Heavy-duty hydrogen fuel cell trucks a waste of energy and money

FCEV Heavy truck: PEM hydrogen fuel cell on-board reforming. U.S. Department of Energy Vehicle Technologies Program, Estimated for 2020. Source (DOE 2011).

Figure 1. FCEV Heavy truck: PEM hydrogen fuel cell on-board reforming. U.S. Department of Energy Vehicle Technologies Program, Estimated for 2020. Source (DOE 2011).

Preface.

Sir William Robert Grove invented the fuel cell or “gas battery” in the 1840s, but the discovery of the “fuel cell effect” by Christian Friedrich Schoenbein dates back to 1838. The first practical fuel cells were not built until the Gemini and Apollo space programs in the 1960s and are still used in space today. The difference between building a successful fuel cell and a commercially successful fuel cell, however, is the same difference between putting a man on the moon and putting 10,000 men on the moon every day at an affordable price.

[ Fuel cells are seen as an alternative to batteries, because batteries may always be too heavy to move trucks:

Battery electric trucks (BEV) may never work out. Even if 5 to 10 times as much battery energy density (Wh/kg) were achieved and other technical issues solved, they’d still weigh too much: 2 to 4 tonnes (4400 to 8800 pounds) in a 40 tonne truck. Today’s batteries are 5 to 10 times heavier than 2 to 4 tonnes (ICCT 2013). This is why the Ports of Los Angeles and Long Beach ruled out Battery-electric (BEV) trucks, which need a 7,700 pound battery that cuts too much into payload, and only goes 100 miles, half as far as required, and are out of service too long and too often, recharging for 4 hours every 120 miles (Calstart 2013).

Turning hydrogen back into electricity with a fuel cell is only 24.7 % efficient (.84 * .67 * .54 * .84 * .97). There are multiple stages where energy is lost due to inefficiencies at each step: Natural gas upstream and liquefaction, hydrogen on-board reforming, fuel cell efficiency, electric motor and drivetrain losses, and aerodynamic/rolling resistance (Figure 1).

Since fuel cell electric trucks are terrible at acceleration, they always have a second propulsion system, usually a battery, making them orders of magnitude more expensive than an equivalent diesel truck, $1,300,000 versus $100,000 respectively.

Batteries and fuel cells both have reached technical hurdles to overcome that may never be, given the little time left before energy decline, and how long both have been around with little improvement — batteries for 210 years and fuel cells for 180 years.

Hydrogen is not a renewable, since 96% of hydrogen is made from natural gas. The four percent that isn’t is so expensive it is only made for applications that require extremely pure hydrogen. Since impurities gum up fuel cells over time and lower their efficiency, clearly hydrogen from water would be a great idea – both renewable and enabling fuel cells to last longer. But we are far from that. For a full discussion of why hydrogen will not solve our problems, see my post Hydrogen, the Homeopathic Energy Crisis Remedy.

Absent hydrogen pipelines, delivery requires a $250,000 canister truck weighing 40,000 kg delivering a paltry 400 kg of fuel, enough for 60 cars. The same truck can carry 10,000 gallons of gas, enough to fill 800 cars. The hydrogen delivery truck will eat a lot of energy itself: over a distance of 150 miles, it will burn the equivalent of 20% of the usable energy in the hydrogen it is delivering (Romm 2005).

Trucks don’t use hydrogen tanks because they take up 10% of payload weight (DOE 2011), or fuel cells, because the best only last 2500 hours but need to keep on going at least 14,560 hours in long-haul trucks and 10,400 in distribution trucks (den Boer 2013).

Alice Friedemann www.energyskeptic.com author of “When Trucks Stop Running: Energy and the Future of Transportation”, 2015, Springer and “Crunch! Whole Grain Artisan Chips and Crackers”. Podcasts: KunstlerCast 253, KunstlerCast278, Peak Prosperity]

**ARB. November 2015. Medium- and heavy-duty fuel cell electric vehicles. Air Resources Board, California Environmental Protection Agency.**

Medium- and heavy-duty Fuel Cell Electric Vehicles (FCEV) are primarily in demonstration stages in walk-in delivery vans, refuse, and semi-tractor drayage trucks.

Medium duty FCEV’s are mainly used to extend the range of battery electric trucks (BEVs).

Hydrogen is typically dispensed at 35 MPa for medium- and heavy-duty FCEVs; pressures greater than this can be achieved and maintained at a greater cost. To compress hydrogen to 35 MPa requires 2 to 4 kilowatt hours per kg (kWh/kg)

Barriers to FCEV for medium and heavy-duty trucks:

Vehicle cost bus: $1,300,000 versus $500,000 for a diesel bus.
Vehicle cost (truck): even higher due to heavier payloads
Cost of hydrogen fuel
Cost of fuel cell power plant. At $3,000/kW for a 150 kW fuel cell system, the power plant cost is $450,000
Cost of 40-50 kg fuel tank, frame, and mounting system is $100,000
Service station costs of $5,000,000 and O&M costs of $200,000/year
Distribution of hydrogen fuel (corrodes pipes, distributed by diesel-burning trucks now)
More frequent fueling (the fueling infrastructure for FCEV medium and heavy-duty trucks is not known since there aren’t any commercial MD/HD trucks yet)
Lack of hydrogen service stations
Significantly higher costs for FCEV than diesel trucks
Hydrogen tanks weigh a lot
Hydrogen tanks take up a lot of space
Their weight and size reduce range
Hydrogen is more expensive than diesel fuel
The only public hydrogen stations in California are for light duty cars. Because of the high pressure at which they dispense hydrogen, as well as different fueling protocols and nozzles, they are not compatible for use with current fueling protocols for medium- or heavy-duty vehicles.
FCEV can’t handle acceleration well so there is always a 2^nd propulsion system like batteries, which adds to their cost
Tanks can go on the roof of buses, but trucks do not have enough space for a tank (though there is room for the fuel cell which is roughly equal to a conventional diesel engine with a similar power rating
Only PEM fuel cells with low operating temperatures, high power density, and so on are suitable, but they are too fragile to endure the rough ride of a truck
FCEV use too much platinum metal group elements which are limited and expensive

What is an FCEV? A FCEV is a vehicle with a fuel cell system that generates electricity to propel the vehicle and to power auxiliary equipment. Hydrogen fuel is consumed in the fuel cell stack to produce electricity, heat, and water vapor—no harmful pollutants are emitted from the vehicle. FCEVs are typically configured in a series hybrid design where the fuel cell is paired with a battery storage system. Together, the fuel cell and battery systems work to meet performance, range, efficiency, and other vehicle manufacturer goals. FCEVs have higher efficiencies, quieter operation, comparable range between fill-up, and similar performance to conventional vehicles.

Most suitable applications. Vehicles that are centrally fueled, operated, and maintained, returning to the same base at the end of the day.

NRC. 2003. Energy and Transportation: Challenges for the Chemical Sciences in the 21st Century. National Research Council

Excerpts about hydrogen fuel cells:

The most important part of a fuel cell is the membrane, which must be an ion conductor, an electronic insulator, an impermeable gas barrier and also possess good mechanical strength. However, the key issues in making a practical fuel cell are non-electrochemical. These include the acts of delivering the gases to the fuel cell membrane, removing the water, removing the heat from around the system, and controlling humidity and pressurization of gases. There are still many challenges for electrochemists, chemists, and chemical engineers. For example, a membrane that is more tolerant of environmental conditions for gases of varying pressures will allow for the elimination of various system components, which can be very expensive due to their use of stainless steel. The technical challenge is in fabricating a membrane to be thin enough so that the hydrogen side of the gas supply does not need to be humidified. However, as membranes get thinner, reliability over long periods of time becomes an issue due to faradaic losses. If the membrane is too thick, additional components must be added to humidify the hydrogen.

In a vehicle fuel cell stack, which has over 400 cells in series, the situation is even more complicated. Well over 90 percent of fuel cell industry funds are not spent on the membrane but on moving these gases in and out of the fuel cell stack, managing the system, and creating the environment where the membrane can do its job. Fuel cell research, however, is mainly performed in a lab where gases are supplied at exactly the right humidity, pressures, and so on. The actual commercial problem, development of a fuel-cell-powered vehicle that has a life of 15 years and 150,000 miles under terrible external environmental conditions, has not been approached. Fuel cell technology may be developed to permit its use for power generation in the near future, but the cost is prohibitive for vehicle transportation.

Tolerances are also not well understood. A fuel cell stack with over 400 cells operating in this environment contains sealant, which is literally miles long. Seals will start to fail after the fuel cell is bumped and jostled on the highway and while temperature shifts between hot and cold, and the cell is turned off and on. With zero tolerance for safety failures, hydrogen leaks cannot occur with these vehicles. Additionally, every cell has to be identical or the system cannot be managed. Unfortunately, that kind of tolerance control is not yet available.

An ideal fuel cell system will have minimal components outside of the stack and will operate using ambient, unhumidified hydrogen. Although fuel cells are very efficient, they do not release much heat through the exhaust. Even though they generate less heat than an internal combustion engine, the system requires the addition of cooling components due to the generated heat in the cooling stack. However, if this stack can generate less heat, then radiators, pumps, and coolant will not be required.

The standard for a modern vehicle requires it to start within 2 seconds at worst. A fuel cell starts well within 1 second. However, fuel cells, including hydrogen fuel cells, do not operate well at subfreezing temperatures. This is because fuel cells are basically a liquid interface device and need liquid-phase water to operate. Running the system under the conditions of a highway environment is possible, but the current cost is too great for commercialization.

Practical use of hydrogen in vehicles may never happen until there is a better method to store hydrogen, especially since onboard reforming of hydrogen at a reasonable cost may not be a possibility.

The use of hydrogen requires additional infrastructure for production and transportation. One method is to use electrical energy to produce hydrogen, but power grids are very inefficient. Another is the use of a natural gas pipeline, which is also wasteful since it involves the liquefying and re-evaporation of gases.

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References

Calstart. 2013. I-710 project zero-emission truck commercialization study. Calstart for Los Angeles County Metropolitan Transportation Authority. 4.7.

den Boer, E. et al. 2013. Zero emissions trucks. Delft.

DOE. 2011. Advanced technologies for high efficiency clean vehicles. Vehicle Technologies Program. Washington DC: United States Department of Energy.

ICCT. July 2013. Zero emissions trucks. An overview of state-of-the-art technologies and their potential. International Council for Clean Transportation.

Romm, J. J. 2005. The Hype About Hydrogen: Fact and Fiction in the Race to Save the Climate. Island Press.

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