There are two major green energy choices that people are considering to power small-to-medium size, mobile applications like cars and next generation, drone airplanes: rechargeable, lithium-ion batteries and hydrogen /fuel cells. Neither choice is an energy source as such, but rather a clean energy carrier. That is, batteries and fuel cells are ways to store and concentrate energy from other sources, like solar or nuclear plants for use on the mobile platform.
Of these two, rechargeable batteries are the more familiar: they are used in computers, cell phones, automobiles, and the ill-fated, Boeing Dreamliner. Fuel cells are less familiar but not totally new: they are used to power most submarines and spy-planes, and find public use in the occasional, ‘educational’ toy. Fuel cells provided electricity for the last 30 years of space missions, and continue to power the international space station when the station is in the dark of night (about half the time). Batteries have low energy density (energy per mass or volume) but charging them is cheap and easy. Home electricity costs about 12¢/kWhr and is available in every home and shop. A cheap transformer and rectifier is all you needed to turn the alternating current electricity into DC to recharge a battery virtually anywhere. If not for the cost and weight of the batteries, the time to charge the battery (usually and hour or two), batteries would be the obvious option.
Two obvious problems with batteries are the low speed of charge and the annoyance of having to change the battery every 500 charges or so. If one runs an EV battery 3/4 of the way down and charges it every week, the battery will last 8 years. Further, battery charging takes 1-2 hours. These numbers are acceptable if you use the car only occasionally, but they get more annoying the more you use the car. By contrast, the tanks used to hold gasoline or hydrogen fill in a matter of minutes and last for decades or many thousands of fill-cycles.
Another problem with batteries is range. The weight-energy density of batteries is about 1/20 that of gasoline and about 1/10 that of hydrogen, and this affects range. While gasoline stores about 2.5 kWhr/kg including the weight of the gas tank, current Li-Ion batteries store far less than this, about 0.15 kWhr/kg. The energy density of hydrogen gas is nearly that of gasoline when the efficiency effect is included. A 100 kg of hydrogen tank at 10,000 psi will hold 8 kg of hydrogen, or enough to travel about 350 miles in a fuel-cell car. This is about as far as a gasoline car goes carrying 60 kg of tank + gasoline. This seems acceptable for long range and short-range travel, while the travel range with eVs is more limited, and will likely remain that way, see below.
The volumetric energy density of compressed hydrogen/ fuel cell systems is higher than for any battery scenario. And hydrogen tanks are far cheaper than batteries. From Battery University. http://batteryuniversity.com/learn/article/will_the_fuel_cell_have_a_second_life
Cost is perhaps the least understood problem with batteries. While electricity is cheap (cheaper than gasoline) battery power is expensive because of the high cost and limited life of batteries. Lithium-Ion batteries cost about $2000/kWhr, and give an effective 500 charge/discharge cycles; their physical life can be extended by not fully charging them, but it’s the same 500 cycles. The effective cost of the battery is thus $4/kWhr (The battery university site calculates $24/kWhr, but that seems overly pessimistic). Combined with the cost of electricity, and the losses in charging, the net cost of Li-Ion battery power is about $4.18/kWhr, several times the price of gasoline, even including the low efficiency of gasoline engines.
Hydrogen prices are much lower than battery prices, and nearly as low as gasoline, when you add in the effect of the high efficiency fuel cell engine. Hydrogen can be made on-site and compressed to 10,000 psi for less cost than gasoline, and certainly less cost than battery power. If one makes hydrogen by electrolysis of water, the cost is approximately 24¢/kWhr including the cost of the electrolysis unit.While the hydrogen tank is more expensive than a gasoline tank, it is much cheaper than a battery because the technology is simpler. Fuel cells are expensive though, and only about 50% efficient. As a result, the as-used cost of electrolysis hydrogen in a fuel cell car is about 48¢/kWhr. That’s far cheaper than battery power, but still not cheap enough to encourage the sale of FC vehicles with the current technology.
My company, REB Research provides another option for hydrogen generation: The use of a membrane reactor to make it from cheap, easy to transport liquids like methanol. Our technology can be used to make hydrogen either at the station or on-board the car. The cost of hydrogen made this way is far cheaper than from electrolysis because most of the energy comes from the methanol, and this energy is cheaper than electricity.
In our membrane reactors methanol-water (65-75% Methanol), is compressed to 350 psi, heated to 350°C, and reacted to produce hydrogen that is purified as it is made. CH3OH + H2O –> 3H2 + CO2, with the hydrogen extracted through a membrane within the reactor.
The hydrogen can be compressed to 10,000 psi and stored in a tank on board an automobile or airplane, or one can choose to run this process on-board the vehicle and generate it from liquid fuel as-needed. On-board generation provides a saving of weight, cost, and safety since you can carry methanol-water easily in a cheap tank at low pressure. The energy density of methanol-water is about 1/2 that of gasoline, but the fuel cell is about twice as efficient as a gasoline engine making the overall volumetric energy density about the same. Not including the fuel cell, the cost of energy made this way is somewhat lower than the cost of gasoline, about 25¢/kWhr; since methanol is cheaper than gasoline on a per-energy basis. Methanol is made from natural gas, coal, or trees — non-imported, low cost sources. And, best yet, trees are renewable.
Pingback: Volvo-Benz Fuel Cell: Another Daimlers Gem Going Unnoticed – Zillion Lending
Pingback: Hydrogen powered trucks and busses | REB Research Blog
Pingback: A clever, sorption-based, hydrogen pump | REB Research Blog
Which one is the best for alternatives as energy sources for delivery vehicles? Lithium-ion batteries or hydrogen fuel cell? If so, why?
Going by Tesla’s recent announcement, clearly batteries cost a lot less than $2000/kWh.
Pingback: Hydrogen breakthrough could be a game-changer for the future of car fuels
Pingback: Hydrogen cars and buses are better than Tesla | REB Research Blog
Pingback: New hydrogen generator from REB Research | REB Research Blog
One small point: ISS uses banks of nickel-hydrogen batteries. The station’s power requirements are far too large for fuel cells to be a reasonable option.
Another data point: the standard 2rd generation Toyota Prius battery carries 1.31 kWh new to total discharge, and carries a replacement cost of $2200 to $2600 according to Consumer Reports. Dividing the average, $2400, by 1.31 kWhr gives $1832/kWh, but even that’s optimistic: they get worse with age, and you’re not supposed to discharge the batteries completely if you expect them to achieve full service life. This is the most popular large battery pack replacement in America as best I can tell, and the price is about what I’ve claimed. The DoE has decided to help reduce the battery cost for some plug in cars, and for the ISS, for all I know. But my point was not to compare DoE influence, but to compare tanks of hydrogen with these batteries without government support. A tank of hydrogen to hold 1.31 kWh would need to hold about 800 std liters of hydrogen. Assuming a working pressure of 200 atm (3000 psi), the volume of the tank would be 4 liters (about 1 gallon) — and there is no way that a 1 gallon tank costs $2400. Even at 30 liters, 1 cubic foot, it’s hard to believe the price would be $2400.
The second-generation Prius is a hybrid, more than a decade old, and uses a NiMH battery. That’s a completely unreasonable comparison.
I have a much better example, even though it’s old (the oldest highway-capable production EV) and had an extremely small production run (less than 2,500 were manufactured) – both of which substantially increase costs. In 2009 the cost of replacing the battery system on a Roadster was $36,000. Since the battery capacity is 53kWh, that makes the price $679.25/kWh. And since Tesla didn’t have much money in 2009 we can assume they weren’t selling them at a loss.
But there’s more. Because they’ve been around since 2008, we also have a few years of data to look at, and letting us see how long the batteries actually last. An independent study conducted 7 months ago found that the average Roadster lost just 1.6% of its battery capacity per 10,000 miles driven. That means you’d need to make 768 full cycles for the battery to reach 70% capacity, which Tesla considers “dead”. The actual replacement cost is therefore $0.88/kWh at the full retail price, or $0.29 at the $12,000 pre-paid price.
Another notable point is that the Roadster is a sports car, which are generally limited to weekend driving. Compared with a daily drivers like Model S, Leaf, Volt, etc., capacity losses per cycle due to time are substantially higher.
So, just to be clear, I’ve quoted the actual retail price from 5 years ago (when lithium-ion batteries were four times as expensive) of a replacement battery for an extremely small production run car (making it more expensive due to economies of scale) that loses an unusually large amount of its capacity sitting in a garage (making the cost/cycle higher) which is sold by a company which (at the time) couldn’t afford to subsidize replacement parts. With all of those cards stacked against it, it’s still one fifth the price you’re claiming.
> they get worse with age
As do fuel cells. Today’s vehicular fuel cells last about 150,000 miles. I tried to figure out replacement costs, but nobody is selling them.
> you’re not supposed to discharge the batteries completely if you expect them to achieve full service life
This is correct, but that 500 cycle lifetime estimate is already based on full discharge cycles (hence why the Roadster surpasses it by such a wide margin). In fact, if you never discharge a lithium-ion battery past 50%, its lifetime increases to 1,500 full cycles.
And again, fuel cells have similar issues. Frequent starts and stops have an enormous adverse effect on the stack’s lifetime.
> This is the most popular large battery pack replacement in America as best I can tell
And it’s a completely different battery technology in a completely different class of vehicle. Not only that, the capacity is less than 1/18th the capacity of the (notoriously small) Nissan Leaf, so the economies of scale skew it way out of line.
> The DoE has decided to help reduce the battery cost for some plug in cars
I assume you’re talking about the federal tax credits for EVs. According to the IRS, the credits would also apply to fuel-cell EVs if anyone actually sold them.
> and for the ISS
…what?
> for all I know.
> But my point was not to compare DoE influence, but to compare tanks of hydrogen with these batteries without government support.
You just said “for all I know”. How can you adjust for something that you claim you don’t even know exists?
> and there is no way that a 1 gallon tank costs $2400
That tank isn’t much good without a fuel cell, is it? Just add that into the price and see how it compares to $2,400.
Also, you responded to the wrong comment.
Where did you get the figure of $2,000/kWh for Lithium-Ion batteries? That seems to be off by an order of magnitude. At that price the 85kWh Tesla Model S battery *by itself* would cost $170,000 – 2.5 times the cost of the entire car.
A modest estimate for a high-volume EV manufacturer would be $200/kWh, though Tesla is pre-selling Model S replacement batteries for $141.18/kWh. Assuming a 500 cycle lifetime, that puts the generic battery at $0.4/kWh and the Model S battery at $0.28/kWh. Add electricity at $0.12/kWh puts the generic battery at $0.52/kwH and the Model S battery at $0.40/kWh.
The data I used was a year old, and was an average based on the cost of replacement batteries for several brands of hybrid cars. Prices have dropped since then, but not by that much — except for Tesla. Even in 2014, replacing the battery pack on a Chevy Volt still costs $34,000. That would be $2,125/kWhr assuming GM’s energy numbers, 16 kWhrs/ pack, and full discharge, or $3,540/kWhr based on the usable power when new, 9.6 kWhr. As you might expect; the cost per KWhr will increase as the storage power decreases with use. Even when I wrote this, Tesla’s prices were far cheaper than $2000/kWhr, and far cheaper than anyone else’s; and the difference is even greater today. Replacement Tesla battery packs appear to cost about $200/kWhr, cheaper than the cheapest on-line products without necessary shielding, cooling, and cell-load leveling ability. I don’t know why. Perhaps they are really good at manufacture; perhaps they are loosing money on every pack. I’d consider them one data point out of many, but their importance is rising as their sales do. If I were to rewrite the article today, I’d pick a price closer to $1400/kWhr, but I still would not base everything on Tesla.
You’re delusional. $34,000 is the price of an entire Chevy Volt *before* tax credits.
GM’s MSRP for the 2013 Volt battery pack is $2,994.64, which works out to $0.36/kWh. Considering that li-ion batteries can be refurbished, and that the price doesn’t include a core charge, that price may even be a bit high.
Also, note is that lithium–titanate batteries are beginning to appear in EVs. Not only can they charge much faster (Toshiba claims a 90% charge in 10 minutes), they also have a cycle lifetime 12 times longer than current lithium-ion technology. Within a few years battery-powered EVs will be using batteries that are likely to outlast the rest of the car.
Pingback: Element 1 – Hydrogen | Matt's Notebook
Pingback: My failed process for wood to green gasoline | REB Research Blog
Excellent illustration of the issues between the two and the superiority of hydrogen and fuel cells.
One basic difference is weight and means of storage.
To add range, lower recharge time, I have to add more batteries. This significantly affects weight (even hybrid cars carry around several hundred pounds of battery). Whereas with hydrogen, I can add or expand lightweight storage tanks.
The difference is that to increase storage with batteries, I am increasing in three dimensions, so it’s proportional to volume, r^3.
But with hydrogen, using storage tanks, it’s proportional to surface area, r^2. And again, with the latest technology from companies like Quantum, these can be very very thin and strong.
How does Hydrogen-CNG stands as compared to Hydrogen and battery run vehicles in the short-term or immediate term perspective?
If you are talking about vehicles for long-distance use, hydrogen or CNG seem like easy winners. They are cheaper, specially CNG, when you include the cost of the battery, they both refuel fast, and the distance per fueling is greater. For short and medium hauls, there’s a lot to be said for a Prius hybrid, or a high quality gas engine. Tesla cars look cool, but they don’t go that far, need slow recharges, and cost a fortune — and they’re the best of the class in batteries.
Pingback: My steam-operated, high pressure pump | REB Research Blog
Pingback: Nuclear Power: the elephant of clean energy | REB Research Blog