Saturday, September 19, 2015

Energy 101 by Dr Sam Sheldon at GeorgiaTech

US energy supplies
  • Natural Gas 36%
  • Oil 26%
  • Coal 20%
  • Nuclear 9%
  • Biomass 5%
  • Hydro 3%
  • Wind 1.2%
  • Geothermal 0.25%
  • Solar 0.17%
US Energy Production History (Quadrillion BTUs)

Coal obtained from open and underground mines, a problem with coal energy production is the CO2 production which is causing global warming and also the ash produced as a by-product is dumped into ponds etc but for how long. Transportation of coal can be just as coal as mining it. 

Natural Gas combustion also produces CO2 (also water), transportation is low cost.

Oil exports are dominated by Saudi Arabia 22% of total oil, Russia 18%, Iran, UAE, Kuwait, Nigeria at 6% each. Oil combustion also produces a lot of CO2. 

Natural gas liquids are by-products of natural gas production, Ethane, Propane, Butane, Pentane.

Ethanol produced primarily from corn due to ease of production, 10-85% ethanol in all gasoline production. 1 unit of Ethanol production requires 0.8 units of  fossil fuels (coal and natural gas mainly)

Cost of fossil fuel/Million BTUs
1 BTU heats 1 point of water up 1 degree Fahrenheit

Oil demand is 75 million barrels per day (17% passes through Strait of Hormuz - choke point) - OPEC produces 30 mbpd. Saudi Arabia primarily controls the price.

OPEC production and Oil price relations

Solar energy can be obtained @ 300 BTU/hour/square foot. 1Kw/Square metre. Best position for it is to have it tilted south, the optimum tilt = latitude directly south. Best option is two axis tracking flat plate.

Solar Panel angle

Summary

Energy Conversion - 55% energy resources are lost due to inefficiency of conversion process




Coal power plant


Wind Turbine


Alternative solar technologies

A look at the efficiency levels of various power producing technologies shows that these technologies have a lot of room for improvement, despite some of them being several decades old. Efficiency improvements could in itself do so much in reducing our carbon footprint and damage to the environment. Add to that, the plant capacity utilization on an annual basis being about 40-50% means there is a mismatch between supply and demand.

Electric Technology Efficiencies
Renewable Energy Technology Efficiencies

84% of the global warming 'effect' is because of CO2. 10% from methane.  A molecule of methane causes 25 times more damage than a molecule of CO2.


70% of oil is used for transportation, so how good environmentally are electric cars. Electric cars are not zero emission since electricity production emits CO2. An electric car needs 0.34 kw-hr / mile. 1 kw-hr produces about 1.2 lbm (545 grams) of CO2. Hence for each mile driven, amount of CO2 emitted is 0.4 lbm. Gasoline driven cars emit about 19.6 pounds/gallon. So depending on cars mileage, you can calculate CO2 emission/mile. For a prius hybrid which does 50 mpg, CO2 emission is equivalent to an electric car. // The prof is super anti-electric cars, so numbers used might be a little biased ;)

Toyota Prius is a hybrid car which uses braking energy to energize the car, high MPG. No electricity required, same range as gasoline car. Chevy Volt is a plug-in hybrid car which runs 40 miles just on battery and then switched to a gasoline/electric hybrid. Has a good range. Nissan Leaf is an electric car which doesn't need any oil, but range is limited to 100 miles or so. Upto 300 miles on a Tesla but the prof doesn't say so. 

Ocean Energy - Wave energy requires large areas to be adopted, Tidal energy would get in the way of navigation and infrastructure requirements are too high. Lightning energy is too sporadic in time and location. Electric power transmission/distribution - 'Smart grid' is being implemented, DC (long distance) versus AC (usable, less line loss), wireless has limited use. Solar/Wind Electric energy storage is economically not very viable as yet.

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