(Photo by kqedquest on Flickr)
As hybrid vehicles become more common on streets around the world, we should think about how we are powering these vehicles. The hybrid model used by Toyota, Honda and other automakers depends on a mixture of regenerative braking, powerful batteries and gas engines to extend fuel mileage. Companies like the Scuderi Group and Motor Development International, two developers looking to compressed air retrofits to clean up traditional combustion vehicles, have questioned this model recently.
Scuderi Group is a Massachusetts-based engine developer that is currently developing prototypes of its split-cycle engine design. Unlike the typical four-stroke diesel engine, the Scuderi split-cycle engine is broken into two units with a compression and power cylinder in each unit. Compressed air is pumped into the compression cylinder, travels across the gas passage and enters the power cylinder. The gas passage contains timed valves that maintain steady pressure through all four cycles, allowing for improved efficiency and combustion.
The Scuderi Group’s split-cycle engine is not yet available for sale but its characteristics make it promising for compressed air advocates. Scuderi Group researchers claim that the engine could increase fuel efficiency by 30% and reduce nitrogen oxide emissions by 80% when installed properly. Once the split-cycle engine is ready for production, Scuderi says that it could be installed in existing vehicles without replacing tooling and other parts.
Luxembourg’s Motor Development International (MDI) has entered two vehicles into the Progressive Automotive X Prize utilizing compressed air drive systems. The three-seat OneFlowAIR can reach speeds of 96 miles per hour, travel up to 60 miles on compressed air and produce 75 horsepower. The CityCAT is a six-seat coupe with a dual-fuel engine, using compressed air for 60 miles before switching to gasoline for extended range. While X Prize judges scrutinize these prototypes, MDI is creating backup generators and forklifts that can produce great amounts of power at relatively low prices.
MDI and Scuderi Group will need to contend with several issues before making compressed air retrofits available to the public. In order to facilitate commutes and out-of-town trips, compressed air tanks and other parts will need to be designed with aerodynamics and operational range in mind. These manufacturers will need to work closely with leading automakers and parts makers to fit compressed air hybrid systems with factory tooling. The issue of retrofitting costs to eco-friendly consumers will diminish as competitors step to the foreground and scale up operations for mass distribution; the only question remaining is the timetable for this niche element of the hybrid car market to become commercially viable.
