The AVE uses a tornado-like vortex to concentrate the mechanical energy produced during upward heat convection where it can be captured. A vortex engine consists of a cylindrical wall open at the top and with tangential air entries or deflectors around its base. Heating the air within the wall using a temporary heat source such as steam starts the vortex. The heat required to sustain the vortex once established can be the natural heat content of the warm humid air or can be provided in cooling towers located outside of the cylindrical wall and upstream of the deflectors. The continuous heat source for the peripheral heat exchangers can be waste industrial heat or warm seawater. The intensity of the vortex is regulated by restricting the flow of air with dampers located upstream of the deflectors. The vortex can be stopped by restricting the airflow to deflectors with direct orientation and if necessary opening the airflow to deflectors with reverse orientation.

The electrical energy is produced in turbo-expanders located upstream of the tangential entries. The pressure at the base of the vortex is less than ambient pressure because the density of the rising air is less than the density of the ambient air at the same level. The outlet pressure of the turbo-expanders is sub-atmospheric because they exhaust in the vortex.

The cylindrical wall could have a diameter of 200 m and a height of 100 m; the vortex could be 50 m in diameter at its base and extend up to the tropopause. An AVE could generate 50 to 500 MW of electrical power.

Thermodynamic Basis

The Atmospheric Vortex Engine has the same thermodynamic basis as the solar chimney. The physical tube of the solar chimney is replaced by centrifugal force in the vortex and the atmospheric boundary layer acts as the solar collector. The AVE needs neither the collector nor the high chimney. The efficiency of the solar chimney is proportional to its height which is limited by practical considerations, but a vortex can extend much higher than a physical chimney.

The average upward convective heat flux at the bottom atmosphere is 150 W/m2, one sixth of this heat could be converted to work while it is carried upward by convection. The heat to work conversion efficiency of the atmosphere is approximately 15% because the heat is received at an average temperature of 15 °C and given up at an average temperature of minus 15 °C. The average work produced in the atmosphere is therefore 25 W/m2. The total mechanical energy produced in the atmosphere is 12000 TW (25 W/m2 x 510 x 10E12 m2) whereas the total work produced by humans is 2 TW. The mechanical energy produced in a single large hurricane can exceed all the energy produced by humans in a whole year.

The thermodynamic basis of the AVE is consistent with currently accepted understanding of how energy is produced in the atmosphere. Atmospheric scientists call the mechanical energy produced when a unit mass of air is raised reversibly from the bottom to the top of the troposphere Convective Available Potential Energy (CAPE). CAPE during periods of insolation or active convection is typically 1500 J/kg which is equal to the mechanical energy produced by lowering a kilogram of water 150 m. The vortex would transfer the mechanical energy down to the Earth's surface where it would be captured.

The existence of tornadoes proves that low intensity solar radiation can produce concentrated mechanical energy. It should be possible to control a naturally occurring process. Controlling where mechanical energy is produced in the atmosphere offers the possibility of harnessing solar energy without having to use solar collectors.

Process Potential

The process could provide large quantity of renewable energy, could alleviate global warming, and could contribute to meeting the requirements of the Kyoto protocol. The AVE has the potential of providing precipitation as well as energy. There is reluctance to attempt to reproduce a phenomenon as destructive as a tornado, but controlled tornadoes could reduce hazards by relieving instability rather than create hazards. A small tornado firmly anchored over a strongly built station need not be a hazard.

The AVE could increase the power output of a thermal power plant by 30% by converting 20% of its waste heat to work. The power increase results from reducing the temperature of the cold sink from the temperature at the bottom of the atmosphere (15 °C) to the temperature at which the atmosphere radiates heat to space (-15 °C).

The process could be adapted for use with all existing thermal power plants, whether they are coal fired, natural gas or nuclear. The main requirement for the AVE is a steady supply of low-grade heat. The temperature of the saturated air coming out of power plant cooling towers is higher than that of the warm humid air responsible for the energy of tornadoes and hurricanes.

The process could be developed with relatively little engineering effort. The technology is similar to that of cooling towers and turbine-generators. The upward heat convection process responsible for producing energy in the AVE is the process responsible for producing the circulation in natural draft cooling towers and in natural circulation boilers. Engineers with experience in the power industry would be good candidate for developing the process.

Electrical utilities are invited to consider participating in the development and commercialization of the AVE. The unit cost of electrical energy produced with an AVE could be less than half the cost of the next most economical alternative. Additional electrical energy would be produced without additional fuel. The process is protected by patent applications and could become an important source of electrical energy.

Initial development work would concentrate on producing stable vortices. Under favorable conditions, it should produce a steam assisted vortex with a station 10 m in diameter and a self-sustaining vortex with a station 30 m in diameter. Learning to control large vortices under all conditions will be an engineering challenge. Developing the process will require determination, engineering resources and cooperation between engineers and atmospheric scientists. There will be difficulties to overcome, but they should be no greater than in other large technical enterprises.

Additional Information

In December 2004, a detailed description of the AVE including drawings and thermodynamic calculations was published as a White Paper in Energy Central's Knowledge Center.

On September 29 2005 the Economist had an article on the AVE which resulted in a lot of media attention: http://www.economist.com/science/displayStory.cfm?story_id=4455446

There is much more information including: drawings, presentations, and technical publications on the AVE web site: http://vortexengine.ca