Energy & Environment I NAME:

HW#4

Due Friday, October 26, 2001

ANSWERS MUST BE TURNED IN ON THESE SHEETS IN THE SPACES PROVIDED. YOU MUST SHOW ALL WORK.
    1. Fig 2.6, p 55, of the text tells you how much energy the average American uses in one year. Convert this to kwh. Fig 1.8, p 12, of the text tells you how much of this is used for residential purposes. Determine how much energy (as kwh) the average American uses for residential purposes.

      2. (2pt) ANSWER for annual per capita energy use as kwh:

       

      (3pt) ANSWER for annual per capita residential energy use as kwh:

       

       

       

       

       

      Suppose you are an average American energy-wise, and you wish to generate an amount of electrical energy equal to one-half the per capita annual residential energy consumption. That is, you decide to mount on your roof solar PV panels that over the year would generate an amount of electrical energy equal to one-half the per capita annual residential energy consumption. Determine the capital cost of your solar PV system, the roof area required (as sq meters), and the cost of the electricity generated (as cents/kwh, assuming a 30 year lifetime of the system, and simple economics, ie, cost/kwh = capital cost/total kwh generated over 30 years).

      Note:

      Unit cost of solar PV system = $7500/kw-rated-peak.

      Solar panel power rating = 0.12 kw-rated-peak/sq meter.

      Capacity factor for Seattle = 0.12 = average kw actually generated/kw-rated-peak.

      (2pt) ANSWER for electrical energy as kwh you wish to annually produce with your solar PV system:

       

      (4pt) ANSWER for the electrical energy as kwh your solar PV system would annually produce if it continuously ran at the rated-peak power:

       

       

      (4pt) ANSWER for the rated-peak power of your solar PV system as kw:

       

       

       

       

       

       

      (4pt) ANSWER for the area of your solar PV system as sq meters:

       

       

       

       

       

      (3pt) ANSWER for the total cost of your solar PV system as $:

       

       

      (4pt) ANSWER for the unit cost of the electricity produced by your solar PV system as cents/kwh:

       

       

       

      Are you ready to buy a solar PV system and install it?

      (3pt) ANSWER with your reason:

       

       

       

      What if you lived in Honolulu, where the capacity factor is at least 0.20 and the residential cost of electricity is about 15 cents/kwh? Would you buy now?

      (6pt) ANSWER backed up with your reason:

       

       

       

       

       

       

       

    2. If you were an average American energy-wise, how much energy (as kwh) would you annually use for transportation?

      3. (3pt) ANSWER for amount of energy as kwh annually used for transportation by an average American:

       

       

      Now determine your personal annual transportation energy use (as kwh). That is, determine how much you annually use for your car, for riding in friends’ and relatives’ cars, for riding the bus, and for riding in trains and airplanes.

      ANSWER with calculation for the energy (kwh) you use per year driving your car:

       

       

       

       

      ANSWER with calculation for the amount of energy (kwh) annually used by friends and relatives transporting you:

       

       

       

       

      ANSWER with calculation for the amount of energy (kwh) annually used by you in riding the bus:

       

       

       

       

      ANSWER with calculation for the amount of energy (kwh) annually used by you in riding in trains and airplanes:

       

       

       

       

      (21pt) ANSWER for your total annual use of energy (kwh) for transportation:

       

       

      How do you compare with the national average?

      (3pt) Explain:

       

       

      Are you overlooking any transportation energy you used?

      (8pt) Explain:

       

       

       

       

       

       

    3. During the winter of 2000-01, the spot price for natural gas in California peaked at about $30 per million BTUs. In order to break even, what would have been the price of the electricity produced by a gas-fired power generator? Note: the fuel cost is the main cost borne by the power generator.

(15pt) ANSWER with calculation for the break-even unit cost of electricity produced from natural gas having a price of $30/million BTU.

 

 

 

 

 

Compare your answer to the break-even cost of electricity produced from $2 per million BTU gas (the current spot price) and $1.2 per million BTU coal.

Be sure to consider the efficiency of generating electricity from natural gas, and from coal.

(5pt) ANSWER with calculation for the break-even unit cost of electricity produced from natural gas having a price of $2/million BTU.

 

 

 

(10pt) ANSWER with calculation for the break-even unit cost of electricity produced from coal having a price of $1.2/million BTU.