http://www.ck12.org Chapter 3. Making A Difference
Figure 20.36:Trams work nicely in Istanbul and Prague too.
hydraulics and flywheels salvage at least 70% of the braking energy.Compressed air is used for regenerative braking
in trucks; eaton.com say “hydraulic launch assist” captures 70% of the kinetic energy. The flywheel system of
flybridsystems.com also captures 70% of the kinetic energy. http://www.flybridsystems.com/F1System.html
Electric regenerative braking salvages 50%.Source: E4tech (2007).
Electric batteries capable of delivering 60 kW would weigh about 200 kg.Good lithium-ion batteries have a specific
power of 300 W/kg (Horie et al., 1997; Mindl, 2003).
the average new car in the UK emits 168 g CO 2 per km. This is the figure for the year 2006 (King, 2008). The
average emissions of a new passenger vehicle in the USA were 255 g per km (King, 2008).
The Toyota Prius has a more-efficient engine.The Prius’s petrol engine uses the Atkinson cycle, in contrast to the
conventional Otto cycle. By cunningly mixing electric power and petrol power as the driver’s demands change, the
Prius gets by with a smaller engine than is normal in a car of its weight, and converts petrol to work more efficiently
than a conventional petrol engine.
Hybrid technologies give fuel savings of 20% or 30%.For example, from Hitachi’s research report describing hybrid
trains (Kaneko et al., 2004): high-efficiency power generation and regenerative braking are “expected to give fuel
savings of approximately 20% compared with conventional diesel-powered trains.”
Only 8.3% of commuters travel over 30 km to their workplace.