Each year, due to growing population and energy demands, the United States faces increasing dependency on conventional fossil fuels. However, in the past few decades renewable energy has begun to expand in both residential and commercial sectors of the United States. a)
i. The U. S. uses roughly 4.0 million Gigawatt-hours per year in electricity. Currently 50% of our electricity comes from coal. If every 1.0 kilowatt-hour of coal burned releases 2 lbs. of carbon dioxide, how much carbon dioxide is released from burning coal for electricity each year in the US?
ii. What will be the reduction of carbon dioxide entering the atmosphere each year if coal usage could be reduced by 15% by utilizing solar energy?
iii. List and discuss TWO advantages to using wind energy to generate electricity.
b) Identify and describe a type of passive OR active solar heating method.
c) Give one advantage and one disadvantage to the method you described above in question b).

A) (i) 4*10^12 Ibs , (ii) 600 * 10^9 Ibs  

(iii)

B) The use of  bricks or stone that can absorb the solar heat easily when the sun rays heat them up and this solar heat absorbed . is a typical example of a passive solar heating system.

C) Advantage : It is mostly cost free

disadvantage : there is no storage mechanism

Explanation:

A) Given that U.S uses roughly 4 million Gigawatt-hours per year in electricity and 50% of the electricity comes from coal

i) Determine how much carbon dioxide is released from burning coal each year

since 50% of electricity comes from coal

The Total energy produced by coal =2*10^12 Kw-h. also

1.0 kilowatt-hour of coal burned releases 2 lbs.

hence the Total amount of Carbon dioxide released from burning coal each year = 2 * 2 * 10^12 =  4 * 10^12 Ibs  

ii) Determine the reduction of carbon dioxide entering the atmosphere each year if coal usage could be reduced by 15% by utilizing solar energy

= 15% 0f 4*10^12

reduction of coal usage by 15% = 600 * 10^9 Ibs hence the amount of coal entering the atmosphere is reduced by 600 * 10^9 Ibs

iii) Advantages of using wind energy to generate electricity

B) Passive solar heating system

The use of  bricks or stone that can absorb the solar heat easily when the sun rays heat them up and this solar heat absorbed . is a typical example of a passive solar heating system.

C) advantage and disadvantage of solar heating system

Advantage : It is mostly cost free

disadvantage : there is no storage mechanism

we can conclude that the melting point of table salt is above room temperature (it's actually 801 deg c). the melting point of mercury must be below room temperature (- 39 deg c).

14 days is the half-life of phosphorus-32