Internal combustion engines generate heat, much of which is lost to the environment. To put it more bluntly, most of the heat energy produced by your automobile, which could be used to produce electricity, is wasted.
If German exhaust system supplier Eberspaecher has its way, some of that currently-wasted heat may go back into powering a steam turbine, that may some day replace the alternator. The concept is simple: water is piped into a housing that surrounds part of the exhaust system. Residual heat from the exhaust vaporizes the water, producing steam that drives a miniature turbine blade. The turbine can then spin agenerator, which can either supplement or replace a conventional alternator.
Since most alternators are driven by engine belts, they rob power and increase fuel consumption, at least to some degree. The Eberspaecher-designed turbine system has the potential to generate up to 1,100 watts of power, which thecompany equates to a reduction in carbon dioxide emissions of 10 g/km.
That's not the only technology the company is working on; a second design (which could easily be used in conjunction with the company's turbine generator) can translate residual heat directly into electricity. The system uses the temperature differential between the hot exhaust gas and the ambient air to produce electricity, which can be used to lessen the load on a car's alternator. This system produces about a third as much power as Eberspaecher's steam turbine, but even this is enough to reduce carbon dioxide emissions by as much as 5 g/km.