Stabilizing climate: Shifting to renewable energy

Dr. Huidae Cho
Institute for Environmental and Spatial Analysis...University of North Georgia

1   Shifting energy economy


2   Turning to the wind

ND, KS, and TX

  • Have enough harnessable wind energy to run the entire US economy.

SD is developing a megawatt wind farm.

  • Produces 5x the energy needed for all state residents

Wind energy can be exported.

Scotland is developing an off-shore wind farm.

  • Produces almost all of the energy needed for the UK

Wind farms can be planted among crop fields and livestock grazing areas.



2.1   Analyzing the availability of wind energy in the United States

Faster than 6.5 m/s suitable for wind farm


Purple, red, and blue

  • The best locations for home wind turbines

Orange and pink

  • Could provide substantial home energy use savings

2.2   Wind resource in Georgia


Plans for Georgia’s Wind Energy Make Slow Progress – But State Utilities Still Push Forward

2.3   Home wind turbines


Home Wind Power: Yes, in My Backyard! (YIMBY)

U.S. Department of Energy’s Guide to Small Wind Electric Systems, a free publication for homeowners

Possible problems

  • Not enough wind
  • Injury to birds
  • Zoning restrictions
  • Cost
  • HOA

3   Solar cells and thermal collectors


Photovoltaics (PV) ⇒ Electricity

Solar thermal collectors (STC) ⇒ Heating

Both are made from silicon-based semiconductors and thin films.

Both convert sunlight directly into energy.

STC can convert sunlight into heat. For example, rooftop solar water heaters.

PV use is growing 45% annually.

Initially, PV production was located in Germany, US, and Japan.

Solar cells convert 15% of solar energy into a usable form.

4   Solar energy to villages


4.1   Andean (South America) villages

Candles ⇒ Solar cells

Cost for solar cell installation over 30 months < Monthly outlay for candles

4.2   Indian villages

Villagers in India use kerosene lamps, yet can install solar systems for $400.

Kerosene lamps

  • Account for 29% of CO2 emission in these regions
  • Use 1.3 million barrels of oil per day (half the oil production of Kuwait)

A solar PV system replaces two kerosene lamps and will pay for itself within 4 years.

Then becomes a free source of electricity.

4.3   International solar energy programs

Buying a solar PV system ⇒ Buying a 25 year supply of electricity

The initial cost is high ⇒ The World Bank and the UN Environment Program

The World Bank helped over 50,000 homeowners in Bangladesh to purchase solar cell systems.

5   Energy from the earth

The heat in the upper six miles of the crust = 50,000x energy found in oil and gas reserves

Half the world’s generating capacity is found in the US and Philippines.

Electricity from geothermal power plants

  • Iceland 27% of their electricity
  • Philippines 26%
  • El Salvador 23%


  • Volcanoes
  • Shift plates: Potential earthquake zones
  • Hot springs/baths: Geology study would be beneficial

5.1   Pacific Ring of Fire

Countries bordering the Pacific in the Ring of Fire

  • Chile, Peru, Colombia, Mexico, US, Canada, Russia, China, Japan, Philippines, Indonesia, Australia


5.2   Other geothermally rich countries

Along the Great Rift Valley of Africa

  • Kenya, Ethiopia, those around the Eastern Mediterranean


5.3   Large-scale geothermal energy

Geothermal heat is used to grow vegetables in greenhouses during the winter.

  • Russia, Hungary, Iceland, and the US

Aquaculture (fish farms) use warm water from underground.

  • China, Israel, and the US
  • California supports 15 fish farms producing over 10 million pounds of fish for supermarkets

If the four most populated countries along the Ring of Fire invested in geothermal energy, this would become the leading world energy source.

  • US, Japan, China and Indonesia

How a Geothermal Plant Works (5 mins)

6   Plant-based sources of energy


Forest industry byproducts: Biofuels

Sugar industry byproducts: Bagasse & Molasses

Urban waste—Sewage filtration and composting systems

Livestock waste—Sewage filtration and composting systems

Plantations of fast-growing trees—Silviculture

Crop residuals—Also can be used for feeding livestock

Urban tree and yard wastes


6.1   Other thoughts on plant-based energy

Byproducts, residues, and waste would be better sources of energy than corn fuel

  • Do not put a drain on food supply
  • Do not increase food prices

Waste-to-energy plants burn garbage for heat.

HOWEVER, we need to work towards a zero-garbage economy.

Recycle more than discard.

Burning garbage would not be the answer to our landfill problem.

  • Harness methane for heat?

Crops are used to produce biodiesel and ethanol.

Liquid conversion of plant-based energy is more efficient than burning waste.

7   Hydropower: Rivers, tides, and waves


Visiting Hoover Dam

Buford Dam: A unique little powerhouse


7.1   Not just dams—Kinetic wave power

Captures the energy of waves.

Float systems and coastline wave capture systems can convert the movement of waves to electricity.

This energy can be placed into the electricity grid.


7.2   Ocean current energy


7.3   Local examples of hydroelectric energy


Historic Sylvan Falls Mill

In Rabun Gap, GA

Celebrating its 175th year of operation

Unique in that it is located below a 100-foot cascading waterfall

Powered by a 27-foot water wheel

  • One of the largest in the US

The original wheel was wooden.

A steel wheel was installed in 1950.

8   Energy

Primary energy

  • Energy form found in nature, not human-engineered yet
  • Energy received as input to a system that generates secondary energy

Secondary energy

  • Human-engineered energy such as electricity
  • Energy generated by converting primary energy
  • Delivered to end users for final consumption

8.1   Energy flow


8.2   Primary energy flow


8.3   Total primary energy supply (TPES)

\begin{split} \mathrm{TPES}&=(\mathrm{Production}+\mathrm{Imports})-(\Delta\mathrm{Storage}+\mathrm{Exports})\\ &=\mathrm{Production}+\mathrm{Imports}+\mathrm{Initial~Storage}-\mathrm{Final~Storage}-\mathrm{Exports} \end{split}


  • Production: 1,000 kg of oil equivalent
  • Imports: 500 kg of oil equivalent
  • Initial Storage: 200 kg of oil equivalent
  • Final Storage: 400 kg of oil equivalent
  • Exports: 300 kg of oil equivalent
  • TPES = 1,000 + 500 + 200 - 400 - 300 = 1,000 kg of oil equivalent for domestic use

8.3.1   TPES per capita (kg of oil-equivalent)


8.3.2   The World Bank 2013 TPES data


9   Homework: TPES individual assignment

Energy data of a hypothetical country

  • Production: 5,000 kg of oil equivalent
  • Imports: 6,000 kg of oil equivalent
  • Initial Storage: 2,000 kg of oil equivalent
  • Final Storage: 1,000 kg of oil equivalent
  • TPES: 5,000 kg of oil equivalent

How many kg of oil equivalent does this country export?

Now, if this country didn’t import any primary energy (Imports = 0), yet kept the same TPES, how many kg of oil equivalent would this country be able to export?