Tuesday, September 27, 2005
London Hosts Public Fuel Cell Demonstrations
The 9th Grove Fuel Cell Symposium in London England will have a public exhibition of fuel cell technologies. Trafalgar Square (October 3rd) and the Queen Elizabeth II Conference Centre (October 4th-6th) will host several fuel cell demonstrations, including cars, taxis, portable chargers and residential systems. You can also take a ride in a fuel cell bus, the Mercedes A-class fuel cell car and the fuel cell MicroCab Taxi.
Bus trips will depart at the following times:
Tuesday 4 October 2005
13.15, 14.30, 16.15
Wednesday 5 October 2005
10.25, 12.10, 14.15, 15.30
Thursday 6 October 2005
On the last day of the Symposium it is possible to ride in the MicroCab Taxi, F-cell A-class Mercedes and Daimler Chrysler bio-diesel vehicle. Tours will depart at the following times:
10.30, 11.30, 14.30, 15.30
Sunday, September 18, 2005
How the hydrogen and fuel cell companies are doing
Not surprisingly, the fossil fuel sector is doing the best, the coal power companies are actually beating the oil & gas sector. Out of the renewable energy technologies, wind power is the best followed by the photovoltaic industry, then the hydrogen and fuel cell industry and finally the biomass industry.
The next figure shows how the hydrogen and fuel cell industry is dong compared to the total market indicators (Dow + Nasdaq + S&P 500) and also the entire energy sector (accumulation of all the energy sectors in the above figure).
The energy sector blows everything out of the water. The total energy sector is up by 49% since January 2005, the fuel cell sector is up by 4.04% since January, the Dow is up by 0.36%, the Nasdaq is up by 3.43% and the S&P 500 is up by 4.36%, all since January.
The hydrogen and fuel cell sector closely follows the market indicators. I was at a a green energy conference a few weeks ago and there was a business professor tracking the same thing and he concluded that investors don't perceive the hydrogen and fuel cell industry to be energy related, they perceive it to be more technology related and that's why it follows the market indicators more so than the true energy companies.
Toshiba To Release Methanol Fueled Fuel Cell For MP3 Market
Toshiba's 100mW fuel cell is in the Guiness book of world records as the world's smallest fuel cell. Also interesting to note, Toshiba has also developed a Li-ion battery that is able to charge to 80% capacity in only 60s.
Friday, September 09, 2005
Denmark Researchers Claim Hydrogen Storage Breakthrough
In comparison, the energy densities of other fuels are: Gasoline 34MJ/l, Diesel 39MJ/l, LPG 24MJ/l, Ethanol 22MJ/l, Methanol 16MJ/l, AMMINEX 13MJ/l, Liquid H2 8MJ/l, 700atm H2 5MJ/l, 350atm H2 3MJ/l, 1atm H2 0.01MJ/l, Li-S 2MJ/l, Conventional Li-ion 1MJ/l.
This work was published on sept 7, 2005 in the Journal of Materials Chemistry. The hydrogen storage system is based on metal ammine complexes, they tested Mg(NH3)6Cl2. This material is a salt that can be compacted into a pellet to obtain a high volumetric density. At elevated temperatures, between 77-347C, the ammonia (NH3) is released and it is fairly simple to produce H2 and N2 from that released ammonia. The solid state hydrogen storage is completely reversible, meaning that the depleted salt MgCl2 can easily be regenerated into Mg(NH3)6Cl2. This is how the process works:
From the article: "The only drawback is that metal ammine complexes deliver hydrogen in the form of ammonia. This can be used directly as fuel for a solid oxide fuel cell without further reaction."
There wouldn't be much point in using this system to run a solid oxide fuel cell though because SOFCs are primarily used for stationary applications and the ammonia might as well be trucked to the location of the SOFC instead. Hydrogen storage is mostly required for polymer electrolyte fuel cells (PEMFC) that most people think will pwer their cars some day.
This hydrogen storage material though only releases hydrogen with an energy input of 43KJ/mol (to releases the ammonia) + 32KJ/mol (to convert ammonia into hydrogen) = 75KJ/mol. Although the PEM fuel cell reactions are exothermic (meaning they give off heat) there would not be enough heat released by these reactions even if the PEM fuel cell was operating at 700C, which it can't because of material constraints.
Where the "required" column is the energy required to extract hydrogen from this hydrogen storage technique after using the waste heat generated by the fuel cell and the "% of H2 energy content" column is how much energy would be taken away from the hydrogen due to the fact that energy must be put into the system to release the hydrogen.
So what this means is that if the PEM fuel cell could operate at 300C (which it can't at the moment), then this hydrogen storage system would reduce the energy content of the hydrogen that it produces by 19%. Much better than liquefied hydrogen which requires about 50% of the energy content of hydrogen. But I think that the PEMFC as it is today is dead, because it has to be able to operate at elevated temperatures to minimize the energy losses of these hydrogen storage technologies.
Thursday, August 25, 2005
Chemical could improve PEMFC efficiency
The study was published in the Journal of the American Chemical Society. From the article:
Further investigation into 1H-1,2,3-triazole and its derivatives, especially copolymers with suitable acidic groups, may lead to new membranes with excellent properties for a new generation of PEM fuel cells to be operated at temperatures above 100C with much higher energy efficiencies.
Sunday, August 21, 2005
Current status of hydrogen storage
Hydrogen storage is the biggest technical challenge that we have to overcome if we want to be driving hydrogen fueled cars. The problem with hydrogen is that it’s the smallest molecule in the world, with 2 protons and 2 electrons, and so it’s very difficult to store. You can’t pump hydrogen through a natural gas pipeline for instance because it will diffuse through the steel and you’ll end up losing most of your hydrogen before you can use it. You have to be very careful what materials you use to store hydrogen too because, just say you’re storing it as a gas, the hydrogen molecules in the gas cylinder are continuously moving around and hitting the sides of the cylinder and so it actually structurally weakens the gas cylinder. So there’s a lot challenges in storing hydrogen. There are a couple of ways of doing it though. Of course there’s the compressed hydrogen gas storage or you can liquefy hydrogen and store it as a liquid, or you can store hydrogen in carbon nanotubes or you can store it in a solid like sodium borohydride for example, which has a chemical formula of NaNH4, and when you react NaBH4 with a base, you end up with hydrogen gas and some other things.
Here's a podcast about the current status of hydrogen storage.
As explained in the podcast, the Department of Energy is focusing on compressed hydrogen (5000-10000psi) and liquefied hydrogen for near term hydrogen fueled vehicles. The long term plan is to develop solid state hydrogen storage, which means metal hydrides and chemical hydrides. The overall goal is to allow vehicles to travel for 300 miles without refueling.
More specifically, by 2010, the DOE wants to develop and verify on-board hydrogen storage systems achieving 2 kWh/kg (6 wt%), 1.5 kWh/L, and $4/kWh.; by 2015, 3 kWh/kg (9 wt%), 2.7 kWh/L, and $2/kWh.
Here's a quick overview of some of the hydrogen storage technologies that the D.O.E. is working on:
The simplest way of storing hydrogen is to compress hydrogen and stuff it into a gas cylinder at very high pressures. Right now we can store hydrogen gas pretty easily at a pressure of 5000psi. And obviously the higher the pressure, the more hydrogen you can store. But at 5000psi, we don’t meet that 300 mile range that the D.O.E is targeting, and so the solution is to use higher pressures. Right now there’s work going towards 10000psi compressed hydrogen gas tanks, which is progressing very nicely and will get us up to the 300 mile range, and it’ll reach the 6 wt% hydrogen requirement, but there are extra costs associated with the materials that are needed to get up to those pressures and the fabrication methods don’t seem to be very flexible so meeting the cost target is the big issue. Another problem with compressed hydrogen is that it’s very expensive to fill up. Compressing hydrogen to 10000psi is not cheap, energy wise, for anybody interested, going from atmospheric pressure, which is 14.5psi to around 10000psi requires 2.21kWh/kg of H2, that’s the equivalent of 10 cents Canadian per kg of hydrogen, for me at least, which would add about 50 cents to the cost of a fill up because 5kg of hydrogen will do you about 300 miles these days. An extra 50 cents doesn’t sound that bad, but it would be about 25% of the cost of filling up with hydrogen, which is targeted to cost $1.5/kg.
A lot of people are also concerned of having compressed gas cylinders in their cars though, because they think that if they get into an accident, then having 5000psi or 10000psi gas cylinders would be just like having a rocket in their car, if the gas cylinder ruptures, then there is trouble. I think it’s probably a valid fear, the gas tanks are pretty strong in some locations but at the neck they can be very weak, I’ve heard stories of these gas cylinders going through huge concrete walls and actually there’s a scene from the last James Bond movie where he’s chasing somebody in a hospital in Cuba and blows a hole through the wall with a gas cylinder, that’s what it would be like in your car. But on the other hand, hydrogen leaking through the gas cylinder isn’t really a problem.
Current cost status:
5000psi tanks: $15/kWh (73% reduction in costs)
10000psi tanks: $18/kWh (78% reduction in costs)
Hydrogen can be stored as a liquid in a cryogenic container. But first you have to cool it down to -240C, which is -400deg F, which is 33 Kelvin. That’s cold. This has two problems, first of all the amount of energy required to liquefy the hydrogen, and also what’s known as the boil-off effect. The energy required to cool hydrogen from room temperature to -240C is somewhere between 1/3rd to 1/2 of the energy content per unit weight of hydrogen. So that means that if you’re going to be liquefying hydrogen, you’ll only be able to use half of the potential energy of hydrogen, which doesn’t start you off on the right foot. The idea of liquefying hydrogen is pretty much dead. To make things worse, at those low temperatures, hydrogen will boil off, even if the cryogenic container has the best insulation, hydrogen will boil off and the gas will leak out of the container. So it’s not an option for anybody except NASA.
$6/kWh (33% reduction in costs)
Solid State Systems: Metal Hydrides and Chemical Hydrides
Ok, this type of hydrogen storage can get pretty complicated and I’m not up to speed on it, I know there’s at least one listener out there who used to work on metal hydrides, maybe he could explain it to us. So from what I gather, there are metal hydrides and complex hydrides, and I think the complex hydrides are sometimes also called chemical hydrides. Basically what happens for metal hydrides is that the metals will absorb hydrogen, and in the process of absorbing hydrogen, lots of heat is released. If you want to get that hydrogen back, then you have to supply heat and the hydrogen will be released for you to use in your car. So you would have some type of metal chunk in your car supplying hydrogen when it’s needed. The big challenge here is to find the right combination of metals that will release hydrogen by supplying the minimum amount of heat. For example, MgH2 requires 25% more energy to release the hydrogen than what’s contained in the hydrogen, so we can’t use that. Then there’s a group called the complex metal hydrides, which are looking more promising. The reason why they’re better involves a lot of chemistry which I don’t want to learn about or talk about, but one promising complex metal hydride is lithium boro-hydride, or LiBH4, which can hold about 18% hydrogen by weight. So remember the goal by 2010 is to hold 6% hydrogen by weight, but that’s 6% by weight of the entire system and this 18% is only by weight of the complex metal hydride, it doesn’t include any balance of plant components that might be needed. But nevertheless, it sounds promising. Another promising material is NaBH4, my friend Flora Lo does research on NaBH4, what happens is you react it with a base and you get hydrogen and some other stuff that has sodium and boron in it. The big problem is getting the right rate of hydrogen and that depends on how fast the NaBH4 reacts with the base. So, as far as I know, NaBH4 is one of the most promising long hydrogen storage methods in the long term because it can be recycled and it can hold lots of hydrogen.
There are lots, mostly because these systems are still very much in the research and development stage. They include hydrogen capacity, right now they just can’t store enough, the regeneration of these hydrides and also the lifetime of these hydrides isn’t very long right now, you can’t go through many cycles. Also, people just don’t understand how they work, there aren’t any test protocols or independent testing facilities, and it’s still a little tricky to envision how these hydrides would work exactly, how would you refill your chemical or metal hydride, it would have to be a lot different concept than going up to a gas station and filling up with hydrogen, it might involve taking the spent hydride out, physically, and trading it in for a hydride full of hydrogen.
Metal Hydrides Current status:
$16/kWh (75% reduction in costs)
Chemical Hydrides Current status:
$16/kWh (50% reduction in costs)
Figure 1 and Figure 2 below show the improvements over today's technology that is required for each of the hydrogen storage techniques to meet the 2010 and 2015 targets respectively.
Figure 1 and Figure 2 below show the improvements over today's technology that is required for each of the hydrogen storage techniques to meet the 2010 and 2015 targets respectively.
Figure 1. Improvement over today's technology that is required to meet DOE hydrogen storage targets by 2010.
Figure 2. Improvement over today's technology that is required to meet DOE hydrogen storage targets by 2015.
Liquefied hydrogen looks good in these two figures but the problem is the energy associated with cooling the hydrogen to -240C (-400F), which is between 1/3rd - 1/2 of the hydrogen's higher heating value (142 MJ/kg). The cost/kWh doesn't include the cost of cooling the hydrogen, just the cost of the materials.
Figure 3 and 4 show the current status of hydrogen storage technologies in absolute terms.
Figure 3. The current status of today's hydrogen storage technologies in voulmetric and gravimetric terms.
Figure 4. The cost of today's hydrogen storage technologies.
Hydrogen storage is definitely a big concern. But all of these targets that have been set by the DOE are to make hydrogen fuel competitive with gasoline so that the end user will have a minimal behavioral change. What if our behavior now is wrong though?
Friday, August 19, 2005
Fuel cell powered fork-lifts move ahead
Lead acid batteries used today typically last 4 to 8 hours and large distribution centers often change batteries over 300 times per day resulting in lost productivity and increased operational cost. Cellex’s fuel cell power units eliminate battery changing, run longer than batteries, maintain consistent power delivery to the lift truck and refuel in one minute.
There is also a strong economic case for using a PEM fuel cell in a fork lift because they replace about 3 lead-acid batteries each. Ballard Power systems will be providing 27, 4.8kW PEM fuel cells to Cellex, which Cellex will use in their Beta fork lift version trials with Wal-Mart. Cross posted to theWatt.com.
Hydrogen in your future?
I think $1.99/kg for H2 is very cheap. A recent project done by yours truly (and others here at theWatt) shows that it's probably more like $14/kg, of course it depends on how the H2 is made.
The efficiency of fuel cells
First of all, we have to define the Gibbs free energy. This is defined as the "energy available to do external work, neglecting any work done by changes in pressure and/or volume". In a fuel cell, external work involves moving electrons around an external circuit and any "mechanical work" is not used by the fuel cell directly, it is possible to combine a fuel cell with a turbine in a combined cycle system though.
This post isn't a thermo lesson, there are plenty of resources from plenty of people who know plenty more about thermodynamics than I do. But to calculate the Gibbs free energy of the reactions occuring in a fuel cell, you have to first know what reactions are occuring in the fuel cell. We'll take the PEMFC as an example:
|1/2O2+2H++2e- <--> H2O|
|H2 <--> 2H++2e-|
|H2+1/2O2 <--> H2O|
Gibbs free energy is defined as: dG = dH - TdS
To calculate the Gibbs free energy (dG), we do the old:
dG = n*gf products - n*gf reactants
trick, where n is the number of moles and gf is the Gibbs free energy of formation.
So for the PEMFC, we'll have dG = 1 * gf, H2O - 1/2 * gf,O2 - 1 * gf,H2
gf changes with temperature and state, which means that in order to calculate it, you'd need to do some integrals and find some heat capacities as a function of temperature and it's not stuff you'd want to do by hand (it's not too hard but it's just long) and probably not stuff that most people who might possibly be reading this would ever want to know about. Lots of thermodynamics text books will have tables of these values as a function of temperature.
So, for convenience sake, here is the Gibbs free energy for the PEMFC reaction:
H2 + 1/2O2 <--> H2O
|Phase of water||Temp (C)||dGrxn (kJ/mole)|
If there are no losses in the fuel cell, or if the processes are reversible, then all of the Gibbs free energy is converted into electrical energy, but this never happens.
The efficiency of the fuel cell is defined as:
Eff = dG/dH or Eff = 1 - TdS/dH
The maximum energy from any fuel is achieved by burning it, this is the "enthalpy of formation", dH. This is found in a similar way for the Gibbs free energy of reaction, I'd recomend looking it up in tables though because it depends on temperature and you'd have to do some more integration.
So, what I'm really leading towards is a comparison of the maximum theoretical efficiencies between a heat engine (using the carnot cycle) and a fuel cell. Of course, the Carnot efficiency is (T1-T2)/T1 where T1 is the operating temperature of the heat engine and T2 is the temperature of the exhaust (assuming exhaust is at 25C):
So then, at low temperatures, fuel cells have a high "theoretical" efficiency compared to a heat engine, as the temperature increases though, the "theoretical" fuel cell efficiency decreases and the "theoretical" heat engine efficiency increases. At around 750C, the Carnot efficiency and the fuel cell efficiency intersect.
Remember though that these are maximum theoretical efficiencies. They are very hard to reach. It gets even a little more complicated as well. In practice, high temperature fuel cells are actually more efficient than low temperature fuel cells because the losses (explained in another post) are smaller at higher temperatures.
So, there you go, that's all about fuel cell efficiencies. Real world efficiencies for fuel cells are around 35-45%. This can be bumped up to 80% for high temperature SOFC fuel cells when recycling the waste heat.
Honda FCX (fuel cell vehicle) review
The NY Times has a review of the Honda FCX (for Fuel Cell Experimental) car which is the first zero-emission (this is debatable), hydrogen-driven vehicle to be certified by both the Environmental Protection Agency and the State of California for everyday commercial use. The journalist was given a week of unsupervised fun with the car. Honda says that the car cost about $1-2 million to develop, there are only 20 of them in existence. The engine is an 86 kilowatt (107 horsepower) fuel cell coupled with an ultracapacitor which is charged from regenerative brakes, two 5000psi hydrogen tanks are used in the car which gives a travel range of about 190 miles (305km). The vehicle has a top speed of 93 miles an hour and takes about 11 seconds to accelerate to 60 miles an hour. The car can start up at -20C (-4F), but the startup time under these conditions was not given. Fuel efficiency of 57 miles per kilogram of hydrogen (this would be roughly equivalent to 57 miles per gallon of gasoline since 1 gallon of gasoline has about the same energy content as a kilogram of hydrogen). Also, hydrogen is expected to cost $3/kg by 2008 which would mean that in 2008, the operating cost of this car would be about $0.05/mile.
Thursday, August 18, 2005
DaimlerChrysler aims for 100,000 FC cars by 2015
ENV hydrogen bike about 1 year from commercialization
Intelligent Energy is finalizing development of it's ENV Bike ("envy"), a motorcycle built around IE's state-of-the-art fuel cell, "The Core." According to specs (1.7 MB pdf), the bike can go up to 80 km/h (50 mph), and a single tank lasts 100 miles and takes, can run continuously for four hours before the fuel cell needs re-fueling less than 5 minutes to refuel. "The Core," the fuel cell powering the bike, is fully removable and can function at temperatures up to -40°C. In the future, Intelligent Energy is considering creating a suite of remote-power products running from the core. An article from The Toronto Star (not available online) suggests it may be available as early as next year, and for as little as $16,000 CAN.
The BBC is also reporting that the motor bike is so quiet that it might be fitted with an artificial "vroom" because of worries its silence might be dangerous. The fake engine noise device would help alert road users. Cross posted to theWatt, and here.