Structures for Stratospheric Particle Injection

Large volcanoes periodically inject aerosols into the stratosphere, cooling the planet by scattering incoming solar radiation. Injection of suitable particles at 20 km has been identified as the least expensive geoengineering option to ameliorate the temperature rise associated with a doubling of CO2 levels, and the technology most likely to be effective. This paper considers the engineering issues associated with two methods of conveying particles to 20 km (65,000 feet); building fixed towers or the use of pipes supported by tethered balloons. A fixed mast would need to be an order of magnitude taller than any structure built to date. It raises major issues of self-weight buckling and would require either new materials or an increase in production of high strength composites by many orders of magnitude. A balloon-supported tether to reach 20 km altitude does not have buckling issues and appears much more practicable with relatively small development costs.

Various options for such a design are considered, including the material from which it might be fabricated and some of the technical problems that have to be overcome.