Door mux op maandag 29 januari 2007 10:27 - Reacties (3)
Categorie: -, Views: 2.697


We have arrived at the final station of fuel cell cars. This is the end. We have seen how hydrogen is quite an annoying fuel to use in many respects and how other fuels have their share of drawbacks as well. We've gone over the technical details of a bunch of fuel cell types. I have even talked a bit about the economics of it all. Today I want to talk about what I think will be the future, and what we as a society should strive towards. A bit less technical details, but I hope it will be interesting nonetheless!


The shape of things to come

I have alluded to this before: I am a very big fan of CGP Grey and his robot future. Even without an impending singularity - the point at which computers have similar cognitive capabilities to humans - it is very clear that self-driving transportation machines - autos - are here, they work and they will only get better, cheaper, safer and more popular. As much as car enthusiasts will try to tell you otherwise, most people use cars to get from A to B and not much more. It is unnecessary to have to drive yourself. It is tiresome, you are very limited in speed because of the unstable human-car control system, it uses roads exceedingly inefficiently and people tend to make a bunch of mistakes on every journey, long or short. Computers are better. Self-driving cars will dominate in the near future. I'm betting money (and I have bet Reddit Gold on this with some random internet stranger already) that a significant proportion of human-transport will be autonomous within five years, and a majority will be driving in autonomous cars in 10 years.

The pace at which autonomous vehicles in general are improving is mind-boggling. Just a few years ago (2011) Caterpillar started a pilot program with self-driving hauling trucks in a single mining operation; today the majority of copper mining haulers are autonomous. In the entire world. Just a year ago the Google self-driving car clocked in its 700 000th mile without incidents. The two incidents it did have? Of course, they occurred when the car was being driven by a human.

Back in April 2014 it couldn't handle rain and certain traffic situations very well - this has mostly been solved by now. In less than a year. It was already better than most human drivers, now it's roughly as good as the most experienced drivers in the world working at the top of their game - but it can sustain this level of competency all the time. And other companies are competing as well; all software/tech companies of course. Because autonomous vehicles are not a car problem, they are a software problem.

I can't place the accent of this narrator. She sounds strange, doesn't she? Is she a robot, too?

And think about it. Cars are stationary almost 95% of the time. They not only cost a bunch of money to buy and operate; they take up the majority of valuable space in cities. Roads and parking spaces take up a giant proportion of urban land area. This doesn't have to be. A single autonomous car can service dozens of people, having to stop only to recharge once in a while. Even if this autonomous car needs to contain a million bucks worth of electronics and batteries - which it doesn't, but just for the sake of argument - it would still be significantly cheaper than everyone having to have their own car. There are very large economic incentives to make this a reality as soon as possible, both on the service side as well as on the user side. And as we know, economics ALWAYS win. In the future, cars will not have to be ubiquitous. The landscape doesn't have to be littered with these scars upon the name of engineering.

This is not to say that cars as a status symbol or cars for fun driving will go away. Of course people will have hobbies. But they will be hobbies, in places where people do hobbies. On tracks, on designated road spaces. Not on the main traffic arteries.

BEVs are the future
Battery electic vehicles, or BEVs, are going to be the dominant type of car in the future. The two biggest reasons for this are:
  1. EVs give practically unlimited design freedom
  2. Electric drivetrains are the most efficient and most versatile drivetrains
Let me expand on this a bit. EVs - whatever actual energy carrier you use - can be made in any shape because unlike internal combustion engine cars, the actual engine is tiny and can be placed very near or - in the near future - inside the wheels. This is then connected by means of wires to the energy source, which can be anywhere and in any shape. This frees up a bunch of space in places that were traditionally reserved for essential drivetrain stuff. All the engine gubbins in front can be transformed into a much more effective (and shorter) crumple zone and storage space. The torsion frame in front of/underneath the car can be greatly reduced, as the full engine torque doesn't need to be transferred through the car frame anymore. You still need to fit in a large amount of batteries or something like a fuel cell, but this can be positioned much more favourably. The Tesla Model S demonstrates this design freedom to a great extent - even though it's only a very early EV design.

OK, the Model S is a giant car, but despite its performance-driven nature it still has more luggage space than most 'practical' family cars

But design freedom goes much further than just the physical. Electric drivetrains have much more ideal and predictable properties. Their torque-speed curves are basically straight lines. Power control is immediate and precise, with greatly reduced drivetrain inertia to slow down the response. This makes EVs much easier to use for self-driving cars than combustion engine cars.

The versatility of electric drivetrains stems from the fact that any type of fuel or even fuel-less energy sources can be made into electricity quite efficiently. You don't have this kind of versatility in gasoline or diesel powered cars. Even though those two liquids are chemically strikingly similar, you can't fill up either car with the other fuel. Let alone use coal or nuclear pellets. This leads to all kinds of perverse economic constructions like the OPEC; who have the freedom to put any price on their scarce resources because of nothing else than geography and culture. With electric cars, there is basically infinite competition from anybody with free view of the sky. Talking about solar.

The solar singularity is here

Solar energy is taking off like nobody's business at the moment. Fueled by a 15-25% year-on-year price drop over 8 years now, a system that would have been economically unviable in 2007 (§4/Wp) is now better than grid parity (§1/Wp) and still dropping double-digit percentage points per year. Actually, module price drops have been accelerating, with installation and electronics costs seeing only minor cost reductions (which is the most important reason for prices not dropping faster). Energy from new static solar installations is approaching §0.05/kWh in the Netherlands, and about §0.035 in southern Europe. This is considerably cheaper than energy from any other power source, and there is no technical reason that stops prices from dropping further considerably in the near future. Of course, the sun only shines during the day, so solar energy is no solution for the general energy problem. But it sure as heck is a great way to charge your electric car for almost-free.

In general, total vehicle ownership costs can be broken down as:
  • 35-40% depreciation
  • 30-35% fuel
  • 25-30% other
In the Netherlands, fuel is actually a significantly larger part of the entire equation, as the Dutch drive quite a lot and fuel is relatively expensive. Fuel costs clock in at a little more than 40% here. Imagine that part being basically free. Of course, there will be costs associated with electricity distribution and other practical concerns, but the energy itself is free. You can even put solar panels on the car (or car manufacturers can integrate them), providing up to 20% of the energy required for driving. The electric drivetrain and batteries (or some other directly-charged-by-electricity) are essential to this kind of tech working. This is the great versatility promise of battery-electric cars. It would be much, much harder to for instance do on-board water splitting in a fuel cell powered car with those same power sources, and because of the inherent inefficiency of such systems you would need about twice the energy to get just as far. Another way of saying this is that solar BEVs are a very short-cycle way to get energy for driving.


How 'free' is free? At the moment, residential installations in the Netherlands and Germany hover between §1 and §1.50/Wp; at the roughly 1500 hours of insolation we get per year this yields 1kWh/Wp per year. The economic lifetime of such an installation is 20 years, with typical maintenance costs hovering between §0.10-§0.30/Wp over the entire installation period. This means that you pay between §1.10 and §1.80 for 20kWh - effectively. About §0.055-0.09/kWh. Residential installations have relatively good pricing as there are no costs associated with land lease or ownership, nor infrastructure costs. Costs of commercial installations are significantly higher because of this.

For the next 10 years, depending on who you believe solar prices will at least halve. Complete installed price for an economically sensible installation (small installations will always have more overhead). This translates to residential prices of §0.03-0.04/kWh over lifetime. This is about a third of the price of utility electricity in the US and about 1/5th to 1/9th of the price of electricity in Europe. For a typical vehicle, fuel costs would go from about §0.10/km (15km/L @ §1.50/L) to about §0.005/km (125Wh/km @ §0.04/kWh). Of course, as demand for oil-based fuels reduces prices will go down significantly, but it is unlikely that ICE car fuel prices will ever be able to match solar electricity prices.

So, about batteries
Lots of Tesla Model S pictures in this post.

The reason why people like fuel cell cars and don't like batteries is the public perception that batteries don't get them far enough and cost a lot. This is true to some extent, certainly at this moment. Vehicle range of BEVs - affordable ones (not looking at Tesla) - is pitiful compared to even the crappiest ICE car. However, range anxiety - as this is called - is not actually warranted in most cases. And because of the charging versatility of cars, it's not likely to be a problem for BEVs either way in the future.

First of all, any range argument can be quite easily counterargued by saying that depending on where you live, between 90 and 99% of all vehicles can be functionally replaced by a 100-mile range BEV without any travel move being impacted by battery range. That is to say: the vast majority of cars never drives more than 100 miles in one go in their lifetime, and most of the long-distance driving is done by a small group of drivers in specific cars. Which can use something else. That's fine. These changes don't happen overnight.


However, I am not saying batteries aren't actually limited. As much as battery technology has advanced in the last 10 or so years because of the sharp rise in lithium ion battery production, by far most improvements have been process tech and cost reductions. Lithium ion batteries are going to be, barring any very fundamental breakthrough, limited to about <300Wh/kg. Why? This is actually a very fun calculation. Lithium ion batteries are, like fuel cells, reduction-oxidation or redox cells. The two technologies aren't that dissimilar. As such, batteries store charge by ionizing lithium and some other oxidizer at the electrodes in the battery.

Lithium can 'store' one electron per atom, so you need 6.24 x 1018 lithium atoms to store one coulomb of charge. There are 6.022 x 1023 atoms in one mole of lithium, which stores 96508 coulombs. One mole of lithium weighs 6.94 grams and has a half-reaction redox potential of -3.05V. This means that 6.94 grams of Li can store E = Q x V = 96508 x 3.05 = 294kJ or 81.8Wh, which gives us the incredible energy density of 11781Wh/kg for lithium as a chemical energy carrier.

So... why... what!? This is awesome! This is about on par with other chemical energy sources like fossil fuels. Well, the devil here is in the phrase 'half-reaction'. This is only half of the story. For a redox reaction you need both the reduction reaction (which is the ionization of lithium) as well as an oxidation reaction to happen. And that's where things go wrong pretty quickly. But, just to give quick closure to this chapter: theoretically, a battery with only a lithium anode can exist. It would use oxygen from the air as the oxidation agent, and as such this is called a 'lithium air'-battery. As of now this is a fairytale; there are numerous practical problems with actually making this a reality and there is absolutely zero outlook on an actual working lithium air battery within the foreseeable future.


In actual practical lithium ion batteries, we cannot use lithium metal directly. The anode is usually made from a lithium salt, for this example we'll be looking at LiCoO2. The second side of the equation, the one missing above, is generally performed by carbon in the form of graphite. This is generally called the cathode (although more accurately we should be referring to the electrically positive and negative electrodes, as the two sides switch roles whether they charge or discharge). For each electron 'stored' in the reaction, we need to lug around one carbon atom, one cobalt atom and two oxygen atoms. These weigh 12.011 + 58.933 + 2 x 15.999 (+6.94 for the Li) g. This accounts for a 15.83x increase in reagent mass for the same amount of charge, to get to a maximum theoretical energy density of 744Wh/kg. Unfortunately, even that is way too optimistic for any kind of future battery technology, as a couple of quite severe technical problems (e.g. short circuiting through dendrite formation) don't allow the electrodes to be so close to each other that they can quickly exchange ions. So we need to introduce a lithium ion-conducting electrolyte in between the electrodes, which necessarily increases the mass again. A few different types exist, from polymer membranes (hey, remember PEM fuel cells? These are surprisingly similar!) in lithium-polymer cells to lithium halogen impregnated paper-like electrolytes in the familiar round lithium ion cells found in e.g. the Tesla Model S. This is a surprisingly large contribution to the mass of a lithium ion cell, and limits the theoretical energy density to around 300-350Wh/kg.

As long as we make fully contained complete redox reaction pair batteries, i.e. recheargable lithium ion batteries, this is pretty much an unavoidable brick wall. With current generation battery packs peaking at about 175-200Wh/kg, the best possible improvement we will ever be able to make is about a twofold increase in capacity and that's it. In other words: battery packs in electric vehicles will necessarily always weigh a couple hundred pounds, whatever you do.

So why do I think batteries are not a dead end? Well, contrary to fuel cells, batteries have a pretty bright future as far as cost reduction goes. As battery production has ramped up, vehicle-grade battery packs have fallen from $450/kWh (2007, A123) to $140/kWh (2014, Tesla). With the raw materials being plentiful, relatively widespread and very cheap, the majority of cost goes into process tech and packaging. This is something that is very optimizable as production volume goes up. So even though weight can't necessarily be reduced that much, cost can easily halve in the next 5-7 years with some speculating that Tesla will announce a sub-$100/kWh price point this year already for its residential battery pack (battery only).

As you can see, this is a very big case of 'depending on who you ask'. Predictions vary quite wildly

There are still some concerns; some more important than others. Environmental concerns around battery production and the associated pollution of lithium mining are mostly unimportant; the amount of pollution generated by the considerably higher amount of fossil fuels required for ICE powered cars easily offsets this. Recycling is an increasingly hard problem as optimal battery technologies make it hard to recover materials from lithium ion batteries. Lithium in general has fairly poor recycling characteristics. But again; the environmental and user benefits have been shown to, even now that the technology is still in its infancy, still outweigh the environmental downsides of traditional vehicles. And there is no fundamental reason why EVs wouldn't become better in the future whereas fossil fuel use is a guaranteed dead end with unescapable environmental concerns on both short and long term.

But our infrastructure isn't up to snuff!
Another often heard problem with electric cars is that our infrastructure will not hold up to the high peak demands from charging cars. This is slightly true, but not likely to cause big problems in the long run. This kind of runs into a ocmmon misconception in that cars/mobility are a huge drain on resources/large cause of greenhouse gas emissions. It's kind of sad that I have to touch on this so late in this blog series, but: cars ain't that bad. Yes, certainly, cars are incredibly inefficient and guzzle seemingly enormous amounts of energy from unsustainable sources. But if we look at the total CO2 output of all of humanity, all transportation put together accounts for only about 11-14%. Of that, only about 35% is embodied in personal transportation by passenger car. The rest is trucking, commercial use passenger cars, aviation, shipping and light motor vehicle use. That is: only about 4% of all CO2 emissions can be attributed to cars. If we look at actual pollution, cars amount to almost nothing. Actually, tire wear and emissions from the production and disposal of cars is a larger weight on the environment than the actual use of cars.

One of the clearer illustrations I could find of the relative impact of EV charging on UK infrastructure

This parallels electricity use by electric cars. If all of our cars suddenly become BEVs, electricity use won't increase tenfold. It wouldn't even increase twofold. Of course, even a twofold increase in capacity does require some extensive retooling, especially in third-world countries like the USA where the electrical grid is woefully undermaintained. But the investment in infrastructure to make this happen is absolute peanuts as compared to the infrastructure changes we'd need for, for instance, hydrogen or methanol fuel cell cars.

The real challenge here is not that we need to build twice the infrastructure we have; it is that we should decide right now how we intelligently charge our cars. If everybody hooks up their car to a charger when they get home, the peak demand will increase dramatically. If instead smarter charging strategies are used - spreading the load over for instance an entire night - the infrastructural problems will be negligible.

Mythbusting: Fuel cells are a conspiracy by Big Oil

Right at the end of this blog series I'd like to tie up some loose ends in the general discussion of fuel cell vehicles. One of the most important observations about fuel cells are that at least for the first few decades, the majority of hydrogen production will have to be done by reforming natural gas. With Big Oil - the OPEC, Russia, Nigeria, Norway, Brazil and the US - making so much money off of oil production, they don't want to see us going to free energy. So they invent something that looks and smells 'green' but actually isn't: fuel cells. That way, they can keep selling us oil, in the form of reformed natural gas. Sounds like a credible conspiracy? I'm not buying it.

For one, the costs and technical challenges that hydrogen production, storage and sale encompass are astronomical. Big oil has had decades of hundreds-to-thousands of percents of profit margin on their oil products to subsidize the oil and gas infrastructure we have today. Hydrogen is fundamentally incompatible with most of this infrastructure, but the catch is: there is no guaranteed market, no large-scale dependence and no revenue stream to bootstrap such a big infrastructure project.

Another big red flag is the fact that traditional oil companies have historically shown very little interest in this market. All of the sponsors for our hydrogen-powered race karts Forze I and Forze II were technology and tool/hardware companies. Only one or two companies can be tangentially associated with the oil industry; DSM being the only large one (who supplied resin for the carbon fiber body parts). Other international teams as well as the Formula Zero organization saw barely any interest. The hydrogen supplier was Linde, a company who mostly supplies fertilizer companies and other industrial purposes. And this goes for most of the hydrogen fuel cell market; the main players are struggling medium-sized companies like Hydrogenics and Nuvera who, if anything, have only seen a lot of competition from Big Oil.

If hydrogen fuel cells are going to become a big thing in the future, I don't expect oil companies to have much of anything to do with it. A hydrogen economy requires radically different thinking from traditional oil and natural gas-based industry.

Toyota's recent decision to go all-in on FCVs

Another interesting thing that has happened very recently, is Toyota's announcement of the Mirai FCV:
Today, we are at a turning point in automotive history.
A turning point where people will embrace a new, environmentally-friendly car that is a pleasure to drive.
A turning point where a four-door sedan can travel 300 miles on a single tank of hydrogen, can be refueled in under five minutes and emit only water vapor.


Our fuel cell vehicle runs on hydrogen that can be made from virtually anything, even garbage!
It has a fuel cell that creates enough electricity to power a house for about a week.


The name we’ve given to our new car is Mirai, which in Japanese means “future.”
We believe that behind the wheel of the Mirai, we can go places we have never been, to a world that is better, in a car that is better.
For us, this isn’t just another car. This is an opportunity – an opportunity to really make a difference. And making a difference is what Toyota is all about.
The future has arrived. And it’s called Mirai.
You have to admit, that is some serious tech porn

This announcement was followed in January of this year with an opening and royalty-free licensing of a whole lot of fuel cell patents. This seems to be a large swing in Toyota's R&D, which of course produced battery-ICE hybrids like the Prius. A lot of people go so far as to say Toyota is going all-in on fuel cells and abandoning BEVs completely.

However, reading into it a little more deeply, things start making a lot more sense. Of course, at the current state of technology Toyota would not be able to make a production FCV. For all intents and purposes, the Toyota Mirai is a specialty car that serves more as a public technology demonstration than something you can properly buy. Production volume is announced to be 700 in 2015, going up to 3000 in 2017. For comparison, Tesla is now producing 50 000 Model S EVs annually, and they are an absolutely microscopic car company. Typical production volume for cars nowadays is in the hundreds of thousands.

Toyota aren't bluffing though. They have serious, innovative technology under the hood and I do believe they hope FCVs will be a big thing in the future. As far as I'm concerned, the Mirai is only a very minor step up from the concept that the FCX Clarity was a couple of years ago. They sure aren't going all-in. The Mirai is testing the waters and seeing if this fuel cell thing catches on or if BEVs will prevail. By opening their patents they hope for more competition in the fuel cell camp to fight off BEVs.

I don't think they will succeed. Judging from the information released, they haven't found any solutions to the fundamental problems with FCVs. They haven't made the Mirai magically less complex and they haven't sufficiently reduced platinum loading in the stack to allow for sufficiently large production volume. Maybe they have another trick up their sleeves, but I doubt it. They even doubt it because they're not actually putting much money at risk with their comparatively tiny production volume and R&D budget.

In any case, start stocking up on platinum. Prices are sure to go up as fuel cells become a hot topic once again.


We're done, we are at the end of a journey through the tech inside fuel cell cars - and other future cars. I don't want to leave you with a feeling of negativity. Yes, I am saying that fuel cell cars don't work, in any shape. I'm saying that batteries are better, in every way.

This part of the blog was futurology, i.e. talking about things in the future with a little bit of scientific backing. It's not complete hand-waving. I've discussed essentially two possible futures:
  1. Either cars as we know them are going away completely, being replaced by about 1/10th the amount of completely self-driving, non-owned transportation service autos
  2. or car ownership will remain, BEVs will dominate because of their significant economic, complexity and comfort advantages over all other alternatives
Either way, fuel cell vehicles make little sense. For future number 2, it would just require too much infrastructure for very little benefit to the end user. Cars would have to get more expensive and it will take a very long time before future 2 can be a reality.

Future 1 can be a reality in 5 years. This year already, multiple auto makers have announced production (i.e. you can buy them!) 90% self-driving cars. Tesla and Volvo are at the forefront here, the rest will certainly follow shortly. Uber has announced they want to move in the direction of a completely self-driving car fleet in 5 years. This is possible. The question is: will these self-driving cars be a minority or will it be disruptive?


I am just a dude, I am not an expert in basically any of the fields I have spoken about. I know enough about them to make some general statements and do some general back-of-the-envelope calculations, but a lot of the nuances are at best slightly vague and at worst completely unknown to me. I've been corrected multiple times on my application of diffusivity and catalysts. Not in ways that undermine my point, but just to show: this is not gospel.

I hope you enjoyed my extensive treatise of fuel cell cars and my short overview of battery electric cars. Again, I don't make a single dime on these blogs, I do these because I adore the subject matter. I realize that even with 120kB of text I still haven't even scratched the surface, let along the dozens of handwavy statements and predictions I made without proper scientific evidence to them. Leave a comment if you found a problem, error, false claims or if you just want to engage in a discussion about any of the points I raised. Don't agree at all? Do you have good reasons? Write your own blog post! Be sure to leave a link here.

Because this is actually important stuff.