Energy Sources

You must be able to describe and compare the Earth’s major energy sources that are used for generating electricity. To help you structure clear answers to exam questions of this type I suggest that you use the SLAP! approach.

SLAP! is my acronym to help you to remember the things you should think about when writing about energy sources. It stands for;

• Sustainability (Is the energy source renewable at the same rate as it is being used? And is this going to remain the case for the foreseeable future?)

• Location (Is the energy source limited to specific locations, such as the sea or tidal estuaries?)

• Availability (Is the energy source available all of the time, every day of the year? And is it constantly available or does its availability vary in a predictable way. Or is its availability a bit random?)

• Pollution (Does the energy source create pollution when it is being used or is there long-term pollution that occurs when constructing or decommissioning facilities that use the energy source? In all cases, you must be specific about the exact pollution rather than just saying “it damages the environment”. In fact, avoid putting “it” in the answer to any exam question!)

As an example, let’s think about solar energy, which is completely sustainable because we will have sunlight illuminating the Earth for as long as the Sun exists (which is going to be much longer than humans will be living on Earth). Sunlight shines on the entire planet but some locations have clearer skies and less variation in daytime hours during the year so although solar energy is available everywhere it will be more reliable as an energy source in some locations than it would be in others. As far as pollution is concerned, construction of solar cells will cause manufacturing pollution but there is no chemical pollution caused by the use of solar cells. Some people say that large solar farms look ugly because they change the local environment, which may affect local wildlife, but these are generally considered to be minor effects.

Having read this example, you should be able to choose a different energy source and go through the same steps to evaluate its advantages and disadvantages. Doing this for each of the energy sources that you are expected to know (fossil fuels, nuclear fission/fusion, bio-fuels, wind, tides, hydro-electricity and the Sun) is an excellent way to review your knowledge of this particular topic. And remember that this topic is very likely to be in your final examination because it is an important cross-over between school physics and life in the real world.

SLAP! is, I hope, a sufficiently memorable term that you will easily associate with energy sources given that a slap generally involves transferring energy in a very visual (and audible) way!