I. Energy

B. Renewable1. Hydroelectric

• Currently supplies ~20% of electricity production worldwidea. Small (<30 MW)

• Less impact but less power than large facilitiesb. Large (>30 MW)

• Includes immense dams with potentially large impacts• Ex – Itaipu Dam (Brazil, Paraguay, Argentina) = 12,600 MW• Ex – Three Gorges Dam (China) = 18,200 MW

• Benefits• Inexpensive, once facility exists• Minimal environmental impact – Little pollution, no GHGs• Many facilities already in place• May permit flood control• Relatively efficient and nondestructive

• Concerns• Limited use geographically• Environmental degradation in flooded areas• Environmental degradation downstream• Detrimental to some aquatic animals (Ex – salmon)• Tropical dams trap organic material methane• Rainfall variation can reduce reliability

http://www.nwd-wc.usace.army.mil/report/colmap.htm

I. Energy

B. Renewable2. Wind

• Power captured with wind turbines• The Dakotas and Texas have sufficient wind capacity to

supply energy needs of entire United States• Benefits

• “Free”• Minimal environmental impact – Little pollution, no

GHGs• Can produce electricity without being connected to

power grid• Multiple uses of land

• Concerns• Limited use geographically• Inconsistent energy source• Expensive to maintain• May be dangerous to birds/bats• Low power density• Eyesores (offshore?)• Weather effects?

Skegness

I. Energy

B. Renewable3. Solar

• Can be generated bya. Focusing heat of sun on central point that heats up; heat used to

produce steam, which turns turbineb. Photovoltaic (PV) cells – Convert energy from sun directly to

electricity; each PV panel typically produces small amount of electricity, but panels can be grouped

• Benefits• Abundant – “The amount of solar radiation striking the

earth over a three-day period is equivalent to the energy stored in all fossil energy sources.”

• “Free”• Minimal environmental impact – Little pollution, no GHGs• PV systems have no moving parts, need little maintenance• Can produce electricity without being connected to power

grid• Concerns

• Limited use geographically• Inconsistent energy source• Expensive: $0. 17-0.32/kWh vs. $0.04-0.06/kWh on latest bill• Requires special materials to harvest energy• Low power density; long-term storage of energy

I. Energy

B. Renewable4. Biomass and Waste

• Biomass fuels include residues from logging; mill operations; processing of wood, pulp, paper, fiberboard; agricultural crops; livestock and poultry operations; food processing; demolition (urban wood waste)

• Waste fuels include combustible residues from industrial processes, municipal solid & liquid wastes

• Currently supplies ~15% of electricity production worldwide, more in developing countries

• Benefits• Readily available fuel• Inexpensive• Reduces waste stream

• Concerns• Emissions – Especially for waste combustion• Low fuel density• Technology still being developed (mainly emissions)

I. Energy

B. Renewable5. Geothermal

• Heat from deep within earth captured and used to turn an electric generation turbine

• Benefits• Inexpensive• Minimal environmental impact – Little pollution• Energy security – US has extensive resources

• Concerns• Limited use geographically• Not truly renewable (water injection can prolong life

of geyser field)• Geothermal emissions may include CO2 and H2S, as

well as various toxic compounds• Not economically viable in most areas• Geological risks

I. Energy

B. Renewable6. Biofuels

• Bioalcohols• Biodiesel• Biogas

• Benefits• Renewable• Energy security• Reduced waste stream for raw materials• Reduced environmental impacts vs. other energy

sources• Concerns

• “Food vs. Fuel” – Elevated food prices• Not carbon neutral or carbon negative• Growing crops & processing for fuel requires land

and water• Pesticides may contaminate local aquifers• Emissions from biofuels (air pollution)

Gibbs et al. 2008

Righelato and Spracklen 2007