Science & Technology in Action

4th Edition

Energy and Efficient Rail Travel

Iarnrod Eireann

Jnr Science Cert
Regenerative braking systems save energy but are not suitable for all types of transport. They are most useful in urban transport systems which have frequent stops between relatively short trips.
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Lesson excerpt

The rising cost of fuel is driving public awareness of the need to use fuel in a more efficient and environmentally sensitive way. The proliferation of motor cars causes traffic congestion and greatly reduced fuel efficiency. The only viable solution is to reduce dependence on private cars by increasing the availability and frequency of public transport – in practice, bus, tram and train. The cost per person-kilometre is lower for trains than for any other form of powered transport.

Energy sources

  • Energy sources can be categorised as follows:
  • Fossil fuel such as coal, oil or gas (combustion engine or electricity generation)
  • Renewable fuel (wood or other organic material)
  • Nuclear power (for heating and electricity generation)
  • Geothermal (for heating and electricity generation)
  • Photovoltaic (low power electricity generation)
  • Fuel cells (electrolysis <=> electricity generation)
  • Solar heating (mainly for heating water)
  • Wind and tide (mainly for electricity generation)
  • Electricity (which can be generated using other energy sources mentioned above or by hydro-electric generators, photo-voltaic cells or thermoelectric generators)

Energy storage
Energy can be in effect ‘stored’ by conversion to other forms. Practical types of storage include:

  • Electrical (using a rechargeable battery)
  • Mechanical (in a flywheel)
  • Chemical (electrolysis of water to generate hydrogen for fuel cells or combustion)
  • Hydroelectric (pumped water storage – for large scale systems)

Photovoltaic cells
In practice the energy sources for vehicular transport are combustible fuel or electricity from photovoltaic cells or from batteries. Photovoltaic cells on their own are not feasible for transport; they are typically used in conjunction with batteries and combustion engines.

True or False?

  1. The cost per person-kilometre is lower for trains than for any other form of transport
  2. Photovoltaic cells can generate high power electricity
  3. It is more efficient in terms of energy to travel by electric train than by diesel train
  4. Lubrication can remove friction in wheel bearings
  5. Regenerative braking would be cost effective in the Dublin to Waterford railway line
  6. As Electric trains are light; they are more cost efficient
  7. DMU allows extra passenger capacity to be added at the same time as motive power