Why the need for Alternative Energies?

Based on known oil reserves and the worldwide consumption rate, most estimates suggest this reserve has only 50 more years of production left in it its important that this is believed!

In the US, 89% of our total Energy Budget is Fossil Fuel Based

Fossil Fuel combustion represents a global environmental problem

Most alternative energy sources have little polluting side effects

Clearly, environmental pollution is unavoidable so informed decisions must be made.

Forms of Pollution:

• Atmosphere - Global: Greenhouse gases
• Atmosphere - Global: Acid Rain
• Atmosphere - Local: Smog
• Groundwater - Local: Nuclear Waste ()
• Surface Water - Local: Oil spills
• Thermal Pollution - Local and Global: Waste Heat
• Local Land Use: NIMFBY mail Not in My Back Yard: build that thang over thar

Global Impact of Sources of Energy Generation:

• Fossil Fuels totally disrupts the Carbon Cycle and is non-equilibrium. Eventually, enough Carbon Dioxide will be in the atmosphere to effect things seriously. We may, in fact be there already

• Solar Energy Intensive use of Land Area due to low efficiency. Significant thermal pollution. For instance, a 1000 MW solar facility would dump 10,000 Megawatts of heat into the local atmosphere. Its unclear what the effects of this would be but this is like an Urban Heat Island

• Hydro The world or the US's potential has not been fully tapped. No pollution for this but serious alteration of free flowing waterways.

• Windpower structural/virtual pollution but not much else

Air Pollution:

Normally the carbon content of fuels (which is high) oxidizes during the combustion process to form CO2 (carbon dioxide)

Incomplete combustion leads to the formation of CO:

2C + O2 --> 2CO

Sources of CO pollution: (million tons per year)

Motor Vehicles ------------->  54
Aircraft ------------------->   2
Coal -----------------------> 0.7
Fuel Oil -------------------> 0.1
Industrial Wood Processing--> 8.8
Forest Fires ---------------> 6.5

Automobiles dominate because the combustion of gasoline under conditions of high pressure is quite incomplete

Some Internet Resources on Pollution:

Pollution Prevention Home Page

Major listing

For the future our choices are:

• Invest in discovery of new oil reserves (e.g. Off-shore, shale oil)
• Invest in Clean Coal Technology as 20% of the worlds supply of Coal is in the US
• Invest in Renewable Energies

Every form of energy generation has environmental fall-out. Can we pick the best one globally and or locally? As long as the decisions are driven by "voodoo" economics (i.e. heavy subsidy), intelligent decisions are not likely to occur.

Most forms of alternative energy genearation require much less of an organizational infrastructure. This means that a shift to alternative energies means a loss of jobs. This is undesireable to most politicians.

What happens if we try to be objective and evaluate our choices via some standard considerations, such as:

Evaluation Criteria for Alternative Energies:

• Capital Costs
• Operating Costs
• Efficiency
• Is it renewable?
• Energy Storage Requirements
• Pollution
• Environmental Modification
• Levelized cost to the consumer
• Feasibility on Large Scale
• Individual Homeowner Independence
• Unit Capacity
• Loss of Jobs

Comparative Table

Evaluation	Solar Thermal	PV	Hydro	Wind	OTEC	Tidal	GEO	Biomass
Capital Costs	Large	Large	Enormous	Moderate	Enormous+	Enormous	Small	Small
Operating Costs	Moderate	Moderate	Neglegible	Small	Unknown	Neglegible	Small	Moderate
Efficiency	15%	5--10%	80%	42%	7% +	25%	100%	25%
Renewable	Yes	Yes	Yes	Erratic	Yes	Yes	NO	Maybe
Storage	Not Needed	Unclear	Built-IN	Essential	Not Needed	Unclear	Not Needed	Not Needed
Pollution	None Really	Waste Heat	None	Visual	None	None	Steam Plumes	Particulates; CO
Levelized Costs	25 cents KWH	16 cents KWH	4 cents KWH	4.5 cents KWH	Unknown	Unknown	Low	Unknown
Environmental Impact	Moderate	Large	Enormous	Small	Unknown	Outrageous	Small	Moderate
Large Scale	Too Expensive	Possible but Expensive	Proven already	Very Possible	The Solution	Discrete Locations	Discrete Locations	Net Energy Gain?
Small Scale	NO	Difficult	Low Head --> Legal	Definitely	NO	NO	NO	Absolutely
Unit Capacity	1000 MW	Depends on Acreage	2000-6000 MW	Highly Variable	As large as you need	250 MW	1000 MW	50-100 MW
Employment Opportunties	Few	Few	Few	Few	Lots to build it	Some	Few	Many

What about Energy Storage?

Options:

• Battery Farms:
  • Acres of batteries; charged by transmission lines during periods of low demand
  • Returned to transmission lines during periods of high demand
  • Designed for load levelling
  • One Acre could store about 400 MW-hours of energy and deliver 40MW of power (for 10 hours)

  We need better batteries period (also for electric vehicles): US is investing in this

• Pumped Hydro:
  • Not many locations lend themselves to this
  • Process is 64% efficient which is pretty good

• Flywheels:
  • Need to optimize energy-to-mass ratio which is material dependent
  • Fused Silica has 25 times the energy storage per kg than lead-acid batteries
  • Flywhees are promising

• Hydrogen
  • Very high energy density storage per kg
  • No naturally occuring sources
  • Separate H from H₂0 is energy intensive
  • Not economically viable unless shipped large distances from point of production

• Compressed Air
  • Thermodyanimcs tells you that when you compress air the temperature goes up melts the pressure containment vessel
  • Have to cool the air as its compressed energy intensive
  • Not very practical

Bottom line(s):

Wind energy coupled with advanced battery design has real promise.

OTEC provides a truly large scale solution

Solar PV does not look economically viable

As of 1998 there remains little incentive to not look for new oil reserves

Previous Lecture Next Lecture Course Page