You own two vehicles. A car that gets 25 miles to the gallon and a truck that gets 20 miles to the gallon. You are moving to a new house that is 80 miles away. You estimate that you will need to take four loads over in your truck but six if you use your car. Assuming gas costs $4 a gallon, how much will you spend in fuel if you use the truck, and how much if you use the car? Which one will you choose?
Your new house is 35 miles from your work, but 15 miles closer than your old house. You work five days a week, 50 weeks per year. How much less will you spend driving to work this year than you did last year? You drive your car to work.

The average American burns about 6.7 metric tons of oil-equivalent in fossil fuels each year. Average terrestrial net primary productivity is 0.0037 metric tons/ha/yr.

How many hectares of land would it take to supply one person's fuel use through present-day photosynthetic production?
Earth's total land area is approximately 15 billion ha. What percent of earth's land would one person need to produce the equivalent of their yearly fossil fuel supply?
If each person on earth consumed energy the way Americans do, what percent of earth's land would be used for fuel production? (Round the current human population to the nearest billion.)

Coal from source A produces sulfur at a rate of 18g per 100kg of coal. Coal from source B produces sulfur at a rate of 42g per 275kg of coal. Source A sells coal for $0.60 per kilogram and Source B costs $1.40 per kilogram.

How many grams of sulfur would be released from the combustion of $100 of each source of coal (round your answer to the nearest tenth of a gram)?
We use about 7 billion metric tons of coal worldwide per year for electricity generation. Using the least polluting coal source, how many kilograms of sulfur would be released per year?

A power plant has a capacity of 500 MW. This is the maximum electrical output of the plant when it is operating. The plant has a 0.9 capacity factor, a measure of the actual time a plant operates. The capacity factor is a fraction of the total time that the plant could operate.

According to the U. S. Department of Energy, a typical home in the U. S. uses approximately 900 kWh of electricity per month.

How many homes can the power plant support?

An Energy Star air conditioner unit costs $300 while a standard unit costs $200. The two units have the same cooling capacity. The Energy Star unit costs 5 cents per hour less to run. If you buy the Energy Star unit and run it for 12 hours per day for 6 months of the year, how long does it take to recover the $100 extra cost?

You are about to invest in a 66-inch flat screen TV. These TVs come in both Energy Star and non-Energy Star models. The cost of electricity is $0.15 per kilowatt-hour, and you expect to watch TV an average of 4 hours per day. (too much)

a. The non-Energy Star model uses 0.5 kW (half a kilowatt). How much will it cost you per year for electricity to run this model? 4b. If the Energy Star model uses only 40 percent of the amount of electricity used by the nonEnergy Star model, how much money would you save on your electric bill over 5 years by buying the efficient model?