Hydrogen fueled cars and buses are as clean to drive as battery vehicles and have better range and faster fueling times. Cost-wise, a hydrogen fuel tank is far cheaper and lighter than an equivalent battery and lasts far longer. Hydrogen is likely safer because the tanks do not carry their oxidant in them. And the price of hydrogen is relatively low, about that of gasoline on a per-mile basis: far lower than batteries when the cost of battery wear-out is included. Both Presidents Clinton and Bush preferred hydrogen over batteries, but the current administration has favored batteries. Perhaps history will show them correct, but I think otherwise. For whatever reason, there is not a hydrogen bus, car, or boat at Disney’s Experimental Community of Tomorrow (EPCOT) — nor is there an electric bus car or boat. I think it’s a mistake.
Compare the best current hydrogen and electric vehicles currently on the road. The Honda Clarity, debuted in 2008 has a 270 mile range and takes 3-5 minutes to refuel with pressurized hydrogen at 350 atm, 5150 psi. By contrast, the Tesla S-sedan that debuted in 2012 claims only a 208 mile range for its standard, 60kWh model (the EPA claims: 190 miles) and requires three hours to charge using their largest, 20 kW charger. The replacement cost of the batteries is $12,000 as subsidized by DoE; without the subsidy, the price would be more like $40,000.
Part of what hurts the range of battery vehicles is that the stacks are very heavy. Despite using modern lithium-ion technology, Tesla’s 60 kWh battery weighs 1050 lbs including internal cooling, plus another 250 lbs for extra structural support. By contrast, Honda Clarity fuel cylinders weigh only 150 lb. They require another 120 lb. for the fuel cell stack and lithium-ion battery, about 30 lb. and 90 lb respectively. The net effect is that the Tesla-S weighs 1135 lbs more than the Clarity; 3582 lbs vs 4647 lbs. Largely because of this extra 1135 lbs the Tesla gets worse mileage, about 3.3 mi/kWh or 0.19 mile/lb of battery versus 60 miles/kg of hydrogen for the Clarity suggesting 3.6 mi/kWh at typical efficiencies.
High pressure hydrogen tanks can be smaller than batteries if the pressure is high. The higher the pressure the smaller the tank for a given range. The current Clarity takes 350 atm, 5,150 psi hydrogen to save tank space, and the next generation (shown below) takes higher pressure hydrogen to save space. But high pressure is not necessary. A reasonable car could be made to use 335 atm hydrogen (5000 psi) stored, for example, in four cheap 8″ diameter tanks (ID), 4′ long. At these dimensions the tank might be made from 0.065″ Maranging (aged) stainless steel (UTS = 350,000 psi, density 8 g/cc), surrounded by 0.1″ of aramid fiber (UTS = 250,000 psi, density = 1.6 g/cc). With this construction, each tank would weigh 14.0 kg (30.5 lbs) empty, and hold 11,400 standard liters, 1.14 kg (2.5 lb) of hydrogen at pressure. These tanks would cost about $1500 total, and provide a range of 273 miles. This is 40% more range and a far cheaper cost than the standard Tesla S.
Now lets now compare fuel cost. My company, REB Research, makes hydrogen generators that produce 75 slpm of ultra pure hydrogen by steam reforming methanol-water in a membrane reactor. A generator of this type produces 9.5 kg of hydrogen per day, consuming 69 gal of methanol-water. At 80¢/gal for methanol-water, and 10¢/kWh for electricity, the hydrogen costs $2.50/kg., or $5,000 over a 120,000 mile life. This is somewhat cheaper than gasoline, but about twice the dollar per mile cost of a Tesla S if only electric cost is considered. The hydrogen car is much cheaper on a per-mile basis, though when you include the fact that the battery has only a 120,000 mile life. A 120,000 mile life is short for a luxury car, and very short for a truck or bus.
The charge time advantages of hydrogen are extreme for busses and trucks, as the fuel use and battery size is larger, and the range targets are longer. A bus or truck can expect to get 1/4 the mileage of a car; you can build a hydrogen bus with five 20 foot x 8″ tanks of the above construction. Fueled at 5000 psi., such buses will have a range of 420 miles between fill-ups, and a total tank weight and cost of about 600 lbs and $4000 respectively. By comparison, you are unlikely to build an electric bus with more than a 300 mile range, and even this will require a 6000 lb., 360 kWh lithium-ion battery that takes 18 hours to charge from a 20 kW charger. You could cut the charge time in half, to 9 hours a 40 kW charger (100 Amps at 400 V for example), but even that is excessive compared to 10-20 minutes for fueling with high pressure hydrogen.
While hydrogen generators are not cheap — about $500,000 including the cost of a compressor, the cost of a 40 kW DC is not much less when you consider the cost to run a 100 Amp, 400 V line to an appropriate spot for charging. Add to this the time lost by buses having to stand around for hours once or twice per day while the battery charges. Tesla has shown there are a lot of people who value cleaner transport if that comes with comfort and style; a hydrogen car can meet that handily, especially when you consider the comfort of longer range and not needing hours to recharge.
Robert E. Buxbaum, February 12, 2014 (Lincoln’s birthday). Here’s an essay on Lincoln’s Gettysburg address, on the safety of batteries, and on battery cost vs hydrogen. My company, REB Research makes hydrogen generators and purifiers; we also consult.