Yesterday’s Wall Street Journal special report: “Innovations in Energy” featured an article discussing the abundance of natural gas and the viability of using it as an alternative to gasoline and diesel fuel. (In a separate article, the report also highlights the Scuderi Engine as an emerging engine technology.)
The natural gas story points out how the resource provides a double positive when it comes to justifying its use: Not only is it cheaper than oil, its emissions are much cleaner than gasoline or diesel. But even though various obstacles continue to prevent passenger car owners from quickly making the switch (cost, infrastructure, etc.), steady development and adoption is taking place in the commercial truck and bus market.
Whenever this topic arises, we are often asked about the advantages of a Scuderi Engine – and its “Air-Hybrid” air storage capability – when running on natural gas. One example is the commercial bus.
Buses normally lend themselves quite well to hybridization. This is because of the nature of the drive cycle they are subject to, with frequent starts and stops in an urban environment. This type of driving creates a large number of opportunities for storage and reuse of the vehicle kinetic energy. This is quite taxing for electric batteries, as batteries have reasonably good energy density, but poor power density.
Alternative hybrid concepts, such as flywheel, hydraulic or pneumatic, are perhaps more suited to bus applications. This is because the alternatives concepts may not be as vulnerable, and may be better matched to the high frequency and rate of the energy storage/reuse required by the bus drive cycle. More specifically, in the case of pneumatic (or air) hybrid systems, the overall cost of the system could be reduced and the issues associated with lithium (and other rare earth elements) could be eliminated.
The Scuderi Air-Hybrid concept has shown, in several simulation studies, to exploit well the regeneration opportunities in a typical bus drive cycle. In one study, simulations have predicted that it would be capable of a possible 11-17 percent reduction in fuel consumption.
This generator/storage capability make the Scuderi Engine one of the most unique internal combustion technologies. For a more technical description on how the air-hybrid system works, we recommend reading the latest technical paper presented by Southwest Research Institute at Aprils SAE World Congress.