Hi I am studying Resources and displacement and I was solving one problem but I
ID: 1229800 • Letter: H
Question
Hi I am studying Resources and displacement and I was solving one problem but I really had no idea how to do it.
can you please help me to get answer... :(
We have condition
If the earth receives 88,000TW of energu from solar sources and is 500 trillion dquare meters (500 * 10^12 for those that like numbers this way) in size.
and I would like to know
How many watts/square meter does this represent ?
and
If one watt of energu flow is equal to a joule of energy oer second, how many Joules fall on a square meter of the earth's surface every year?
then
If 12 percent of thoes solar energy resources could be harnessed , how long would it take for an average 50 square meter solar array to fill up a car with the energu equivalent of 15 gallon thank of fasoline ?
Please help me... I seriously have no idea how to this question.. :(
Explanation / Answer
Okay, so a Terrawatt (TW is 10^15 watts), simply divide 88,000x10^15 by 500*10^12 to get 176,000 watts/square meter Next, calculate how many seconds are in a year 60 in a minute, 60 minutes in an hour, 24 hours a day 365 a year 60*60*24*365 = 31,536,000 joules per year. The best figure I could find for the energy provided by combustion of one gallon of gasoline is 132 MJ or 132000000 J. If I understand the question correctly, when it says harnassing 12% of those solar energy resources, I take it to mean that given the efficiency of solar technology, 12% of what falls on one square meter can be utilized, so 176,000 * 0.12 = 21,120 per square meter, times 50 for a 50 square meter array = 1,056,000 J Now, we want to provide the energy equivalent of 15 gallons of gas with an energy content of 132000000 J per gallon, 15 * 132000000 = 1,980,000,000 J. 1,980,000,000/1,056,000 = 1,875, This means it would take 1,875 seconds, or 31.25 minutes, for the solar array to provide the same energy as a 15 gallon tank of gasoline. Hope that helps!