Requiem for LightSail Energy

Image Credit: LightSail Energy

I've published multiple posts concerning LightSail Energy and its Chief Science Officer, Danielle Fong. I was enthusiastic about the the Lightsail Energy compressed air energy storage technology concept, wherein a water mist was to have been used during compression in order to produce a quasi isothermal compression process and consequently reducing thermal losses. And I wasn't alone in my enthusiasm, such notables as Vinod Khosla, Bill Gates, Peter Thiel, Total, and others invested somewhere in the vicinity of $80MM in LightSail.

But, despite the confidence of these very bright investors and the large amount of capital invested, LightSail Energy is, according to co-founder Stephen Crane, in a state of "hibernation." I follow Ms Fong on Twitter and, off and on, have corresponded with her. I haven't read anything from her with respect to the fate and apparent demise of LightSail, but the tenor of her Tweets is that she's moved on.

This saddens me because, the potential of near-term success of hydrogen fusion as an energy source notwithstanding, I am firmly convinced of the urgency of weaning ourselves from near-total reliance on fossil fuels for energy and saving those resources for applications for which substitution is extremely difficult such as transportation fuels (airlines, transoceanic shipping for example). Electricity is the low-hanging fruit here, albeit a pretty high low-hanging fruit! We have wind, solar, hydro, geothermal, and other ways to harvest energy that don't directly involve the burning of fossil fuels and all of them result in the generation of electricity.

But the most bountiful categories are solar and wind (hydro, while certainly a large contributor, has mostly been "built out," i.e., the best sources have already been exploited) and those are intermittent sources. In order for them to provide so-called "base load" power, a method of eliminating this intermittency must be employed. This can be accomplished in part by wide geographic dispersion, but the holy grail would be the ability to store energy when the wind blows and the sun shines.

Currently, nearly all new storage installations involve large lithium ion battery installations. But Li ion batteries, while good and continuing to improve, have downsides. They degrade over time, they require assiduous management both to preserve lifespan and to prevent issues of thermal runaway. And, in comparison to large scale pumped hydro storage (PHS) and compressed air energy storage (CAES), the energy capacity of Li ion battery installations is not as large (see chart below, note the log-log scale).

Image credit: unknown

Image credit: LightSail Energy

In the chart, you'll find the "Large CAES" installations in the upper right hand corner. However, the two installations plotted use underground caverns as their containment vessel and need natural gas heating in order to function. LightSail was developing modular units of much smaller size using above-ground storage in tanks. And, in what now seems to have been a last-ditch effort to continue, LightSail began an attempt to market the tanks they'd developed and, apparently, delivered at least one.

Unfortunately, the LightSail web site is gone and with it, I'm afraid, is the investors' money and the hopes and dreams of Danielle Fong.

LightSail yet again

Image courtesy of LighSail Energy

This will be a short one. LightSail Energy, a startup with innovations in compressed air energy storage, has already appeared in my writing twice, the most recent being after co-founder Danielle Fong was generous enough with her time to take me on a tour of their facility in Berkeley. In the first article I mentioned that I'd delve deeper into the thermodynamics of their process. After the second Ms. Fong mentioned that, in general, she felt that I'd been fair and accurate but that my skepticism regarding LightSail's ability to manufacture systems in the facility I visited was unfounded. Hmm... "uncalled for" is the actual quote. I'd like to take a look at both, but first the manufacturing capacity.

Image courtesy of LightSail Energy

As it happened, it turned out that I hadn't seen the whole facility. Further conversation with Ms. Fong revealed that LightSail's existing Berkeley facility does have some manufacturing capabilities and, in fact, has production runs of tanks in particular. It should be noted (and I've seen Fong tout this publicly in some of the amazingly large number of video presentations in which she's featured) that LightSail states that they have designed, prototyped, tested, and produced tanks with unprecedentedly high merit indices. These tanks can be sold for uses other than compressed air energy storage.

Further, LightSail is able to assemble, commission, and sell their compressor expanders out of their R&D facility. Thus, while LightSail is unlikely to be able to meet full scale production of their storage units at the Berkeley facility in the event that their compressed air energy storage technology takes off at the scale that the Company envisions, it's clear that they do, in fact, have significant manufacturing capabilities there. I stand corrected.

More on LightSail Energy

Image credit: Cody Pickens, Wired.co.uk

It's difficult finding post topics if I insist that they meet certain criteria: can't take so long to research and write that my family/work/school life is disrupted; must be something about which I have some level of knowledge and the ability to do sufficient research and investigation to post intelligently; must be something that I think my (very few) readers will find to be interesting; and must not simply parrot something someone else said (other than the clear links to other sites with, perhaps, a comment).

But it's clear that LightSail Energy and, in particular, Danielle Fong are of interest to the sort of person who may follow my blog. I posted an article about Ms. Fong and her firm a few months ago and was surprised to receive a Tweet from her. In the interchange that followed, she was kind enough to agree to show me LightSail's facility should I be in her area. As it happened, this week I had a meeting with another firm (to be described in a subsequent post) at UC Berkeley. LightSail is located in Berkeley and Ms. Fong, despite being jet lagged, agreed to show me around.

Because her Company is in a developmental stage and I was simply a visitor, I felt that it would have been inappropriate to photograph the facility or record Ms. Fong's replies to my many questions so readers will need to take my word for what I saw and heard. I mentioned to her that I would be completely respectful of any proprietary information, she said that she was ok with my mentioning pretty much anything (though, on two occasions, she asked that I be circumspect). I want to be, if anything, overly cautious in this regard.

My first impression was that LightSail's facility looked very much like a prototyping facility. They have a large machine shop with CNC machining equipment, a robust metrology lab, assembly areas, and design facilities. There's certainly no hint of "vaporware."

Image Credit: Progressmedia.ca

Since I have a machine shop in my garage and my Company has a large amount of material testing equipment, I was surprised that, while seeing the facility and the components being assembled was fascinating, Ms. Fong's answers to my endless questioning were even more interesting.

As one can find from various biographical sketches (Fong's autobiographical sketch is here), her educational background is that of a physical scientist and LightSail certainly incorporates this background into its business. But, as our conversation continued, I was compelled to ask how much of her working time is spent on: politics; fundraising, mechanical engineering issues, science, and management. Her answer, unsurprisingly, was that "it depends" but I got a strong impression that it's less science and engineering these days than it is management and fundraising.

I asked Fong about her plans with respect to commercializing the technology. It's clear to me that LightSail can't be a manufacturer, at least in their present facility. She said that they do have the ability to produce a limited number of systems, using components from various vendors and others that they produce internally. I'm rather skeptical of that aspect.

In discussing field implementation, Fong mentioned that LightSail has three sites currently in their backlog. One of them has been mentioned in other news articles, she didn't name the others. I'll certainly be looking forward to following the development of these projects.

Fong responded to my questions about some somewhat negative press regarding some layoffs at LightSail by stating that the need for these layoffs was more operational than financial in nature. She believes that LightSail is a stronger and more efficient firm as a result. As a partner in a mid-sized business, I can certainly acknowledge that this is plausible.

I asked Fong about the merger between two firms, General Compression and SustainX, that could be regarded as competitors in the area of compressed air energy storage (CAES). She generally disregarded the viability of SustainX's system (though SustainX also claims to use water during the compression process to attempt to approximate isothermal compression, one key to LightSail's technology). Among other things, Fong mentioned the sheer size of the SustainX system as being non-viable. Reading between the lines of the various articles discussing the proposed merger, it appears as though Fong is correct as it seems that SustainX will not move forward with above-ground storage (current CAES systems store air in underground caverns, typically salt domes, and General Compression follows this model).

On the political and policy front, surprisingly to me, Fong was not enthusiastic about LightSail's participation in California's energy storage mandate. She is of the opinion that the commercial marketplace is the best filter for storage technologies. Fong mentioned to me that someone from the Department of Energy asked her what policy initiatives might jump start a sound energy path for the U.S. Fong answered that immigration reform would top her list, pointing out the very strong representation by immigrants in successful startups. She pooh-poohed tax reform.

Fong mentioned on several occasions that many of LightSail's technical personnel come from a background in auto racing. While I was surprised to hear this, in thinking about it further, it makes sense. Racing is a world of extremely demanding performance of mechanical components under great pressure and where innovation in mechanical design can win the day (a good driver and lots of money help too). Fong introduced me to a couple of these mechanical technicians in front of a huge valve (perhaps 60 centimeters in diameter) that was likely a titanium alloy with a titanium nitride coating.

I asked Fong about the time frame her firm's investors anticipate for a so-called "liquidity event," i.e., for them to see a financial return on their investments. These investors include Vinod Khosla's "Khosla Ventures," Bill Gates (needs no hyperlink), Peter Thiel, Total Energy Ventures, and now, apparently, Chinese VC firm Haiyin Capital, and others. She replied that they all have a relatively long investment time frame and that LightSail does not feel pressured to deliver an immediate return on investment (though she did mention a couple of very specific time frames).

Finally, we spoke in general about the need for storage and the wastefulness of burning fossil fuels (ultimately limited in supply, fracking, sands, shales, etc. notwithstanding) to generate electricity when various renewable sources can ultimately meet our needs. LightSail's technology, along with many other developing storage technologies, can make this possible by overcoming the inherent intermittency of wind and solar to enable these sources to provide "base load power" and reliable peaking power (though some will argue that the need for base load power is a myth). Following the progress of LightSail Energy will be fascinating, combining my interests in energy, thermodynamics, entrepreneurship, and finance.

Note for the video below: LightSail's technology involves removing the heat (poor thermodynamic phraseology, I know) during compression of air with a water mist and reusing the heat either during expansion or for building heating, process heat, etc. Danielle Fong seems pretty "rad" to me, so "Cool It" by She's So Rad seemed a perfect fit.

OK, enough negativity

There's no doubt that I've spent a lot of keystrokes pointing out things that won't work or won't live up to their hype, from solar chargers to harvesting of kinetic energy. And, while I have posted favorably or at least neutrally on a few things, I seem to have had more fun debunking than bunking.

So I'd like to spend a bit of time discussing what appears to me to be a promising technology and one that, if it fulfills its promise and comes to fruition, would be a potential game changer.

It's no secret that I'm of the opinion that, whether for the reason of the finite amount of fossil fuels available to be exploited ("peak oil") at prices that can sustain an economy or for the reason that the extraction and burning of fossil fuels for energy results in the release of massive amounts of CO₂ and other greenhouse gases, we need to reduce and ultimately eliminate our reliance on fossil fuels for other than production of products needing their chemistry (almost everything really, from pharmaceuticals to plastics to fertilizers).

Thus, I want to see the increasing penetration of renewable energy for all purposes (including transportation). For a couple of the leading candidates, wind and solar, intermittency is a big issue (though others will argue that it's not such a big deal). This is the case not only because intermittent sources will, on occasion, generate more energy than can be used and not enough at others, but also because the grid relies on very fine adjustments of both energy and frequency.

So, what is required to solve this issue? Without a doubt, the ability to store solar or wind generated electricity at times when supply exceeds demand would be outstanding. It would also enable renewable energy to be supplied at a steady rate.

There are a variety of technologies for grid scale storage of electrical energy:

• Pumped hydro
• Compressed air
• Batteries (various varieties, a promising type for this use is the "flow battery")
• Molten salt, hot oil, etc. in solar thermal plants
• Power to gas (e.g., electrolyze water to produce hydrogen for fuel)
• Others (see here)

I want to look at compressed air energy storage and a startup called "LightSail Energy." Their concept is to utilize a variant of compressed air energy storage ("CAES"). The idea is that, typically, compressing air heats the air and, when the air is stored, in cooling the air

loses much of its total energy. LightSail adds a fine mist of water during compression. The water (with its very high specific heat) absorbs the heat of compression and the hot water is stored for process heat or whatever. Then, when the air is utilized, heat (either from the original heating or elsewhere), is added so that the escaping air, which cools upon expansion, has increased energy to be utilized in the piston compressor/expander. So the idea is to use the renewable source to compress air, remove the resultant heat with a water mist, store the hot water for use in a heat exchanger, add heat when the air is discharged through a turbine piston expander. A schematic drawing from a LightSail patent application is to the right.

It should be noted that there are other firms out there using other media to capture and reuse the heat of compression of air in energy storage systems, one such is Energy Storage Power Corporation who uses oil for this purpose. A schematic diagram of their process is at left.

LightSail's Chief Scientist and one of its founders is Danielle Fong. Fong is a prodigy who dropped out of junior high school at age 12 to attend college, from which she graduated at 17. She was accepted into a Ph.D. program at Princeton but dropped out (or took leave) to move into something with more immediate applicability in the energy field than plasma physics.

There are a LOT of videos out there with Fong carrying the flag for LightSail (see here, here, here, here, and here for examples). She's photogenic, is "aww shucks" humble, wears interesting clothes, and what media outlet doesn't love an attractive female child prodigy Ph.D. candidate dropout who's founded a startup that can be stated in the blurbs to have the potential to "change the world" (and, as can be seen in the intro photo at the top left, I'm not immune)? One thing I respect about Fong is that, in articles about her firm, she'll address naysayers directly and without obfuscation in the comments.

LightSail claims, I would assume potentially, a round trip thermal efficiency of 90% and shows a working 200 bar, 250 kW prototype (200 bar is about 20 mPa (megapascals) (and, by the way, can one nest parentheses in textual material?)) at a one-way efficiency of 71%. 

LightSail's Technology page (interestingly, the landing page for the site) describes smaller "Power Units" of 250 kW power and "Storage Units" of 750 kWh capacity, clearly highlighting the distinction between rate of energy delivery (250 kW in the "Power Units") and storage capacity (750 kWh "Storage Units"). When I simply assume an ideal gas and evaluate the work that can be done by isothermally expanding [edit: a cubic meter of compressed air] from 300 bar (about 30 mPa) that LightSail is aiming for and ignoring the work against the atmosphere, about 48 kWh is available and so 30kWh certainly seems realistic if a close approximation of isothermal expansion can be achieved. Long term storage, though, will require lots of thought and engineering with respect to the thermal energy carried off by the mist.

According to Fong, LightSail's storage technology is capable of storing and delivering 30 kWh (kilowatt hours) per cubic meter of storage space. Thus, we can infer that the 750 kWh Storage Unit will occupy 25 cubic meters. For reference, a standard shipping container (to the extent that such a thing exists) has a volume of 38.5 cubic meters. Ok, how much is 750 kWh? At my house, my family of four uses electrical energy at the rate of, on average, about 2 kW (embarrassingly enough) or about 1,460 kWh/month. So these 750 kWh would last me a bit over half of a month at my house. My Company's headquarters laboratory facility uses, on average, just short of 750 kWh/day. That facility has about 15 people working there. I don't have (and LightSail probably does not have, though I can't imagine that they haven't made some estimate) any figures on what such a Storage Unit will cost.

The California Public Utilities Commission (CPUC) has mandated that the State bring 1.325 gigawatts of storage on line by 2020. So, at 30 kWh/m^3 storage capacity, how much volume would be needed to meet this mandate? Infuriatingly, there's no way to know! California uses electricity at an average rate of about 34 gigawatts, so 1.325 gigawatts represents the ability to deliver a bit under 4% of the State's electrical energy but there's no way to know for how long. The state has said 1.325 gigawatts but did not (so far as I can find) mandate capacity so there's no telling how long the systems to be implemented could deliver these 1.325 gigawatts. An hour? A day? I've posted on this frustrating situation before.

Such details aside, LightSail has discussed storing the compressed air in underground caverns for utility scale storage and that's a VERY big step up from a 750 kWh Storage Unit. But with funding from Vinod Khosla's VC firm, Bill Gates, Peter Thiel, and Total Energy, there's a fair amount of confidence in LightSail.

A deeper excursion into the thermodynamics of this system will follow and I believe that that will shed light on possible integration of such a system into our generation/transmission/distribution system. My initial feeling is that it's likely to be most useful for such things as frequency regulation rather than solving the intermittency problem thwarting confidence in the wide scale implementation of solar and wind generated energy.

I'll acknowledge that the only connection between this video and LightSail is the word "Sail." But I just wanted to use any excuse to embed this song. It's hard to believe that it's the Beach Boys.