[Marxism] Electric Cars
rholt at planeteria.net
Sat Aug 5 12:35:25 MDT 2006
Here we go again, comrades....
There are some facts to consider re. electric cars, busses, and the
First on the small internal combustion engine. I take as an example a 30
hp marine diesel of ancient vintage designed to run at 2500 rpm ±10%
manufactured for the last 30 years by Yanmar, a Japanese company.
Running at 2500 rpm at its maximum output, this engine produces 18.5 KW
and consumes 0.63 gal/hr (±6%) of diesel fuel, which has a thermal
equivalent (i.e., burned completely) of 135,000 BTU/gal. Arithmetic now
shows that the engine burns the equal of 85,500 BTU of fuel per hour
with an energy potential of 24.8 KW. Since the useful power is 18.5 KW
(i.e., all friction, waste heat, etc. is not included as "useful"), the
efficiency is 18.5 / 24.8 = 75%.
Electric motors can be made with almost as high an efficiency as you
want, but the weight and material costs begin to skyrocket above 92 -
93%. So the power lost by the cited internal combustion engine is 3
times greater than the modern electric motor. But...
Batteries: A lithium-metal-hydride battery cell (if the ones I have are
representative) charges at 1.42 volts and delivers most of its charge at
1.25 volts. This is 88%, a very good number for any battery.
Nevertheless, efficiency of the battery-motor combination is 81%. One
can get a lot of power from a battery in a hurry, but the losses go up
as the *square* of the rate of power draw. The same holds for the losses
during charging. Since I don't yet have at hand cells designed for very
rapid charge and discharge rates, I can't testify as to their efficiency
but I can say they are not likely to be better than the 88% I've
measured. (The batteries I have measured are designed to charge at a
rate of 50% of their ampere-hour capacity. I.e., a 200 Ahr battery is to
be recharged at a 100 amp rate.) The aim of current research is to
increase battery capacity (stored ampere-hours) relative to their
weight, bulk and cost. Increasing their charge rate is subject to the
*square* law of diminishing returns and not much improvement is expected
if efficiencies are maintained.
Delivering electric power to the customer is woefully inefficient except
for major users like metal smelting and refining. The "power grid" is
barely operable, to say nothing of its efficiency. For the last century,
the engineers have been asked to minimize the capital cost of power
distribution first, maintenance second and reliability third, and
efficiency is down, down the list. For example, the current power
distribution transformers are efficient only because they cannot be made
less efficient and be kept from burning up. And so forth. Delivering
power from Hoover Dam to Los Angeles or from Niagra Falls to New York
City is a disaster from an efficiency standpoint. Off the top of my
head, I'd say the efficiencies fall below 80%, and again, the losses
increase as the *square* of the demand rate. As an aside, one advantage
to nuclear power could be (possibly, perhaps, maybe) the short distance
between generator and consumer. Assuming that car batteries are charged
at off-peak hours (to minimize that nagging square law loss), we would
be fortunate to get a fuel-to-horse power efficiency of 65%. This number
- 10% below the naked diesel - should not discourage us, but rather get
our heads out of the clouds.
100 million efficient electric cars would present a technological
challenge to a socialist America, to say nothing of the beserk
capitalist state we have. There are many challenges besides the
transport of individuals that might occupy us first.
Please: notice of any errors or omissions should be sent on or off line
to me pronto.
Anthony Boynton wrote:
>In regard to David Walter's post, and I guess an
>earlier discussion, there is a lot going on with
>electric cars, beyond the Telsa (the silicon valley
>luxury electric sports car David mentioned.)
>I suggest readers check out ZAP and Obvio. ZAP is an
>electric car distributor in California which has been
>importing cars to the USA from China. The cars are
>very small, very slow, and have a short range. Now ZAP
>has invested in a Brazilian company, OBVIO which plans
>to produce a much faster car, with greater range, and
>significantly reduced charging times. ZAP has signed a
>contract to buy 50,000 of these cars and import them
>into the USA.
>Brazil and China both have government supported R&D
>programs to develop alternative fuel cars, and have
>put significant resources into electric car
>Electric cars, even with lead acid batteries, are
>definitely more environmentally friendly than are any
>fossil fuel burning vehicles.
>In the first place, current electric motor technolgy
>is 2-3 trimes more eneregy efficient than internal
>In the second place electricity can be generated
>without burning fossil fuels, and without burning any
>carbon: wind, tidal, geothermal, hydroelectric, solar
>and nuclear are all possible. (All have their
>environmental prices, but none emit CO2 into the
>In the third place even thermal generation burning
>fossil fuels in a large plant is cleaner than burning
>fossil fuels in millions of small engines. There are
>economies of scale which include the possiblity of
>burning at higher temperatures, for more complete
>combustion, and investing in very expensive
>technololgy to clean the "exhaust".
>As David said, rapid advances in battery technology
>are the key to advances in electric car development.
>This is not just because of environmental issues, but
>because of practical issues. Lead acid batteries are
>very heavy, must be recharged freqently, and take
>hours to recharge.
>To power a small four door sedan converted from
>interanl combustion to electric power requires between
>12 and 20 standard 12 volt lead acid car batteries.
>The range of such a car between recharging will be
>anwywehre between 60 and 200 miles, its maximum speed
>is likely to be less than 60 mph (depending on
>design), and it could take up to 8 hours to recharge
>the batteries (depening ont he system used).
>Converting internal combustion cars to electric is a
>growing trend, with more than 100,000 such vehicles no
>the road in the USA and Canada.
>The guy who is the key player at Tesla has been
>promoting this trend for years. In fact, they even
>have electric drag racers, which accelearate up to 200
>mph on short runs.
>Right now I have an old Mazda 323 sitting in my garage
>waiting for me to get enough money to buy the rest of
>the parts to convert it into Colombia's first electric
>All the best, Anthony
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