Why Liquid Hydrogen is Used As a Fuel in Spacecraft

  • By: David
  • Date: November 14, 2022
  • Time to read: 4 min.

why liquid hydrogen is used as a fuel in spacecraft

The most difficult fuel for spacecraft is liquid hydrogen, even when compared to methane and/or kerosene. However, liquid hydrogen is a very efficient fuel and provides better gas mileage than kerosene for rocket engines. Therefore, Congress has mandated NASA to continue using liquid hydrogen in its main engines.

Liquid hydrogen has a high energy density

Liquid hydrogen has low energy density and is difficult to store. It needs special handling and cryogenic storage. It also leaks at a rate around 1% per hour. It also has safety concerns similar to other hydrogen forms. For example, it can liquefy atmospheric oxygen, posing an explosion hazard.

Flammability is another issue. Liquid hydrocarbons are flammable and should be handled with extreme care. Hydrogen is flammable and will burn at temperatures of 5500oF (3038oC). Protect liquid hydrogen from heat and keep it in a controlled environment.

Gaseous hydrogen has a volumetric density of 26,1 kg/m3. This means that a 55-ton truck would need 50-70kg to travel 500-600km. Liquid hydrogen on the other hand has a volumetric density of only 70kg/m3. Onboard hydrogen storage capacities between 5-13 kg are required for light-duty vehicles.

Hydrogen is the lightest known gas in the universe. It weighs almost nothing and has an extreme gravimetric energy density – a kilogram contains a large amount of energy. Moreover, its volumetric energy density is very low, meaning that a kilogram of hydrogen requires a lot of space.

Rockets also use liquid hydrogen as fuel. Many companies in the satellite launch business use liquid hydrogen as a propellant. The Delta III & IV have liquid-hydrogen upper stages while the Space Shuttle has the liquid oxygen/liquid hydrogen stage. The European Space Agency developed a liquid-hydrogen upper stage for its Ariane rocket. Although liquid hydrogen was not tested in the Soviet Union until the 1980s it was discovered by the Russian Angara rocket.

Hydrogen is also an excellent alternative fuel for light-duty, long-range aircraft. Many commercial airlines are looking at hydrogen as an alternative fuel. Airbus has three hydrogen-fueled aircraft concepts. The company has given the concept the name “ZEROe” – zero emissions – and it expects to launch its first commercial hydrogen-fueled aircraft by 2035.

Liquid hydrogen liquefying costs

Liquid hydrogen for spacecraft fuel requires special handling. It is also susceptible for leakage, with around 1% of its volume escaping each day. Liquid Hydrogen has many safety concerns. It can liquefy atmosphere oxygen, which can cause an explosion hazard.

Even with modern technology, hydrogen costs are not cheap. Liquefied hydrocarbon weighs around 71 kilograms/cubic meter and costs about a thousand bucks per tonne. The LCOE (low cost of liquid hydrogen) is about seven times that of LNG. This is because hydrogen is less energy-dense per volume than LNG, and requires much less energy to liquefy. This is a relatively small cost considering liquid hydrogen’s 60% conversion efficiency.

Tanker trucks carrying liquefied hydrogen are the main way to transport the fuel. Fuel tanks still require an energy-intensive pressure system. This can negate any energy benefits from hydrogen. But there is an alternative. It’s possible to store and transport liquid hydrogen in your car, but it would be expensive and would require a lot of energy.

Liquid hydrogen remains expensive. It is impossible to produce polluting-free hydrogen on large scale. It is still far too expensive and inefficient not to be able to replace oil. We must continue to search for breakthroughs in technology and develop the technology needed to realize a hydrogen economy.

Liquefying liquid hydrogen is a costly process, and the energy consumed is high. Liquifaction is a process that uses about one-third the hydrogen’s energy. Liquifaction requires high pressure, high temperatures, and high temperatures. A facility for industrial use is required.

Spacecraft can still be powered by hydrogen, despite the high cost. There are however many challenges. Firstly, hydrogen is subject to stringent standards, and the gas is prone to leaks and bubbles. This would impact the efficiency the spacecraft.

The second is hydrogen transport. There are many ways to transport hydrogen, including liquid hydrogen. However, there are many challenges. It is difficult to keep the gas cold. The temperature range of hydrogen is very close to the temperature of outer space. A 40-foot container is capable of carrying around 3,000 kilograms (about 3) of hydrogen.

You will need to store liquid hydrogen at -252° Celsius

The key to storing liquid hydrogen at -252 degrees Celsius is the ability to maintain a stable temperature. There are many ways to do this, including using a hydrogen storage cell. Reversible chemical reacting between hydrogen, certain metal atoms is the most promising. These methods are made from materials like magnesium and alanates. These materials are relatively lightweight but can store large quantities of liquid hydrogen. They can also keep at low temperatures.

A spacecraft must ensure that the fuel tank is properly insulated from heat sources in order to store liquid hydrogen at -252°F. If it’s not, liquid hydrogen may leak out through tiny cracks between welds. To construct a rocket capable of safely using liquid hydrogen, you need to be skilled in engineering.

Methane is an economical alternative to hydrogen, as it can be stored at 161 degrees Celsius. Methane tanks don’t require cooling or insulation, which allows the spacecraft to take up less space. The outer solar system’s abundance of methane is another important factor to consider when choosing a fuel.

However, the volume of hydrogen is still substantial under standard atmospheric pressure. It is necessary to reduce the volume. Hydrogen is the lightest of all gases. A liter of hydrogen weighs in at 90 mg. This is eleven-times lighter than air. To reduce its volume, you can increase pressure.

There are many different types of hydrogen tanks. Some are strap-mounted, others are permanently attached. These are more lightweight and are ideal for high pressure storage. In addition, they are also lighter than type I tanks, which is the most common type of hydrogen tank.

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