Physicist Tom Murphy at Do the Math has an excellent analysis of the increasing number of alternative energy sources that are being explored as substitutes for fossil fuels. Titled The Alternative Energy Matrix, Tom looks at 20 different energy sources and the obstacles that must be overcome to make each one a viable and practical solution to our energy requirements.

Tom then created the matrix below which classifies each energy source on the basis of a number of criteria including its abundance, difficulty of extracting energy, intermittency, demonstrated, ability to produce electricity and heat, can it be used for transportation, public acceptance, small scale vs. large scale, and its efficiency.  Then he uses a colour code to determine if the energy source is adequate (green); marginal (yellow); or insufficient (red).

Here is his matrix.



You can read what Tom has to say about each individual energy source in his post.  As you can see, there is no silver bullet.  Tom says: “Looking at some of the main trends, very few options are both abundant and easy.” Or as economists say, there is no such thing as a free lunch. Each source has its benefits and costs and no one source will deliver all of our energy needs this century for transportation, light, heat and power.

Tom goes onto say:

Intermittency mainly plagues solar and wind resources, with mild inconvenience appearing for many of the natural sources.

Electricity is easy to produce. We have loads of ways to do it, and are likely to pick the easiest/cheapest. We won’t necessarily get far down the list if we’re covered by things at the top end (assuming my rankings have any validity and some economic correlation).

Transport is hard. Concerns over peak oil played a huge role in making me sit up to pay attention to our energy challenges. Electric cars are the most obvious way out, but don’t do much for heavy shipping by land or sea, and leave airplanes on the ground.

Few things face serious barriers to acceptance: especially when energy scarcity is at stake.

A few options are available for the homestead. A passive solar home with PV panels, wind, and some method to produce liquid fuels on site would be a dream come true. Here’s hoping for artificial photosynthesis!

The missing category here is cost, although difficulty may be an imperfect proxy. As a result, some of the high-scoring options may be more costly than we’d like. Actually, some of the lowest-scoring options are the costliest! If you’re expecting that we’ll replace fossil fuels and do it on the cheap, you might as well learn to bawl on the floor kicking and pounding your fists, tears streaming. This is our predicament. We have to buck up and deal with it, somehow.

When I first approached the subject of energy in our society, I expected to develop a picture in my mind of our grandiose future, full of alternative energy sources like solar, wind, nuclear, biofuels, geothermal, tidal, etc.  What I got instead was something like this matrix: full of inadequacies, difficulties, and show-stoppers.


If you go to Tom’s homepage, you can read in more technical detail what he has to say about each of the energy sources in his matrix.

Tom has done us all a valuable service in taking this hard look at our alternative energy future.


Tags: , , , , , , , , , , , , , ,