Preface. There are 3 articles that I summarize below:
- ARB. November 2015. Medium- and heavy-duty fuel cell electric vehicles. Air Resources Board, California Environmental Protection Agency.
- NRC. 2003. Energy and Transportation: Challenges for the Chemical Sciences in the 21st Century. National Research Council
- NACFE. 2020. Making sense of heavy-duty hydrogen fuel cell tractors. North American council for freight efficiency. It has additional information in hydrogen fuel cell (FCEV) trucks.
Figure 1 reveals why hydrogen fuel cell trucks are incredibly inefficient. Turning hydrogen back into electricity with a fuel cell is only 24.7 % efficient (.84 * .67 * .54 * .84 * .97) as shown in figure 1. 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 drive-train losses, and aerodynamic/rolling resistance.
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.
Hydrogen is not a renewable, since 96 to 99% of hydrogen is made from natural gas using natural gas, but at least it can be made cheaply around the clock that way.
Hydrogen generated with solar power could only be made 10 to 25% of the time (the capacity factor) when the sun is up, and electrolysis of water is so expensive it is only made for applications that require extremely pure hydrogen, mainly NASA. The amount of space rebuildable contraptions like solar and wind take up is a problem as well. To use wind power to produce 700 Terrawatt hours of hydrogen would require wind turbines taking up 40,154 square miles (Ford 2020).
Hydrogen pipelines are too expensive to build at length, since they are corroded and embrittled by hydrogen. Yet delivery would require a $250,000 canister truck weighing 88,000 pounds (40,000 kg) delivering a paltry 880 (400 kg) of fuel, enough for 60 cars and just a few trucks. A diesel truck can carry 10,000 gallons of gas, enough to fill 800 cars. The hydrogen delivery truck cannibalize much of its energy: 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).
For a full discussion of why hydrogen will not solve our problems, see my post Hydrogen, the Homeopathic Energy Crisis Remedy and other related articles listed at the end.
Alice Friedemann www.energyskeptic.com author of “When Trucks Stop Running: Energy and the Future of Transportation”, 2015, Springer, Barriers to Making Algal Biofuels, and “Crunch! Whole Grain Artisan Chips and Crackers”. Podcasts: Collapse Chronicles, Derrick Jensen, Practical Prepping, KunstlerCast 253, KunstlerCast278, Peak Prosperity , XX2 report
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 far from being commercial due to many barriers:
- Vehicle cost (bus): $1,300,000
- 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
- Tank 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 2nd 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% 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.
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.
End note: Sir William Robert Grove invented the hydrogen fuel cell or “gas battery” in the 1840s. 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. We’re running out of time to invent a good hydrogen fuel cell, they’ve been around 180 years, and peak oil may have occurred in 2018 (Patterson 2019).
NACFE. 2020. Making sense of heavy-duty hydrogen fuel cell tractors. North American council for freight efficiency.
A few bits and pieces from this document.
Currently there are less than 8,573 hydrogen fuel cars, 48 buses, and 20 prototype trucks, most of them in California, where there are 15 retail hydrogen stations.
Estimates of an electric future with both battery electric and fuel cell vehicles will need anywhere from 2X to 8X the amount of electric energy produced today. Similarly, little of today’s hydrogen production is used for transportation. The production of both electricity and hydrogen will need to aggressively increase; and in lockstep, the demand for both will need to dramatically increase.
Today there are only a handful of prototype fuel cell demonstrator trucks in existence, each built to be successful for certain applications. Since there are only pilot vehicles, mainly in Switzerland, this report can’t say much about how they operate in real life. The costs of hydrogen, vehicles, and hydrogen production all must come down significantly to make hydrogen economically competitive with alternatives.
In order for trucks to use hydrogen, all of the following must be in place: H2 production plants need to be built and produce H with economies of scale 2) There has to be a demand for H (market penetration), 3) A distribution network must exist from production facilities to end users, 4) The delivery technology to quickly deliver high pressure H fuel in volume needs to be developed 5) Storage technology to safely and efficiently store hydrogen for distribution, fueling, and onboard the vehicle in place 6) H technology must be reliable, 7) Cheap electricity is required for electrolysis, 8) Battery cell costs must come down and energy density increase, 8) H must be safe and technicians, drivers, and emergency personnel trained to deal with problems 9) The Green H must be sustainable, available, and affordable
Quickly ramping up both electricity supply and demand, in the matter of a couple decades or less, is challenging. Application of funding can only do so much. Innovations will be required across a range of technologies.
- Green: electrolysis of water with electricity from renewable resources. Zero carbon emissions
- Turquoise: thermal splitting of natural gas, instead of CO2 solid carbon produced
- Pink / purple / red: produced by nuclear power electrolysis
- Black / gray: from natural gas using steam-methane reforming
- Yellow: electrolysis with grid electricity
- Brown: from fossil fuels, usually coal, with gasification
- Blue: gray or brown with CO2 sequestered or repurposed
- White: byproduct of industrial processes
The truck manufacturing marketplace is entirely about supply and demand. The annual trucking market demand for new vehicles and the annual trucking manufacturing output range from 150,000 to 300,000 vehicles per year. In 2020 there were zero Class 8 fuel cell trucks produced.
In 2030, 30% of new Class 8 vehicles would optimistically be approximately 100,000 vehicles a year. There are an estimated 1.8 million Class 8 trucks hauling freight trailers in the United States today. In total, there may be up to 4 million Class 8 vehicles registered in the United States with the lives of those vehicles ranging from 12 to 20 years or more.
Trucks are long-term capital investment tools. Commercial vehicle populations change slowly. The vehicles have long life spans. It can take 20 years or more for a new technology to completely supplant an existing one through normal market attrition.
Hydrogen fuel cell trucks can be superior to Battery electric trucks if
- Zero emission at tailpipe important
- Tractor tare weight critical to maximizing payload
- Long distance routes over 500 miles common
- Winter conditions significant
- Green or blue H available
- Incentivized Hydrogen use
- Less mountainous
As Steve Hanley of CleanTechnica summarized, “Making electricity to electrolyze hydrogen which is then used in fuel cells to power vehicles is not as efficient as making electricity and using it to power vehicles directly in the first place. Every time energy gets converted from one form to another, there are losses. The more transformations there are, the more losses occur.”
How do Heavy-duty Hydrogen Fuel Cell tractors (FCEV) vehicles work?
In all cases, FCEV also need to have batteries.
A battery dominant FCEV uses the fuel cell to charge the onboard batteries. The batteries then directly power the electric motors. As the batteries deplete running the motors, the fuel cell provides some replacement of energy, but the battery dominant system expects that the duty cycle will reduce the state of charge (SOC). Sized correctly for the duty cycle, the vehicle ends it shift before the battery SOC is completely depleted. Complete depletion generally means some low SOC cutoff typically around 20% SOC . The fuel cell then recharges the parked truck prior to its next shift.
A fuel cell dominant vehicle will use both the fuel cell and the battery pack to power the electric motors. The battery pack serves to handle short demand peaks, like accelerations or short hills, while the fuel cell is sized to provide continuous power to the motors for a typical average duty cycle load. There is a balance between planned typical loads and peak loads that dictates how much battery and how much fuel cell is required for the expected duty cycles. Designers need to statistically predict nominal and off-nominal loads to properly size the systems for the end user. A dedicated route with predictable freight loads and repeatable traffic and weather conditions can allow smaller battery packs for a fuel cell dominant system. Variable routing with a wide variety of payloads and complex traffic and weather conditions may require a more battery dominant system with greater battery capacity to compensate for the unpredictable duty cycles. Conversely, this variable route also might be served by having larger fuel cell(s) rather than battery packs
While spherical hydrogen tanks are the optimum for the weight-to-strength ratio, they do not package well on trucks. Long, constant diameter cylinders with rounded ends are the primary shape to consider. These shapes are very similar to those evolved for CNG-based trucks where they are typically packaged behind the cab in modular units. Placing the tanks behind the cab increases the wheelbase. Placing the tanks in this region also requires maintaining adequate swing and dip clearances to trailers, so trailer gaps need to be maintained.
Ballard said, “Using an estimated specific density of 36kg tank weight per 1kg of hydrogen yielded a tank weight of 3910kg (8,600 lbs.)” in its report on the potential of applying fuel cells to NACFE’s Run on Less Regional demonstration fleet diesel vehicles. The net weight impact was estimated by Ballard “to weigh 7,750 lbs. (3,520kg) more than a diesel truck.” A gauge for estimating relative weight impact of fuel cell tractors is that current CNG trucks are approximately 1,500-2,000 lbs. heavier than their diesel counterparts, the added weight due to the net impact of the tanks, plumbing and frame length versus the parts removed from emission systems. The current prototype battery electric drayage trucks are approximately 7,000 to 10,000 lbs. heavier than diesel, NACFE learned from consultations with a variety of sources operating these early prototype vehicles. Fuel cell tanks will be somewhat heavier than their CNG counterparts in order to deal with the higher pressures.
Carbon fiber has become a material of choice to use in hydrogen tanks for vehicles. Carbon fiber has the strength of steels yet is 10%-30% lighter for the same performance. They can be three to five times more energy intensive to fabricate than conventional steel, according to the DOE group that evaluates and promotes lightweight material manufacturing and use, the Advanced Manufacturing Office (AMO). There are cost increases with using carbon fiber over steel, as lightweight materials generally carry cost premiums since they are more expensive in energy, time and effort to make.
Fuel Cell buses
There are 14 operating today, with an average cost of $1,920,000 ($1,270,000 to $2,400,000). They are not yet at the commercial stage, but in the technology demonstration state. Class 8 trucks are significantly more demanding than buses, which will require many years of development to reach the commercial stage. heavy-duty trucks see 80,000 miles to more than 140,000 miles per year pulling heavy loads in all weather and traffic conditions. Where buses have known dedicated routes and conditions, with generally slower speeds and passenger friendly stopping and accelerations, heavy-duty trucks see highway speeds and urban travel with more demanding stops and starts due to their 60,000- to 80,000- lb. vehicle weights. It’s not that automotive and bus technology cannot migrate to trucks, but the systems that do migrate must go through significantly greater validation to achieve reliability, environmental and performance requirements as outlined in NACFE’s Defining Production report .
Efficiency: While the vehicle fuel efficiency is an important indicator, a whole system perspective is also needed — what is termed well-to-wheel (WTW) as opposed to tank-to-wheel (TTW) or well-to-tank (WTT)
Well to wheel (WTS) versus tank-to-wheel (TTW) and well-to-tank (WTT)
WTW quantifies the entire system from extracting oil in the ground, to transporting it to a refinery, to refining it into diesel fuel, to transporting the diesel fuel to a truck stop, storing it and ultimately delivering the fuel into a truck’s fuel tank, and then finally consuming the fuel to move the truck down the road. Efficiencies for the total system are much more challenging to measure because details of all intermediate steps are not always visible and quantifying them through prorating can be complex.
From a public policy perspective, the real killer for H2FC cars is their wind-to-wheel (or solar-to-wheel) inefficiency. Driving a small family car 100km, whether H2FC or BEV, uses 15kWh of motive energy at the wheels. For the BEV, taking into account losses on the grid and in the battery cycle and drive train, that translates into a need to generate 25kWh at the plant where the electricity is generated. The equivalent for the H2FC car, given losses in electrolysis, compression, transport, storage and reconversion of hydrogen, is at least 50kWh. Put simply, hydrogen cars are half as efficient as BEVs – and there is no reason in physics to think that will change. There is reason why [Teslas’s] Elon Musk calls them “fool cell” cars. BEVs are 2X to 3X more efficient than hydrogen fuel cells on a WTW basis
Hydrogen-based tractors may not be viable for all routes in the U.S. or Canada due to unacceptable levels of risk in locations such as the Eisenhower Tunnel in Colorado or other tunnels and enclosed spaces like warehouses or underground facilities. The challenge is that transporting highly combustible fuels is sometimes restricted on routes. Fuel haulers have additional rules to follow. A hydrogen fuel cell truck is hauling not only a highly combustible fuel, it is hauling a 10,000 psi storage container. A further modern element of concern is intentional use of these vehicles as weapons in terrorism. This risk is likely similar to that faced by fuel haulers, which may necessitate additional driver certification and background checks for hydrogen powered tractors.
Adding to the complexity of defining the system is that physically making the vehicle and the infrastructure to support it also factors into the net system emissions. For example, while a wind turbine spinning in Texas is emission free in providing energy, prior to that point, fabricating, shipping and installing the wind turbine blades and parts are not emission free, and typically require fossil fuel energy expenditures to get the raw materials and then to manufacture (under business as usual). These wind turbines are capital investments which wear out in use, and parts must be disposed of, again requiring energy expenditures and having environmental considerations.
- Making the most energy dense battery from the palette of the periodic table
- Hydrogen, the Homeopathic energy crisis remedy
- Diesel is finite. Trucks are the bedrock of civilization. So where are the battery electric trucks?
- Just 16,000 catenary trucks would use 1% of California’s electricity generation, all vehicles 2.5 times more power than available
- All Electric Trucks. Probably not going to happen. Ever. Why not?
- Hybrid electric trucks are very different from HEV cars
- Electric truck range is less in cold weather
- Utility scale energy storage batteries limited by materials and few locations for pumped hydro, compressed air
- Roger Andrews: California public utilities vote no on energy storage
- Electric Grid Energy Storage
- Would Tesla, li-ion batteries, SolarCity or SpaceX exist without $4.9 billion in government subsidies?
- Electric vehicle overview
- What is the life span of a vehicle Lithium-ion Battery?
- EPA LCA study lithium-ion battery environmental impact, energy used, recycling issues
- Bloomberg News: Tesla’s new battery doesn’t work that well with solar
- Renewable Energy can’t supply more than 30% of electricity without revolutionary battery breakthrough
- Revolutionary understanding of physics needed to improve batteries – don’t hold your breath
- American Physical Society: has the Battery Bubble Burst?
- Batteries are made of rare, declining, and imported minerals
- Battery energy density too low to power cars
- Notes from “The Powerhouse: Inside the Invention of a Battery to Save the World” by Steve LeVine
- Why aren’t there Battery Powered Airplanes?
- Given the laws of physics, can the Tesla Semi really go 500 miles, and what will the price be?
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.
Ford, J. 2020. The world must look beyond sun snd wind for hydrogen. We need lots of the gas, and cheaply, if it is to help replace liquid carbon fuels. Financial times
ICCT. July 2013. Zero emissions trucks. An overview of state-of-the-art technologies and their potential. International Council for Clean Transportation.
Patterson, R. 2019. Was 2018 the peak for crude oil production? oilprice.com
Romm, J. J. 2005. The Hype About Hydrogen: Fact and Fiction in the Race to Save the Climate. Island Press.