Coming Work on the Grid

Renewable Energy is highly geography-dependent, and is not, by and large, near where electricity is needed.

Best wind power is in Wyoming & S Dakota and over water, best solar power in New Mexico, Arizona, Nevada & California.

Wind and Solar are unreliable, need to get them from multiple areas to back each other up.

Political Changes NeededAnalogous to federal interstate highway system

Currently, grid is handled on a state or regional basis,adjacent regions don't cooperate.

Sometimes states with abundant power refuse gridprojects that would enable the energy to be sold to otherstates because local voters want their energy kept cheap.

Source: MIT Review Magazine

Wind (Including Coasts)

Source: MIT Review Magazine

Geothermal

P: Power: WattsI: Current: AmpsV: Voltage: Volts

R: Resistance: Ohms

P = I*V= (V/R)*V= V*V / R

Heat Loss for a given RHL = I * V = I * (R * I)

= I*I*R

So doubling the voltage and halving the current keeps powertransmitted the same, but cuts heat loss by a factor of 4.

So long distance power transmission is always doneat high voltages.

Around 2 million volts it becomes problematic, soyou stay well below that.

DC vs AC

Changing magnetic fields induce electriccurrent (thereby heat) in anything nearby the conducts (like sea water).

AC creates a changing magnetic field,DC does not.Underwater power lines, especially through salt water,

tend to be high voltage DC.

Advantages of High Voltage DCLow Power Loss – 3% per 1000kmCheaper WiresTechnology for 2-point problem has been proven for decadesCan communicate between differently synchronized gridsAC grids have to be highly synchronized, DC ones don't

Advantages of High Voltage ACCheaper Switching and Distribution EquipmentMuch more widely used and understoodHVDC is generally only done for single endpointsystems, with AC, one power station can feedseveral cities.

Probable Verdict:Still some R&D on HVDC switching & distributionBig payoffs for DC over long distances

Wind with help: $0.071 / KWh (Forbes)Wind without help: $0.091 / KWh (Forbes)Wind $0.061 - $0.084 / KWh (Sci Am)Coal $0.079 / KWh (Forbes)Natural Gas $0.081 / KWh (Forbes)Geothermal $0.062 - $0.076 / KWh (Sci Am)Nuclear $0.105 / KWh (Forbes)Solar $0.25 / KWh (Forbes)Solar-Thermal $0.20 - $0.28 / KWh (Sci Am)Solar-Photovoltaic $0.47 - $0.70 / KWh (Sci Am)

Energy Costs

Subsidizing Photovoltaics

Suppose the government provides tax breaks & credits to bringcost of photovoltaics down to $0.20 / KWh.

US Annual Power Consumption: 4 trillion KWh.Say 10% of that is solar photovoltaic

Cost to government: 4e12 * 0.1 * ($0.45 - $0.20) = $100 billion= $300 / person / year

Solar Thermal and especially wind are much more attractive for largescale power generation, at least until photovoltaic costs come down alot more..

What Americans Are Paying for Electricity

Land Requirements of Alternative Energy

Wind: 16,000 kW / square mile (Questar Natural Gas Corporation)Solar: 64,000 kW / square mile (Questar Natural Gas Corporation)

US Peak Energy Requirement: 1,000 GWSize of US: 3.8 million square miles

Therefore:Land to meet energy requirements by wind: 1.6% of US (note a lot of that could be off coasts)Land to meet energy requirements by solar: 0.4% of US (would all have to be on land)

For perspective, South Dakota is 2.0% of US land.Note land with windmills can still be used agriculturally, solar land cannot.