A few weeks ago, I was attempting to run Cat 6 UTP cable for gigabit Ethernet from our house to the garage in a pre-existing conduit. After a very frustrating attempt involving a fishtape, various strings, a flashlight, and lots of scrambling around in the crawlspace under the kitchen, I was convinced that it was not possible to pull the cable through all the corners in the crowded conduit without damaging the cable. My next thought was, “I need . . . cable . . . lubricant. I bet that exists.” A quick trip to McMaster yielded 7431K41, a quart bottle of Ideal industries’ Yellow 77 Plus cable pulling lubricant.

The next weekend, I re-pulled a new cable slathered in Yellow 77 Plus. The force required was reduced by an order of magnitude. I was gleeful.

Anyway, I just wanted to help distribute global knowledge a little more evenly: cable pulling lubricant exists! Also: gigabit Ethernet to the garage!

Due to an unlikely confluence of world energy trends, my interest in engineering, and the internet, lots of people ask me how they can get my job as a renewable energy engineer. Most of them don’t want my job literally, but they do want to work on the engineering side of renewable energy. I generally don’t mind answering that kind of question, but I’m busy enough that I thought it would be worthwhile to summarize my answers to the basic questions. I realize that this will probably make more people email me rather than fewer, but at least we’ll be able to skip the first few questions; the efficiency of the world should be slightly higher.

What do I do first?

Try as hard as you can to perform engineering immediately. If you can get an internship or an entry-level job, do it now. Your employer will wish that you had waited until you had more skills, but that’s their problem, not yours. Do not wait until you have completed engineering school– you might hate engineering, and school is expensive in time and money.

People hate engineering?

Yes, they do. Engineering is the impossible job, never completed, too complex to understand in full, always held up by details, perverted by marketing, unending in unexpected wrinkles. Years later, you realize your approach was wrong. Plus, it’s boring.

You should assume that engineering is not the right job for you. You have to be indoors almost all of the time. You must sit at a desk and use a computer most of the day. Most of the results of your labor will be thrown away or, if you’re lucky, recycled for the next design. You will be asked to resend spreadsheets to people who will not understand them. If you aren’t truly obsessed with solving hard problems, it’s not for you. If you cannot artificially sustain your interest in dry topics, it’s not for you.

Yeah, yeah. What if I can’t get a job right away?

There are two second-tier classes of tasks: figuring out whether engineering will satisfy you and learning basic engineering skills. If you pay attention, you can figure out whether engineering satisfies you as you develop your skills.

If you want to be a mechanical engineer, you have to learn a CAD program like Solidworks. It is extremely likely that your first job will involve a lot of Solidworks. You might end up using Proengineer or Catia rather than Solidworks, but most renewable energy companies are startups, so Solidworks, the cheapest of the lot, is most common. If you’re well-suited for mechanical engineering, you’re probably already building stuff in your basement or garage or living room; model your next project in CAD before you build it.

If you’re leaning more toward electrical engineering, you have to learn to lay out circuit boards. The most common software packages for PCB layout among startups are, I think, Eagle and Altium Designer (formerly known as Protel). Eagle is popular because the free version is legal, but Altium Designer is more powerful and pleasant to use. Lay out a simple PCB and send it to AP Circuits for fabrication. For $50-100, you’ll have your first set of PCBs.

What else do I need to learn?

Even if you want to be a mechanical engineer, you have to learn the basics of electronics. Read chapters 1-4 and 6 of Electronic Circuits and Applications by Senturia and Wedlock, even though it’s from 1975 (thanks to Max Davis for the recommendation). Other people will recommend The Art of Electronics by Horowitz and Hill; I think Senturia and Wedlock is much clearer. If you can take a class where you get to take a soldering iron, that’s a great step, before or after reading about the topic.

You also have to learn some kind of computer programming. The languages you might learn include: C, C++, Java, C#, Python, PHP, Javascript, Perl, and Ruby. I’d start with Python or Ruby, especially if you have no programming experience. If you have any interest in embedded electronics, like the brains in battlebots, you need to learn C. If you hate or fear computers, learning to use LabView is probably your best bet.

You should also learn how the internet works. Reading the chapter 1 of Richard Stevens’ TCP/IP Illustrated, Volume 1, is a good start. If that goes well, read chapters 2-4, 9, 11, 14, and 17, plus the Wikipedia page on HTTP. I’d also recommend reading C. J. Date’s Database in Depth. If you make it halfway through, you’re ahead of most database programmers.

That sounds like a lot of work.

No, it doesn’t. That sounds like what you want to do with your spare time anyway. If you don’t want to learn this stuff, go do something else. There is a lot of work in the world that needs to be done; engineering is only the optimal solution if you’re obsessed with engineering or bad at optimization. We need good dentists, scientists, nurses, welders, luthiers, lawyers, and cheesemakers as well. Especially the cheesemakers.

But what about engineering school?

You must go to engineering school. It will take 1-5 years, depending on your background and what school you go to. There is a very slight chance that you can gain enough proficiency in engineering to make it without engineering school, but it’s much more likely that you won’t have the skill or discipline to teach yourself engineering faster and more cheaply than engineering school would. You can probably learn basic mechanics of materials or some math on your own, but learning advanced topics on your own is painful and slow.

For renewable energy, make sure you pay attention during thermodynamics and heat transfer. You need to take a statistics course as well.

No, you should not get a PhD.

Wait, you’ve barely mentioned renewable energy.

Renewable energy engineering is a broad field. The major skill you need is the ability to understand the physical principles that drive complex systems. For example, when someone says to you on the street, “I have a remarkable new device that will allow this skyscraper to capture all the energy it needs from the wind or sun,” you listen politely. You do not need to know the details of the geometry of their vertical axis wind turbine or their solar concentrating lens because you know that the power density of wind and solar energy flows is 100-1000 times less than the power density of a skyscraper. When they have stopped talking, you ask them what power density they expect to reach. They stare at you blankly, and you can continue on your way, certain that you have not missed an opportunity.

Even when you are not turning down equity opportunities on the street, you should expect your engineering to run in a pattern that starts with the application of broad principles. Once you have an approach that can work in theory, you develop the details.

Beyond a broad engineering education, you need to learn the basics of solar, wind, and biofuels, plus or minus whatever you’re interested in.

I’d start with Vaclav Smil’s books:

• Energy: A Beginner’s Guide
• Energy at the Crossroads
• An excerpt from a 1999 Smil book, hosted, probably illegally, by Jeff Feddersen at NYU

Then I’d read in the subject areas.

Solar: Applied Photovoltaics by Wenham, Green, et al.
Wind: Wind Turbines by Erich Hau is outstanding.
Biofuels: Ahindra Nag’s book is at least decent.

So I just read books for years?

No. As I said at the outset, most important is that you start engineering right away. Build something today, and measure whether its performance is in accordance with theory. The renewable energy field is rife with crackpots; we need well-educated engineers to solve our worsening energy problems. Get to work, now.

I don’t know a damn thing about jatropha oil.

Some time ago, I heard that a friend of mine was starting a biofuels company that would import jatropha from Africa and turn it into biodiesel. At the time, I was skeptical of the plan. “Jatropha? What the hell is jatropha? Your feedstock is something I’ve never heard of– how plentiful can that be?”

The next day, I was in the MIT library reading renewable energy journals, and I noticed an announcement that a 15 MW combined heat and power plant run on jatropha oil was under development in Belgium.

It’s a little late, but I wanted to let the internet know that I was wrong, and my dear friend Jesse was right. I don’t know a damn thing about jatropha oil.

I am excited to report a personal engineering milestone: something I had a hand in designing is visible from space. In the picture, the item of note is long, skinny, horizontal, and white.

I wasn’t the lead designer, I didn’t build the thing, and I can’t say what it is, but the first iteration CAD model created of this thing was made by me.

I hope it is not interpreted by aliens as a message. “__” is not as friendly a welcome as I would like to give to our new overlords.

I’m taking notes at the 4th Annual Conference on Clean Energy in Boston today; I figured I might as well share what I learn with the world.

The Massachusetts Technology Collaborative has funded MTPV, a start-up in the Boston University Photonics Center, with $500k. (I think this is actually not news to the world, but it was news to me.) MTPV has an interesting technology. Their scheme is a variation on thermophotovoltaics (TPV). In conventional TPV, you put a very hot plate next to a solar cell. The cell absorbs the radiation coming off the plate, allowing you to get electricity from heat. Unfortunately, the efficiency is quite low. MTPV does the same thing, but with the hot plate ridiculously close to the solar cell. Their claim is that when the gap between the cell and the hot plate reaches the micron level (the M in MTPV is for micron), the efficiency increases dramatically, and they have some test data to prove it.

Maintaining a consistent micron-scale gap is a mechanical challenge. They do it by putting small bumps on the surface of their hot plate and then clamping the plate to the cell. They have some clever geometry that minimizes the heat transferred through the bumps, as that is also an efficiency loss.

Investment pitch #1
Srikanth Gopalan from Boston University described a “solid oxide membrane” which takes in waste and steam and emits syn-gas and 7 cc/min of hydrogen gas per cm^2 of membrane. Dr. Gopalan and his colleague Dr. Pal have three year plan that requires $500k per year for device testing and scale-up by 2011.

Investment pitch #2
Scott Faris, CEO of Planar Energy Devices, says that Planar is making metallic lithium batteries. 4x capacity and 10x lifetime, 80% cost reduction. Doesn’t catch on fire like metallic lithium batteries used in cellphones in the past. There are no liquids in their batteries. They bury the lithium anodes under solid glass electrolyte. Faris says that Planar is using “the Miley Cyrus strategy,”– the best of both worlds– using thin film technologies, but scaling up to the size of prismatic batteries.

Planar has two products in development at present: a small battery called the PowerPlane: 25 x 29 mm, 12 mAh, and the larger PowerBlade, 100 mm by 100 mm, 4.8 Ah, 520 Wh/L. The PowerBlade is being tested by the military at present. Planar is pursuing Series B funding for pilot production.

Side note: Faris followed the irritating standard of the battery industry and quoted capacity in amp-hours rather than watt-hours. Amp-hours is not a measure of energy capacity, but of the number of electrons that can be induced to flow out of the battery. For example, a 1200 mAh NiMH battery contains around 20% less energy than a 1200 mAh alkaline battery because the NiMH battery runs at ~1.2 V, while the alkaline runs at ~1.5 V.

I suspect that this amp-hours habit developed because lead-acid battery manufacturers wanted to hide the fact that their voltage dropped as the battery discharged, making the amps that come out near the end of a discharge cycle less powerful than the amps near the beginning. If you speak in terms of amp-hours, you can avoid this embarrassing truth. Generally, modern batteries have a much flatter discharge curve, so watt-hours ends up being a linear multiple of amp-hours. Modern batteries have much less to hide in this regard, though there is still the variation across chemistries to account for. Nonetheless, the habit persists throughout the battery industry.

Investment pitch #3
Andrew Dillon, CEO of Varentec, described their solid-state electronic transformer that operates at 20-50 kHz. Dillon claimed that their transformer is 10x smaller and lighter than those of competitors that operate at 1 kHz, and costs 25-40% less. Undersea transmission, as required of offshore wind turbines, requires DC for efficient operation; photovoltaics also produce DC, so making transformers will be a lucrative business in the next few years. They want $1M for their first 1 MW high-voltage DC system, which they hope to build in 8 months of 2009.

Investment pitch #4
John Thomson, President and CEO of Yield Energy. They are a biogas developer. There are already 5000 biogas plants in operation in Europe, but no utility scale plants in the US. They use expired food products from grocery stores and waste from restaurants as their feedstock. Negotiated exclusive rights to proprietary pre-processing technology from Fitec in Germany. They have 6 sites currently under development; the first is near Toronto, Canada.

Investment pitch #5
Chris Sauer of ORPC started with a bold statement: “We have saved the best for last today.” They’ve raised $2M and have recently tested their kinetic tidal generator in the Bay of Fundy. The systems are “horizontally-mounted cross-flow turbines” that look like helical Darrieus windturbines or Gorlov turbines on their sides. The turbines are made of composites and foam so they float. They tie the turbines down to the sea floor for operation and release for service. Unlike their competitors in New York, Verdant Power, they have no cantilevered blades. Sauer says they can get 250 kW per bladeset in a 6 knot current; 1 MW in a module of 4. He claimed their costs are 6-7.5 cents/kWh for a location with a peak current of 6 knots.

If all goes according to plan, their first module of 4 bladesets will be installed in Q4 2010. Their first commercial installation will be in Q4 2011 in Western Passage up near Lubec. ORPC has raised $4.5M so far; they’re hoping to close Series A funding $10M in Q1 of 2009.

One of their competitors, Natural Currents, also had a table in the expo hall.

Somerville locals Second Wind also had a booth in the expo hall. (Disclosure: my employer has worked for Second Wind.) They make various tools for measuring how much wind is available in different places. Their latest product, the Triton (540 kB PDF), looks like a megaphone the size of a dumpster, pointed at the sky, with a solar panel bolted to the side of it. The thing is absolutely amazing. It emits sound waves at a slight angle from the vertical. The reflections that come back are Doppler shifted, and staggered in time. The frequency shift is proportional to the air velocity and the delay is proportional to the height. They can change the direction of the signal, so they can tell wind direction too. Their range is around 160 meters. This is so much better than setting up a tower with a bunch of wind vanes and anemometers. I predict that these guys will own the market in a few years.

So that’s how I spent my morning. The rest of the day was debugging a PLC in a warehouse.

After a little bit of work and screwing around with installers, I have programmed an FPGA for the first time. I wrote a short bit of Verilog that creates a 4-bit counter in a Xilinx Spartan 3A FPGA. Now, when I feed the FPGA a 50 MHz square wave on a certain pin, it counts the rising edges and outputs the count on 4 digital lines. Of course, it has to start over when it gets to 15.

The oscilloscope screenshot below shows the two highest order bits counting up in binary in response to the input signal.

Counting at 6.25 MHz

This may seem like a stupid way to spend your time– who needs a 4-bit counter? You may be right.

However, the theory is that one skilled enough in Verilog might be able to develop not just a 4-bit counter, but, for example, a microprocessor with a custom co-processor designed for ephemeris calculations (or whatever calculations suit you). In reality, it’s more likely that I would buy the Verilog to make the microprocessor and then just write the custom math processor myself.

It may prove a useless skill, but it definitely makes me less worried that some 14-year-old cyborg is going to make me obsolete in the next 45 minutes.

Sharon and I recently moved to a new house, which resulted in a switch from Speakeasy DSL to RCN cable. As a result, we now have a TV signal coming into our house. Strangely, I don’t think I have ever lived in a building with a cable connection, except for a 6 month stint in graduate school when I was busy enough building robots that I don’t remember what room my roommates had the TV in.
But now, I get to explore television as a visitor from the mid-80s. Here’s what I remember from 1984 or so:

• The Jeffersons: a show about a family with the last name “Jefferson”
• Rhoda: a show about a woman named “Rhoda”
• The Dukes of Hazzard: a show about a family with the last name “Duke” who live in Hazzard County. To liven things up, these Dukes engage in hazardous motoring in an orange car. This makes the name of the show a pun.

Now, show titles are abbreviated: CSI, ER, 24, NCIS. I don’t know what these shows are about, but from the ads I’ve seen, they’re about law enforcement and medical emergencies. We now have multiple editions, like CSI: Miami and CSI: New York. There appear to be a lot of shows about law enforcement, but that may be just an illusion induced by shows with opaque titles like Naruto (from a tv.com summary, I gather: a demon fox, an evil spirit trapped inside a baby, and “shinobi,” which is a word I don’t know). With the exception of the evil spirit trapped in the baby, which is creepy, these are trends that I expect to see in America, the land of the fearful, where Sarah Palin gets airtime. I’m happy to report that despite 150 channels, I don’t feel like I’ve missed much in the last 20 years.

However, I did discover something new that I didn’t expect: the glorification of the mistreatment of kids. One instantiation is “The Principal’s Office.” Pitched as a reality TV show on TruTV (I guess “tru” is the reality TV version of “true”), the episode I saw followed a high school principal around the halls as he caught kids beating on each other. The kids were taken to the principal’s office, where he yelled at them, and the kids squirmed in a mix of resentment and embarrassment. It’s obvious that the presence of a camera escalates the conflict between the kids and the principal, so we can safely assume that the goal of the show isn’t to document a good principal at work. All that leaves is a man yelling at kids. The “man yelling” part doesn’t bother me in the least, but I don’t like the “at kids” part. “Hey, troubled kid, if you let us humiliate you on national TV, we’ll give you $200.” (Review from the Boston Globe with some more details.)

The second show is one on FuelTV called Camp Woodward. It’s a thinly disguised advertisement for a sports camp in Pennsylvania that focuses on skateboarding, BMX and rollerblading. In the episode fraction I saw, one of the counselors explains that when he’s at home in Florida skateboarding by himself, he doesn’t throw tantrums, but when he’s trying to teach kids to skate, if he can’t land tricks, he gets angry and swears. Another section of the show details the tribulations of a 13-year-old who thinks his $100 for food has been stolen by rollerbladers. After being berated by his mom via cell phone, he finds his money in his shorts pocket. He repeats the lesson that he has learned that you should deposit all your money at the camp canteen as soon as you can, lest someone steal it.

Both of these shows mystify me– I don’t understand why suffering kids are now fair game for entertainment.

Morbid prediction: a reality show with the following theme will be produced in the next decade: life of a child soldier or life in a refugee camp. I think that’s the bottom, and I don’t see what else is going to stop us.

A gentleman by the name of David Fisher has been getting some attention (examples: WSJ, New Yorker, Inhabitat) by describing his design for a new building in Dubai. It would be best for the world if bad ideas like these were ignored and forgotten, but without some knowledge of engineering, it’s not obvious that his ideas are bad.

Fisher’s tower is like a shish-kebab on a vertical skewer, where the skewer is an elevator shaft and the food are the apartments. Each apartment can rotate around the elevator shaft. This alone is perhaps impractical, or ugly, or dumb, but not impossible. If you could find a wealthy fool who wanted to build this, you could probably pull it off.

Where Fisher crosses the line into territory that I defend is with his claims about renewable energy. He says that there will be a wind turbine between each apartment, and solar panels on the roof of each apartment. According to his website, the building will “generate electricity for itself as well as other nearby buildings, making it the first skyscraper designed to be self powered.” As Walter says in The Big Lebowski, “OVER THE LINE!”

Before we even look at the available energy closely, we can be certain that it won’t work. One of the central problems of renewable energy is its low power density. According to the ever trusty Vaclav Smil, wind and solar typically yield 1-10 W/m^2; skyscrapers require in excess of 1000 W/m^2, (Energy in Nature and Society, pp. 311, 317). But perhaps Mr. Smil is wrong. Let’s take a closer look.

Judging by the drawings of Fisher’s tower (since removed), it would be about 300 x 50 m. Ignoring the narrowing of the tower as it rises, roughly 20% of the area is devoted to wind turbines. That’s around 15000 x 0.2 = 3000 m^2. (Fisher has described two versions of the tower, one at ~300 m with 60 floors, another at 420 m with 80 floors. Here, I analyze the shorter of the two.)

Fisher claims that the average wind speed in Dubai is 16 km/h, or 4.4 m/s.

Assuming a Rayleigh distribution for the wind speed, the average power available as kinetic energy in the wind is (6/pi) * 0.5 * (density of air) * area * (average velocity)^3.

The density of air is 1.2 kg/m^3.

That’s (6/3.14) * 0.5 * 1.2 * 3000 * (4.4^3) = 290 kW. If the wind turbines were 30% efficient, which would be pretty good for a vertical axis turbine stuck in a building, the yield would be 100 kW.

This ignores the narrowing of the building, the lack of wind near the ground, and obstruction from other buildings.

The building has around 50 m * 50 m * 60 floors = 150000 m^2 of floor space, so the areal power density is about 0.67 W/m^2. Say a room is 5 m in a side, so it has area of 25 m^2. That gives you 17 W per room.

But let’s not leave out the solar power! Fisher claims that 20% of each roof will be exposed to sunlight. On average, then, if photovoltaics yield around 1 W/m^2, we should expect a power density based on floor area of 0.2 W/m^2, which is another 5 W per room, 22 W total. That might be enough to light a single compact fluorescent light bulb in each room.

Oh, and the average temperature in Dubai is 27 C. I guess they can run the air conditioning when all the lights are off.

I should end by saying that I share Mr. Fisher’s enthusiasm for renewable energy. My concern is that his tower of epic fail gives the work that I spend all day on a bad name. We should be building wind turbines and installing solar panels as fast as we can, but we should do it in ways that optimize their performance. Put the solar panels where they will never be shaded by the floor above them, and put the wind turbines on ridgelines where the wind is strongest. Integrating turbines and panels into buildings with the expectation that they will produce energy to spare is moronic.

(And all you energy reporters should be ashamed of yourselves for repeating Fisher’s void claims without any skepticism. That means you, Paul Goldberger and Evelyn Lee!)

Here are a couple little code excerpts that took me some time to figure out. I’m hoping that Google might help the rest of the world’s MSP430F2012 programmers save 5 minutes. (If they all find it, a total savings of 55 minutes!)

The MSP430F2012 defaults to a clock speed of 1 MHz, sourced from an onboard DCO. In order to get the DCO to be accurate, you have to load calibration constants from flash.

BCSCTL1 = CALBC1_1MHZ; // DCO calibration: set range
DCOCTL = CALDCO_1MHZ; // DCO calibration: set DCO step and modulation

Then you can initialize the timer to count in increments of 100 ms.

TACCTL0 = CCIE; // CCR0 interrupt enabled, compare mode
TACCR0 = 50000;
TACTL = TASSEL_2 + ID_1 + MC_1; // SMCLK as source; divide by 2; up mode

Anyway, I hope this is useful to someone out there.

Philip Taubman had an interesting article on the front page of the New York Times yesterday: “Top Engineers Shun Military; Concern Grows.” The article profiles an engineer by the name of Paul Kaminski who worked for the Air Force designing planes for several decades. Kaminski now heads a task force that is attempting to deal with the difficulties the military is having recruiting engineers. According to Taubman, the number of engineers working for the Air Force has decreased 35-40% over the last 14 years. The reasons cited for the decline include:

• better pay in high tech firms
• more cachet at Google or the like
• more engineering students from foreign countries who can’t get security clearances
• lack of exposure to new technology in the military

Strangely, Taubman omits what I suspect, perhaps foolishly, is the central cause– top engineers are driven to solve problems. As I consider the central problems facing the world today, I do not notice an alarming lack of weapon systems. The US military is already extremely good at killing. If you’re really a top engineer, you can choose where to work. I can’t imagine why someone would be drawn to weaponry when there are so many obvious unsolved problems elsewhere.

As an interesting footnote, the article gave no hints of what Mr. Kaminski’s task force will do about the lack of people willing to carry out the jobs they have in exchange for the salaries they offer. One solution might be to stop trying to build so many damn weapon systems.

I have told my sons that they are not under any circumstances to take part in massacres, and that the news of massacres of enemies is not to fill them with satisfaction or glee. I have also told them not to work for companies which make massacre machinery, and to express contempt for people who think we need machinery like that.

–Kurt Vonnegut, Slaughterhouse Five