The Electric Motorcycle, Part 1

Basics of electric-vehicle power systems.

Harley-Davidson LiveWire static side view

I was a two-stroke guy until everything went four-stroke in the 1980s. I had a choice: I could either learn about four-strokes or go stand in a corner and pout. I figured both two-strokes and four-strokes burn the same fuel, mixed with the same air, and perform the same four essential power-cycle functions of compression, combustion, exhaust, and intake, so they are really the same engine, packaged in two different ways. So I got over the change and learned about cam-lobe center angle and airflow through ports with poppet valves in them. I learned lots of interesting stuff.

Now we are feeling the tickle of another big change, as governments and futurists tell us that electric vehicles can and must solve important social, health, and other problems, and must gradually replace today’s fleet of internal-combustion-powered motorcycles, cars, and trucks.

Some people I meet are preparing comfortable corners in which they plan to stand and pout—no electric appliance cars for them! Others, like myself, are trying to learn more about this notional electric revolution, so I have tapped out this umpteen-part series on what I’ve learned so far.

Necessary Realism

Electric vehicle advocates proudly tell us their machines emit zero pollution. That is true only at the point of use, as 88 percent of our electricity still comes from sources that emit plenty of pollutants into the environment. If the energy in all the liquid fuel burned annually by this nation's vehicles is to be replaced by electricity, decisions will have to be made as to how that will be generated.

Sources of Electric Power

Electrical machines are highly efficient, but the processes by which the electricity that powers them comes into being are less so. Here is a 2013 tabulation:

Energy Source Percent of National Power Percent Range of Efficiency
Coal 39 35
Natural Gas 27 35-60 (higher figure is for combined cycle)
Nuclear 19 35
Hydroelectric 7 95
Biomass 1.48 35
Geothermal 0.41 35
Solar 0.23 12-25
Wind 4.13 20-35
Petroleum (diesel) 1.0 45
electric car vs gasoline graphic

The Cost of Change

Thirty years ago, many foresaw a coming “hydrogen economy,” in which hydrogen gas would be sold at every gas station, and vehicles would be powered by electricity generated in onboard hydrogen fuel cells. A major attraction was that when hydrogen is reacted in such cells, the only waste product produced is water.

Several sticks went into the spokes of that particular wheel of progress:

1. There is no easy, cheap source of uncombined hydrogen. It takes just as much energy to separate the hydrogen and oxygen that make up water as can later be recovered from their reaction at 100 percent efficiency. This reveals that hydrogen is not an energy source but rather an energy carrier. A typical fuel cell efficiency is 50 percent.

2. Highly compressing or liquefying hydrogen for efficient onboard storage requires yet more energy. No network for the large-scale production, distribution, and sale of hydrogen exists. Such a system would require investment comparable to what created the present system of petroleum extraction, transport, refinement, distribution, and sale.

3. No investment “angels” saw a potential for profit in stepping up to fund such a changeover. We live under market capitalism, not a centrally planned economy.

Some believe that such developments as Tesla’s favorably reviewed electric automobiles prove that electric vehicles for all will soon materialize. They feel that Tesla’s national network of 116 “Supercharger” charging stations are just the first green shoots of “electric springtime.” That will happen if business can earn a competitive profit from it.

Anyway, enough heavy stuff. Onward to the technology!