Alternative Energy Sources

Alternative Energy Sources
Solar
Wind
Hydropower
Tidal Power
Biomass
Geothermal

Solar Power

Types of Solar Power
Active
Passive

Active Solar Power
Energy from sun is stored in a “thermal mass”
When needed, heat from thermal mass is then pumped throughout structure

Active Solar Power
This also refers to electrical generation using solar power
Two ways to do this are photovoltaic cells and huge commercial electric facilities
This shows the diagram for the house seen in the previous slide. The PV panels are on the roof

Large-scale Solar Electric Site

Large-scale Solar Electric Site
These facilities use solar power to heat water to form steam. The steam goes to generate electricity just as in fossil fuel or nuclear electric plants.
No release of air pollutants
No electricity generated at night
They do work on cloudy days, though.

Passive Solar Power
Works on the principle that hot air rises and cool air sinks (convection)
Solar heats air and it moves through convection through the structure or to thermal mass

Passive Solar Power
Mass wall or “Trombe Wall
Using back wall as “mass”
To rest of house

Solar Power
Benefits
Abundant
No greenhouse gases, few other pollutants
Simple, minimal repair needed
Cheap over the long term
Detriments
Retrofitting needed if structure is not already designed as passive solar
Has limitations, night, some locations better such as south rather than north facing slopes
Initial capital outlay can be high

All areas have viable amounts of solar energy

Some solar power history
Solar power furnace was used by Lavoisier to discover elements, particularly nitrogen
Solar power water distillation used by French Foreign Legion and still used today!

Wind Power

Wind power
Can be used for mechanical tasks, e.g. pumping water
Can be used for generation of electricity for direct use or storage in batteries

Mechanical Power Windmills
High torque, low-speed to pump water, grind grain, saw wood

Electrical Power Windmills
High speed, low torque machines
Will turn themselves off if wind speed exceeds their limits

Effects of windpower
No greenhouse gases
Few other pollutants
Cheap
Abundant
Simple
Some noise pollution
Metal blades interfere with TV & radio reception
Aesthetic pollution
No evidence for bird death, but can kill bats
Positive Negative

Where is wind power available?
Wind power not highly suited to these areas

Hydropower
Electric Mechanical

How hydropower works

Negative effects of Hydropower
Flooding the land
Displacement of local inhabitants
Local climatic changes
Tectonic activities (Earthquakes)
Loss of species (aquatic & terrestrial)
Loss of normal nutrient flow down river
Changes temperature of water, too

Positive Effects of Hydropower
Can generate electricity
Can do mechanical work, e.g. grind grain
No greenhouse gases
Initial construction provides jobs

Tidal Power

Tidal Power
Essentially entails placing a dam across an ocean inlet and harnessing the energy as water moves in and out with the tides
Positive & negative effects are same as hydropower
Tidal dam

Biomass Energy

Biomass Pros & Cons
Burning biomass gets rid of solid waste
Creates energy
Creates new markets for crops
Burning biomass releases CO2 and other gases associated with combustion
Creates solid waste from ash
May cause more grasslands to be planted to corn

Ethanol production: not environmentally benign

Geothermal Energy

Where is Geothermal in the U.S.?

Primarily in western U.S.
Pros – Can be used for electricity generation, space heating, cooking & low temperature industrial
Pros – Inexpensive after initial outlay
Pros – No greenhouse gas emission
Cons – same problems as we see with oil drilling
Cons – Localized distribution

How does it work?
Drill to deep, hot rock
Either wet system where heated water belowground is used
Dry system sends aboveground water belowground to get heated
Resulting steam can be used for a number of purposes