Energy

Drivetrains

Have you noticed that modern cars and trucks have complicated transmissions, but 100 year old steam locomotives don't? Why do we need transmissions anyway? Isn't there a better way to drive wheels? A short introduction to drive trains addresses these questions and suggests ideas for more efficient vehicles of the future.

Cold fusion

In 1989, Pons and Fleischmann announced controversial research results called Cold fusion. During that time, I was finishing my physics degree at Maryland. I was also working at the Laboratory for Plasma and Fusion Energy Studies. Needless to say, the faculty and staff at LPFE and the physics department were very interested. What followed next was one of the most provocative experiences I have had the fortune to witness.

Solar power

Based on data from the CIA World Factbook, the average electric power consumption is:

  • World: 0.26 kW/person (2002)
  • United States: 1.44 kW/person (2002)

In 2002, persons living in the United States consumed roughly 5.5 times more electric power than the world average.

Here's a great link on solar insolation for the US at different times of the year:

http://www.wattsun.com/resources/insolation_maps/flat_plate.html

Given an average annual insolation of 5 kWh/day-m2 and total US consumption of 440000 MW, and a conversion efficiency of 35%, the area necessary to produce the required energy is:

6034 km2 or 2330 mi2

This is about 0.066 % of the US land area. If all solar energy was collected in Arizona (one of the two states with highest solar insolation), only 6% of it's land area would be required. Of course, transmission to the rest of the US is non-trivial.

More details can be found here.

Based on the above numbers, the average US resident consumes about 1400 Watts or about 33.6 kWh/day.

Of course, these are average numbers. It could be cloudy for a week or more. If water towers were used to store energy: A 100m (300 foot) tall, 1000 gallon water tower can store about 1000 kWh of energy. One person would require a tank of about 34000 gallons capacity to store electricity for one day. A 1 square mile lake 10 feet deep at 100 meter elevation can store enough energy for 9000 people for 1 week.

The end result is that it's possible for solar to work on a very large scale, but development cost is apparently considerably higher than that for coal fired plants. One figure places solar electric production at $0.15 / kWh, which is more than twice the typical cost from a coal plant.

Basically, the current economics don't support it.

Land and water area by state:

http://www.infoplease.com/ipa/A0108355.html

Energy and geographic information for the US:

http://www.cia.gov/cia/publications/factbook/geos/us.html

E85 Ethanol

From http://www.e85fuel.com/index.php

E85 is an ethanol based fuel made from corn.

One bushel of corn produces 2.7 gallons of ethanol in addition to several valuable co-products.

Food calories

Given average daily consumption of 2000 food calories, this is equal to:

  • 8.3 million Joules
  • 2.3 kWh
  • 7830 BTU
  • 0.0626 US gallons of gasoline
  • 1 cup of gasoline
  • 2.8 cubic millimeters of Uranium (fission)

Biomass

http://www.hort.purdue.edu/newcrop/proceedings1999/v4-282.html

At present 1.3 million ha, approximately 6% of the US corn, is used in production of approximately 1 billion (B) gallons of ethanol each year. Estimates of future corn production of ethanol have been as high as 5 B gallons/year with potential net benefits to agricultural income of over $1 billion to US farmers (House et al 1993). However, recent analyses suggest that it is unlikely that corn can supply more than 22.5 B gallons of ethanol annually because of competing demands for corn.

This is an ethanol yield of about 311 gallons/acre of corn. Assuming a retail price of $1.5, the gross revenue is about $467/acre.

Nuclear power

Uranium facts

  • Concentration - uranium ranks 48th among the most abundant elements found in natural crustal rock.
  • Density - uranium is very dense. At about 19 grams per cubic centimeter, it is 1.6 times more dense than lead. Density increases weight. For example, while a gallon of milk weighs about 8 pounds, a gallon container of uranium would weigh about 150 pounds.
  • Melting Point - uranium boils at about 3,818 degrees Celsius (about 6,904 degrees Fahrenheit).
  • One ton of natural uranium can produce more than 40 million kilowatt-hours of electricity. This is equivalent to burning 16,000 tons of coal or 80,000 barrels of oil.
  • The price of uranium was approximately $8.75 per pound at end of 1998.
  • Electrical energy for one person for one year in the US requires:
    • 0.9 cubic inches of Uranium
    • 840 gallons of coal
    • 112 cubic feet of coal (a cube 4.8 feet on each side)
  • A 1000 Megawatt power plant operating for 20 years requires about
    • 7400 cubic feet of Uranium
    • 2.7 shipping containers of Uranium
    • 70 million tons of coal
    • 590,000 shipping containers of coal
  • A lifetime supply of electrical energy for one person would require about $390 worth of Uranium