I.
Energy
B.
Renewable
1.
Hydroelectric
•
a.
b.
•
Currently supplies ~20% of electricity production worldwide
Small (<30 MW)
•
Less impact but less power than large facilities
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.
Renewable
2.
Wind
•
•
•
Power captured with wind turbines
The Dakotas and Texas have sufficient wind capacity to
supply energy needs of entire United States
Benefits
•
•
•
•
Skegness
•
“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?
I.
Energy
B.
Renewable
3.
Solar
•
a.
b.
•
Can be generated by
Focusing heat of sun on central point that heats up; heat used
to produce steam, which turns turbine
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.
Renewable
4.
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.
Renewable
5.
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.
Renewable
6.
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