[ale] OT CFL cleanup / LED light bulbs starting to become affordable

[Alex Carver]

On 7/3/2013 10:26, Jay Lozier wrote:
> +1 humor
>
> The EPA's definition of "green" jobs and mine are very different. I prefer to
> focus on the entire process not just one aspect of the problem. Often "green"
> iniatives just shuffle the type of pollution problem and pollution sources
> around without really reducing the overall pollution.
>
> For a variety of reasons I view all-electric cars as environmental pollution
> shuffling resulting no net gain. There may be a substitution of some heavy metal
> pollution in lieu of carbon dioxide. This may not be a wise trade-off. And the
> location of the carbon dioxide production has been moved from the tail pipe to
> the power plant.


Sure CO2 has been moved to the power plant but we need to also consider 
efficiencies of scale, too.

It could be argued that an electric car and a gasoline car generate 
about the same amount of pollution in their manufacturing/assembly 
process for most of the vehicle (the engine versus motor is something 
different).  So assembly is a wash for pollution reduction.

The battery of an electric does have issues with mining for lithium and 
the pollution generated by the mining process.  However, other battery 
technologies may resolve that issue (polymers, organics, higher energy 
densities for existing designs, etc.)  But, I could also argue that less 
oil has to be located and mined/extracted/shipped because the car is 
electric not gasoline.  So it may still be a wash but, if not, the 
difference is a bit more subtle.

The big difference is the power plant (both in the car and for the power 
grid.)  An internal combustion engine isn't terribly efficient at 
producing motion from fuel.  Most of the energy in gasoline (well over 
75%) is lost as heat.  Our cars do not use heat to generate motion, they 
use the rapid expansion of gas to push pistons and mechanical linkages, 
all of which also sap some energy.  By the time you get the rotary 
motion to the tires, a lot of energy has gone away to heat that is lost 
to the environment (and waste heat is another form of pollution.)

An electric motor, however, converts electromagnetic energy to motion 
directly.  The result is a much more efficient conversion with less 
waste.  A well designed induction motor can be upwards of 60-70% 
efficient in converting the input energy to rotation.  That's better 
than the 25% or less of the gasoline engine (25% is being extremely 
generous.)  A well designed car power train can also reduce the number 
of linkages required from the motor to the wheels (all-electric cars do 
not technically need a traditional mechanical transmission system.)  So 
now the energy loaded into the battery can do more work than you get out 
of the same amount of energy sent to a gasoline engine[1].

Go over to the big power plant on the grid.  The power plant takes 
advantage of the fact that burning fuel can create far more heat than 
any other method energy conversion.  So it doesn't burn the fuel to 
cause an explosion like a combustion engine.  It burns the fuel to 
generate tremendous amounts of heat which is transferred to water to 
produce superheated water and steam.  Send that through a turbine and 
you get your electricity.  The conversion here from fuel to electricity 
is about 60% efficient (depends on the type of power plant, some are 
better.)  That's higher than the 25% for the gasoline engine conversion 
to rotary motion.  There is less wasted heat at the big power plant than 
in the gasoline engine.  Additionally, there is the reduced pollution by 
not having to truck around tanks of gasoline to gas stations.  All the 
fuel goes in bulk quantities to a few central locations by more 
efficient means (trains, large tanker ships, etc.) instead of to 5,000 
locations by tanker truck.  The quantity of fuel consumed by the power 
plant to power an electric car will be less than the fuel consumed by 
the gasoline car especially if you count in all the hidden energy sinks 
(e.g. the tanker trucks to the gas stations, the electricity required to 
run oil refineries to create gasoline while oil fired power plants can 
typically burn a much wider range of fuels with less need for refined fuel.)

At the end of the day is the savings huge, hard to say without running 
the numbers meticulously but I would argue that there are pollution 
savings to be had by an all-electric vehicle.


[1] Gasoline, like all the other fossil fuels, is incredibly energy 
dense.  There is more energy per pound of gasoline by several orders of 
magnitude than there is in a lithium battery.  This is what causes the 
range problem for electric cars.  However, if a gasoline engine could be 
as efficient with that energy as an electric car, gasoline cars would 
have ranges of well over 1,000 miles per tank.  The big push is to make 
the batteries weigh less, cram more energy into every cubic inch of 
battery, and to do that very quickly.  Reaching those goals unlocks the 
power of an all-electric car.