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Coming Work on the Grid

Explore the challenges and potential solutions for grid improvement in order to effectively distribute renewable energy across different regions and maximize its potential. Discusses the advantages of high voltage DC and AC transmission, as well as the cost and land requirements of various renewable energy sources.

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Coming Work on the Grid

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  1. 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.

  2. Political Changes Needed Analogous 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 grid projects that would enable the energy to be sold to other states because local voters want their energy kept cheap.

  3. Source: MIT Review Magazine

  4. Wind (Including Coasts)‏

  5. Source: MIT Review Magazine

  6. Geothermal

  7. 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 power transmitted the same, but cuts heat loss by a factor of 4. So long distance power transmission is always done at high voltages. Around 2 million volts it becomes problematic, so you stay well below that.

  8. DC vs AC Changing magnetic fields induce electric current (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.

  9. Advantages of High Voltage DC • Low Power Loss – 3% per 1000km • Cheaper Wires • Technology for 2-point problem has been proven for decades • Can communicate between differently synchronized grids • AC grids have to be highly synchronized, DC ones don't • Advantages of High Voltage AC • Cheaper Switching and Distribution Equipment • Much more widely used and understood • HVDC is generally only done for single endpoint • systems, with AC, one power station can feed • several cities. • Probable Verdict: • Still some R&D on HVDC switching & distribution • Big payoffs for DC over long distances

  10. 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

  11. Subsidizing Photovoltaics Suppose the government provides tax breaks & credits to bring cost 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 large scale power generation, at least until photovoltaic costs come down a lot more..

  12. What Americans Are Paying for Electricity

  13. 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 GW Size 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.

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