Disqus - Latest Comments for daniellefong

Re: LightSail’s Secret Plan to Slash the Costs of Compressed Air Energy Storage

Danielle Fong — Wed, 29 Apr 2015 15:10:11 -0000

No the Caterpillar engines weren't cheap to develop, and we've raised more than $62 million dollars, because our compressor and tanks aren't too cheap to develop either. But the market for energy storage is going to be in the tens to hundreds of billions of dollars, so if you can pull it off an have a good approach it's a worthwhile trade.

Interestingly, sliding friction and wear, which you can never quite get to zero, still does decline exponentially when you decrease engine speed. This is an empirical relationship that's been discovered.

The presenter is cute but I think they overstate their remarks.

But the main thing that you should consider is that batteries are effectively moving parts. The electrodes literally dissolve and replete themselves every cycle. If sliding past something seems to you like a problem for wear and for lifetimes, imagine dissolving and replating it!

Unfortunately there's a fundamental challenge that battery makers have to overcome. If during the replating process they use a simple surface and the ions replate in a flat way, then you get low surface area, and hence high resistance, so you can't use it to get high power or you get very high inefficiency. If you use a complex surface with a lot of surface area for your electro, you grow filaments and tendrils with fractal complexity, and these again increase resistance because of the distance to the charge collectors, and ultimately they cause the mechanical failure of the battery. Most batteries choose the latter approach; the former approach is only useful for very long duration batteries.

Maybe some group will solve this, but for now it seems like we're rather lonely on our path to long lifetimes.

Re: LightSail’s Secret Plan to Slash the Costs of Compressed Air Energy Storage

Danielle Fong — Wed, 29 Apr 2015 15:01:19 -0000

First, thanks for sharing the love.

It's hard to make out because that's a photograph of a slide I gave, but the left most comparison is for lithium ion batteries at the projected cost and lifetime for 2020.

As Wayne Gretzky said, you've got to skate to where to puck is going.

Those cost projections are absolutely regulatory compliant, they are for tanks we have designed which are designed to (and shall soon pass, knock on wood), ASME certifications. They must withstand bullets, elevated pressure cycling tests, chemical attack tests, 60000 cycle tests, long term high temperature creep tests, low temperature tests, a test where you impact it with a 15kg steel pyramid, a test where you cut into it 40% of the wall depth and then cycle it 5000 times, etc.

Re: LightSail’s Secret Plan to Slash the Costs of Compressed Air Energy Storage

Danielle Fong — Tue, 28 Apr 2015 23:11:05 -0000

They also did not figure out how to make low cost tanks.

You are right enough to be skeptical of such numbers, of course it remains to be seen, and, for context, in the conference I made clear that this was risky, preliminary, and we were not there yet. Nonetheless, we have stated our intentions. Based on a hard headed analysis, we believe it is possible, and that we will get there. Since we're not public about that analysis, by all means be skeptical about whether we can do it. But it's silly to suggest that we just made up some number and put it in powerpoint. Emphatically not true.

Re: LightSail’s Secret Plan to Slash the Costs of Compressed Air Energy Storage

Danielle Fong — Tue, 28 Apr 2015 23:07:07 -0000

Yes, they are a very rigorous company and are quite serious about their commitment to better energies. There are not many oil companies that could even contemplate a $1.4 billion investment in a solar company.

Re: LightSail’s Secret Plan to Slash the Costs of Compressed Air Energy Storage

Danielle Fong — Tue, 28 Apr 2015 23:05:52 -0000

Hi Chris,

These are good questions. It's very important to have a system that is:

a) long lived (possible with maintenance or replacement or overhaul of some of the components)

b) reliable (i.e. either does not degrade suddenly, or degrades on moderately in performance but does not cease to function.)

c) maintenance is not overwhelming.

Automotive engines are a convenient comparison to compressors. However, there's a tradeoff between how hard you run the engines and their lifetime. You can get a very significant increase in engine lifetime by running it less aggressively; it is almost an exponential increase. Heavy duty diesel generators, which are intended to run very often and last a long time, use this strategy -- they stay well away from the effective 'red line' of an automotive engine.

If you look at diesel generator manufacturer like Caterpillar, with a strong reputation, you'll note operational intervals between 22500 and 33000 services hours between major overhauls (between 7500 and 11000 for cylinder head overhauls).

Here's a maintenance manual. https://safety.cat.com/cda/... They're pretty thorough; I'd be impressive if half of the owners do those checks at half the frequency, and many of the things they require for a checkup can and will ultimately be automated with sensors and an intelligent chip on the machine.

Importantly, in an overhaul, you're not replacing everything -- the bearings, gaskets etc. are checked and individual components are replaced if need be, but most of the parts and capital investments are preserved. Good shops can do a light overhaul in a day with a team of 4, and a heavier one in two days.

This isn't true for batteries. They degrade at a certain minimum pace regardless of how they are used, and the cells are degraded throughout the process and at the end of 8 - 10 years, must be scrapped or recycled.

Ultimately, what we aspire to is this: with semi-regular checkups, replacing the couple of wearing components, and not running the machine too hard, we can have machines operating for decades, as very many compressors and diesel gensets have done.

Re: LightSail’s Secret Plan to Slash the Costs of Compressed Air Energy Storage

Danielle Fong — Tue, 28 Apr 2015 19:38:08 -0000

I will readily accept that there's science risk in our secret plan. Not sure why that would piss me off, even slightly ;-)

Re: Layoffs at LightSail, Khosla-Funded Compressed-Air Energy Storage Startup

Danielle Fong — Tue, 17 Feb 2015 23:12:26 -0000

Impressive, but it's not a great fit for our tech!

Re: A lot of hot air? Why energy storage matters

Danielle Fong — Tue, 17 Feb 2015 23:11:59 -0000

It's a reciprocating piston compressor, mechanically like an engine.

We vary the valve timing, so that as the pressure drops, the valves open for longer and more air is added. The power stays relatively constant that way, and the efficiency stays high.

Re: Backed By Gates And Thiel, Danielle Fong’s Lightsail Sets To Revolutionize Energy Storage

Danielle Fong — Tue, 17 Feb 2015 23:10:48 -0000

Hello everyone, Danielle Fong (from the article) here.

This is cross-posted at http://daniellefong.com/201...

Thanks for the coverage and interest. This article slipped my notice, and it seems that there are some misconceptions I should clear up.

1. Why is energy storage so important now?

First, here’s the main point. The objective is to make solar and wind cheaper than power from fossil fuels, and available whenever it is needed. To do that, you need energy storage. Only since about 2004-2005 has it been broadly true that solar ad wind energy are cheaper sources than energy from oil. Now, economical energy storage is needed to make it available whenever people need it most.

2. What’s new about our approach?

Second, we know that Compressed air energy storage is not new!

But we’ve made several significant improvements to the state of the art that significant reduce the cost and increase the efficiency, and we calculate that this allows us to make stored solar energy cheaper than power from diesel fuel. That’s a very big deal, if we can do it.

Probably the most important advance is the reduction in cost. We’ve kept relatively quite about this, but we’ve developed the worlds lowest cost air tanks using composite technology. Though the fibers we purchase are more expensive than steel per pound, they are vastly stronger, and thus about 2-3x cheaper for the strength you get than steel. That’s an advance by our cofounder and CEO Steve Crane, and spearheaded by Dr. Neel Sirosh.

We’ve also reduced the number of cylinders needed. Previously, to compressed and expand to and from 200 atmospheres of pressure, you’d need at least 5-6 compression stages, and 5-6 expansion stages, and 4-5 intercooler heat exchangers in between the compression stages, and 4-5 interheaters in between the expansion stages. That’s a lot of equipment.

With our technology, we only need two compression stages, because we avoid many thermal problems by using water spray (more on that later).

The same compression cylinder stages can be used for expansion — the compression cylinders are also used to expand the air. This is what we mean by reversible.

3. What do we mean by “Our system is fully reversible.”

This refers to slide 3 in our main page / technology page.

http://www.lightsail.com

"OUR SYSTEM IS FULLY REVERSIBLE
To store energy, an electric motor drives an air compressor. To deliver energy, we reverse the process–the air compressor becomes an expander, and the electric motor becomes a generator.

Heat from compression is stored or routed to nearby buildings, providing heating. During expansion, heat is extracted from storage, or buildings providing air conditioning. This dramatically increases building energy efficiency."

Unfortunately, it has been confusing to people that we use the term “Reversible” in this context. Sorry about that. There is a specific meaning for reversible in thermodynamics, but we thought people would know that is not what we meant, since a thermodynamically, perfectly reversible system is impossible. We thought it would be clear that what we meant is that we use the compression cylinders as expansion cylinders, and the electric motor as an electric generator — that’s what the animation shows (see here, on the “Our system is fully reversible” slide, click the arrows).
Apparently, we have been confusing people! Sorry about that. Our mistake.

4. We figured out how to increase the efficiency dramatically

In previous attempts at compressed air energy storage, air got hot when you compressed it. Very hot. So hot that people had not figured out how to capture it practically. To store the air, they had to cool it, and they just rejected the heat to the atmosphere — turning it into waste heat.

Hot air is at a higher pressure * volume, all else being equal. So you have to expend more energy compressing it. Rejecting the heat means that the air decreases in pressure * volume, and you get less energy out when expanding. This effect was responsible for more than 50% of all of the efficiency losses of previous compressed air energy storage systems.

Our approach is:

a. injecting a dense, cool water mist in during compression to cool the air, keeping the energy needed for compression low,
b. holding onto the warm water in an insulated container,
c. and injecting the warm water mist back into the air, keeping the air pressure higher longer and increasing the energy you get back out

This has been very successfully demonstrated, and we’re getting better and better at it. Many people thought it was not practical (would break the compressor), or wouldn’t work (some thought the heat transfer would be too slow), but we’ve proven that it does. It’s still hard work ahead to optimize this and launch the product, but that’s the approach we’re using and it really works.

5. There’s more information online!

Lastly, there’s more information available.

Our website: http://lightsail.com/ gives more details.

This talk also should help. https://www.nantucketprojec...

Also, there’s a lot of patents, though the material is pretty dense.

—

I’m not going to go through all of the comments here, but if anyone has further questions they can ask me here in this thread or on twitter at @DanielleFong

Best,
Danielle Fong, Cofounder and Chief Science Officer, LightSail Energy

Re: A lot of hot air? Why energy storage matters

Danielle Fong — Tue, 13 Jan 2015 14:19:05 -0000

RE: Size, it's about 1 MWh per standard shipping container, once we get to 300 atmospheres (we're at 200 right now. )

Scaled to familiar scales, the average american home uses 30 kWh / day. That will take about 1 m^3, or about the volume of a small refrigerator.

We don't think the size is prohibitive, and neither do our customers...

Re: Layoffs at LightSail, Khosla-Funded Compressed-Air Energy Storage Startup

Danielle Fong — Mon, 11 Aug 2014 12:55:57 -0000

For other readers, some clarifications are in order:

- While I don't speak for Peter Thiel, I believe that his point is a valid one -- namely that the problems of sustainable energy cannot be solved by matters of sales or policy alone -- we need new technology also (perhaps mostly.) Historically new technologies has emerged primarily from startups and primarily from those run by genuine technologists.

- While we are very happy to be *invested in* by billionaires, this doesn't come close to granting us unrestricted access to their checkbook. We have every bit the challenge to be as efficient a company as we can be, hopefully so that they will choose to invest in us next time.

- While it was an incredibly painful thing for us to do, we had to make the changes required to be as efficient and lean an organization as we could be. The layoffs were very painful for us, but the reorganization was a success, and we are moving faster and more efficiently at lower cost than before. We should also note that the employees who we had to let go were given generous severance packages, and have had our support in finding new opportunities. They are great people and have been very able to find great new projects to work on.

- I can speak only for myself and my cofounders here, but I believe that everyone involved in the LightSail effort is genuinely motivated by making a difference in the world. Many of us have left vastly more lucrative and less risky positions to try to make this a success. Money is a means to an end. But building a profitable business and making cost effective technology is possibly the *only* means to the end of transforming the world's energy infrastructure. Unfortunately, that does mean that there are compromises.

Hopefully, other readers will recognize the difficulty and complexity of the situation, and might be helped in some way by this dialogue.

Re: Layoffs at LightSail, Khosla-Funded Compressed-Air Energy Storage Startup

Danielle Fong — Fri, 16 May 2014 14:02:18 -0000

Absolutely true. But Utilities started with those technologies slowly, by dipping their toes in the pool. Scale comes later...

Re: LightSail Gets $37.5M From Thiel, Khosla, and Gates for Compressed Air Grid-Scale Storage

Danielle Fong — Fri, 16 May 2014 04:34:47 -0000

There's pretty good evidence 15 minutes is not everything utilities want. Every grid currently dependent on fuel oil, from Hawaii to India to Japan, could save money by displacing it with renewables. To get well beyond a 20% displacement, you need storage, and long durations. That's a multi-billion dollar market.

Re: LightSail Gets $37.5M From Thiel, Khosla, and Gates for Compressed Air Grid-Scale Storage

Danielle Fong — Fri, 16 May 2014 04:30:00 -0000

Sorry about what was apparently a confusing graphic.

The efficiency values are cumulants. The graphic is attempting to show a process by which 70% of the electricity in becomes electricity out. That would be a very good efficiency value; one in which we aspire to attain, eventually.

Re: LightSail Gets $37.5M From Thiel, Khosla, and Gates for Compressed Air Grid-Scale Storage

Danielle Fong — Fri, 16 May 2014 04:28:29 -0000

That's a misconception; assets under management are not identical to returns. Most investors in hedge funds, and Clarium in particular, had to call back their funds due to the liquidity crunch during the crash in '08.

The relevant information: "Although the fund eventually recovered, with losses of only 4.5% for 2008 compared to the average of 20% for other hedge funds, most investors had already pulled out their investments. Subsequent down years have reduced the fund's assets under management to $681M as of December 2010.[4]"

http://en.wikipedia.org/wik...

Also, I believe you're using defraud in an improper manner. I *think* you're trying to accuse him of being a poor investor, which, measured by returns, he surely isn't, though just as surely there have been bad years and bad bets. Defraud means to obtain by deception, which I don't believe is your claim -- if it is, you have brought no evidence.

Re: Layoffs at LightSail, Khosla-Funded Compressed-Air Energy Storage Startup

Danielle Fong — Fri, 16 May 2014 04:20:43 -0000

This is actually a pretty decent note, trying to tackle a subtle subject.

I agree with much of, but not all of what you said. In particular I believe you are correct in saying that the key (if not dominant) reason for why conventional CAES has not spread was its geographic dependency, which not only limited where you can put it, but in so doing reduces the energy storage value significantly.

However I disagree with one critical part of the philosophy: comparison with simple cycle combustion turbines instead of combined cycle plants.

The justification is somewhat subtle, and many missed it, (including LightSail when we first started to analyze the value of the gas in conventional CAES)

The reason is the following: if the natural gas is not burned in the CAES system *and* there is an ideal, alternate storage system, it would be fated for a combined cycle gas system (most probably).

The heat rates of modern combined cycle plants are roughly in the range of 5700 - 7000

From this table 5 (page 9) in GE's literature.

http://www.physics.orst.edu...

When comparing against other energy storage systems, assuming that they could displace the vast majority of CT usage, it seems that logically, the combined cycle plant is a better comparison for the opportunity cost of that gas. The economic principle is to measure the cost of energy for the total energy system, and minimize it, fuel and all.

(I agree, by the way, that if there is no other comparison energy storage system, and you are comparing conventional CAES to a CT, then the previously outlined methodology you describe is reasonable).

---

I will say, however, that if you didn't use fuel to power your expansion, and you didn't have the efficiency gains that regenerative air energy storage (or, theoretically, adiabatic CAES) gives you, and you didn't have access to very large underground caverns, then it would be quite challenging to launch that technology.

---

My best guess for why conventional CAES hasn't taken off is that the scale of project is very large. It is a very big challenge to get utilities comfortable with such large project risk.

At LightSail, we hope that by starting smaller, we can build up a track record with many projects over time, before having to tackle the mega-projects that traditional CAES is slanted to.

Danielle Fong
Chief Science Officer
LightSail Energy

Re: Layoffs at LightSail, Khosla-Funded Compressed-Air Energy Storage Startup

Danielle Fong — Fri, 16 May 2014 04:00:37 -0000

Thanks for your interest.

Today the is no commercial system available for small scale mini-grids. You need to have a compressor and an expander, tanks, and heat exchangers, and a motor generator and power electronics.

Nobody packages these in a commercial product today -- we are endeavoring to make a 250 kW system to be piloted in a few installations next year, with a wider release the year thereafter. That is probably a larger system than you need.

Using the sea or groundwater as a cooling source is a good idea theoretically, and sometimes practically, for increasing efficiency. Some day we would work this into the system.

Likewise with direct wind compression. An interesting theoretical idea with a lot of potential, but considerable practical challenges in integration.

Ultimately all these things are possible, but we believe the right path is to make a focused effort on core technology before branching out.

Danielle Fong
LightSail Energy
Chief Science Officer

Re: Layoffs at LightSail, Khosla-Funded Compressed-Air Energy Storage Startup

Danielle Fong — Fri, 16 May 2014 03:48:47 -0000

Rumors of our death have been greatly exaggerated.

One must steer the ship before the iceberg is underneath it.

As for your point about subterranean storage, it is quite a good one. For very large storage installations, in the right geographies, caverns are a definite cost saver -- perhaps 30 - 50% of the overall project cost. But (a) it requires very large scales to be a cost saver, (b) it requires very specific geographies, and (c) it is not economically necessary.

In summary, we are not a failure, we will continue to try to not be a failure, and if we do ultimately fail, it would probably be for the considerable financial, organizational, and technological difficulties of launching a new energy technology -- not the tank storage vs cavern storage reasons you describe.

Danielle Fong
Chief Science Officer
LightSail Energy

PS: If you listen to Peter Thiel carefully, you'd note that he never said he was against cleantech, he said that it had largely been a disaster. We came to him with as case as to why, and a case as to why we'd avoid this. He admitted the case to court; today and for the next year at least, the jury is still out.

Re: Layoffs at LightSail, Khosla-Funded Compressed-Air Energy Storage Startup

Danielle Fong — Fri, 16 May 2014 03:47:54 -0000

While why you say is true, I will point out that we are neither killed, nor has thermodynamics had too much to do us refocusing the company.

The reasons to refocus are far more mundane; delays in procurement, mechanical development, and an anticipated rocky fundraising environment. It is the financial and organizational constraint, not the physical constraint, that we're laboring under.

Nothing we're doing contradicts thermodynamics --- and at the moment our thermal efficiencies are good -- albeit they still leave room for improvement.

Also, we do not usually play rock.

Danielle Fong
Chief Science Officer
LightSail Energy

Re: The Pollinator: Nell Waters

Danielle Fong — Fri, 11 Oct 2013 01:16:25 -0000

Doppatch zipline? I'm in.

Re: The Transformer: Danielle Fong

Danielle Fong — Fri, 11 Oct 2013 01:03:22 -0000

Many thanks to 7x7 for helping spread the good word, and to Robert Schlatter Photography for making me look gorgeous. It is all so kind.

For the interested, I told Christine Ryan that the distinguishing character of a truly revolutionary idea is the magnitude of it's unintended consequences.

Giving people control over their own power, I believe, is one of the most impactful and positive things I can imagine. But the side effects of the additional freedom and independence granted, I believe, will be as positive and important as they are almost impossible to predict.

Re: Danielle Fong - 40 Under 40: Ones to Watch - FORTUNE

Danielle Fong — Thu, 19 Sep 2013 20:18:45 -0000

I am beyond honored to be chosen for the spotlight by Fortune Magazine. On behalf of my team at LightSail Energy, I thank our investors, customers, and everyone who reached out and supported us in innumerable ways, big or little.

We strive to do you proud.

Re: Camus for Founders, Abridged

Danielle Fong — Sun, 19 May 2013 13:04:15 -0000

the absurd woman delights

Re: Entire Cities Could Run on Compressed Air

Danielle Fong — Sun, 11 Nov 2012 22:24:52 -0000

Cost of ten years of operation:

Providing power on demand, at a specific capacity factor, including operations and maintenance, energy cost, inefficiency, capital cost, and financing cost, for ten years.

Present-worth cost:

The cost to the present day. This includes the fact that there is depreciation over time, O&M and energy costs may change over time, etc. See http://en.wikipedia.org/wik...

Re: Entire Cities Could Run on Compressed Air

Danielle Fong — Sun, 11 Nov 2012 22:20:41 -0000

Seems pretty reasonable, but it's important to take a grain of salt with press releases. Ours too of course. Most importantly, we've yet to demonstrate low cost. Our materials costs are very, very low, but these are not the only costs!