Renewable & Inexhaustible Energy Sources

Control PowerCVHS

Energy vs. PowerEnergy is defined as “the ability to do work”

Power is a term used to describe the measure of work being done (rate)

Energy & Society

Without energy, Life would not be possibleEnergy not only powers modern technologies including transportation, etc., but is also necessary to power living organisms (people, animals, plants, etc.)

Sources of Energy

Nonrenewable RenewableInexhaustible

Nonrenewable Energy

This is a source of energy that once used, cannot be replenishedExamples: Coal, Natural gas, Nuclear, etc.

Renewable EnergyThis is a source of energy that can be replenished if it is used.Examples: wood, ethanol, food, etc.

Inexhaustible EnergyThis is a source of energy that can be considered permanent (at least for a few million more years).Examples: Sun, Wind, Waves, Geothermal

Renewable & Inexhaustible EnergyTo combat the ill effects, and high costs of nonrenewable energy sources, new technology must be developed.These new energy technologies must heavily rely on renewable and inexhaustible resources in order to be sustainable

Renewable Energy Sources

AnimalsPlantsBiomass

AnimalsSource of foodSource of work energy (especially in underdeveloped countries)Why are animals considered to be renewable and not inexhaustible?

Plants: WoodOne of the earliest used fuelsDespite a decline in the 1900’s, wood is once again a popular choice as a home heating fuel.Can be converted to “wood gas” (methanol) in liquid or gaseous formsConcerns:

Trees must be immediately replanted to compensate for long growth periodsBurning wood releases pollutantsCreosote Build-up

                                                         

Plants: Alcohol

Can be produced from a variety of plant life including: Corn, Sugar beats, Sugar cane, and wood.Used to run internal combustion engines, etc. (E85, Regular gas usually includes ~ 10% ethanol)Major Forms: Ethanol & MethanolConcerns:

Corn ethanol cuts in on a source of foodStill produces pollution

Biomass Bioconversion is a process that burns or converts waste organic material into a useable form of energyIncinerators burn biomass to produce electricity

Anaerobic Digestion can be used to produce methane gas which can be burned like Natural Gas or Propane

Inexhaustible Energy Sources

SunWaterWindGeothermal

SunMost energy sources derive their stored energy from the sun, including plants, trees, wind, etc.The sun provides an almost limitless source of energy that can be collected to produce heat (thermal) or electrical energy.

Water: HydroelectricUsed for decades as an energy source for electricity generationUses the power of moving water to spin a turbine, which turns a generator to produce electricityMost large scale sites have been developed in the US, meaning that only smaller sites may yet be utilizedThree Gorges Dam Expected Finished output 22,500 MW

Water: Tides & WavesUses the force of tides and waves to produce electricityVery clean, but may interfere with natural ecosystems, and fishing locationsTide generators can only be used in certain locations

Water: OTECUses the temperature differential between surface water and deep water (energy stored in water by the sun)Warm water creates steam (spins turbine) cool water condenses steam back into a liquidCan be used to produce electricity at remote ocean locationsProblems:

Can only be used in certain locations (temp. differential)Dumping large amounts of cold water into the ocean can damage the ecosystem

Water: HydrogenHydrogen is a very energetic & clean fuel source, but is scarce in its natural stateWater molecules can be split to produce Hydrogen and OxygenRequires large amounts of energyTwo Forms: Electrolysis & Pyrolysis

Pyrolysis

WindUsed for hundreds of years as a mechanical energy sourceNow used to produce electricity in large scale wind farms, and residential settingsProblems

Noisy Large areas of land/ sea required

GeothermalUses steam from the earth to spin a turbine and produce ElectricityProblems:

LoudSmellyMay produce Pollution

Heat pumps can also be used to heat water to ~ 55° F for home heatingProblems

Must be used in conjunction with another energy source

Conclusions

Dependence on Fossil fuels must change sooner or later due to environmental concerns, and the fact that they will someday run outMany forms of energy will need to be implemented to replace fossil fuelsEach, has problems associated with it that must be weighed against its benefits