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Renewable Energies

Study Guide: Heating a Pool with Natural Gas and Renewable Energy

Heating a Pool with Natural Gas

Scenario:

  • Mrs. Grapes has a 20,000-gallon pool heated by natural gas.

Initial Temperature:

  • Water starts at 70ºF, heated to 85ºF.

Calculation Questions:

  1. Calculate BTUs needed to raise temperature:Formula: BTUs = (Gallons) x (Weight of water) x (Temperature Increase)

    • Weight of Water: 1 gallon = 8 lbs ⇒ 20,000 gallons = 160,000 lbs

    • Temperature Increase: 85ºF - 70ºF = 15ºF

    • BTUs Calculation: 160,000 lbs x 15ºF = 2,400,000 BTUs

  2. BTUs needed with furnace efficiency:

    • Efficiency: 75%

    • Total BTUs Needed: BTUs Needed / Efficiency = 2,400,000 BTUs / 0.75 = 3,200,000 BTUs

  3. Natural gas needed:

    • 1 cubic foot of natural gas = produces 1,000 BTUs

    • Cubic feet needed: 3,200,000 BTUs / 1,000 BTUs = 3,200 cubic feet

  4. Cost of heating:

    • Cost of Natural Gas: $5.00 per 1,000 cubic feet

    • Total Cost: (3,200 cubic feet / 1,000) x $5.00 = $16.00

Renewable Energy Overview

Definition:

  • Renewable energy sources are replenished faster than they are consumed.

Major Advantages:

  • Produce less air pollution than fossil fuels.

  • Generally cause less land disruption compared to fossil fuel extraction.

Major Disadvantages:

  • Many renewable sources may not meet energy demand alone.

  • Geographic limitations may affect energy production.

  • Some renewables have lower EROEI compared to fossil fuels.

Biomass Energy

Definition:

  • Biomass refers to organic materials that are or were alive (e.g., wood, charcoal, manure).

Pros:

  • Generally inexpensive and easy to obtain.

  • Provides cooking heat in developing regions.

  • Conversion to biofuels can substitute fossil fuels.

Cons:

  • Overharvesting leads to ecological damage.

  • Emissions from burning can contribute to air pollution.

Different Renewable Energy Sources

Solar Energy:

  • Uses solar radiation for heat or electricity.

  • Pros: No emissions during use, cost-effective long-term.

  • Cons: High initial manufacturing costs.

Wind Energy:

  • Uses wind's kinetic energy to generate electricity.

  • Pros: Nondepletable, no pollutants.

  • Cons: Intermittent resource, potential wildlife hazards.

Hydroelectric Power:

  • Electricity from kinetic energy of moving water (e.g., tidal, run-of-river).

  • Pros: Reliable, minimal air pollution.

  • Cons: High construction costs, potential environmental disruptions.

Geothermal Energy:

  • Extracts heat from below Earth's crust.

  • Pros: Low emissions, reliable.

  • Cons: Limited geographical applicability.

Hydrogen Fuel Cells:

  • Convert hydrogen into electricity.

  • Pros: Low environmental impact.

  • Cons: High extraction costs, energy-intensive processes.