Apollo command module power was supplied primarily by fuel cells that used hydrogen and oxygen as feedstock to produce electricity, producing drinking water that astronauts consumed as drinking supplies.
NASA developed this technology as batteries would add too much weight, and the group that created these cells, now known as HyAxiom Inc, still produces them today in their South Windsor plant.
Hydrogen
Hydrogen, the most abundant element on Earth, can be found primarily in water and accounts for over two-thirds of its mass. As an element, hydrogen exists as part of life forms on this planet and serves as the main fuel in rocket propulsion systems due to its ability to be burned like fossil fuels while producing equal power output without producing greenhouse gasses that contribute to climate change – unlike carbon dioxide emissions produced when burning fossil fuels; burning hydrogen leaves only water waste behind in its wake!
NASA was in need of a reliable power source in the 1960s in order to send astronauts on missions to the Moon and back. Engineers at Johnson Space Center in Houston discovered fuel cells as the ideal solution, offering more energy per pound than batteries could during long missions. While fuel cells had existed since 1891, no practical application had ever been found for them until that point.
Apollo missions utilized an alkaline fuel cell (AFC), which combined liquid hydrogen and oxygen to generate electricity, waste heat, and drinkable water. This type of fuel cell proved ideal as it was lighter and more efficient than solar panels of 1960s; plus tanks for hydrogen and oxygen were significantly fewer in mass. Furthermore, AFC produced water as a byproduct – an essential aspect for astronaut health and comfort.
Each fuel cell power plant in the Command/Service Module comprised 31 individual fuel cells connected in series. When operating at normal power levels, each cell generated between 27 and 31 volts of electric current. Each power plant also cooled reactants using a coolant system; cryogenic liquid hydrogen and oxygen were stored in relatively small tanks on board the spacecraft to minimize volume requirements.
Apollo Command/Service Module fuel cells were designed for easy operation with minimum maintenance required; however, regular checks and component replacement were necessary. A Teflon seal between each nickel plate prevented an electrical short while ceramic insulators in reactant lines prevented hydrogen leakage outside the cells. Each fuel cell was kept at 10.5 psi above electrolyte pressure in order to keep reactants from coming into contact with liquid electrolyte solutions.
Oxygen
Fuel cells combine hydrogen and oxygen to generate electrical power as well as produce water for consumption or reconstituting dehydrated food, providing electrical power as a by-product. They were utilized extensively during Apollo missions as the main power source for Lunar Excursion Module (LEM), Command/Service Module (CSM), as well as providing some power for this particular Apollo CSM Fuel Cell Powerplant Assembly now on display at the Smithsonian Museum in Washington, DC.
During the 1960s there was much excitement regarding fuel cells as an energy source. According to an article in Nickelsworth Magazine, many scientists believed fuel cells would rival nuclear power as revolutionizing power production.
As with other forms of energy production, fuel cells use chemical processes to produce electricity. However, unlike batteries which only store it temporarily, a fuel cell generates electricity by employing electrochemical reactions; these produce electrons which then pass through internal circuits to form electric current.
Fuel cells produce power used to run electrical devices, provide thrust for Lunar Excursion Module and manage environmental systems. Hydrogen and oxygen produced from fuel cells were combined in LEM to generate electric power and water supplies for astronauts; until mission completion when conventional batteries took over powering it.
Fuel cells provided a significant source of electrical power for Apollo 13, but were far from guaranteed. On one mission, an oxygen tank beneath them ruptured, releasing large amounts of oxygen into the service module and forcing crew members to shut down fuel cells immediately to avoid further damage.
This was an essential lesson learned about the reliability of Apollo fuel cell systems. They were tested extensively during unmanned Apollo test flights AS-202 and AS-502, as well as during Apollo missions, Skylab missions, and Apollo-Soyuz missions; not only were feasibility analyses completed but the tests verified all necessary ground support equipment as well as operational checkout procedures were in place.
Electrocatalysts
Electrocatalysts are key components of fuel cells. They facilitate the chemical reactions that generate electricity and heat while stabilizing them – they’re responsible for producing both electricity and heat, too! Unfortunately, electrocatalysts tend to be expensive; researchers are actively exploring more cost-effective alternatives, like 2D new materials (MXenes for instance) with exceptional surface properties to enhance catalysis redox catalysis.
MXenes-based fuel cells can be utilized for many different applications, including the generation of clean energy. They’re especially well-suited to use in hydrogen-oxygen fuel cells found in hybrid and electric vehicles to produce more power with less gasoline use, reduce carbon emissions and noise pollution, as well as produce additional benefits like noise pollution reduction and lower emissions.
Alkaline fuel cells convert liquid hydrogen and oxygen to electricity and water, offering an attractive lightweight alternative to traditional petroleum tanks. Operating at cryogenic temperatures makes these fuel cells ideal for space travel while their more reliable power source means no periodic recharge cycles need be scheduled with batteries.
JM provided electrocatalysts to power fuel cells on the Apollo moon mission, providing both power and drinking water for astronauts. Today, this technology is making a comeback in the energy industry.
Recently, platinum was the main electrocatalyst for fuel cells; however, due to its cost and difficulty of stability in high temperature environments like those present in fuel cells. Therefore, scientists have begun exploring various materials as potential solutions that might increase Pt-based cells’ efficiency and stability while at the same time exploring other precious metals and alloys as potential candidates.
To reach the desired performance, an electrocatalyst must support large surface area of Pt nanoparticles and tolerate electrochemical oxidation of intermediates that requires oxygen at its surface. To combat these challenges, scientists have devised a way of controlling nanoparticle dimensions while decreasing Pt loading by adding metal supports.
Powerplant
Powerplants on board Apollo spacecraft provided both electricity and pure water for drinking purposes – this was especially advantageous as spacecraft batteries could only store limited energy, cannot produce more than they were charged up for, and took up valuable space in power systems. A fuel cell was therefore an ideal choice to power their mission.
Fuel cells drew hydrogen and oxygen from the atmosphere, combined them to make electricity, then returned the waste stream as water back to the crew. Hydrogen and oxygen pressure were controlled so as not to disrupt this reaction process; powerplants were located within a compartment of the Service Module as this provided most of its power during flight.
Two fuel cell power plants were intended to meet normal electrical loads while another served as backup. Tests had indicated their capability of performing their function properly; MSC expected its system to function flawlessly except during Earth reentry leg.
These fuel cells were the most advanced to fly into space. Their predecessors on Gemini and Apollo spacecraft used similar technology. Unfortunately, however, these weren’t considered safe due to being stored inside an asbestos fiber matrix and potentially containing potassium hydroxide which could seep through and cause health concerns for crew.
Fuel cells also require venting, which was another key concern. Venting must take place under high pressure, creating an inert atmosphere requiring special equipment and procedures.
Apollo 13’s final decision to shut off fuel cells was one of many strategic steps taken by its crew members that contributed to their survival. Powerplants were closed within an hour of an accident occurring, giving enough time for Odyssey’s battery bank to recharge before reentry. Had fuel cells been left open, Odyssey may never have received sufficient power.