David MacCay was a remarkable fellow. Curious and cross-disciplinary, he worked in applied math, physics and engineering research at Cambridge. Passionate about doing something about global warming, he happened to be a great communicator. I had a few interactions with him: first about thirty years ago playing with neural networks and later in the mid 2000s as he was putting together Sustainable energy – Without the Hot Air - probably the clearest book written on energy production and demand. You can still buy the book and proceeds go to support some good charities. David updated the book online until his early death in 2016. It's free online, but the printed version is a better experience.
The book is written at two levels - one for folks without a mathematical background and a somewhat deeper version that assumes an understanding of high school physics. David goes into depth building easy to understand models and then plugs in numbers from past and present technologies. The last step is where the book is flawed. Enormous advances have been made in solar and wind power technology and prices have fallen dramatically. A few of David's conclusions relevant ten years ago are now dated. For example he shows that wind power and solar are insufficient for the UK, even in an ideal world without existing infrastructure and bureaucratic inertias. The last two roadblocks still exist almost everywhere, but the underlying story has changed.
Brian O'Callaghan's group at THAT other English university have published an updated look at solar and wind energy in the UK and come to the conclusion that they are practical and nearly sufficient at scale. Here's the summary of their policy paper. Their technical papers are solid and thorough. I suspect Sir David would be proud.
In addition to getting an important update, there's an important lesson here. When describing current and future technology scenarios it's extremely important to lay down some clear thinking that is largely independent of current and future inputs. The basis of this type of scenario is really just a solid foundation that's waiting for inputs. It's rare to see ones that work twenty or more years in the future. David's did and does... it just needed updated inputs.
Several people have been in contact with questions about a new physics paper on a room temperature superconductor. It’s a big thing it’s real and if it can be developed into something practical. I skimmed the paper at first and then gave a more careful read. So here are a few early comments.
First the background. Superconductors conduct electricity without resistance, but there are caveats. The most useful ones need to be cooled to liquid helium temperatures. At normal atmosphere pressures that’s about 4.2 K .. really cold! (absolute zero is 0 K). Helium is very expensive, in short supply if you want scale and expensive to liquify and keep in a liquid state. LHe temperature superconductors are used in superconducting magnets that produce very high magnetic fields - physics experiments, maglev vehicles and MRI machines are major users. For the last 25 years or so we’ve had superconductors that work at liquid nitrogen temperatures. LN2 is comparatively inexpensive and fairly easy to handle. The problem is they don’t support high electric currents or magnetic fields.. There’s been a lot of focused research working on this with the best materials known as ReBCO (rare earth barium copper oxides) - there’s a largish family. They do support relatively high current densities and magnetic fields at liquid hydrogen temperatures. LH2 is between LHe and LN2 in temperature. It’s much cheaper than liquid helium. Currently the cost of LH2 temperature superconductors is about four times that of conventional materials in high field magnets. Getting down to the same cost would be a big thing.
There has been work on much higher temperature superconductors - some work suggested it could be done at room temperature, but at very high pressures. That was a couple of years ago, but there are questions with the experimental work and the very high pressure requirement makes it impractical. But if it turns out to be real, it could provide useful insight.
So onto the current paper. It shows superconductivity at and somewhat above room temperature (up to 400 K!) and at sea level pressures.
Reading the paper I see a number of red flags. It hasn't been peer reviewed yet. None of the authors is known in the field and they’re from an institute that doesn’t have a track record. Important discoveries are sometimes made outside of the field, but it’s VERY rare. They talk about critical (magnetic) field and critical current. Both numbers are extremely low - far too low to be practical. Also critical current doesn’t mean anything .. the right metic is critical current density. It’s not a typo .. their graph shows current rather than current density. More troubling is they don’t find a Tc (critical temperature).. they only state it’s still superconducting at 400 K. The fact they can’t make it go away raises red flags.
You also need to demonstrate the Meisner effect - the exclusion of magnetic fields - it gets technical, so I won’t go into details, but just noticing a drop in resistance isn’t enough. They do claim a Meisner effect, but their graph doesn’t show it. It looks like garden variety diamagnetism.
There are a few other technical issues, but I think I've made my point.
They offer a theory of what’s going on, but it’s ad hoc-ish. That’s not really a problem - an experimental result doesn’t need a theory. But why do they try? red flag.
It should be easy to replicate. Their technique strikes me as sloppy. It’s possible they’ve discovered something. We’ll know quickly as this should be straightforward to try and replicate. If it’s real and the magnetic field is what they show, it isn’t practical. It would offer a window into a different class of materials to try.
For now, color me skeptical. Extraordinary claims require extraordinary evidence. They don’t offer much in the way of evidence. I worry we have another Pons and Fleishmann paper. A big sin was P-F publicly claimed they had made a fusion breakthrough with cold fusion and the media jumped onto it. At least these guys don’t seem to be banging the publicity drum.
LH2 class superconductors may be very practical for many commercial applications in the next five to ten years. That’s a very important area that could become commercial soon. It would be even better if it can work at LN2 temperatures, but so far it’s been disappointing.
The opening ceremony of each Olympic game is filled with pageantry and sometimes, with the lighting of the cauldron, drama. In my mind the most electrifying occured in the 1992 Barcelona games when Paralympian Antonio Rebollo performed some serious diablerie.
Across the ocean in New Providence, New Jersey David and Mary watched the scene on a small black and white television as they shared pedaling duties. David was pedaling at the time and gasped. Fortunately there was a flywheel.
Their parents didn't allow television in the home, but both of them had been involved in competitive kayak and canoe events. Lynn had been an alternate for the Montreal Olympics. Introducing Mary and David to the Olympics was a good idea, but Al decided to make it educational. The kids would be given an exercise bike, a generator, access to a television and help from their mechanical engineer father and mathematician mother. They had a few weeks to work things out.
When the the friction wheel generator was finally adjusted and working, they were shown how much power they produced and how much power various televisions used. A twelve year old could keep a small color set going for a short time, but that was it. They wisely chose the black and white set. Through trial and error they ended up with a bicycle chain transmission and abandoned the exercise bike for one of their own on a homemade stand. They could now produce nearly twice the power for the same amount of perceived work. A flywheel was added to make everything smoother. They had something by the opening ceremony and the kids spelled each other off and developed an amazing sense of how long the commercials lasted. They saw the torch lighting.1
It's too bad they had a standard generator. Something with better magnets would have had increased efficiency. Not enough to move them into a color set (if they were a few years older and more athletic they probably could have managed), but certainly a better experience. The strength of the magnetic field in a generator or motor is centrally important. The strongest fields come from superconducting magnets, but they need to be cooled to near absolute zero rendering them impractical for most applications.
Electric vehicles use either induction or permanent magnet motors. The permanent magnet designs tend to be lighter and are more efficient.2 There's a rub. You're trying to optimize cost and magnetic field strength (among other things). Rare earths like neodymium work much better than the cheaper ferrite-based magnets and have generally taken over the medium and high end automotive market.3
The problem with rare earth materials isn't that they're rare .. they fairly comment. They are, however, unevenly distributed and difficult and toxic to mine and process. Most of the active mining and processing is in China and it's an environmental disaster. The US had a single mine in California in the fifties. Since then it's had t an up and down existence including being closed for economic and environmental reasons. With the interest in EVs it's back in operation again and the US has gone from 0% of the world's production of neodymium to about 15% in about seven years. In theory the mining and processing and safer and less toxic than the Chinese effort. Production should increase in the future. The US is also largely unexplored - serious mineral exploration has only just resumed after a 60 year hiatus.
The higher cost has some companies, notably Tesla, talking about going to ferrite permanent magnets. They'd be heavier, less efficient, but would be cheaper and may be the core of lower-end vehicles. Another alternative is to use a more efficient vehicle. Electric bicycles and other micromobility solutions use small motors. You can build 50 to 200 electric bike motors with the materials from one Tesla-class motor. Not only that these vehicles are very practical for the short trips that dominate much of our mobility needs. Sadly some areas have saddled themselves with transportation infrastructures that encourage inefficiency.
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1 Mary continued in the families sport tradition and went to Princeton on a fencing scholarship. She found she was interested in aeronautical engineering and went on for a Ph.D. I heard she had something to do with the rotor design on the Ingenuity helicopter currently flying on Mars.
2 There are often questions about how permanent magnets work. Most people have seen electromagnetic induction in school. A current flows if you move a magnet in a coil of wire and a current through a wire produces a magnetic field. Permanent magnets are more difficult to talk about .. I've done it at least once, but this short video is a nice intro.
3 There are other rare-earth based magnets, but a neodymium alloy is the most common. It's an allow of neodymium, iron and boron - Nd2Fe14B - that forms a crystalline structure. They have widespread use outside of EVs.. GM and Sumitomo Metals independently developed them about 40 years ago to get away from much more expensive and brittle samarium–cobalt magnets.
There's a lot of talk about tetrataenite (an iron-nickel structure) permanent magnets. In theory they have better magnetic characteristics than neodymium alloys and should be much cheaper, but they're off in the future. If they happen, expect some unhappy rare earth mining companies.
Once a year I read BP's Energy Outlook. They have a record of serious greenwashing, so anything from them (or the other fossil fuel companies) requires a bit of skepticism, but this year's report took a turn from the normal path. They suggest global oil demand peaked in 2019. There have been any number of 'peak oil' predictions, but most refer to extractable supply - a bit more on that later. While the BP predictions are more scenarios than rigorous predictions, it's significant that a large oil company believes oil demand is, and will continue to, drop.
BP outlines three scenarios: Accelerated, Net Zero and New Momentum. I'm guessing they'd prefer the New Momentum scenario, and will probably lobby and use other tactics to move in that direction, but the bottom line is they see less oil coming from the ground.
I think they're transportation modeling is too conservative. Electrification will probably take place much more rapidly than predicted. Granted there's a lot of inertia in fleet replacement given how long cars last, but the assumptions strike me as too slow. They don't seem to be taking into account the likely unbundling of transportation. Horace Dediu has been a big proponent of unbundling and points out most trips are local and short. [side note: you really need to follow Horace as well as well as David Levinson if you have any interest in the future of ground transportation] It makes no economic or environment sense to use a two ton car, gas or electric, to make a three mile trip. While much of North America has saddled itself with legacy transportation infrastructure and little imagination of what is possible, change is coming to Europe and it seems likely the developing world will favor very inexpensive electric micromobility solutions.
Back to peak oil. M. King Hubbert was a geophysicist with the Shell Oil Company in the 50s when he started looking at long term oil production predictions. All tended to make use of variables that weren't well pinned down. Hubbert's model was simple assuming once a discovery was made, production would increase exponentially as more resources and efficiencies are brought in. At some point a peak is reached and an exponential decline begins. The model can apply to any region, or groups of regions, assuming all of the discoveries are taken into account. It also assumes the impact of new technologies occurs at a constant rate.
On the extraction side the so-called Hubbert curve has accurately modeled many oil fields and regions - notably the US through about 2005.1 When dramatic new technologies appear - like practical fracking, shale and tar sands production, and computer guided drilling - you effectively add new sources. It's an interesting resource mining curve that's been used in many areas outside of oil production. Hopefully we'll move to a point where most extractable oil is left in the ground and oil exploration becomes a thing of the past.
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1 It may look like a Gaussian or Bell curve, but it doesn't die off as quickly. It takes the form
Three weeks ago breathless reports on the 'breakeven' fusion event at the National Ignition Facility began to appear. While a remarkable achievement, it's more a marker of progress along a long and difficult path rather than an event promising a hopeful turn in decarbonizing the energy supply.
Nuclear fusion has been hyped since the late 1950s. Fission based reactors turned out to be straightforward. All you had to do was refine uranium ore and then control a reaction to heat water and run an otherwise conventional power plant. The cold war led to any number of atoms for peace projects suggesting a nuclear everything future. The realization that nuclear fusion was much more efficient and "cleaner" than fission led to optimism and work on controlled fusion. After all, it happens all the time in stars doesn't it?
Power from nuclear fusion has been twenty years in the future ever since. Science and technology have made serious progress, but the challenges are great. There's also the issue of cost per kilowatt-hour. If you build a plant that produces more power than it takes to run it, will it be economically competitive with other low or no-carbon solutions?
There's a simple invention → development → application → change arc of technology mindset that doesn't describe the real world. It turns out you can travel a good distance along the arc only to see failure. The garage-worthy helicopter, supersonic airliners and dirigibles have all be built and commercialized, but have failed for a number of reasons that are likely to keep new versions failing for the foreseeable future. Somehow the dream factor persists in many of these and new failures continue to rhyme.
There are hugely successful inventions that have solved a problem, but turn out to have a deadly flaw that caused great harm. DDT, chlorofluorocarbons and leaded gasoline are obvious examples. Less obvious are inefficient transportation. Standardizing on 3,500+ pound vehicles to move people a handful of miles on average trips has led to millions of traffic deaths, a large pollution toll and a structuring of infrastructure and where and how people live that is proving difficult to change even though much better choices exist. Sometimes tend to fire, aim and then look for damage around the target. Sometimes it takes decades and change is expensive.
There are a wishlist class of inventions where some progress is made, but effective deployment is a long way off (fusion power plants) or unlikely as the underlying approaches are flawed at this point (self-driving cars, hyperloops, neural implants, space elevators, nuclear powered cars and airplanes, etc.)
It's very easy for an imaginative artist or writer to sketch an idea that is technically impossible. We have a tendency to sort through the chaff and find amazing predictions from a hundred years ago. It's useful to realize how much noise there is and that these things didn't happen in the author's or their children's lifetimes. Still - every now and again you run across something that stops you. This is one of my favorites - not only because it suggests wireless video communications, but it also nails the social element of two people ignoring each other so they can look at a screen.
Then there's a class of necessary arcs that we need to get past application and into wide-spread use. Flexible power distribution to move power from generation to where it can be stored or used. An advanced worldwide pandemic monitoring system. Water management and treatment to deal with changing local climates as well as use needs. More efficient agriculture that can deal with changing climates. Changes to transportation and housing infrastructures that are less damaging. Some of these aren't terribly sexy, but require social and political will - areas where progress is often very difficult. And in the background there needs to be investment in fundamental science. While progress can be difficult to predict, historically it's easy to predict that there will be unexpected discovery that can lead to something useful down the road.
It's fun to enjoy the stories writers and artists weave. Creating your own is a great way to work with the imagination of a nine year old on a rainy day. Time and interstellar travel won't come along with scores of other ideas that help move stories along.
The short version is it’s a remarkable technical and scientific achievement. Controlled human-made power from fission is easy - last week marked the 80th anniversary of the first reactor. Fusion - what powers the stars - is much more difficult on Earth. The necessary temperatures are far greater than those found in most stars. A star like the Sun gets away with a very slow and low power density reaction that would be impractical for generating power on Earth. It turns out the power density of the core of the Sun is about a quarter of your metabolic density and close to that of a lizard. To get around this different fuels are needed along with much higher temperatures. Still, if you can only figure it out, it sounds like the perfect goal - fuel from water and no radioactive waste.
The first serious attempt at magnetic confinement look place about 60 years ago .. it, along with every other effect until this last week failed. Those that achieved fusion required more input power than the power they produced. The figure of merit is Q: the ratio of the power of the fusion reaction divided by the power required to ignite and sustain it.
The laser confinement experiment announced focused a short pulse of light - about a billionth of a second - from 192 lasers onto a small gold container that vaporized to generate x-rays that collapsed a diamond coated fuel pellet of deuterium and tritium. The power of the laser light was 2.05 MJ (megajoules — a gallon of gasoline is 121 MJ, a hot dog in a bun is about 1.5 MJ) and the fusion explosion yielded 3.15 MJ. A Q of about 1.5. What isn’t mentioned is the efficiency of the lasers or the facility isn’t included - or the efficiency of extraction power from the miniblast. The lasers are less than one percent efficient so you can see there’s a long way to go.
This facility has been running for about a dozen years. It has been solving enormous engineering and applied science problems along the way as well as contributing to the pure science of understanding plasmas at this scale and temperature. Even the fuel pellets are very difficult to make and test. They have to be extraordinary symmetrical and most are rejected in testing - usable pellets are very expensive. What has been achieved is not a prototype, but rather a triumph of instrumentation technology along with the control of some difficult to manage parameters.
Moving this line of fusion forward seems like a long shot. A factor of five improvement may be possible with a redesign, but they need more than a thousand. Not impossible, but there’s a long path ahead.
There are other design types that confine microwave heated plasmas. Getting it right and working will take many years - probably decades and then there’s the issue of what does a facility cost compared to other types of power stations.
I hope work goes forward, but not at the cost of workable technologies that address global warming *now*. There’s so much that can be done, but very little political will.
Why are we paying someone to heat parts of our house we aren't in?
This was one of my Dad's deep questions. Two adults, two kids and three dogs in a small house subject to Montana winters. Cold snaps could be deep and long - a week or more with highs well below 0° F ( -18° C) weren't uncommon. More impressive were the lows: -30° F (-35°C) came at least once every Winter and record lows were below -40°. Dressing for it was a necessary skill. Inside the home my Dad controlled a powerful technology - the thermostat.
When people were around during daytime the thermostat was set to 62°. The nighttime setting, from 9 PM until the first person got up at about 5:30AM, was 55° If people were out of the house the setting was 52°. As far as I could tell these were his fundamental constants. Warm clothing, sweaters, quilts (my parents cheated and had an electric blanket) made it comfortable and sometimes even too warm. There was only one thermostat and a few areas of the house were always a bit colder or warmer. The dogs found the warmest regions at dog level. They also had warm blankets that they'd drag around where needed.
Since then I've learned a bit about home heating. Some of the best information on home energy measurements comes from England. They found standard modern construction homes see seven to ten percent energy savings for each degree celsius drop between 15° and 20° C . Lowering the thermostat setting from 70° to 61° (21° to 16° C) could translate to 30 to 40% reduction in your heating bill. It could also make a serious impact in places facing severe gas shortages this coming Winter.
There are other tricks. A big key is to heat the people and not the airspace where they aren't. We had a small, partly finished family room in the basement. We were there a lot during the Winter as it was the warmest room in the house. Four people and three dogs radiated body heat along with four 150 watt lamps in the ceiling and a small electric heater (pro tip -- if you have a male dog, don't put one of these on the floor). My Dad had a tendency to drop the thermostat to nighttime levels when we were down there. Most of our books lived there and a long work bench allowed my sister and I to work on homework and hobbies. There was a TV, but it didn't get used that much. It's where we told stories.1 In the Summer the warm rugs on the floor came up and the room was a naturally cool place to escape the heat of the un-airconditioned home.
The English studies I came across note the average English home was heated to 13° C (55° F) in 1970 rising to 20° C by 2000. Our house wasn't all that different from the average English house.
There are many other tricks for saving energy - insulation, heat pumps and so on, but they won't happen in Europe before this Winter for most people. Insulation, done improperly, can be a two edged sword. Forced air heating, the most common type in the US, fills the house with heated air. Insulation keeps as much of the heat as possible inside. The problem is that often the air is trapped inside. Stale air can be unhealthy (VoCs, high CO2 levels, etc.). There's a simple technology that can help - in fact you needn't look farther than your nose. Your nose is a heat exchanger. Cold air comes in and is heated up without releasing much of your body heat when you exhale. Most industrial buildings and some homes have heat exchangers - they're required by many building codes to keep super insulated homes healthy. Something to look into if your place is heavily insulated.
Localized radiant heat allows you to circulate some air from the outside and still be comfortable - you're heating people rather than the air. You've probably noticed Scrooge's chair, in many adaptations of A Christmas Carol, has a high back curved sides. These were common in the Victorian era.. sit in front of a fireplace and focus the warmth. People have experimented with heated chairs with good results - notably work at Berkeley in the past decade.2 (They also designed and tested cooled chairs for the Summer). People who live on the Japanese island of Hokkaidō modify the short legged Japanese family tables by putting a blanket over them and a small heater underneath. I've used one of these visiting a couple from Sapporo when they were living in NY and was amazed how well it worked in their otherwise chilly house. Teenagers like them for other reasons when their parents aren't home.
In short there are many paths to clever - no silver bullets, but a lot of silver buckshot. Twenty or thirty percent conversation levels are quite realistic for many people. I won't mention adventures in an unheated 15 foot trailer with three dogs at -25°F (my mother thought colder temperatures were dangerous)
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1 Nordic families seemed to tell a lot of stories. Our heritage isn't Nordic, but many of our neighbors were and some of that rubbed off on us.
Andrew Revkin and I had a brief exchange about the power of labels. Both of us object to the phrase "climate emergency." Even though it is an emergency that could escalate into an existential threat, people don't respond to labeling longer term threats as emergencies. I've been suggesting we've entered an adaptation epoch. Andrew, a much better communicator, is still searching.
The past two or three years have taught us short term temperature excursions can be dramatic. Last year the Pacific Northwest recorded previously unheard of temperatures - the highest in the area in at least 7,000 years and probably much longer. This Spring it was South Asia. Last week record heat came to England and parts of Europe. These events are probably going to be more common and time goes on and greenhouse gas levels continue increasing.
Wet bulb readings of 35°C (95°F at 100% humidity) have long been considered unsurvivable. A person in good physical shape would probably die in a few hours. Such events are extremely rare. Until the past decade they've only been recorded a few times and then only for an hour or so. They're increasing in frequency and length - mostly in the Indian subcontinent. Finding cooler spaces for people is a matter of life and death.
It's become clear the 35° number was something of a guess. Recent careful work shows it's more like 31° for young people in good physical shape. Older and compromised people have lower limits. The Tokyo Olympics had periods with wet-bulb temperatures in the upper twenties. Athletic performance during these periods was certainly compromised (I saw it happen to a friend).
What can be done? Cities suffer from heat island effects. All of the asphalt and concrete increases the local daytime temperature and holds them at higher levels at night. (hot nights may be harder on the body than hot days). Air conditioning helps, but it costs money and a power grid that not everyone has access to. Reducing the amount of asphalt and concrete while planting trees can make a big difference. It's a great justification for reducing the number of cars and roadways in cities (green spaces are a key motivating reason for the dramatic change currently underway in Paris). Unfortunately green spaces are usually linked to wealth. In many places racism and redlining have produced some of the worst heat islands.
There are other tricks that are easily implemented. White paint on roofs can make a difference. Paint that holds up to temperature and monsoons for the better part of a decade isn't cheap, but is becoming more popular. In Western countries more reflective shingles are appearing. Some of these look fairly normal, but are highly reflective in the infrared and can make a difference in cooling bills.
And you can send some of the excess heat directly to space.
If you're in a very dry area go outside on a clear night and look up. Feel the cooling on your face. Now hold a piece of cardboard between your face and the stars. You'll notice a warmer feeling. Remove the cardboard and your face gets cooler.
Your body glows - you've undoubtedly seen infrared photos and videos of people. We radiate photons at a variety of wavelengths, but it peaks around 9.5 microns - about twenty times longer than visible light. The atmosphere is transparent to visible light and also from 8 to 13 microns. Photons from our bodies can radiate to space. Deep space is really cold (a bit over 2° above absolute zero) so your face is radiating some of it's heat directly to space - enough that you can feel the cooling.
Clever material engineering has produced materials that are good at absorbing the heat around them and then radiating it into space. It's enough to reduce cooling requirements - at least in places with very dry atmospheres. There's still work lowering costs and making the surfaces last longer, but it's something else to try.
Back to the idea of an adaptation epoch. Many things will need to be tried and efforts will stretch for generations. There's enormous opportunity. It's both sad and dangerous there's so much 19th century political inertia, but I'm optimistic more clever people, organizations and governments will finally emerge. As a species we don't have a choice if we want to survive.
Patent reading is something I avoid as recreation. They're written in a humorless formal style that's perhaps a shade more entertaining than Vogon poetry. Sometimes you have to go through them trying to sort out the claims and their feasibility. I generally translate them into images and numbers I can understand in the process of plowing through. It was during that process that my jaw dropped. Someone had successfully patented something that was clearly impossible. It violated the underlying physics - the patent office usually catches these mistakes early on. Someone had already spent a fair amount of change. At least I could alert my client.
The patent was trying to harvest waste energy. That's all and good - more of it should be done, but it claimed to be more efficient that was possible.
A good deal of engineering is concerned with efficiency. The story of the steam portion of the Industrial Revolution amounted to increasing the efficiency of extracting energy from fossil fuels. Steam engines are a case in point. There was a huge need for them pumping water from mines and the early engines made an impact even though they were extremely expensive to run. James Watt and others came up with clever hacks and improvements continued for over two centuries. (The chart shows how much energy can be extracted from a kilogram of coal. The highest level corresponds to an efficiency in the mid forty percent region)
There are many forms of energy... heat, light, motion, electric, chemical, nuclear, gravitational , and so on. These are usually grouped into two types when considering how work is done: kinetic and potential. In general something happens when energy moves from one form to another. But what is energy? The dictionary and some high school science texts say it's the capacity to do work. OK .. so what's work? Dictionaries often say it's a measure of energy transfer when an object is moved. Nothing like circular arguments, eh? During the 19th century the definition was a point of contention in physics, but before going into that consider a roller coaster.
Roller coasters are great ways to explain the transfers between kinetic and potential energy. If there wasn't any friction or wind resistance you could start a car off at the highest peak and it would move around the track coming back to where it started. Gravitational potential energy would turn into kinetic energy as the car dropped and the kinetic energy would turn back into potential energy as it went uphill. Of course there is friction from the wheels against the track and air resistance. The wheels, axle bearings and track heat up, pieces vibrate, air swirls and sound is generated. If you add all of these up you can account for the total energy of the system. You might even be able to harvest some of these, but in general that's a difficult task.
Much has been and is being done on recovering lost energy. Regenerative braking in electric cars, using waste heat from power plants to heat buildings (combined heat and power), etc. Unfortunately there are limits to how much can be recovered. As the waste heat is closer in temperature to its surroundings, the less efficient extraction will be. This was a fatal error in the patent I looked at. It assumed air temperature was much colder than it really is.
Back to a definition of energy. Emmy Noether showed that for every conserved quantity in physics there's a corresponding symmetry and visa versa. Noether's theorem is central to physics. It's one of those things that makes you gasp when you first realize how it works. Among other things it shows time invariant processes are those that conserve energy. If you fall off a building at noon or two o'clock the result will be the same. Falling under the influence of gravity doesn't depend on time and energy is conserved. Unfortunately really diving in requires some serious math. You can get an idea of what's going one from this non-mathematical discussion by a physics grad student. So if you're curious and remember some high school physics:
In the meantime note that we waste an incredible amount of energy. Not only are we staring down the barrel of global warming, but paying for energy is expensive by itself. There's a lot of low-hanging fruit out there. The problem is often getting people to imagine.
There's a nice vantage point in Point Loma in San Diego with a monument to Juan Rodriguez Cabrillo. In 1542 he made the first contact with the indigenous people of the area. Not much happened, but sailing Northwards a few days later he noted smoke hanging over what is now Los Angeles. Enough that he called one of the bays Baya de los Fumos - Bay of the Smokes.
It's not clear what caused the smoke. The Los Angeles region hosts three types of temperature inversions, each capable of trapping air masses close to the ground allowing smoke to build. The region may have had one of the highest population density in North America in the 16th century, so it's possible the smoke was from thousands of fires - the region certainly held smoke in later centuries. It's also possible there were large fires in the hillsides fanned by Santa Anna winds.
Before WWII Los Angeles, apart from areas around chemical plants, had fairly clear air most of the time. That all changed after the war and by the fifties a thick brownish much often dropped visibility to a few blocks. The brown smog was different from either smoke produced by wood fueled fires or the smogs coal burning was know for.
While the LA area was a natural environment for temperature inversions, it also hosted centers of intellectual curiosity. A few years after the war Los Angeles decided to tackle the problem and created the first air pollution district in the country. Arie Jan Haagen-Smit of Caltech managed to figure out what it was by 1950. Sorting out how it was produced took a few more years. He was able to show eighty percent came from the automobile.
Caltech became a breading ground for ideas to deal with automotive smog. By the mid 1960s Haagen-Smit and others were thinking about modern incarnations of electric cars. Wally Rippel was a student fascinated by the idea of electrifying transportation. His aha moment came when he showed electrifying the automotive fleet would only require a twenty percent increase in electricity generation. (the number today is considerably less than ten percent). Wanting to move things along Rippel did what any Caltech student would do. He challenged MIT to a race.
The Caltech team added over a ton of lead acid batteries to an old VW van for the Pasadena → Cambridge trip, while MIT converted a Corvair for their trip to Pasadena. MIT finished about a day and a half faster, but they broke down several times requiring towing more than once. The van, on the other hand, just motored through without incident and were declared winners.
The 70s saw further development at several engineering schools. Recognizing batteries were heavy, Caltech worked on early hybrid cars that would drive short distances on power from smaller battery packs before starting up a gasoline engine. Along the way they develope regenerative braking to boost efficiency. The first energy crises hammered home the idea that efficiency was important. A Scientific American article appeared in 1973 telling the story of efficiency and declaring a person on a bicycle one of the most efficient forms of transportation in nature .. Steve Jobs later riffed on that calling personal computers bicycles for the mind. An electric bike would be about twice as efficient as a human powered bike. That led to work on motors and controllers. Unfortunately the American book disappeared and plans for a safe cycling infrastructure died. Electric bikes would have to wait a few decades.
In the 80s Rippel was working with Paul MacCready's AeroVironment, something of a Caltech spinoff, on a specialized, almost anything goes, solar powered car for the five day World Solar Challenge race in Australia. GM footed the bill for Sunraycer team and the car buried the competition. GM engineering worked with them and the collaboration continued. Learnings from the solar races went into new motor and controller designs as well as a recognition that aerodynamics were very important gave people the feeling something practical could be done. Enthusiasm within GM's engineering community talked the company into building the EV1 - the first production modern electric car . GM corporate didn't know what to do with it.. much has been written on how and why the project was killed after three years of production and extremely enthusiastic customers. Other than its batteries, the EV1 was more sophisticated than current electric cars.
Rippel and a few others from the EV1 experience founded AC Propulsion, building a demonstrator called the tzero. More a proof of concept, it was sportscar designed to impress wealthy tech types defeating a stream of Ferraris and Porsches along the way. Martin Eberhard tried to convince them to take it to production, but the jump in scale was too much for them. Instead he co-founded a company called Tesla well before Musk entered the scene.
Electric car history has many threads. I'm familiar with this as I heard bits and pieces in school and through people I know. The deeper story requires many more angles, but it's sticking how much can take place with just a few people.
I'm a believer in efficiency and infrastructure. Moving towards safe active transport (walking, cycling and e-bikes) offers a much greater improvement over conventional electric cars. (long story, willing to argue)
A bit of early history. International Rectifier funded a solar car project in 1960. Silicon solar cells were still very new and exotic. IR provided solar cells to the space program, but wanted to grow a commercial market. Doing the math they realized powering a home would be incredibly expensive, but a short range vehicle for city use might be practical earlier. To make a statement they sent a solar panel to Charles Escoffery who converted a 1912 Baker Electric. The world's first useable solar car.
Finally the clean air work starting at Caltech lead to catalytic convertors, reformulated gasoline and any number of environment regulation that have saved many lives. That work was an innovation.