to be sited at a mine outside of Adelaide—the Angas Zinc Mine near Strathalbyn, currently in care and maintenance.

I’ll answer a few questions.

Who Are Hydrostor?

They appear to be a Canadian company based in Toronto according to their web site, which has this prominent statement.

Hydrostor is the world’s leading developer of Advanced Compressed Air Energy Storage (A-CAES)
projects, enabling the transition to a cleaner, more affordable and more flexible electricity grid.

There is also a video on the home page.

What Technology Do They Use?

This description is from the AESA article.

The technology works by using electricity from the grid to run a compressor, producing heated compressed air. Heat is extracted from the air stream and stored inside a proprietary thermal store preserving the energy for use later in the cycle. Compressed air is then stored in a purpose-built underground cavern, which is kept at a constant pressure using hydrostatic head from a water column. During charging, compressed air displaces water out of the cavern up a water column to a surface reservoir, and during discharge water flows back into the cavern forcing air to the surface under pressure where it is re-heated using the stored heat and then expanded through a turbine to generate electricity on demand.

An animation describing Hydrostor’s A-CAES system is available on YouTube.

I found the video worth watching, as it answered most of my questions.

Where Could Systems Be Installed?

This paragraph from the AESA article talks about the location of the energy store in South Australia.

By selecting the Terramin Angas Zinc Mine, the project will repurpose existing underground mining infrastructure as the A-CAES system’s sub-surface air storage cavern, benefiting both the electricity grid in South Australia and the local community by converting an unused brownfield site into a clean energy project that drives economic development. Hydrostor acknowledges Terramin Australia Limited’s support in developing the project and the technology’s beneficial application to South Australia.

I can think of a couple of mines in the UK, where such a system can be installed.


Hydrostor’s technology is standard process engineering, with all components and construction techniques well-proven in many decades of use.

I shall be watching Hydrostor with interest.


May 13, 2020 Posted by | World | , | 1 Comment

Cheesecake Energy Receives Investment From The University Of Nottingham

The title of this post, is the same as that of this article on NewsAnyway.

This is the introductory paragraph.

Cheesecake Energy Limited (CEL) today announced it has received investment from the University of Nottingham to support UK-wide pilot programmes for the company’s energy storage solution.

Thse two paragraphs are a brief description of the company, their technology and what they do.

Cheesecake Energy Limited is a fast-growing startup developing energy storage at 30-40% lower cost than the current market leader, lithium ion batteries. Its system uses compressed air and thermal energy storage to achieve high efficiency, long lifetime and dramatically lower environmental impact. 

Founded in 2016, the company has already established itself within the Nottingham, and wider East Midlands energy ecosystem — having secured initial interest from local councils and bus services for pilot programmes. The company is currently designing a 150 kW / 750 kWh prototype system for completion in Q4 2020 which will be deployed with a local bus depot for charging of electric buses using renewable energy.

This is the home page of their web site, which proudly announces.

The Greenest Battery In The World

We’ll see and hear that slogan many times in the next few years.

A few of my thoughts on the company.

Cheesecake Energy’s Technology

Cheesecake Energy says it uses compressed air and thermal energy storage to achieve high efficiency, long lifetime and dramatically lower environment impact.

Three other companies also use or may use compressed air to store energy.

As Cheesecake appear to be using a thermal energy storage, have they found a unique way to create another type of compressed air storage?

Battery Sizes

How do the sizes of the three companies batteries compare?

  • Cheesecake Energy prototype – 150 kW – 750 kWh – five hours
  • Form Energy for Great River Energy – 1MW – 150 MWh – 150 hours
  • Highview Power for Vermont – 50MW – 400 MWh – 8 hours
  • Hydrostor for South Australia – 50+MW – 4-24+ hours

The Cheesecake Energy prototype is the smallest battery, but Highview Power built a 750 KWh prototype before scaling up.


  1. The first figure is the maximum power output of the battery.
  2. The second figure is the capacity of the battery.
  3. The third figure is the maximum delivery time on full power.
  4. The capacity for Hydrostor wasn’t given.

The figures are nicely spread out, which leas me to think, that depending on your power needs, a compressed air battery can be built to satisfy them.

Charging Electric Buses

Buses like this Alexander Dennis Enviro200EV electric bus are increasingly seen in the UK.

And they all need to be charged!

Cheesecake Energy say that their prototype will be deployed with a local bus depot for charging of electric buses using renewable energy.

  • An electric bus depot should be a good test and demonstration of the capabilities of their battery and its technology.
  • Note that according to this data sheet of an Alexander Dennis Enviro200EV, which is a typical single-decker electric bus, the bus is charged by BYD dual plug 2×40kW AC charging, which gives the bus a range of up to 160 miles.
  • With a 150 kW output could Cheesecake’s prototype charge two buses at the same time and several buses during a working day?
  • Would DC charging as used by Vivarail’s charging system for trains be an alternative?

To me, it looks like Cheesecake are showing good marketing skills.

I do wonder if this size of charger could make the finances of electric buses more favourable.

Suppose, a bus company had a fleet of up to a dozen diesel single-decker buses running services around a city or large town.

  • How much would they spend on electricity, if they replaced these buses with electric ones?
  • Would being able to use cheaper overnight energy to charge buses in the day, be more affordable?
  • Would electric buses run from renewable electricity attract passengers to the services?

These arguments for electric buses would also apply for a company running fleets of vans and small trucks.

To me, it looks like Cheesecake are showing good engineering/marketing skills, by designing a product that fits several markets.



May 11, 2020 Posted by | Energy Storage | , , , , , , | 3 Comments