Energy efficiency

Energy efficiency

1. Energy input = power(w) x time (s)

2. Calculating efficiency

   • to calculate efficiency we need to know the energy going in and the useful energy output
     • Efficiency= (useful energy/ Total energy input) x 100

3. power station efficiency

   • CHP- combined heat and power
     • 45% of its energy is wasted in the cooling water. it is used to heat the local houses. the efficiency is up to 80%
   • CCGT- combined cycle gas turbines
     • new gas stations have been made more efficient by using CCGT. these use natural gas to power a jet engine which turns a generator. then they create steam with the exhaust gas to drive another generator. this method is up to 55% more efficient and can start up easily and quickly to anwer demands for electricity rises.