Space Transport and Engineering Methods/Energy

Energy Sources

This page lists the sources of energy that can be used for space projects. By making a matrix of energy sources vs propulsive forces, you can categorize all possible propulsion methods. The law of conservation of energy states that energy can neither be created nor destroyed, merely transformed, so all energy for a project must come from a preexisting source.

For vehicles the energy is typically stored internally before departure, or uses stellar light. Infrastructure projects, as distinct from vehicles, generally need continuous sources of energy to operate. Over time that can amount to more than can be stored internally, so they often depend on external sources like sunlight.

Mechanical Sources

A. Compressed Gas

Compressed gas is a low density energy storage method. It is often used for tasks like cold gas thrusters and pressurizing liquid fuel tanks. Its chief advantage is simplicity, requiring just a storage tank and a valve. When larger total amounts of energy are needed, a higher density but more complex system is often preferred.

B. Potential Energy

Potential energy is the ability of a system to do work by virtue of it's position. In space projects this is usually position relative to the gravity well of a massive object such as a planet. An example is a simple space elevator. While raising a cargo, electricity is converted to potential energy of height. When lowering a cargo, the potential energy can be extracted back to electricity.

C. Kinetic Energy

Kinetic energy is that which an object possesses by virtue of it's motion. It is calculated as 1 / 2mv² where m is the object's mass and v is the velocity. An object in orbit has both kinetic energy in it's orbital velocity and potential energy in it's altitude. In an elliptical orbit, it continuously exchanges altitude for velocity, but the combined total stays the same. Rotating objects such as flywheels store kinetic energy calculated by a different method, since different parts are moving at different velocities.

Chemical Sources

Chemical energy comes from an arrangement of atoms in a higher energy state which is converted to a lower energy state via a chemical reaction, releasing the difference. Combustion is the most common way to release the energy. Batteries are characterized by a reversible reaction, so that the same device can store and release energy multiple times.

D. Fuel-Atmosphere Combustion

The Earth's atmosphere contains 21% free Oxygen, which reacts with many other compounds to release energy. In the case of aircraft, a hydrocarbon fuel such as kerosine is reacted with the atmospheric oxygen. Since only the fuel is carried internally to the vehicle, the energy released, about 43 MJ/kg, is about three times as much as when both are carried internally in a typical rocket.

E. Fuel-Oxidizer Combustion

F. Chemical Battery

Thermal Sources

G. Thermal Storage Bed

H. Concentrated Light

Electrical Sources

I. Power Line

J. Circulating Electron Storage

K. Magnetic Storage

L. Photovoltaic Array

[C1] Anonymous "Conference Record of the Nineteenth IEEE Photovoltaic Specialists Conference- 1987", New Orleans, Louisiana, 4-8 May 1987.

[C2] Anonymous "NASA Conference Publication 2475: Space Photovoltaic Research and Technology 1986: High Efficiency, Space Environment, and Array Technology", Cleveland, Ohio, 7-9 October 1986.

[C3] Chubb, Donald L. "Combination Solar Photovoltaic Heat Engine Energy Converter", Journal of Propulsion and Power, v 3 no 4 pp 365-74, July-August 1987.

M. Solar-Driven Turbine/Generator

[C4] Spielberg, J. I. "A Solar Powered Outer Space Helium Heat Engine", Appl. Phys. Commun. vol 4 no 4 pp 279-84, 1984-1985.

N. Microwave Antenna Array

Beam Sources

O. Laser

P. Microwave

Q. Neutral Particle

Nuclear Sources

R. Radioactive decay

[C5] Lockwood, A.; Ewell, R.; Wood, C. "Advanced High Temperature Thermo-electrics for Space Power", Proceedings of the 16th Intersociety Energy Conversion Engineering Conference, v 2 pp 1985-1990, 1981.

S. Nuclear Fission

[C6] El Genk, M.S.; Hoover, M. D. "Space Nuclear Power Systems 1986: Proceedings of the Third Symposium", 1987.

[C7] Sovie, Ronald J. "SP-100 Advanced Technology Program", NASA Technical Memorandum 89888, 1987.

[C8] Bloomfield, Harvey S. "Small Space Reactor Power Systems for Unmanned Solar System Exploration Missions", NASA Technical Memorandum 100228, December 1987.

[C9] Buden, D.; Trapp, T. J. "Space Nuclear Power Plant Technology Development Philosophy for a Ground Engineering Phase", Proceedings of the 20th Intersociety Energy Conversion Engineering Conference vol 1 pp 358-66, 1985.

T. Nuclear Fusion

[C10] Miley, G. H. et al "Advanced Fusion Power: A preliminary Assessment, final report 1986-1987". National Academy of Sciences report #AD-A185903, 1987.

[C11] Eklund, P. M. "Quark-Catalyzed Fusion-Heated Rockets", AIAA paper number 82-1218 presented at AIAA/SAE/ASME 18th Joint Propulsion Conference, Cleveland, Ohio, 21-23 June 1982.

U. Nuclear Explosions

Matter Conversion Sources

V. Antimatter

[C12] Hora, H.; Loeb, H. W. "Efficient Production of Antihydrogen by Laser for Space Propulsion", Z. Flugwiss. Weltraumforsch., v. 10 no. 6 pp 393-400, November-December 1986.

[C13] Forward, R. L., ed. "Mirror Matter Newsletter", self published, all volumes, contains extensive bibliography.

W. Quantum Black Hole