Author Question: Underdeveloped countries can gain by exploiting low-head hydroelectricity. What will be an ideal ... (Read 42 times)

biggirl4568 · **on:** Jul 28, 2018

Underdeveloped countries can gain by exploiting low-head hydroelectricity.

What will be an ideal response?

Question 2

Compact fluorescent bulbs cost 10 per bulb and last 10 years. Tungsten bulbs cost 0.50 per bulb and last 1 year.

For a given amount of light, a tungsten bulb draws 75 W
and a compact fluorescent bulb draws 10 W. If the cost of electricity is 0.10/kWh and the
bulbs are operated for 2000 h/yr, what amount of money is saved by use of a compact
fluorescent instead of a tungsten bulb over a 20-year period?

nikmaaacs · **Reply #1 on:** Jul 28, 2018

Answer to Question 1

This seems to be the case. The cost of small local dams is not expensive,
especially if local hand labor is used, and the environmental effects are usually insignificant.

Answer to Question 2

Over 20 years, you would use two compact fluorescent bulbs and twenty
incandescent bulbs. The cost of the compact fluorescent bulbs would be 20 (10 x 2),
while the cost of the incandescents would be 10 (0.50 x 20). The yearly energy cost of a
compact fluorescent bulb is (10 W) x (2000 h) = 20 kWh; the monetary cost is 20 kWh x
0.10/kWh, or 2 . The yearly energy cost of an incandescent bulb is (75 W) x (2000 h) =
150 kWh; the monetary cost is 150 kWh x 0.10/kWh, or 15
Over a twenty-year period, the cost of the compact fluorescents will be 20 + 20 x 2 =
60 . The cost of lighting by incandescent bulbs will be 10 + 20 x 15 = 310 . The
compact fluorescent would save 250 over this interval.
No matter which way we look at things, the compact fluorescent bulb is cheaper. This could
also be seen in yearly costs: Compact fluorescent bulbs cost 10/10 + 2 = 3, while
incandescent bulbs cost 0.50 + 15 = 15.50