Sun to Wheel

Biofuels may provide a transition to zero emission fuels but over-harvesting forests and/or agricultural
lands led to the decline of most civilizations over the last 7000 years. Maintaining production on
diminishing soil resources now requires ever increasing amounts of fossil nutrients and fuels. As we
bump up against the finite limits of fossil nutrients and fuels, feeding a growing population will not be
possible much less a growing number of internal combustion engines (ICE).
Ultimately all energy on the Earth comes from the Sun so fuel efficiencies should be measured from the
Sun. Fossil fuels are inherently very inefficient because of the millions of years of solar energy it took to
produce them. Photosynthesis is about 1% efficient at producing carbohydrate energy from solar energy.
The efficiency of producing liquid fuel from carbohydrates varies widely depending on the process and
the distance to the use. Then there is the efficiency of the ICE which yields an overall efficiency for
biofuels from Sun to drive shaft of 0.01- 0.03%.
Producing electricity from solar energy using photovoltaics (PV) is from 5-20% efficient and solar thermal
generation can reach over 35% efficiency without counting the cogeneration possibilities. Current battery
charge/discharge efficiency varies from 80-95%. Electric motors are over 90% efficient including line and
motor controller losses. Total efficiency from Sun to electric motor drive shaft is between 3-30%. This
gives solar charged electric vehicles an advantage 10 to 300 times greater then burning biofuels.
The obvious question is: Why aren’t we all driving zero emission battery electric vehicles?
Of course for EVs to be clean the electricity used to charge their batteries must be generated from zero
emission renewable sources. If EVs are charged with power generated from fossil fuels or radioactive
material the cost of our mobility will be passed on to future generations in the form of poor air quality,
depleted resources, climate change and radioactive waste.

Transportation Efficiency and Reducing Greenhouse Gas Emissions

Most people don’t realize that they use more energy to power their cars than they use to power their homes. For comparison, an energy-efficient home uses about 10 kWh/person/day for lights and appliances and contributes < 200 lbs of CO2/year from the California mix of power plants. Increasing transportation efficiency is clearly the best place to focus our efforts to reduce greenhouse gas emissions. Experts suggest that in order to stabilize Climate Change the US population must reduce its total CO2 emissions to below 2.5 tons/person/year. Even this low number of 2.5 tons assumes that most developing countries will keep their CO2 emissions below 1 ton/person/year. PHEVs offer zero emission for every day commuting and the convenience of traveling 400 miles on one tank of fuel for trips over the battery's capacity. Long trips are relatively infrequent, so PHEVs can decreased fuel consumption by 90% which increases the feasibility of using fuels like ethanol and hydrogen (H2) produced from renewable sources. H2 produced from solar, wind or Hydro is the fuel of choice because no CO2 is generated in its creation or combustion. Of course the best way to cut CO2 emissions is to build and redevelop energy-efficient communities for people instead of cars but that is a topic for another day. As we approach the peak of world oil production (extraction) it is important to reflect on how it came to pass that the developed world would base its entire economy on finite resources. It is also important to realize that corporations are not conscious beings and, for the most part, are incorporated for one reason: to make money. This gives us, the consumers, the ultimate power to be the corporate conscience by choosing how we spend money. It is also up to us to insure that laws and regulators protect essential resources like air, water and soil.

A Clean and Quiet Revolution

By Steve Heckeroth, May 2006

The technologies exist to clean the air, stabilize the climate and maintain our standard of living all at the
same time. By relying on clean renewable technologies we can eliminate much of the US trade deficit
and the reason for war while achieving energy independence.
A quick study of the chart below shows the overwhelming advantages of plug-in hybrid (PHEV) and
battery electric vehicles (EV). EVs are zero emission and can be charged from zero emission renewable
energy sources like the sun and wind. By adding more batteries to hybrid electric vehicles (HEV) plug-in
hybrids (PHEV) can be built which offer the range of gas vehicles (400 Mi.) with the environmental
benefits of electric vehicles for short trips.

The main assumptions used to produce the values in the chart are:
1. The average cost of gasoline over the next year will be approximately $3.50/gallon.
2. The Time of Use (TOU) rate for nighttime charging is approximately $0.05/kWh.
3. There are about 40 kWh of energy in a gallon of gasoline.
4. Burning 1 gallon of gasoline produces approximately 23 lbs of CO2.
* This column includes upstream CO2 emissions for exploration, extraction, transport, refining and
distribution of gasoline, as well as CO2 emissions from the California mix of power plants that produce
electricity to charge electric vehicles.