January 6, 2020. By Kolemann Lutz
In the 2010s and 2020s, humanity made significant progress toward the advancement of water electrolysis, fuell cells, and the transportation, use, and storage of liquid hydrogen to primarily support the green energy revolution on Earth while also enabling a path forward to better use the natural and synthetic H2O throughout the Solar system and Universe.
Imported liquid hydrogen is key to methane propellant production, chemical manufacturing, and fuel cells, a fundamental component toward sustaining settlements on the Moon, Mars, asteroids, and Venus.
The most abundant and lightest element in the Universe, hydrogen is widespread on Earth as a primary component of the world’s oceans. As humanity largely embraced global decarbonization in the 2010s, there has been significant research and progress toward industrial-scale hydrogen production, which could help eliminate a quarter of the world’s CO2 emissions.
Hydrogen fuel cells could become a dominant clean energy source for industry, cross-country haul, and stationary vehicles in the near future. With a series of planned investments from seven of the largest energy companies in Europe, Australia, and Chile, Morgan Stanley estimates an $11 trillion hydrogen market in the coming decades. While hydrogen has an energy density of 120 MJ/kg, almost three times more than diesel or gasoline, and electrical energy density equal to 33.6 kWh per kg, diesel holds about 12–14 kWh per kg. Therefore, every one kg of hydrogen used in a fuel cell to power an electric motor contains approximately the same energy as a gallon (3.78 kg) of diesel. As the commercial applications for hydrogen-fuel cell-based trucking becomes viable around the cost of $3/kg of hydrogen, economical hydrogen-powered cars become economically feasible at around $2 per kg.
Hydrogen Fuel Cells convert hydrogen and oxygen into water while generating electricity and heat. Hydrogen is delivered to the negative anode and oxygen to the positive cathode, which are separated by an electrolyte that allows specific ions to flow. Proton-exchange membrane fuel cells (PEMFC) have many physicochemical advantages over other types of fuel cells, promising to be more powerful, reliable, lightweight, and simpler to operate. PEMFCs can have greater lifespan with significant cost savings compared to alkaline fuel cells.
Glenn Research Center is the focal point for NASA's fuel cell research and development. NASA is designing PEMFCs to provide pure drinking water for spacecraft crews, electricity for spacesuits, airplanes, uninhabited air vehicles, and reusable launch vehicles.
Because the molecular weight of oxygen (32 g/mol) is 16 times the weight of hydrogen (2.016 g/mol), launching hydrogen in the form of water or other hydrocarbons off the planet is not economically feasible with current up mass constraints out of Earth’s 1G to reduce costs. Therefore, importing liquid hydrogen as fuel to nearby celestial bodies is favorable.
Storage of liquid hydrogen requires cryogenic temperatures because the boiling point of hydrogen at one atmosphere pressure is -252.8°C (20 K), which demonstrates a need to find alternative means of storing liquid hydrogen. With a molar mass of 46.03 g/mol, formic acid (HCOOH) can hold nearly 1,000 times the energy as the same amount of hydrogen because it does not need to be stored at high pressures and low temperatures. This makes formic acid a prime candidate for long-term, non-cryogenic hydrogen storage on Earth’s surface.
On the two neighboring CO2-dominated planets, storing hydrogen in the form of liquid methane, which has a molar mass of 16.04 g/mol, is the preferred method because carbon dioxide is widely abundant in the atmosphere and can be easily combined with hydrogen in a Sabatier reactor to generate liquid CH4 propellant for the return vehicle.
While the average SpaceX Starship payload to Mars will be around 100,000 kg, approximately two-thirds of the Starship payload mass would be imported liquid hydrogen. As each kilogram of hydrogen we bring to Mars would allow us to produce 20 kilograms of CH4 fuel, hydrogen and methane hold the potential to become primary fuel sources for Martian surface activities. The 240,000 kg of liquid CH4 Starship would carry in the propellant chamber, which would have a weight closer to 90,000 kg with the reduced gravity (.375 g) of Mars.
As liquid hydrogen can be largely used for rocket propellant, it may also become the primary source of clean drinking water with abundant oxygen quantities in the atmosphere. In a 2010 research study, results showed that water produced by the proton exchange membrane fuel cells (PEMFCs) meets nearly all US Environmental Protection Agency (USEPA) and World Health Organization (WHO) drinking water requirements.
In a typical hydrogen fuel cell, each kilogram of fuel produces 9 kg of water. A hydrogen fuel cell could help produce 490-735+ kg of water and abundance of electricity during a fast round trip Mars mission of 245 days, considering the average human consumes 2-3 kg of H2O per day.
As up to 60% of the water produced on Mars could be collected without condensing systems, a hydrogen fuel cell could also continuously provide 31 kWh of electrical power per day, which is the average household electricity demand in the U.S., and approximately 15 liters of H2O per day.
Bringing extra liquid hydrogen to the surface as critical life support for drinking water could mitigate the billions of dollars in CapEx for designing, building, and operating water ice mining machinery on celestial bodies.
Kolemann Lutz, Co-founder of MarsU, stated, “relying on a majority of water from ice mining, transportation, and purification technologies to support the drinking water requirements for the first crewed missions rather than hydrogen fuel cell technology and the Sabatier reactor on the surface is like trying to accomplish the most difficult task first rather than gradually building up the technological capability.”
2020 turned out to be a great year for humanity's progress, research, and development in opening up two new frontiers on the Moon and Mars. Several innovations, advances, and additional progress rea cited in the articles cited below.
Electrolysis and Hydrogen Production Advances in 2020