Hydrogen FAQ

Hydrogen Questions:

1. Doesn’t it take more energy to make hydrogen than is contained in that hydrogen?

2. How dangerous is it to store compressed hydrogen gas in a passenger vehicle?

3. How much does hydrogen cost?

4. If hydrogen is made from natural gas, aren’t we just shifting from dependence on one fossil fuel (oil) to another (natural gas)?

5. How much will it cost to install hydrogen fueling stations?

6. Doesn’t it take a lot of water to make hydrogen, especially with electrolysis?

1. Doesn’t it take more energy to make hydrogen than is contained in that hydrogen?

Short answer: yes, but this is true of all fuels including gasoline, diesel, propane, natural gas, and, most importantly, electricity.  (The only exception being the much maligned corn ethanol that most experts estimate contains 20% to 25% more energy than was used from fossil fuels to make it, with the difference being provided by sunlight when the plant matter was growing.)

Here is a chart showing the well-to-tank efficiencies of producing some common fuels; gasoline is approximately 83.1 % efficient according to this source [1]. Thus it takes 20.3% more energy (1/83.1)  to make gasoline than is contained in that gasoline. Does this mean that we should stop using gasoline since it takes more energy to make it than is contained in that gasoline?

Long answer: converting natural gas to hydrogen requires approximately 33% more natural gas energy than is contained in the resulting hydrogen (the steam methane reformer to make hydrogen from natural gas and water is approximately 75% efficient on a higher heating value basis.).

But electricity is much worse. A typical natural gas combustion turbine requires something like 3 times more natural gas energy than is contained in the resulting electricity...in other words, older natural gas electrical generators are 33% efficient. By the time you account for line losses in electricity transmission, 3.4 units of natural gas energy are consumed to deliver one unit of electrical energy to our homes and buildings. Modern combined cycle natural gas power plants are more efficient, up to 48%, but it still takes more than twice the energy in natural gas than is in the electricity we finally use.

So should we all stop using electricity since it contains less than half the energy that was used to generate it? Of course not! Electricity is a very clean, convenient, zero emission fuel used throughout our society.

So too with hydrogen, another very clean, zero emission fuel that is more efficient than electricity when made from coal, natural gas or biomass.

2. How dangerous is it to store compressed hydrogen gas in a passenger vehicle?

Short answer: hydrogen is dangerous...almost as dangerous as gasoline, propane and natural gas!

Long answer: compressed hydrogen tanks are extraordinarily strong. They have to be strong to hold pressures between 35 MPa and 70 MPa (350 to 700 bar or 5,000 to 10,000 psi)  These high pressure tanks have been shown to survive simulated rear end collisions at speeds up to 52 mph without leaking. Obviously no gasoline tank could survive such an impact.

Gasoline and propane pose serious risk since their vapors are heavier than air.  Gasoline fumes released in any collision linger beneath the vehicle and are sometimes ignited while people are still alive but trapped inside the wreckage (see section on hydrogen safety). Automobile fires kill an average of 490 people per year in the US, with gasoline responsible for more than half of fatal fires after collisions.

Hydrogen is less dangerous in a collision, since hydrogen is much lighter than air.  Any hydrogen released will rise and disperse quickly, reducing the risk of subsequent fires killing trapped occupants.

So not only are hydrogen tanks much more durable than gasoline tanks, but even if they should leak (a very low probability), they will be less of a risk than a leaking gasoline tank.

3. How much does hydrogen cost?

Short answer: The cost of hydrogen per mile to power a fuel cell electric vehicle is approximately competitive with the cost of gasoline at $2.30/gallon. This assumes that the hydrogen is made by reforming natural gas at the fueling station with existing commercial hydrogen fueling equipment in low production volumes (10 units). With larger scale production, we estimate that hydrogen will cost less per mile than gasoline selling at $1.50/gallon.

Long answer: Hydrogen made from natural gas will cost less than gasoline for two reasons:

  • Natural gas, the current source of most hydrogen, costs up to three times less than gasoline per unit energy, and
  • The fuel cell electric vehicle is approximately two to three times more efficient than a conventional gasoline vehicle (we assume 2.4 times higher efficiency for the FCEV)

For example, the chart below shows the historical cost per mile for gasoline in the US, compared with what hydrogen costs would have been if hydrogen for FCEVs and electricity for BEVs had been made from natural gas in the past, including the future costs based on th 2012 Annual Energy Outlook fuel cost projections to 2035 and linear extrapolations to 2100:

In 2003 the cost of electricity per mile in a BEV-200 would have been less than the cost per mile of hydrogen in a FCEV; this assumes that the BEV batteries are charged 25% in the daytime (industrial electricity prices) and 75% at home (residential electricity prices.) No highway taxes are charged to any fuel. Over time, hydrogen cost per mile would be less than electricity costs per mile based on the EIA’s fuel cost projections. But both alternative fuels would be much lower than the projected cost of gasoline.

We conclude that gasoline used in a conventional (non-hybrid) car will cost three to four times more per mile than hydrogen, and gasoline used in a hybrid will cost at least twice as much as hydrogen per mile.

4. If hydrogen is made from natural gas, aren’t we just shifting from dependence on one fossil fuel (oil) to another (natural gas)?

Short answer: temporarily, yes. But natural gas is considered to be a bridge energy source leading to renewable hydrogen in the future.

Long answer: there are several major advantages in making hydrogen from natural gas instead of making gasoline from crude oil:

  1. Hydrogen made from natural gas used in a FCEV immediately cuts greenhouse gases in half; this is a much larger GHG reduction than either plug-in hybrids or battery electric vehicles with today’s US electrical generators.
  2. The world’s supply of natural gas is slightly larger than its oil reserves.
  3. The world is consuming more oil than natural gas each year, so natural gas will last longer.
  4. For every FCEV put on the road, less oil is consumed.
  5. Since FCEVs are more than twice as efficient as gasoline cars, the amount of oil saved is greater than the amount of natural gas consumed to make hydrogen.
  6. Hydrogen made from natural gas is the least expensive option today; therefore starting off with hydrogen from natural gas will expedite the transition to a hydrogen economy.
  7. The Middle East holds approximate 65% of all known oil reserves, but only 35% of natural gas reserves, so national security is improved to some degree.
  8. Newly discovered natural gas in U.S. shale deposits have substantially increased estimates of remaining natural gas reserves and making hydrogen from low-cost US natural gas will substantially improve our balance of trade and reduce our security threats.

In any case, natural gas is just a transition fuel to start down the pathway to a greener and more sustainable hydrogen future when it will be made from some combination of renewables, digester gases from waste water treatment plants or municipal solid waste (MSW),nuclear or possibly coal with carbon sequestration. We have shown that the consumption of natural gas in this early transition phase will increase US natural gas consumption by just over 10% for a brief period before falling as renewable hydrogen sources take over.

5. How much will it cost to install hydrogen fueling stations?

Short answer: adding hydrogen fueling capability to an existing site will cost several million dollars initially. Surprisingly, the hydrogen fueling capital cost per fuel cell electric vehicle supported is similar to or even much less than the cost per vehicle to provide a charging port for battery EVs.

Long answer: installing a hydrogen generator to convert water and natural gas to hydrogen along with the necessary compression, storage and dispensing equipment will initially cost $3 to $4 million per station. The National Research Council in their 2008 analysis of hydrogen and fuel cell EVs estimated that hydrogen fueling systems in mass production would cost between $400,000 for small stations and $2.2 million for a hydrogen fueling system that could produce 1,500 kg/day of hydrogen, enough to support approximately 2,300 FCEVs.  So the fueling infrastructure cost per vehicle would be $955.

The Idaho National Laboratory surveyed the costs of adding a 120-Volt, 20-Amp (Level 1) outlet for charging PHEVs, and found an average cost of $878. But a higher power 240-Volt, 40-Amp (Level 2) outlet will be required to keep BEV charging times under 8-10 hours. Installing these higher power outlets had an average cost of $1,850 for a commercial site and $ 2,150 for a residence according to the Idaho Lab study. Coulomb Technologies, a maker of electric charging outlets, announced that they would install 4,600 Type II charging outlets for $37 million (including $15 million of federal money) or $8,043 per outlet or $8,043 per BEV. And Hawaii is planning on installing 250 Type II outlets for $4.6 million (Incluidng $2.6 million of Federal funds), or a whopping $18,400 per outlet!

Unlike the hydrogen fueling station that can support thousands of FCEVs, one home charging port is required for each BEV. So the cost per BEV for fueling infrastructure would be in the range between $878 and $8,043.  So BEV charging could be more expensive per vehicle than hydrogen fueling systems at $955 per FCEV.

Furthermore, the Electrification Coalition, a group promoting the deployment of PHEVs and BEVs, has concluded that, in addition to home charging ports, BEV owners will most likely need additional public charging stations available before large numbers of drivers would consider purchasing BEVs.  This Coalition estimates that there might have to be as many as two public charging ports per BEV (in addition to a home charging outlet), which would clearly make the electrical infrastructure for BEVs much more expensive than the hydrogen infrastructure for FCEVs.

6. Doesn’t it take a lot of water to make hydrogen, especially with electrolysis?

Short answer: Yes, it takes about 100 gallons of water to make enough hydrogen to travel 1,000 miles in a FCEV, but making gasoline requires about 160 gallons of water for 1,000 miles of travel in a conventional car. Some analysts have stated that electrolyzing water requires large quantities of water, but it turns out that most of this water is used to cool the generators used to make the electricity, which a) is returned to the river or lake and b) would not apply to hydrogen made by using wind or solar electricity to electrolyze water or from anaerobic digester gas at waste water treatment plants.

Long Answer:  See this report for the details of water consumption for making gasoline, hydrogen, electricity and ethanol. Ethanol requires the most water, especially if the corn crop must be irrigated.  Electricity also requires lots of water, mainly to cool the thermal plants or nuclear plants used to generate electricity (Most of this cooling water is sent back into the river, lake or ocean used to cool the plants.) Bottom line: The water consumption ratios are approximately ethanol ICV = 70 X Gasoline ICV; BEV = 2X Gasoline ICV; and FCEV = 0.7 X gasoline ICV.


[1] Main source for fuel energy efficiencies (First question above): "Energy-Production chains estimated for 1995," by Quanlu Wang and Daniel Sperling, "Energy impacts of using electric vehicles in Southern California," Institute of Transportation Studies, UCD-ITS-RR-92-13, May 1992. Referenced on page 206 of"Alternative Cars in the 21st Century: a New Personal Transportation Paradigm, by Robert Q. Riley, Society of Automotive Engineers, Warrendale, Pa, 1994; the hydrogen from biomass efficiency was derived from P. Spath et al., Biomass to hydrogen production detailed design and economics utilizing the Batelle Columbus Laboratory indirectly-heated gasifier, NREL/TP-510-37409, May 2005, page 30.



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