A Primer on Hydrogen as a fuel

Introduction

There has been much talk and writing of proposed laws by Congress to create a transformational change to renewable power. Some of this has been described as the “New Green Deal”. I have checked the Biden Administration proposed Budget and read what the Democrats have proposed for driving America to a “Net Zero CO₂ America”_(2,3). Based on all of this attention to “Nationalizing American Energy” supply, as one Princeton University Professor referred to it, I thought it would be helpful to create a Blog of information on hydrogen. A place where my friends can visit to learn more about American Manufacturing competitiveness, reliable, affordable electricity and reasonable cost transportation energy. This Blog is my attempt to de-mystify hydrogen as a fuel. Much has been written and hyped for  EV’s (Electric Vehicles). Tesla is perhaps the best known. However, VW, GM, Ford, Porsche, Mercedes and other major automotive manufacturers have made promises to eliminate Internal Combustion Engines by as soon as 2035 and switch to EV’s or hydrogen fuel-cells. Personally, I considered purchasing an electric vehicle but decided against it on the limited range of about 300 miles. The hydrogen fuel-cell vehicles on the other hand, can be refueled much like a gasoline or Diesel  powered vehicle can be. Thus, hydrogen powered vehicles make the most sense for freedom of travel.  The cost likely will be much higher but, at least the performance and range is not limited due to technical limitations as EV’s are. Having said that, maybe the U.S.A. will work slowly into a transition from internal combustion engine powered vehicles to EV and hydrogen power. 

Let’s Assume that we are on a Path to a Hydrogen Economy

There has been much written and talk about hydrogen as part of America’s path to net zero carbon dioxide emissions. It may or may not be practical? For sure, changing to a hydrogen economy will require many changes of industries, fuel distribution network and the electric power system. All things considered, let’s just take a couple pages to review hydrogen as a fuel.

I have worked as a senior engineer in power generation for many years and even to me, there was (and remains) much mystery on the topic of hydrogen as a fuel. So, I thought I would attempt to de-mystify Hydrogen as a fuel and to present some of the facts and details. In an environmentalist’s “Perfect World”, solar and wind would provide all of the energy needed for our ground, sea and air transportation, home heating, air-conditioning, industrial production powering of our Military planes, ships and vehicles and powering our high quality of life. The proponents of hydrogen hope and believe that if they can install enough excess solar and wind power, then the excess power can be used to produce hydrogen. The hydrogen would be stored and then used in internal combustion engines, gas turbines or fuel cells later. Thus, the hydrogen is not a “Primary Fuel” as Fossil, Hydro and Nuclear are now. Hydrogen is a “Secondary Fuel” which means of storing energy that can be used later to generate electricity. When the hydrogen is produced using “Electrolyzers” powered by renewable power, then the hydrogen is referred to as “Green Hydrogen” because there is no carbon used in its production.  Production of hydrogen by electrolyzers has been done for over 100 years and the technology is proven. The U.S. Navy, has used electrolyzers for decades in submarines to produce oxygen from sea water.  About 90% or more of today’s commercial hydrogen is referred to as Grey or Brown Hydrogen. That is because the production of hydrogen is not carbon free and the CO₂ that is released is not captured. There is a Rainbow of Hydrogen colors which are used to describe its production process. They are ranked in order of environmental friendliness, with the least carbon emitting at the top of the list.

• Green Hydrogen is produced by carbon free electrolyzers powered by solar or wind power The stored hydrogen is then utilized for transportation or peak period electricity production.

• Red or Pink Hydrogen is produced by carbon free nuclear power used to produce hydrogen from electroyzers, using off peak electric power to produce hydrogen
• Blue Hydrogen is produced using natural gas feedstock with steam reforming (S-M-R) of the molecules and carbon dioxide capture and storage. 
• White Hydrogen is produced using Biomass with CO₂ capture.
• Grey hydrogen is produced from methane (CH₄) and steam with no CO₂ capture. This, Steam-Methane-Reforming (S-M-R) is the most common method commercial hydrogen is produced today (about 90%). The figures below are from the Chemical Engineering Magazine, Hydrogen Guidebook, This article was first published in May 2010₍₆₎.

• Brown hydrogen is produced using coal as the feedstock with no CO₂ capture and of course, this is the greatest carbon emitting process. 

Fossil fuels are all hydrocarbons and can be utilized as feedstock to produce elemental hydrogen. Methane with four molecules of hydrogen and one carbon (CH₄) is the richest hydrogen fuel that exists in nature and is the most common feedstock to produce hydrogen today, so called grey hydrogen, produced as shown above by S-M-R, (Steam-Methane-Reforming). The ranking of the methods above are listed most environmentally friendly top to bottom. The cost of production is inverse with the least cost from bottom to top. If solar and wind were built at extremely low cost with “free fuel” then of course, the green hydrogen may someday become reasonable cost. However, because hydrogen is a “Secondary fuel”, and requires much energy to produce it, the use of hydrogen for transportation in fuel cells is going to be at a far higher cost than the traditional fuels of gasoline, diesel and jet fuel. Also, hydrogen power will be much higher cost as a stored energy source to power gas turbines during peak electric demand periods when there is insufficient solar and wind such as has recently (California Aug.2020, Texas February 2021) been experienced in Texas and California.

Cost will be discussed more later. Suffice it to say that the equivalent cost per million Btu’s of hydrogen will be multiples of the cost/million Btu’s of gasoline, methane, jet fuel or Diesel fuel. In fact, the commercial cost of hydrogen today (if you can find it to buy) would be in the magnitude of ten times more costly on a dollar/million Btu basis for equivalent energy.

How Much Energy Do We Need?

To try to put America’s energy needs into perspective, we use about 100 Quadrillion Btu’s per year of energy. This is equivalent to about an average of 300 million Btu’s per year for each American. 

The Sankey Diagram below shows the flow of all energy supplied and utilized in America for 2020.

Note the 11.78 Quadrillion Btu’s equivalent in the lower left corner. This is the total renewable energy produced in America in 2020 and if you dig down into the EIA data, most of that renewable energy was produced by (old) hydroelectric power such as at Niagara Falls and Bonneville Power out west. If we are to believe that renewables and hydrogen storage can replace fossil fuels and nuclear power, then I think it is important to understand the total energy needs of America. There are prominent politicians, including our President and Speaker of the House of Representatives that believe we can become carbon free by 2035. The Princeton University and National Academy of Sciences_(2,3) “Net Zero America” presentation(s) included in the references shows an  impractical, highly costly, Ivory Tower path to Net Zero Carbon. Impractical as it is, about 50% of American citizens think it is a desirable path to follow. The energy experts that draw these plans up are smart. They have spent their entire adult lives in America’s finest Universities and they have numerous technical degrees.  It is energy “experts” like these that are advising our top levels of government. They believe that increasing the solar and wind production of America and by completely rebuilding our electric distribution system that America’s demand for total energy for electricity, EV’s, trucking, industrial output and maintaining our high standard of living can be achieved. It is my opinion that they have proven the technical feasibility of producing renewable power and hydrogen, but at what cost? How much disruption of our Industry? How much loss of American competitiveness? How much loss of American manufacturing capacity?

Total Energy Used By the U.S.A.

Before getting into hydrogen as a fuel, the Sankey Diagram above and the next one below, show the actual sources and uses of American energy in 2020. Both the sources of our total energy and the uses of that energy. 2020 was an unusual year because of the Pandemic and our total energy use actually declines from the range of 100 Quadrillion Btu’s per year to about 93 Quadrillion Btu’s. Here is the EIA (US Department of Energy Information Administration) ₍₁₎. 

The preceding two charts show the energy flows in America during 2020. This amount of energy is what it takes for us to enjoy, what we would consider, our normal, productive and happy lives. I think it is prudent to show where our energy now comes from before discussing replacement of the fossil fuels with renewable energy. Note the renewable energy total above is about 12% of America’s total energy supply and if you dig down into the data, most of that is from 75+ year old hydroelectric dams and from non-dispatchable wind. I am getting ahead of myself as Hydrogen is thought to be the secondary energy that will provide a means of storing renewable energy from peak times such as high wind power production at night when normal electric demand is lower.  More will be discussed in Part 2.  For now, try to imagine replacing twenty million barrels per day of petroleum energy plus all the coal and natural gas used in the foregoing charts, with solar and wind as primary sources of energy and hydrogen as a means of energy storage. The huge challenge is to produce enough electricity to eventually charge 280+ million light EV’s (Electric Vehicles) plus our trucking fleet and jet aircraft. Net Zero carbon if attainable, will take numerous technological break-throughs. Yes, the researchers have prepared reports that renewable power and hydrogen storage can technically be achieved. My focus of this Blog will be to help explain the fundamentals of replacing traditional fuels with hydrogen and some basic facts on the properties of hydrogen. Because I have always used US Customary Units and the same for my friends, I will use US Customary units of British Thermal Unit (BTU), Cubic feet, Pounds, Gallons, etc. 

Hydrogen Energy and Comparisons to Traditional Forms of Energy

The fundamentals of Hydrogen as a form of energy. We should keep in mind, that although hydrogen is one of the most common elements on the planet, most of the hydrogen is combined with oxygen as H₂O. Yes, two thirds of the planet is covered in oceans. The next most available and usable form of hydrogen is in common Hydrocarbon Fuels such as Methane CH₄ , Gasoline, Jet Fuel and Diesel Fuel. The most hydrogen rich hydrocarbon fuel is methane with four molecules of hydrogen for every molecule of carbon. The other fossil fuels have much more carbon than hydrogen. The least hydrogen rich Fossil Fuel is coal and may be as little as 3-7% hydrogen most of the additional heating value in coal is carbon. This helps explain the reason why environmental extremists that believe in manmade global warming focus on coal power plants. A rough approximation of carbon emissions of a coal power plant, compared to a natural gas-fueled power plant is, the gas plant will emit about ½ the CO₂ as a coal plant of similar capacity. The primary reason for the reduction is the switching from coal to natural gas for electric power production since about 2012 that has drastically reduced America’s total carbon emissions.

Here is a comparison of the heating value and volume of natural gas (which is mostly methane) to hydrogen.

Methane CH₄               About 1050 Btu’s per std cubic foot               

Hydrogen H₂                About  345 Btu’s per standard cubic foot  

Hydrogen is the lightest element that exists. Thus, the volume of gaseous hydrogen requires about three times more volume per given heating content as methane. Later the impracticality of the low energy density of compressed hydrogen for transportation becomes a design challenge.

Lets take a Look at the Specifications of a Production Hydrogen Fuel Cell Powered Vehicle, The Toyota Mirai

The published spec’s on the 2021 Hydrogen Fuel Cell powered Toyota Mirai:

Three carbon-fiber-reinforced high-pressure tanks hold a total of 5.6 kg of hydrogen—hydrogen sells for $13 to $17 per kg—enough to give the Mirai a range of up to 400 miles between refueling. Similar to filling a car with gas, it takes about 5 minutes to fill the Mirai with hydrogen. The automaker estimates fuel economy at 74 MPGe for the XLE trim and 65 MPGe for the Limited trim, putting the XLE at the head of the pack for efficiency among its hydrogen-powered competitors. (MPGe stands for “miles per gallon equivalent” and is analogous to how far a car could travel on a gallon of gasoline. Hydrogen is sold by the kg.)

Hydrogen at a cost of $13/kg which is equivalent in energy as a gallon of gasoline, is about four times the cost of gasoline for a given amount of energy. A kg of hydrogen is roughly equivalent in energy content (Btu’s and Foot Pounds of work) to a gallon of gasoline. So, when a kg of hydrogen costs $13 that is the equivalent of $13/gallon of gasoline. Helping to balance that, is the higher efficiency of a Fuel Cell and electric motor combination which provides the example 74 MPGe. Which in all honesty, is about the same cost per mile as my Cadillac SRX which gets about 25 MPG on a trip. Thus, Hydrogen is three times the cost but is nearly equal in propulsion power per dollar. (That is, if you can find and buy hydrogen.) Check the “Car & Driver” Magazine article referenced here: https://www.caranddriver.com/features/a36003212/hydrogen-mirai-california-shortage/

In time, the distribution network should get better but the transition from petroleum based fueling to EV’s and hydrogen will take a lot of time to be accomplished without disrupting our Economy and our way of life. Let me put aside my personal love of the internal combustion engine and the beautiful sound of a piston powered race car. Let’s take a look at what hydrogen is and what it can do to provide the energy we need.

Hydrogen Properties

Chemical Symbol                                                                 H

Molecular weight                                                                   1

Commonly Found as water H₂O, Molecular weight        18

Molecular weight of Oxygen     16                                              

Electric power to separate H & O from water/pound           17.7kWh/pound at 100% Efficiency

Typical commercial electrolyzer efficiency                  60-80%

At least 9 pounds of water are required to create                 1 pound of hydrogen

The 9 pounds of water to create 1 pound of water is a minimum. This just includes the feedstock of water required to create hydrogen by disassociation of the oxygen and hydrogen molecules. It does not include the cooling water for the conversion apparatus or electric power production.

Heating Value (HHV) of Hydrogen   61,000 Btu’s/Pound                                    

Heating Value (LHV) of Hydrogen    51,000 Btu’s/pound                                      

Explosive range in air at ambient temperature           4-76%

Expansion ratio from liquid to gas of Hydrogen                    848 X more vol. as a gas than liquid

Green Hydrogen Production

The “Perfect World Scenario” is to use enormous wind and solar farms to produce enough electric power to provide America’s Base load requirements and also have some extra capacity that can be utilized to power Electrolyzers for hydrogen fuel production. The land area needed for wind and solar power is covered by Donn Dears, Mark Mills and others. Suffice it to say, it would take a lot of Real-Estate. One estimation for California to be powered by 100% renewables would require a land mass equivalent to the entire state of South Carolina to do so.

My main points are: There are about 250 million light trucks and automobiles on our roads now. About  37% of our current energy is used to produce electricity. The other 63% of our energy is used for Industrial Production, Transportation and heating. It is impractical and ridiculous to believe that our industrial base and our economy can be converted in fifteen years to power 250 million vehicles, plus millions of heavy trucks, thousands of ships America’s jet aircraft fleet to renewable nergy. Perhaps someday, but not by 2035.

Dick Storm, July 6th, 2021

References:

1. EIA Monthly June 24, 2021: https://www.eia.gov/totalenergy/data/monthly/
2. Princeton University efforts to advise government on “Achieving Net Zero CO₂ America”
3. National Academies of Science report, Achieving Net Zero Carbon: https://www.nationalacademies.org/news/2021/02/new-report-charts-path-to-net-zero-carbon-emissions-by-2050-recommends-near-term-policies-to-ensure-fair-and-equitable-economic-transition-and-revitalization-of-manufacturing-industry
4. Special Report on Hydrogen Fuel, by Donn Dears, Energy Expert: https://ddears.com/2021/06/01/special-report-on-hydrogen/
5. “The Looming Energy Crisis, are Blackouts Inevitable?”, by Donn Dears, 2020
6. Chemical Engineering Guidebook. A Compilation of articles on the topic of hydrogen Technologies, Handling & Developments, 2020 Edition, Published by, Access Intelligence.
7. Mark Mills, The Manhatten Institute, “The Myth of The Great Energy Transition” https://www.manhattan-institute.org/the-myth-of-the-great-energy-transition
8. Airbus Hydrogen Fueled Aircraft info: https://www.airbus.com/en/innovation/zero-emission/hydrogen/zeroe