21-03-2011, 10:09 AM
Space Based Solar Power(2003Animated).ppt (Size: 2.12 MB / Downloads: 332)
Introduction
The Sun is a giant fusion reactor , located some 150 million km from the Earth, radiating 2.3 billion times more energy than what strikes the disk of the Earth which itself is more energy in an hour , than all human civilization directly uses in a year, and it will continue to produce free energy for billions of years.
A single kilometerwide band of geosynchronous earth orbit experiences enough solar flux in one year (approximately 212 terawattyears) to nearly equal the amount of energy contained within all known recoverable conventional oil reserves on Earth today (approximately 250 TWyrs).
WHY SOLAR POWER FROM SPACE?
“Peaking units”, like windmills or ground solar are intermittent, providing power for 25-30% of a day on average. SSP is “baseload” available 99% of the year from GeoSynchronous Orbit. Baseload nuclear or coal plants, are actually available only 90% of the year. It ignores clouds, night, wind and dirt
Unlike oil, gas, ethanol, bio-fuel, and coal, SSP emits no CO2. It is an antenna (or rectenna)! Rising CO2 drives climate change, compounding our massive environmental problems
Drought & Competition for Water - Today's average coal-fired power plant withdraws 25,000 gallons of river water to provide an average household with 1,000 kilowatt-hours a month; 31,000 gallons if nuclear-fired. Natural gas plants use less water than coal.
IMPORTANT FACTS
Space Solar Power (SSP) could Produce 20 Terawatts.
Capacity to meet emission free needs for baseload power
A 3 square kilometer array could produce ~ 1 Gigawatt
1400 watts per square meter, 25% end-to-end efficiency
Variables
Production scale + launch cost, meteorites, PV efficiency, orbit slots
Nanomaterials for dramatic weight reduction of infrastructure
Price may range from 1 to 10 cents per kilowatt-hour or more
HOW WILL IT WORK?
Typical reference designs involved a satellite in geostationary orbit, several kilometers on a side, that used photovoltaic arrays to capture the sunlight, then convert it into radio frequencies of 2.45 or 5.8 GHz where atmospheric transmission is very high, that were then beamed toward a reference signal on the Earth at intensities approximately 1/6th of noon sunlight. The beam was then received by a rectifying antenna and converted into electricity for the grid, delivering 5-10 gigawatts of electric power
FROM SATELLITE TO?
Solar power from the satellite is sent to Earth using a microwave transmitter Received at a “rectenna” located on Earth Recent developments suggest that power could be sent to Earth using a laser Microwaves are received with about 85% efficiency , around 5km across (3.1 miles) 95% of the beam will fall on the rectenna.
RECTENNA
“An antenna comprising a mesh of dipoles and diodes for absorbing microwave energy from a transmitter and converting it into electric Recent developments suggest that power could be sent to Earth using a laser
SPS 2000(A 2025 PROBABILITY)
10 MW satellite delivering microwave power
Will not be in geosynchronous orbit, instead low orbit 1100 km (683 miles)
Much cheaper to put a satellite in low orbit
200 seconds of power on each pass over rectenna
Since a low orbit microwave beam would spread less, the ground based rectenna could be smaller
Would allow collectors on the ground of a few hundred meters across instead of 10 kms
In low orbit they circle the Earth in about every 90 minutes