A gallon of gasoline carries with it about 1.3 · 108 J of energy. Given a price of $3 per gallon, how many Joules can you get for a dollar? Electricity goes for about $0.05 per kilowatt hour. A kilowatt hour is just a weird way to write Joules because a watt is a joule per second, and a kilowatt hour is the number of Joules one would get from running 1000 W times one hour (3,600 seconds). In the form of electricity, how many Joules can you get for a dollar? A standard cubic foot of natural gas carries with it about 1.1 · 106 J of energy. You can get about 5 · 105 British thermal units (BTUs) of gas for a dollar, and there are about 1,030 BTUs in a standard cubic foot. How many Joules of energy in the form of natural gas can you get for a dollar? A ton of coal holds about 3.2 · 1010 J of energy and costs about $40. How many Joules of energy in the form of coal can you get for a dollar? Corn oil costs about $0.10 per fluid ounce wholesale. A fluid ounce carries about 240 dietary calories (which a scientist would call kilocalories). A calorie is about 4.2 J. How many Joules of energy in the form of corn oil can you get for a dollar? Rank these as energy sources, cheap to expensive. What is the range in prices?
The Correct Answer and Explanation is :
Here is the ranking of energy sources from cheapest to most expensive based on the number of Joules per dollar:
- Coal: 800,000,000 J/$
- Natural Gas: 533,980,582.52 J/$
- Electricity: 72,000,000 J/$
- Gasoline: 43,333,333.33 J/$
- Corn Oil: 10,080 J/$
Price Range
The price range between the cheapest (coal) and the most expensive (corn oil) energy source is approximately 79,365:1.
Explanation
- Coal is the cheapest energy source per dollar, as a ton of coal contains a massive amount of energy (3.2 × 10¹⁰ J) for a relatively low cost of $40.
- Natural gas comes second due to its relatively high energy content and affordability, as you get a large amount of energy (around 533.98 MJ) for each dollar.
- Electricity is more expensive due to its production and distribution costs, despite its widespread use and high efficiency in energy transfer.
- Gasoline ranks fourth, largely because of its energy density and the added cost of refining and distribution.
- Corn oil is by far the most expensive source of energy, primarily due to its use in the food industry and relatively low energy content compared to its cost.
This comparison highlights the vast difference in energy costs between fossil fuels and alternative sources like electricity and biofuels.