Free AP Environmental Science Tests
AP Environmental Science FRQ Example 3
After answering AP Environmental Science FRQ 3, you can evaluate this sample response, which would receive a perfect score:
Sample Student Response
(a) One drawback of using natural gas to create hydrogen is resource depletion. Since natural gas is a finite fossil fuel, continued reliance on it for hydrogen production reduces available reserves, leading to higher extraction costs over time and increasing dependence on non-renewable resources.
(b) Natural gas is typically extracted from porous sedimentary rock formations, which have already proven capable of trapping gases over long periods. Since these formations have historically stored natural gas, they are also suitable for carbon sequestration, as their permeability allows CO₂ to be injected and retained underground, reducing greenhouse gas emissions.
(c) A possible environmental problem is CO₂ leakage from underground storage sites. If the stored CO₂ escapes due to faults, cracks, or pressure changes, it could contribute to climate change and pose risks to nearby ecosystems and communities.
(d) Given:
Cost of blue hydrogen = \$1.80 per kg
Cost of green hydrogen = \$4.50 per kg
U.S. annual hydrogen fuel usage = 120,000 kg
Calculation:
To calculate the additional cost, you need to take the difference in cost between blue and green hydrogen, and multiply this by the annual usage:
$(4.50−1.80)×120{,}000$
$=2.70×120{,}000$
$=324{,}000$
(e) Given:
Cost of solar energy = \$60 per kWh
Cost of natural gas energy = \$80 per kWh
Energy required per 1{,}000 kg of hydrogen = 400 kWh
Calculation:
To calculate the cost savings, you need to take the difference in cost between solar energy and natural gas energy, and multiply this by the energy required:
$(80−60)×400$
$=20×400$
$=8{,}000$
(f) Given:
Renewable energy production in 2010 = 425 billion kWh
Renewable energy production in 2023 = 1000 billion kWh
$ \text{Percent Increase} $ $ = \left(\dfrac{\text{New Value} − \text{Old Value}}{\text{Old Value}}\right)×100$
$ = \left(\dfrac{1000 − 425}{425}\right)×100$
$ = \left(\dfrac{575}{425}\right)×100$
$ = 1.3529 × 100$
$=135.29\%$
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