This technology is being developed for commercial use under SpaceDev's Hybrid Rocket Program. Hybrid rockets utilize a hollow cylinder of solid carbonaceous fuel through which a liquid or gaseous oxidizer flows. This stands in sharp contrast to the toxic exhaust of most solid and liquid rockets currently flying.
Hybrid rockets utilize safe, non-toxic and storable fuels.
Hybrid rocket solid fuel is similar to tire rubber or acrylic plastic. It does not spontaneously ignite, or ignite easily, nor does it explode. The simplicity of the hybrid system allows for ease of construction, maintenance and use. Because of their simplicity and the safe nature of the fuel and oxidizer, hybrid rocket motors are inexpensive and relatively easy to mass produce and store, allowing for economies of scale in their construction.