This week, AutoblogGreen reported on the evolution of GM’s fuel cell cars. The new fifth generation fuel cell stack is much smaller than the previous fourth generation stack. Reading the features of the new FC seem to indicate that GM is trying to “turn the corner” on fuel cells – this unit is designed for manufacturing, as well as dramatically reducing the amount of platinum catalyst used by 62.5%, from 80g to 30g (1.06oz) at the same output power level (93kW/120HP). Thats about $1350 in platinum for the fuel cell. The goal is to eventually get the platinum content down to 10g, less than $500, and to manufacture about 10,000 per year by the middle of the 2010-decade.

Technology is still progressing in terms of making fuel cells affordable and small enough to put into a car. But there are still a number of other pieces to get a hydrogen infrastructure in place.

Hydrogen isn’t naturally found: There is no hydrogen mine, or hydrogen reserves. There are a few ways to “make” hydrogen – electrolysis of water (50% efficient) or steam-based reformation of natural gas into hydrogen. Compared to just plugging in a car and charging batteries for an electric vehicle these are less efficient, however there is currently a limit on how many batteries you can put in a vehicle before you start sacrificing passenger room and cargo space. Pure EVs might only have a range of 100-200 miles.

Vehicle Range: Strides are also being made in this arena as well – Toyota recently announced that their FCHV-adv Highlander SUV that got an extrapolated 431 miles per tank (they drove about 300 miles and extrapolated based on the fuel left in the tank). Previously, the range on fuel cell vehicles had been between 200-300 miles per tank.

Hydrogen Fueling Stations: While there are plenty of gas stations, and you have electrical outlets in your home that would allow you to recharge an EV, there aren’t a whole lot of hydrogen refueling stations, let one ones open to the public. California might have 46 retail locations by 2014, but many are private ones that are built for small capacity refueling of fleet test vehicles or OHVs/golf carts.

Fuel Cell Stack Lifetime: The fuel cells at the turn of the century would last for about 35,000 miles. The fourth generation fuel cell as it is now can get 80,000 miles before it needs to be replaced. The new fifth generation will get a little more than 120,000 miles per GM. This is still low compared to a traditional gasoline engine which can last a very long time if the owner takes good care of it.

There is one shining opportunity for fuel cells though. Its to team up with E-REVs and become the alternate generator, replacing the gasoline engine. The two fit together quite well – you don’t need too big of a tank because you only need 300 miles combined (40 on electric, the remainder on FC), turning on and off the FC doesn’t make noise or vibrate, unlike traditional gasoline engines, and they’ll have much lower duty cycles – 120,000 miles for the FC would be enough to outlast the batteries by a large margin. And hydrogen stations wont need much storage capacity because you’ll probably only be filling up every 6-8 weeks (they see a lower visits per FC vehicle), which means their storage infrastructure doesn’t need to bee too large – instead of lots of equipment to extract hydrogen from water or natural gas and the storage to sell thousands of kg of hydrogen per day, they only need the equipment to generate and store a fraction of that.

The year 2015 has been talked about for the production of fuel cell vehicles. Thats about the time I would expect the Voltec power train to start appearing in other vehicles. It would seem to be a great opportunity to allow a few vehicles to be sold – probably geographically limited to start, since the hydrogen infrastructure will still be sparse. As production ramps to 100,000 in 2020 and 1,000,000 in 2025, they can not only displace the electric generator int he Volt and other future E-REV cars, but also the engine in standard plug-in hybrids.

The Volt’s battery is 16kWh, with 50% of the capacity (8kWh) used to propel the Volt the first 40 miles. So how does GM guarantee that it’ll last that 40 miles for the full life of the vehicle? Well, as the total capacity decreases, the Volt can still pull 8kWh of energy from the battery. There are a few issues with this approach however.

First is that the maximum amount of power you can draw from a battery at any given moment depends on the state of charge (SoC) expressed as a percentage of total capacity. Generally speaking, you have a higher maximum power when the battery is fully charged and as the SoC decreases, the maximum power you can draw goes down as well.

This plays into how battery deterioration works over time. A battery’s total capacity will drop over time (both calendar time and cycle count), and that 8kWh needed to power the Volt for 40 miles will go up from 50% of the total capacity. As that percentage goes up, the Volt will need to expand its 50% depth of discharge to get 40 miles. Out of the factory, the battery will discharge between 85% and 35%. However if total battery capacity would degrade over 10 years from 16kWh to 13kWh (roughly 20%), then the depth of discharge would be 61% instead of 50%. We can assume the pack would go from 90% to 30% SoC, so as the battery charge state goes below 35% the pack will be able to produce less power. The issue is how much.

Could this mean that over time, battery only mode (aka Charge Depletion mode, or CD) will have decreased performance? Will 0-60 times, top speeds, etc remain constant over the life of the vehicle? GM would need to build these margins into the battery pack out of the factory, which is currently a large set of unknowns (though GM’s battery testing facility will certainly help answer these questions).

The other factor that plays into this is the cycle life. If the battery is limited to a 50% depth of discharge (DoD), the cycle life will improve dramatically over the 100% depth of discharge bench test. If a battery can go 750-1000 cycles at 100% DoD before losing 20% of the original capacity, the battery can likely take 3 times as many cycles at a 50% DoD (Motorola states that Li-Ion battery cycle counts increase exponentially as DoD decreases from 100%). GM will likely need a maximum of 3,750 cycles (40 miles each) to reach 150,000 miles, though its likely actual battery cycle counts will be closer to 3,000 in real world use. Anyone recharging the battery twice a day (recharging at work for another 40 mile drive home) will likely run up against those cycle counts much sooner.

As a risk to the program and to GM, I think the risk is fairly small. By the end of 2010, GM will have had its battery facility open for over a year. Their ability to test batteries in the worst of environments and to test cells, modules and packs and rack up the cycle counts quickly. Even if GM were forced to replace batteries after 7-8 years for those vehicles in the harshest climates (desert southwest, cold northern climates), the prices of batteries by the time 2018 or 2019 rolls around will be much cheaper (as much as 70% less than the 2010 price) and GM could even monetize the replacement if they offer a discounted upgrade battery (though I don’t know if that’s kosher/legal).

I’ve covered the batteries in question before, I believe they are Hitachi cells specifically designed for hybrid vehicles. They have different characteristics than the LG Chem cells used in the Volt. For hybrid vehicles you carry a small amount of storage (2-3kWh) and pull energy out of the battery quickly to accelerate and to store it quickly when braking. The Volt needs a higher specific energy (storage) while these hybrid batteries need high specific power (horsepower).

The batteries that GM is likely to get have a specific power of around 2,250W/kg. The PDF I link in the above article shows a 3kWh Li-Ion pack, 47kg and 1.4 cubic ft. This would provide for a total power of 90kW (120HP) in an area 41″ x 12″ x 5″. Being able to accept and output that much power could allow the vehicle to drive up to speeds of 35MPH on electricity alone (depending on car weight and other factors). However it is unlikely that GM would use this configuration – their mild hybrid systems only provide 20HP. The minimum battery pack for this size would be about 500Wh (or 8 of the above cells), and a larger 1kWh pack would be able to provide twice that (28kW/40HP).

All other mainstream hybrid vehicles currently use NiMH batteries, which are not as capable of high power output as lithium-ion batteries are. The switch to Li-Ion batteries would not only increase power output (allowing higher all-electric mode speeds), but also a lighter, smaller package. The 3kWh module mentioned above could even power the vehicle at all electric speeds for a few miles (again, depending on vehicle weight, etc).

Cost could be an issue, as these batteries are more expensive than their NiMH counterparts. Lithium-ion batteries command a cost between $800-1000/kWh, while NiMH batteries cost around $200-300/kWh.

via GM-Volt

GM’s new battery development and testing facility in Michigan is over four times larger than their previous facility, provides 64 battery cyclers and 42 climate controlled rooms as well. These facilities to give both individual cells and full battery packs the testing they’ll need to survive the real world environment.

Speaking of the environment, the facility is designed in such a way as to not just waste all that electricity after a battery has been charged and discharged, but to put up to 90% of that power back on the grid or for other uses at the plant.

Half of the space is designed to test the fully built battery packs that will end up in vehicles. This is where the rubber meets the road as far as the battery packs go..

For example, we are able duplicate real-world driving patterns and compress a decade of battery calendar life into 24 months of simulations. The lab also contains a thermal shaker table for structural integrity testing, and a battery tear down area for competitor benchmarking.

This is the type of facility GM will need to eventually develop their own batteries and to test third party cells and packs.

The automotive industry has not only the largest possible demand for batteries over the next 10 years, but is also number one customer in terms of performance demands – batteries that last in all sorts of weather conditions over the course of 10 years and almost 2,000 complete charge/discharge cycles, with enough discharge power to move around a 2,000lb vehicle and its occupants.

The end goal is to secure GM as a leader in battery development and applications. Its also a possible source of revenue – as GM develops chemistries that allow cars to go further with smaller packs, the application of that same battery technology could be used in renewable energy, as well as portable computers and other electronics. So while they make battery packs lighter and more efficient, they also can monetize this technology in other ways, creating cells for laptops, phones and other yet to be invented devices and form factors.

The GM Live Blogging of the event this morning also included videos and some little or previously unknown Volt facts and figures:

• A fleet of 80 Volts (pre-production but both Volt body and chassis together) will be ready within the next few months. Work on the first unit has already started.
• If you’re starting the Volt in a cold conditions (winter in the nothern US) without being plugged in, the engine might be the initial source of energy until the batteries are sufficently warm.
• The engine state (on or off) will have no effect on the performance of the vehicle (so it wont rely on the engine and battery to climb hills as long as the battery has a high enough state of charge)
• The engine will run at a few different RPM levels depending on the car’s electrical load – one single RPM could use more fuel than is necessary if you’re sitting in traffic with little electrical load.
• Gen II Volt should have the same specs (40 miles electric only, 300 miles or more total range), but at a much cheaper cost. Including a bigger depth of discharge range.
• The Volt’s battery could be charged in 15 minutes, however it would require a different infrastructure – the ability to source large amounts of power not typically available at your residence (9.2kWh in 15 minutes is 220V/170A – most homes could at the very most source 220V/70A for a single appliance, or about 40% of what would be needed).
• GM claims that the cost of the battery is well below the $1,000/kWh figure often used.
• GM is on its fifth design iteration of the Volt battery pack, it is comprised of 155 different parts of which GM themselves designed 147 of them.

The article and accompanying video are a good read, and a few things stuck out at me.

First is that GM seems pretty insistent that the battery pack will last as long as it should, and wont need to be replaced. This is in contrast to whats expected by people following the development of the car. GM states that the batteries will last the entire 10 year, 150,000 mile target, but also be suitable to be re-used in a climate controlled environment after their time in the Volt is up. This would be idea for utilities to backup intermittent power like solar and wind. If GM makes 200,000 Volts in the first four years, that’s 3.2GW of batteries that will need recycling after that 10 years is up. Even if you derate their capacity by 25%, that’s still 2.4GW of storage. The average home uses around 11kW, so that 2.4GW of energy storage could store solar power and disperse it to power 30,000 homes over the course of six hours (say, from 6PM to midnight).

Next is GM’s generation 1 model production targets. They said in the video that all first generation Volts will be eligible for the $7,500 tax credit. GM’s limit is 200,000 (which is why I used that figure above), so I would expect a four year first generation run (20K units for year 1, 60K for years 2, 3 and 4), and we would see a generation 2 Volt sometime around the end of 2014. Its fun to think what kind of additional features GM could bring to the table in the second generation – a full sized sedan with a bigger motor and better batteries with a depth of discharge of 80% rather than 50%, and higher watt-hour to weight and volume ratios.

GM also doesn’t seem to have the range extender ready to go. Granted, we’re still a ways away from the official production time, but the test drives GM has offered recently have been electric only. Another point that I liked was that the author indicated that the whine associated with the electric traction motor was non-existent. That will be a huge plus from the user experience standpoint.

No one knows for sure if GM will be able to deliver on time, we wont get a better idea until their 75 integration vehicles are out on the road and they can guage real Volt handling and performance.