"The cure for boredom is curiosity. There is no cure for curiosity" - Commonly attributed to Ellen Parr. It explains why I've never been bored.

## Sunday, August 30, 2015

### A box of rocks?

I've blogged on a few occasions regarding energy storage, most recently a "LightSail Energy redux" (though I'll be updating that in the near future to revise an inaccuracy with respect to LightSail's ability to produce commercially in their existing Berkeley facility). But there are lots of ideas for storage out there, from molten salt to bags of air beneath the sea and many others. But a new one caught my eye not too long ago that seemed out of cloud cuckoo land.

The firm touting this technology is Heindl Energy and their concept is to cut an annulus around rock and space beneath the rock, thereby creating a rock mass piston in a rock mass cylinder. Water would be pumped in to lift the rock when excess energy (or cheap energy if arbitrage is the name of the game) is available and let the rock descend, pumping the water through turbines when energy is needed or expensive.

The idea is that the piston diameter is equal to its length, and it would be raised and lowered a length equal to its radius, so half or more of the piston would always be beneath the ground surface.

One claimed advantage is that, unlike pumped hydro or underground compressed air energy storage, the geological feature necessary for the storage is more easily found (though, obviously, they can't be built just any old place).

Another is that the density of rock is greater than that of water and so a smaller volume of rock is needed for a given potential energy availability (though the factor is only about 2.5 or so).

It's easy to show that the available energy, ignoring efficiency losses of various kinds, is $E=(2\rho_{r}+\frac{3}{2}\rho_w)\pi gr^{4}$  where $\rho_r$ is rock density, $\rho_w$ is water density, $\pi$ is, well, $\pi$, $g$ is the acceleration of gravity, and $r$ is the radius of the rock piston. Note that the length of the piston is $2r$ and the height to which it's raised is $r$. Thus, the storage available scales with the fourth power of the radius. But, since construction is really all about the surface of the piston, it scales approximately with the square of the radius. So, in this case, size truly matters!

A bit of an issue is that the Heidl site "Idea & Function" page gives the energy as $(2\rho_r\frac{3}{2}\rho_w)\pi gr^{4}$. I'm sure it's a typo and I've emailed them to mention it but still, it doesn't lend confidence. Nevertheless, I used Wolfram Mathematica to check on the validity of the table shown on that page and it's actually conservative. They claim efficiency of 85% but I have to reduce efficiency to 57% or so to hit their numbers. Update: I received an email from Dr. Eduard Heindl recognizing the typo and stating that it has now been fixed. Dr. Heindl agreed that such an error on the technical page should not have taken place.

Unlike many storage scheme sites and descriptions, Heidl limits their discussion to quantity (gigawatt hours) and doesn't, as far as I could find, discuss power (the rate at which energy can be delivered by such a system). Both metrics are, of course, crucial and this site has the opposite of my typical frustration. They also provide no discussion of any load following capabilities.

We're talking here about a very large project. Using their numbers, 8 gigawatt hours of storage requires a 125 meter radius piston (250 meters or over 2 1/2 football fields across). Such a piston would weigh about 35.2 million (short) tons! To lift it would require water pressure of about 64 bar (though their table shows 52 bar).

Such pressures would demand a lot from the seals between the piston and cylinder walls, otherwise, the system would act as a 250 meter diameter circular fountain! Heidl discusses the seal system here and it appears to be quite innovative (a rolling seal against, apparently, a steel cylinder sleeve) but I see no indication that a pilot plant has confirmed that it will work. The devil, as always, is in the details.

Finally, how many? If a single 250 meter diameter rock piston can store 8 gigawatt hours, what is required to provide stable delivery from renewable sources so that the need for fossil fuel burning base load, spinning reserve, and peaker plants can be minimized with increasing penetration of intermittent renewable sources? According to Heidl's site, Germany currently needs 1,600 gigawatt hours of storage, of which only 40 have so far been provided. Therefore, Germany currently needs 195 such storage facilities!

In the Q & A, Heidl estimates that the system is of comparable cost to pumped hydro storage at a radius of 100 meters, and less expensive above that due to the scaling factors mentioned above. They also estimate a minimum of 2 years of planning and 3 to 4 years of construction per facility. And my experience is that the grander the scale of the project, the less likely it is to meet budget and schedule estimates. And this has never been tried.

While I think that it's a long shot that this type of system will ever see widespread use, the bigger picture is the scale of the undertaking needed to provide sufficient storage for deep grid scale intermittent penetration regardless of the system used. I think that distributed generation and local storage are key to providing a sustainable energy future through renewable sources.

Note: R.I.P. BB King.

## Friday, August 28, 2015

### While I procrastinate in writing about more important things...

Physicists (one of which I am not) are quite concerned about units and dimensions and use dimensional analysis for a variety of purposes. And if the units in an equation don't match in all terms and across the equals sign, you've erred.

But sometimes this can lead to confusion. For example, torque (exerting a force about an axis) is measured in dimensions of [force]*[length]. It could be pound feet or newton meters or, for the matter of that, dyne centimeters or ton furlongs. But work and energy are also measured in such units. A joule is a newton meter.

Thus, in thinking about my fuel economy as a U.S. resident, I'm accustomed to thinking of miles/gallon but in countries who've adopted the SI (metric) system, people make a very sensible inversion of this and, rather than distance/volume, they use volume/distance, typically liters/100 kilometers. While this isn't an SI unit, it is metric.

But it's also a volume divided by a length or [length]^3/[length] which is [length]^2 or an area. So I converted my 50 m.p.g. to an area to note that my fuel economy is 4.704*10*10^(-8) m^2 or 0.04704 mm^2. Next time someone asks about my fuel economy, I'm going to say "a bit over 47 thousandths of a square millimeter."

It's not surprising to note that Randall Munroe*, of xkcd fame, has beat me to it. I will state, for the record, that I noted his post after composing all but this portion of this one.

*This is the first time I've noticed a photo of Munroe. It always amazes me how little resemblance there is between what I picture someone to look like in my mind and what they actually look like when I see them or their photo. And I always picture them.

## Sunday, August 09, 2015

### Kunstler gets serious

Typically, I ignore James Kunstler and, in fact, I posted the reasons for this. And this is despite that fact that I agree with many of his positions, particularly with respect to the exigency of our energy situation. But his bombastic prose, his need to reuse the same symbols of his disdain for modern U.S. culture (tatoo parlors and tatooed people, suburbs, cars, etc.) to the point of exhaustion, and his extreme repetitiveness finally caused me to stop reading him except on an occasional basis. And, on these occasions, it was the "same old same old."

But Kunstler's most recent post  in his "Clusterfuck Nation-Blog" is different. He doesn't rail on about tatoos, cars, suburbs, salad shooters, cheez doodles, banker boyz, etc. He states without bombast the things that he believes a sitting and any future U.S. President should do and the reasons why. I find it to be compelling and accurate.

I'm sure that I'm far to the conservative side in comparison to Kunstler, but as I've posted repeatedly, the idiocy, ignorance, obstinacy, and intransigence that passes for conservative thought these days disgusts me. The positions taken by Kunstler should be celebrated by true conservative thinkers. He deplores the security state, the militarization of police forces, the thievery engaged in by the financial sector, the revolving door in Washington, DC for lobbyists, cabinet members, congresspersons, etc. between government and private interests, Citizens United, the state of perpetual war and foreign adventurism, etc. A true conservative should applaud every one of these and I do.

Further, Kunstler points out that not one candidate, announced or otherwise, has adopted any significant fraction of these positions, from the buffoonish Trump and the supercilious slime-ball Cruz on the right to the self-appointed rightful heir Clinton and the daft Sanders on the left.

Do I think that Kunstler's post, let alone mine, will move the populace to demand better? No, even though I believe that most would agree with the grievances that Kunstler suggests be "nailed to the White House gate" (though I suspect that anyone approaching the White House with a hammer and nails would be whisked off to Guantanamo at best and shot at worst, particularly were that person to not have the attribute of being caucasian - full disclosure, I'm caucasian).

Kunstler typically generates several hundred comments to each of his posts, this one is no different. Reading them is a somewhat sadder experience, there's a lot of "eat the rich," "burn it down" comments which serve no purpose. But I understand the frustration exemplified by such sentiments.

I don't guess that this deviation from his usual smug, self-satisfied, and precious cleverness indicates a new seriousness, but I'll check tomorrow (his posts come out on Mondays). It's well worth the five minutes it takes to read.

## Saturday, June 06, 2015

### 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.

## Sunday, March 22, 2015

### Your car goes 3.5 m.p.h.?

John Michael Greer, the Grand Archdruid of the Ancient Order of Druids in America, publishes a weekly post at his site, The Archdruid Report. Greer is a much deeper thinker than I, particularly with respect to the interplay between past, present, and future. He describes his area of thought as the "history of ideas," and his grasp is broad and deep, regardless of whether you agree with him or not. A steady diet of The Archdruid Report would certainly depress me, though Greer does not strike me as depressed. He's certainly "cocksure" though, in the sense of certainty of his conclusions.

Nevertheless, I read his posts from time to time and invariably find them thought provoking. Today, in reading his post entitled "Peak Meaninglessness," I found him citing Ivan Illich from "Energy and Equity" (available as a free pdf download) contending that
"Illich’s discussion focused on automobiles; he pointed out that if you take the distance traveled by the average American auto in a year, and divide that by the total amount of time spent earning the money to pay for the auto, fuel, maintenance, insurance, etc., plus all the other time eaten up by tending to the auto in various ways, the average American car goes about 3.5 miles an hour: about the same pace, that is, that an ordinary human being can walk."
Is it true? If it is, does it have any meaning? Since, for reasons that should be obvious, I'm not interested in using my personal financial details for such a calculation, I'll posit an American household earning the median income of $52,000/year. The household consists of a husband, wife, and two children. The husband works 2,000 hours/year and earns$40,000 and the wife works 1,000 hours/year and earns $12,000. As an aside, this family doesn't live in Southern California. The average hourly earning is thus about$17.30/hour. Of course they'll only bring home, at best, perhaps $14/hour after taxes. I'll assume two cars traveling a total of 26,000 miles per year with an average of 1.2 people in the vehicle for 31,200 passenger miles per year. The vehicles average 25 m.p.g. and gas costs$3.80/gallon, so they spend about $3,950/year on gas. One car is a relatively new (say, two years old and purchased for$29,000 on a five year loan at 5% API with 20% down) five passenger sedan. The monthly payment is around $440, or$5,280/year. The other is a minivan on a three year lease with monthly $3,000 at signing and$300/month lease payments, or $3,600/year. They paid$8,800 up front to have the vehicles but, since interest rates on money market investments are close to zero, the opportunity costs are quite low, so I'll use the up front cash divided by the respective term in months. This adds about $2,160 to the annual total. The total to finance the cars is$11,040/year.

They take the vehicles in for scheduled maintenance a total of eight times per year and spend $300 each time (sometimes less, sometimes more depending on the service required by the schedule). The total is$2,400/year.

This family has decent driving records and no teen drivers so the annual insurance premium is about $1,500. The grand total (leaving out car washes, aftermarket accessories, etc.) of annual expenses is$18,890. Wow, that IS a lot of money! Now, this $18,890 takes 1,350 hours (45% of their working hours) of this family's time to earn. So the final result is in: 26,000 miles/1,350 hours is about 19.25 miles per hour. This is about 5.5 times faster than Illich's estimate. So the answer to the first question, "is it true?", appears to be "no." The second question is not so easily answered. The entirety of this family's lifestyle revolves around the vehicles. Without them, it's unlikely (though certainly not impossible) that the$52,000 would be earned. And, while a vehicle undoubtedly constrains them financially, it also enables them to do many things that would otherwise be difficult or impossible. A vehicle-free lifestyle is certainly possible (I've lived such a lifestyle at various times and for various reasons), but this family has decided that the tradeoff is worth it. I WILL say, however, that they'd have been much better off with different vehicle choices. Another way of saying this is that I believe I've made assumptions that are generous to Illich's claim as repeated by Greer.

### Eating energy

In round numbers, there are 7 billion people eating on planet Earth each day. It's pretty clear that my diet here in Southern California is very different from that of a subsistence farmer in Namibia or a subsistence fisherman (or fisherperson) in Madagascar. It's also true that, as a fully grown adult of age 60, I probably consume more calories than my one year old grandson. But I estimate that my daily intake is on the order of 2000 kilocalories per day of food energy and I don't think that long term survival for an adult is possible on much under 1000 kilocalories per day. Of course, not all humans are adults and estimates of population in each quinennial group are available from the UN. Still, for rough estimates, 7 billion people consuming 1000 kilocalories per day will work.

Thus, in raw terms, this equates to humanity ingesting food energy at the rate of 7*10^12 kilocalories per day or about 10 "quads"/year (for some reason, lots of analysis of world primary energy is done in quads, where a quad is 10^15 or a quadrillion btu(a so-called "short scale" quadrillion)). Of course, the amount of chemical energy in our food as measured by bomb calorimetry exceeds this number since we cannot oxidize 100% of the mass that we ingest, the unburned residue leaves us in ... various ways... ahem. And we certainly don't ingest 100% of the food plants we eat. Further, many of us eat the meat of animals who have ingested the plants, or even the animals who have eaten the animals who...

But, in my simplistic model world, I'm going to estimate that 20% of the mass of a food plant is edible, that we burn 50% of it for energy, that meat represents 20% of the kilocalories consumed by humanity, and that the "hit" on losses due to an animal intermediary is the square of the losses inherent in eating plants directly. Thus, 10*0.8*P+100*0.2*P=C where P is the available kilocalories of "primary burnable energy" ("PBE")and C is kilocalories ingested as metabolizable food energy. So we have that 28 kilocalories of PBE are required for every dietary kilocalorie in this model.

So, we're now talking about 28*10 or 280 quads per year in photosynthetically created PBE. Depending on the plant species involved, the efficiency of using solar energy to convert carbon dioxide and water to biomass is in the range of 3% to 6%. I'll use 5% since it makes the arithmetic easy, and thus 5,600 quads of solar energy per year are needed to feed us. Let's move to SI units: the 5,600 quads are 5.9*10^9 terajoules and 5,600 quads/year are 187 terawatts.

This energy comes, of course, from the sun. There are approximately 14 million km^2 or 14*10^12 m^2 of arable land on our planet so, on average, each arable square meter must be responsible for converting (5.9*10^9 terajoules)/(14*10^12m^2)=422 megajoules/year or an average rate of 13.4 watts of incoming solar energy into ingested food energy.

And, as we see in the graphic at right, this is something like an order of magnitude away from the total incoming energy absorbed by the surface of the Earth. While I've looked at other articles that come to different conclusions about solar energy embodied in our food, I'd be shocked if I were off by an order of magnitude. The lesson? There's not a lot of spare capacity in our system for squandering our biota's ability to feed us.

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## Sunday, March 01, 2015

### Rob's aphorisms

There have been a few seemingly simplistic or tautological things that I've incorporated into various situation analyses.
1. If something's wrong, something's wrong. This is a conclusion reached jointly by my closest friend Dr. Captain Right Reverend Frank Hanna (Frank is second from right in this photo from 2000 of the Northern Arizona University Department of Geography and Public Planning), may he rest in peace. It came to us during flying together but has wide applicability in business, at home, and elsewhere. For example, I'm flying at 11,000 feet density altitude, power is at 27" manifold pressure and 2,400 r.p.m. I usually get 142 knots indicated airspeed in this situation, today it's 132. "Huh, oh well, la de da." 10 minutes later: "Oh $*)^%*, I forgot to put the flaps up." If something's wrong, something's wrong. 2. If it did, then it can. Frank was a professor of geology and took students on field trips, sometimes to map geological features. Students would look at, measure, and map some feature, scrunch their brow and say "but can it do that"? Answer: If it did, then it can. 3. If they are, then they do. I got my start in the business I'm now in via performing inspection of various facets of building construction. I'd see some very shady things apparently involving various quid pro quos (quids pro quo?) between contractors and construction managers (who ostensibly represent the interests of the owner of the development). A newer inspector would say "Do they really do that"? If they are, then they do. 4. Everything is dramatically more difficult and complex than you thought it would be, even when you allow for things being dramatically more difficult and complex than you thought they would be. This applies to everything from installing drywall or toilets to welding to applying conservation of momentum to a dynamics problem. Self explanatory. Now, along with always assuring that you're wearing clean underwear (about which I wrote a song decades ago, motivated by a friend who said she couldn't bring herself to commit suicide because she didn't want to be found in her unkempt apartment), applying these should come close to assuring a smooth sail through life's various meanders. You're welcome. ## Sunday, January 18, 2015 ### California's storage mandate solved! This post won't be the first time I've expressed my annoyance with the California Public Utilities Commission over their storage mandate of 1.325 "gigawatts of storage" (scare quotes because this is already mixing apples and oranges - it's analogous to saying "65 miles per hour of distance") by 2020. The linked post gives my more detailed thinking, but this one is just a quickie to bring home the inadequacy of only giving the rate of delivery of electrical energy in the mandate with no reference to the period for which this energy could be delivered. It's obviously (as you'll see) an extreme, but I can meet the mandate as stated for a bit under$2M!

How? A photographer's flash unit takes electricity and stores it in a capacitor. When it's triggered, it quickly (quickly is the key here) discharges the capacitor through a flash tube. Here, we see the Elinchrom Pro HD 1000 flash unit. It can discharge 1000 W-s (photographers use "watt-seconds" but a watt-second is just another name for a joule) through the tube in 1/1430 second. This rate is 1000 watt*second/(1/1430 second)=1.43MW (megawatts). To get to 1.325 GW (gigawatts) I need 1,325/1.43=927 such units. I can purchase each for $1,049.88 ($964.88 if I order no later than January 31) for a total of \$973,238.76. Of course, that doesn't include shipping and some rewiring, so double it.

Now, these units are set to power flash tubes but there's no requirement for that. They simply store energy and discharge it quickly. So, wired in parallel, they could supply the 1.325 gigawatts for about 2/3 of a millisecond. Problem solved!

Of course, the total energy delivered is a bit lacking. It's the 1000 joules*927 Elenchrom flash units=927,000 joules or a bit over a quarter of a kilowatt hour. Still, it meets the mandate and I bet I can have them delivered this year, beating the deadline by some five years.

It's rather shocking to me that our esteemed CPUC has managed to put this mandate in
place with no reference as to capacity. I will agree that rate is important (as I mentioned in the post linked above) but it's foolish to not also include capacity. However, I'm speculating that they aren't even aware of the problem. They are, after all, political appointees and, among the five of them, only Carla Peterman appears to have any sort of energy related experience or education. Mostly, it's attorneys. This is, after all, California!

If you know anyone from Southern California Edison, Pacific Gas and Electric, or San Diego Gas and Electric, please don't tell them. I want to get a good earnest money deposit on my simple solution to their storage mandate woes.