Energy & Environment I

HW#2

Due Friday, Oct 12, 2001

 

A.   Residential costs of energy.  Determine the typical costs of the following energies for our region:

·        Electricity

·        Natural Gas

·        Gasoline

Rank-order these by the cost per unit of energy purchased.  Convert to a common unit of energy (kJ = kilojoule).

 

B.  For one year, plot the energy consumption of your residence, or that of your family residence.  Plot the following versus month, use one graph for all three plots:

·        Electricity as kwh/day vs month

·        Natural gas or propane (if used) as kwh/day vs month

·        Total energy as kwh/day vs month

If you do not have the data for your residence use the data for the residence below.

Then determine the energy costs (as $) for the year.  Determine the electricity cost, the natural gas or propane cost (if used), and the total cost.

 

C. Explain, justify: Which is cheaper to use for heating: electricity or natural gas?  Note: electric furnaces and base board heaters are about 100% efficient, natural gas furnaces are about 80% efficient, and electric heat pumps are about 200% efficient.

Consumption Rate per Month for Natural Gas and Electricity for a 3,500 sq. ft. Residence in Western Washington.

 

Electrical Energy Use Averaged per Day during 96-97

 

 

Average Therms per Day of Natural Gas for 96-97

   

 

                                 Note: 1 therm = 100,000 BTU