Mr. Zarra- AP Enivro Energy Test (Pt 5)
4.) On an annual basis, the per capita electricity usage in Ethiopia is approximately what percent of the per capita electricity usage in the United States? (refer to chart in practice 2)
(0.2/70) = 0.003 (1010kWh p.p. in Eth) (400/300) = 1.333 (1010kWh p.p. in USA) (0.003/1.333) = 0.002 = 0.2%
After 200 million years, only 1/16 of the original amount of a particular radioactive waste will remain. The half-life of this radioactive waste is how many million years?
1 --> 1/2 --> 1/4 --> 1/8 --> 1/16 The whole process takes 200 million years There are 4 arrows 200 million years / 4 = 50 million years
1.) Choose one source of energy in the chart and calculate how many BTU's were consumed by that source in the US 2017: (use nuclear energy) 2.) How many BTU's were consumed from fossil fuels in the US in 2017? (refer to chart in practice 1)
1. Example: Nuclear Energy consumption was 8.79 quadrillion BTU's .09 x 97.7 = 8.79 2. 80% of total, 78.2 quadrillion BTU's 0.8 x 97.7 = 78.2
3.) With moderate winds, a modern large wind turbine can generate about 250 kW of electricity, whereas a large nuclear power plant can generate 1,000 MW. How many wind turbines would it take to generate the same amount of electricity as one nuclear power plant?
250 kW = 0.250 MW 1,000 MW/0.250 = 4,000 wind turbines
A sample of radioactive waste has a half-life of 10 years and an activity level of 2 curies. After how many years will the activity level of this sample be 0.25 curie?
2C --> 1C --> 0.5C --> 0.25C Each arrow = 10 years 3 --> = 10 * 3 = 30 years
In 1997 the World Resources Institute estimated the world's proven oil reserves to be 1,000 billion barrels and the ultimately recoverable reserves to be 2,000 billion barrels. The table below shows the world consumption of oil from 1986 to 1997. 3.) From 1990-1995, what was the percent increase in global oil consumption? 4.) Based on the 1995 rate of consumption, how long would it take to consume the total recoverable reserves of oil?
3. 70-66/66 x 100 = 6.06% increase 4. 2,000,000,000,000/70,000,000 = 28,571 days/365= 78 years
6.) An individual has been driving a passenger vehicle to work, averaging 70 miles a week in a car that averages 25 miles per gallon. The individual plans to purchase a hybrid vehicle that averages 45 miles per gallon. If the individual drives to work 50 weeks a year, how much gas will they save per year if they switch to a hybrid vehicle for their commute?
70/25 = 2.8 gal per week with 25mpg car 70/45 = 1.5 gal per week with 45mpg car 2.8 x 50 = 140 gal per year - 1.5 x 50 = 77.8 gal per year -------------------------------------- 62.2 gal saved per year
5.) A family of four lives in a three-bedroom house and uses an average of 700kWh of electricity per month. The family cools their house for three months during the summer with two window-unit air conditioners that each use 300kWh of electricity per month. What is the percentage of the family's total annual electricity that is used to run the two air conditioners for the three summer months?
700kwH per month x 12 = 8,400 kwH per year AC units use 600kwH per month x 3 months = 1,800 kwH per year from AC 1,800/8,400 = 21% of annual electricity usage from AC
7.) Natural gas is often priced in units of dollars per therm. One therm equals 100,000 BTUs. A certain family uses 500 therms of energy to heat its home annually using a natural gas furnace that is 75 percent efficient. The family is considering replacing its current furnace with one that is 90 percent efficient. Assuming the cost of a therm is $0.30, what would be the family's annual savings in the cost of home heating?
90 - 75 = 15% increase in efficiency 0.15 x 500 = 75 (75 fewer therms would be used) 500 therm x $0.30 per therm = $150 425 therm x $0.30 per therm = $127.50 $150 - $127.50 = $22.50 saved
8.) In many parts of the United States, homeowners use a significant portion of their energy budget to heat their home in the winter. It has been determined that lowering a thermostat by 3°F in the winter can reduce the energy costs by about 12 percent in many homes. An individual homeowner lowers their thermostat by 3 degrees exactly halfway through the billing period. For the month that the thermostat was lowered, the heating bill was $90. How much money did the family save in the month in which they lowered the thermostat setting halfway through the billing period?
If the thermostat was lowered for the entire month, the bill would have been 12% higher than $90. But, the thermostat was lowered halfway through the month so the bill instead is 6% lower than it would have been. .06 x $90 = $5.40 $90 + $5.40 = $95.40 $95.40 - $90.00 = $5.40 saved
1.) Burning one gallon of gasoline in a car releases approximately 20 pounds of CO2 into the atmosphere. One person drives 60,000 miles in a car that averages 30 miles per gallon (mpg), while another person drives 60,000 miles in a car that averages 20 mpg. Over the course of the 60,000 miles, how many fewer pounds of CO2 are released by the 30 mpg car than by the 20 mpg car?
Person 1: (60,000 miles/30 mpg) = 2,000 gal x 20lbs CO2 per gallon = 40,000lb CO2 Person 2: (60,000 miles/20 mpg) = 3,000 gal x 20lbs CO2 per gallon = 60,000lb CO2 60,000lb CO2 - 40,000lb CO2 = Difference of 20,000lb CO2
2.) The town of Fremont Center shares its power plant with the towns of West Fremont and East Fremont. Information about the three towns is shown in the table below. The maximum capacity of the existing power plant is 2,000 MW. (refer to chart in practice 2) a.) Assuming per capita demand remains the same, what will be the approximate power demand in Fremont Center in 40 years? b.) The percent of the total available power currently being used by West Fremont is nearest to:
a. Pop. Future = Pop. Present (1 + r)n r = growth rate (decimal form) n = # of time periods, in this case years Pop. Future = 200,000 (1 + 0.035)40 Pop. Future = 791,852 791,852 x 5kW = 3,959,260 kW or 3,959 MW b. Total available power = 2,000 MW W. Fremont: 75,000 x 4kW = 300,000 kW = 300 MW (300 MW/2,000 MW) = 0.15 = 15%
