Once a year I read BP's Engery 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.
My father never had the thermostat above 60°F and 55° was a more common setting,. At night it would be dropped to 50°. The house was well insulated and the furnace didn't come on that often if it was above freezing. During colder weather we spent most of our time in an insulated room in the basement. We had a lot of sweaters, thick socks, and scarves.
Great Falls, Montana lies just East of the Rocky Mountains. It can be much colder than its latitude suggests as cold arctic air can plunge Southward unimpeded along the Eastern slope of the Rockies. Global warming has changed the climate a bit, but thirty years ago -40° (F or C) would happen every few years and long spells with high temperatures staying below 0°F are not uncommon these days. It also happens to be very windy. The residents are became very good at adapting to the climate.
Our house was small so I slept in a small travel trailer most of the time during my high school years. The only real insulation in the Winter was snow.. There were a lot of blankets, a down sleeping bag, a beagle and two silky terriers. The dogs would make their own beds down to about 40°. Below that they'd join me in the sleeping bag. The only down side from these three dog nights was when the beagle had gas. The sleeping arrangement was always toasty.
Another bit of information comes from David MacKay. Staring in the mid 1960s someone at Cambridge interested in residential heat transport in homes put recording thermometers in a number of homes in town as well as a few other locations around England. The standard Winter daytime temperature was remarkably consistent - about 55° through the 70s. By 2000 it had crept to 62°. Lower readings than Americans expect, but the Brits may dress more practically. It would be interesting looking at the insulation value of standard wardrobes over time. I suspect the emergence of low cost clothing is partly to blame.
Over-reliance on Russian natural gas is presenting an enormous problem in some European counties. Short term solutions other than conservation are non-existent, but conservation holds a lot of promise. Heat people rather than spaces. A few days ago Jheri wrote noting she's working on warm Winter clothing lines for German and Nordic markets on speculation that natural gas will be rationed for a few years. The savings projections I've seen involve thermostat settings of 16°C (61°F) .. I know from experience you can go much lower and be perfectly comfortable. (That said I don't know how some of the high school girls survived with miniskirts back in the day.)
In the medium term there are a number of things that can be done, but I struggle coming up with anything at the home level approaching the impact of serious conservation. The same goes for petroleum usage. Infrastructure changes to encourage cycling can have a non-trivial impact. Fortunately a few locations (Denmark and the Netherlands) have made, or are making (Paris), great headway.
The medium and long term will be dominated by power generation and distribution, but progress can and should be made with "smart" heating and cooling along with smart fabrics. There's much to say about those areas, but for later.
Who knows.. maybe tech can be more meaningful than social media and blockchains..
There have been predictions of a hydrogen economy for decades. At first glance it seems like the ideal fuel. Its specific energy - how much energy you get from a kilogram - is three times higher than gasoline. And the byproducts of combustion with oxygen are heat and water. So why hasn't it happened? It turns out you should think of hydrogen as more of a battery than a fuel.
Hydrogen is the most common element in the Universe and common on the surface of the Earth. Unfortunately the kind we need, molecular hydrogen H2 , is very rare. The only practical way to get it is to use a lot of energy to break down more complex molecules. Methane is the most common, but other hydrocarbons like coal are used. The process uses more energy than burning hydrogen releases and usually produces a lot of carbon dioxide and other waste products.
There are many industrial uses of hydrogen, but the fossil fuel industry has been interested in expanding to new markets like transportation and heating. They have the knowhow - all they need to do is scale their operations. In fact they've been lobbying governments since the 80s and billions of government money have been spent investigating a fossil fuel driven hydrogen economy. A good fraction of the funding went into the development of practical automotive fuel cells - more on that later.
In grade school you probably used a battery and two wires to make a simple electrolysis machine that broke water into hydrogen and oxygen gas. These days the best electrolyzers are something over 70% efficient. Sounds great but there's another problem. The energy per unit volume (energy density) of hydrogen gas at atmospheric pressure is about 2,800 times lower than gasoline. A gas tank for a car would be bus sized. The trick is to compress or liquify it. Compressed hydrogen has about one seventh the amount of energy as the same volume of gasoline. Liquid hydrogen is closer to a third. Larger, heavier and more expensive than gas tanks, but more practical than attaching a blimp to your car.
A hydrogen fuel cell uses hydrogen and oxygen to produce electricity and water. The efficiency of a fuel cell running an electric motor is higher than that of an internal combustion engine so the hydrogen tank is small enough to fit in a car. Before you can fuel the car the hydrogen needs to be compressed or liquified, both of which take a lot of energy. About a third of the energy produced as electricity where electrolysis takes place makes it to the tank. From there you about half of that getting it though the fuel cells and motor to the wheels. But with the right power source it can be carbon-free. Unfortunately most of the hydrogen cars to date use a dirtier hydrogen. And that brings up a marketing term: the color of hydrogen.
Green hydrogen is produced by electrolysis using electricity from a zero carbon source. Brown hydrogen is produced from methane and black hydrogen from coal (much of the industrial hydrogen in Germany and China is black) Both forms have serious production carbon emissions that, when used in a hydrogen car, emit more than a conventional car. Blue hydrogen is an attempt to deal with brown and black carbon emission problem. It't still produced from methane or coal, but the carbon is captured and stored. I consider that something of a pipe dream, but Japan is interested in blue hydrogen produced in Australia.1
Hydrogen is frequently mentioned as the future for low carbon airplanes. Liquid hydrogen would be necessary and huge tanks would be needed. There are several designs on the drawing board that couild happen in fifteen years using turbofans designed to burn hydrogen. They'd still produce some pollution (NOx) from the heat of combustion and the extra water vapor would leave thicker contrails.2
Recent geopolitical issues have raised the issue of using hydrogen to heat homes and businesses rather than natural gas.. after all .. there's a large and very expensive infrastructure in place already. Countries like England are experimenting with hydrogen/natural gas mixtures. You can get away with as much as 20% hydrogen and use the same furnace burners and conventional pipe infrastructure. In the UK new furnaces will have to have a dual fuel mode - natural gas or hydrogen. An infrastructure problem is it takes about three times as much energy to move equivalent amount of hydrogen as methane. Also current pipelines may be too brittle over time. Hydrogen leaks much more easily than methane (which is already a problem) and hydrogen leakage is an indirect greenhouse gas. There are a lot of potentially expensive questions to answer, so I wouldn't pencil this in as a slam dunk. On top of it you need to produce about three times as much energy to heat a house with hydrogen as you would with just electricity. Use a heat pump and electric heating looks even better.
Hydrogen could be used store power for the grid, but that gets into comparing many forms of energy storage, so not now.
My gut tells me hydrogen could see niche applications.. Long distance trucking if battery development plateaus soon (I wouldn't bet on that, but I wouldn't want to be a truck manufacturer) and aviation in the long term (15 years at the earliest).
But a final comment - if you have enough it will gravitationally collapse and fusion ignites - you have a star. We happen to have one. The trick is just one of collection. So in that sense life on Earth and almost everything we do is part of an hydrogen economy, but the convertor is about 150 million kilometers away.
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1 Japan is big on hydrogen and had originally envisioned scaling up nuclear power, but that pathdied with a tidal wave.) At this point I think blue hydrogen has underpants gnome issues.
2 Contrails appear to be serious global warming issues. It's possible that leaving them at night doesn't make sense and flights may have to occur at lower altitudes - say 20,000 feet rather than over 30,000. That would mean slower speeds which means propellers may be practical so liquid hydrogen powering fuel cells to run electric motors may make sense.
Most people don't understand how electric energy flows until they take and Electricity and Magnetism class in college. I've found teaching it without math to be challenging unless your good at drawing or some other type of visualization.. Derek Muller does an excellent job without having to resort to the math!
Maxwell's equations are often the first place a physics student has the wind knocked out of them by sheer beauty.