In some applications, doubts arise as to whether it is better to use an electric motor or to use a thermal motor. One of the important elements in making this decision will be to know the differences in energy efficiency.
Main problems of thermal motors:
- Rising prices of fossil fuels combustibe (oil, coal, etc.)
- Scarce projections of evolution in an immediate future.
- Emission of greenhouse gases.
- Not reversible, when braking, can not generate power.
Main advantages of electric motors:
- You are a clean alternative if we do not consider how the electric power they are going to use has been generated. The electric motor does not generate pollutant emissions in its operation unlike the heat engines of gaolina or gasoil.
- Electric motors can be reversible. One of its peculiarities, extremely attractive to the industry, is that reversible electric motors can reverse this process, that is, they can transform mechanical energy into electrical energy, operated as electricity generators. This would be the case with hydroelectric plants.
- Electric motors may operate connected to mains or batteries.
- Technically an electric motor has a torque availability at low revs much higher than the thermal engine.
- Electric motor offers faster response. Maintenance of electric motors is much less than having no fluids inside and much greater reliability for the same reason.
- Also offers greater control possibilities.
Differences between an electric motor and a generator
In principle, any electric motor can also generate electricity. However, electric drives are way ahead of internal combustion engines. No car engine has yet been invented to suck up exhaust fumes during braking and descents, and turns them into fuel and fresh air.
The electric motor can offer this. It can generate electricity although during its first century of existence, this application has been largely hampered by two drawbacks:
- Your speed and power could not be adjusted easily during operation. Just as it happens with the thermal engines varying the entrance of fuel in the engine cylinder.
- A plug does not work as a "tap water" tap.
Advantages of electric motors in energy efficiency
Electric motors offer interesting advantages of energy efficiency. This efficiency is remarkable in machines such as cranes, elevators, etc .; Since we can transform them into electric generators during downward movements.
What is not so good is that the line always has approximately the same voltage even if the engine works with different loads and generates variable jobs. This must be taken into account again if the engine speed is varied.
Throughout history, the available solutions were inefficient and expensive. Multi-tap transformers had to be used, as in locomotives. The drawback of these transformers is that they were bulky and expensive. Another solution was to limit the electric current with resistances, as in trams. Even so, this was an inefficient solution.