If you are involved in Management or Customer Service and are responsible for communicating the value of smart meters to your utility customers, you don’t want to miss this online discussion - Communicating Smart Meter Value. more...
Join social media mavens Matthew Burks and Amanda Shewmake as they provide an insider's perspective on how HR, communications and marketing professionals in energy companies can harness the power of social media to be more effective and productive. more...
The convergence of power and information technologies in the smart grid has created opportunities for finer grained and broader controls of energy flows. These opportunities can improve electric service in multiple dimensions: lower cost, greater reliability, greater customer satisfaction, and more...
Significant cost over runs. Changing business requirements. A well thought out plan is essential. Attend this free webcast discussion to hear inside hear three experts in utility operations discuss what utilities need to evaluate when they are considering upgrading or more...
The smart grid is shifting the playing field for utilities. And when the game changes, it pays to be prepared. A nimble solutions partner can help you design the solutions that keep operations on track, even as new challenges come more...
Deliver a profitable, productive and commercially successful large scale CSP business in India. Building on the success of past events in USA, Europe & MENA, CSP Today brings to New Delhi the most relevant international experience for the concentrated solar more...
Two day conference that tackles the most important challenges. A blend of European knowledge from the companies who have been installing offshore wind turbines for the last decade alongside local state governing bodies and leading project developers. Permitting, securing long more...
Autovation 2010 is a not-to-miss educational forum that will attract utility executives from around the world looking for new ways to optimize their operations through automation technologies. more...
The North American convention provides a remarkable opportunity to play a part in guiding renewable energy policy for the 21st century. Attendees will create a resolution that, along with similar resolutions already drafted on four other continents, will help set more...
Hosted by the GridWise(R) Alliance and the U.S. Department of Energy, the GridWise Global Forum will convene thought leaders from the highest levels of government, business, NGOS, and academia from around the world to discuss the ultimate enabling potential of more...
Introduction to Natural Gas Trading & Hedging - This program provides a comprehensive understanding of the structures that underlie Natural Gas trading. Beyond Essentials: Option Applications in Energy - This course provides a solid practical and conceptual (non-quantitative) understanding of more...
Electric Business Understanding provides a comprehensive overview of the electric industry. Position yourself for career advancement by gaining a solid understanding of how the electric business works including key physical, market, and regulatory aspects and how market participants navigate this more...
Electric Market Dynamics offers participants an in-depth understanding of North American electric markets and how they function. Enhance your career by furthering your knowledge of market structures, pricing mechanisms, services offered in markets, and how various participants use the markets more...
Gas and Electric Business Understanding provides a comprehensive overview of the natural gas and electric industries. Position yourself for career success by gaining a solid understanding of how each business works, including key physical, market and regulatory aspects, as well more...
We know you have something to say!
There is an immediate need for articles on
the hot topics in the Power Industry!
EnergyPulse, like no other publication,
also provides a means for our readers to
immediately interact with experts like you.
One of our nation’s finest aerospace pioneers, Burt Rutan, provided some rare humor at the ISDC (International Space Development Conference) luncheon May 4. Burt described his continuing dialogue with Mike Griffin, NASA’s administrator, about Mike’s job. Mike suggested that Burt would run NASA the same way as Mike. Burt replied that there would be one difference.
Burt said he would call a big news conference and, with all cameras rolling, he would loudly announce, “This is stupid!!” Then he would return to work. Griffin himself made a similar comment on Sept 27, 2005, "The space shuttle and International Space Station — nearly the whole of the U.S. manned space program for the past three decades — were mistakes.”
The shuttle has cost the lives of 14 astronauts since the first flight in 1981. Roger Pielke Jr., a space policy expert at the University of Colorado, estimates that NASA has spent about $150 billion on the program since its inception in 1971. The total cost of the space station by the time it's finished — in 2010 or later — may exceed $100 billion, though other nations will bear some of that.”
Founded in 1982, Burt’s prize winning firm, Scaled Composites, has an unmatched record of continuous safe and profitable operation – no mean feat for the aerospace industry – or any industry. Respect for Burt’s opinion about NASA’s questionable direction, deserves far more scrutiny and discussion.
NASA’s charter today is virtually non-existent. Since Apollo, no one, including NASA, really knows why or what they are about. Do you know who is on the space station, and more importantly, what they are doing or why? The President has provided a fuzzy dream of “Moon, Mars and Beyond”, but no relevance to America’s crushing environmental, energy and innumerable tightly related problems. Young people I talked with at the ISDC found NASA’s proposed flags and footprints missions barely more than a distraction – hardly an incentive to study engineering or astrophysics.
NASA provides thousands of jobs for many congressional districts. However, aerospace employment has been in decline for fifty years and Burt is right. We can and must demand more for $16 billion than broken dreams and cute new pictures of heavenly bodies. The mission which NASA’s engineers, contractors and scientists, as well as private space companies like Burt’s and our college kids should be pursuing is clean baseload power for our nation’s and the world’s future - Space Solar Power (SSP) from Geosynchronous Orbit (GSO).
First, a brief recap of the looming problems SSP can directly address:
Peaking global oil production – If you haven’t studied this increasingly intense debate recently, read some of the excellent new interviews available such as Matt Simmons, president of the world’s largest energy investment bank at: http://www.financialsense.com/transcriptions/2006/
0429simmons.html
Robert Hirsch reported to Congress that 33 out of 48 of the largest oil producing countries have hit peak. Also will require much more than a decade to transition our civilization away from our oil dependence. Nothing close to the massive efforts needed have begun, although many short-term efforts at conservation and mitigation are underway. See www.odac-info.org Listen to Congressional testimony at http://energycommerce.house.gov/108/hearings/
12072005Hearing1733/hearing.htm
This week’s According to the Financial Times: "Venezuela, the world's fifth-largest oil exporter, has struck a $2bn deal to buy about 100,000 barrels a day of crude oil from Russia until the end of the year.” Can Venezuela meet their current contracts? http://www.rigzone.com/news/article.asp?a_id=31765
Rising CO2 from our fossil-fuel-based energy is causing other great problems:
Weather – As global sea surface temperatures have increased over the past 36 years, the number of Category 4 and 5 hurricanes worldwide has nearly doubled, though the total number of hurricanes has dropped since the 1990s. Swiss Re projected in March, 2004 that “natural disaster costs threaten to spiral out of control, to $150 billion a year in 10 years … forcing the human race into a catastrophe which we can lead ourselves into or avert.” We now know that their prediction was far too low: “2005 was marked by record losses from hurricanes in the North Atlantic, with insured losses exceeding US$ 83 billion.” This means $350 billion in uninsured economic losses, e.g., including lost profits, lost business opportunities, etc.
“The ocean current that gives Western Europe its relatively balmy climate is stuttering, raising fears that it might fail entirely and plunge the continent into a mini ice age. A new study of ocean circulation in the North Atlantic found a 30% reduction in the warm currents that carry water north from the Gulf Stream.” A warmer North Atlantic apparently means more, and more powerful hurricanes. It may also be related to the record cold winter temperatures experienced in Russia this past year (2005-2006).
The ocean’s pH has become 30% more acidic due to the rising CO2 chemical burden it must bear. This affects calcification by organisms including phytoplankton and zooplankton, a major food source for fish and other animals hoping to consume fish.
Declining nutrition – Rice and wheat both have been shown to decline in nutritional value when tested under doubled CO2 as plant-available nitrogen, for making protein, decreases. CO2 will reach those values in mid century, at current growth rates.
Finally, until we have a clean alternative to nuclear energy, we will not be able to prevent nuclear proliferation, even to terrorist sponsoring nations, such as Iran, North Korea and others.
Pressures to respond to cleaning up fossil fuel emissions of CO2 are not new, but have been disastrously unsuccessful and ineffective. In 1997 many American utilities were pressured to clean up their generation by moving to (cleaner) natural gas. (Natural gas emits 68% less CO2 than coal, per Btu.) The US electric power industry responded by building over 200,000 MW of new gas-fired capacity between 1998 and 2002.
This sharply increased natural gas demand. And supplies could not keep pace. Prices soared. Natural gas prices went from $1.96 per thousand cubic ft in 1998 to $7.51 (2005 average) Stabilization to earlier prices is not in sight.
In 1998 the widely referenced USGS / EIA forecasts had claimed there were 35 billion barrels of oil equivalent gas in Mexico — in other word, there was plenty of low cost gas available in North America they reported. But in 2003 the USGS revised their estimate downward to 6 billion barrels of oil equivalent gas in Mexico. Bad gas gauge? No, this is commonly accepted in the oil and gas industry!
Outside North America global reserve data is of extremely poor quality. But 200,000 MW of electric generation was built and operating! The US was blessed with the warmest January on record in 2006, otherwise we would have seen crippling natural gas prices this winter. This bad data problem is shared with oil, also another reason we don’t know and won’t know if we have passed global peak oil production, until it’s too late.
We must demand and meet higher environmental standards and stronger assurances of energy security and reliability. We must reforge the foundations, direction and charter of America’s energy and space development policies toward SSP construction - the only long-term solution for these many problems. Some have suggested nuclear power is the clean safe solution:
“Britain’s recent and comprehensive Sustainable Development Commission (SDC) reports that doubling their nuclear capacity would make little impact on reducing carbon emissions by 2035. Some say nuclear is a more secure source of energy than hydrocarbon supplies from unstable regimes. Proponents say it could generate large quantities of electricity while helping to stabilize carbon dioxide CO2 emissions. But the SDC report concluded that the serious risks of nuclear energy outweighed its advantages.
Research by the SDC suggests that even if the UK's existing nuclear capacity was doubled, it would only provide an 8% cut on CO2 emissions by 2035 (and nothing before 2010).
No long-term solutions for the storage of nuclear waste are yet available, says the SDC, and storage presents clear safety issues.
Cleaning up UK’s 16 nuclear plants could cost more than £70Bn ($US130Bn), according to the Nuclear Decommissioning Authority (NDA).
If the UK brings forward a new nuclear programme, it becomes more difficult to deny other countries access to nuclear energy technology.
Our Cold War drill of nuclear brinksmanship has not been solved; instead the nuclear battle has infected other nations and the energy front, notably Iran and North Korea, with China and other nations not far behind. Until we can successfully point to a better answer, which is SSP, we will fail to stop the spread of nuclear waste, nuclear weapons, nuclear health issues, escalating nuclear fuel worries, and soaring nuclear decommissioning costs, as the Brits are now struggling just to measure. Nuclear power is not the answer to our critical need for safe clean baseload energy. The real answer is that nuclear power plant 93 million miles away, our sun:
With Space Solar Power,
Nuclear waste problems
Nuclear fuel supply worries
Nuclear proliferation problems
Nuclear decommissioning costs
Evaporate …
The only ground presence of SSP is an antenna, (called a rectenna), to receive the power and connect it to the power grids. The massively expensive suggestion of redesigning our power grids for distributed power generation – rather than our current design of major plant power sources – would not even be necessary. This savings alone is worth dwelling on.
Can we really build SSP now? No company(s) or government agency is chartered or capable of assuming the immense financial risk of initiating construction of an SSPS. It would be like asking a company to build Hoover Dam, the Transcontinental Railroad or the Interstate system without Federal assistance. There are simply too many engineering, financial, regulatory and managerial risks for any group to undertake SSP today.
America has faced just such challenges before ... There is a tried and true vehicle, however that could initiate SSP construction today, just as it did in surmounting all those previous challenges. The key is chartering a public/private Congressionally chartered corporation, like Comsat Corp., which was chartered in 1962 to respond to the Russian Sputnik threat – the first communications satellite. It would have all the requisite advantages provided to Comsat. Comsat Corp. opened space to the diverse $100 Billion per year communications satellite business we have today.
A company we call Sunsat Corp. could be chartered – another public/private Congressionally chartered corporation dedicated to building the solar power satellite business. It would have that single purpose. Several subsidy bridges would have to be built as part of this legislation. These would also help refocus our current space program to a real space mission – making Burt Rutan and America’s young folks happy – with a relevant space program again.
The criticism leveled against SSP is that the current prices of space photovoltaics, space transportation, and other necessary commodities is too high for SSP to be profitable. We agree. With zero dollars budgeted for SSP by the US government again this year, we will continue making zero progress toward the magnificent promise of SSP.
If we keep doing the same things, which is nothing, especially NASA’s mind-numbing lack of mission, we will get the same result, – increasing energy, environmental and related problems with no solution in sight. The correct response to this criticism is additional, concomitant legislation to provide an 85% subsidy for space photovoltaic array purchase to new private or public/ private businesses, such as SunSat Corp.
A 50 % subsidy for established space businesses would further increase space photovoltaic array manufacturing. These funds would go to businesses buying space photovoltaic arrays. This would lower costs, increase business and bridge the cost gap for Sunsat Corp.
The chart below shows the subsidy bridge needed for Sunsat to help space photovoltaic thin film producers meet the massive demand and lower cost required. Similar subsidies for ground solar photovoltaic are now provided by many other states, topped by the landmark $3.2 Billion California Solar Initiative.
In the same way, similar learning curves, like Moore’s law, describe other dropping costs of technology with increasing volume, such as the low cost potential available to cut the cost of access to orbit if higher flight rates are achieved by reusable launch vehicles, especially private launch vehicles. A dozen other orbital space pioneers, led by Elon Musk and his reusable vehicle Falcon, are seeking to overcome policies and prices all but blocking new vehicle development in a dismally poor launch market outlook (due to high costs) with their new generation of private reusable launch vehicles.
We recommend legislation concomitant with Sunsat Corp. to provide an 85% launch subsidy to new private or public/ private businesses, such as SunSat Corp, which are contracting for space transportation and 50 % launch subsidy to established businesses contracting for space transportation.
For comparison, Atlanta’s Hartsfield-Jackson and Chicago’s O’Hare International Airports each logged nearly a million takeoffs and landings in 2005.
New generation vehicles – some already in design – would drive the cost lower when higher flight rates are reached. Doubtless many other new space businesses would benefit including lunar development, which has been suggested as a better source of space photovoltaics and materials. But Sunsat Corp, would have one focus only – clean baseload solar energy from GSO to power planet earth.
Sunsat Corp. would need approximately 42,000 flights per year to GSO, of ten metric tons each. (Compare this to the millions of airline flights scheduled daily globally.) Prices would quickly fall once subsidies established market volume.
As Robert Hirsch has pointed out in Congress, nothing is being done to avert the approaching disaster. Together we solve these immense problems, motivate our kids and establish an important mission for our aerospace pioneers by chartering Sunsat Corp.
Call or write your Congressmen:
www.congress.org
Ask them to sponsor the Sunsat Act. A draft copy is available at
www.sspi.gatech.edu/sunsat-how.pdf
For information on purchasing reprints of this article, contact Tim Tobeck ttobeck@energycentral.com. Copyright 2010 CyberTech, Inc.
So which lucky existing utilities get to compete with this new subsidized generation source?
Darel Preble 6.19.06
Actually, as happened with Comsat Corp, many shares would be probably be sold to existing utility companies. AT&T held 29 percent of Comsat shares. As for subsidies, every energy generation there is - "clean coal", oil, nuclear, and the current crop of alternative energies all receive numerous subsidies - http://www.dsireusa.org/ lists many of the innumerable state and Federal ones. As was the case with Comsat, a similiar international corporation would likely be established by Congress at the same time, which would probably have international participation. The Japanese, Europeans, Indians and Russians, which already have active work in SSP would likely be interested. (The US has no active work specifically in SSP, although we now have the largest share of the $100 Billion "space business industry" - primarily based on diverse communication satellites.)
Darel Preble 6.19.06
Oh yes, Sunsat Corp would be a clean baseload generation provider. They would not directly compete with any utility, but simply provide energy to a contracting utility's rectenna - that is the term a "rectifying" antenna, and also the receiving antenna. These are quite large ~ 4 km across. The physics pushes the power delivery toward the large scale plant size, say 1 GW, but phased arrays could deliver to several rectennas at once. Probably typical farming would take place under the rectennas, so "no land" would actually be used.
Roger Arnold 6.21.06
Oh, my! What to say about this?
Having worked at Boeing in the '70s and hung out with the guys who did Boeing's study on SPS, I'm much more receptive to the idea than the average Joe is likely to be. I know it's technically feasible, at some level. But even I have trouble swallowing the idea of a crash program to build solar power satellites as a solution to CO2 emissions. In today's political climate, it has a 0% chance of getting enacted. A massive nuclear energy program would be a lot more credible, and easier to sell.
The only way solar power satellites are likely to get built is if a viable commercial space industry manages to establish itself first. Launch traffic needs to be ramped up, costs brought down, and operations in space made sufficiently commonplace that the leap to SPS is not so much of a leap. That could happen, and I have some ideas about how, but it won't be easy. It certainly can't happen as long as NASA is blocking the road.
Malcolm Rawlingson 6.22.06
Dan,
I'm open to any idea but I think this one is going to be a very hard sell. We would need to have a space industry that is very much more technically advanced than it is now. The biggest problem I have is what to do when something goes wrong (as it invariably will). It is not that easy to just fire up a space rocket and send some mechanics to fix the thing. My experience in nuclear tells me that everything is twice as difficult to do as you anticipate.with this technology everything will be a hundred times more difficult to do.
In the Space Solar Power business repair costs would be (pardon the pun) astronomical.
I would suggest that this idea would likely first be utilised to power Moon bases or Mars bases because the cost of constructing regular power plants in those locations would be very large. Once there is good operating experience then perhaps I could envisage utilising the technology on Earth.
But Dan I think (as much as I like the idea) this one is many years away from reality.
malcolm
Todd McKissick 6.22.06
After reading this and then rescanning it, I finally went to the referenced page just to find out what was being proposed here. The overwhelming sales push got too much to take, but what I came away with is a satellite of what... 4 km / side of solar cells in orbit and then transmitting the energy to Earth via some un-named electromagnetic means? A few questions come to mind.
Has the effort been considered of what it will take to continually align this device between the sun and the rectenna? That's gonna be some feat at the size it is.
Hopefully some form of concentration will be utilized because I can't see sending that many space quality solar cells into space and only using one sun on them.
If more than one sun, then how will it be concentrated? Mirrors and lenses are heavy, reflectors are hard to hold a shape and all three are prone to space damage.
How will the freznel zone of the transmitted power be handled? All waves of energy spread out when propagating.
How will this affect some Earth resident should this get 'stuck' and suddenly bombard his house? For that matter, how will you farm under the rectenna with that much EMI headed at you?
How will this attain a capacity nearing 100% or will we need an extra one for when one eclipses?
How will this be backed up should a failure occur?
I'm still not sure I understand what kind of power can be sent from orbit to the Earth's surface without the inverse square law being broken.
Roger Arnold 6.22.06
Todd,
Those are the sorts of questions I also asked, the first time I heard about the concept. That was sometime in the mid '70s, when I was a junior software engineer at Boeing Aerospace. But it turns out that they all have good answers.
The beam from a solar power satellite is not like the beam from a flashlight--it's not something that needs to be "aimed". The SPS transmitting antenna is best understood as an amplifying phase-conjugating reflector. The receiving antenna transmits a "pilot beam", and the transmitting antenna "reflects" that beam back to its source, amplified a million times over. It's a giant phased array antenna, where the phase of individual transmitting elements is controlled by the phase information received on the pilot beam.
The transmitting array won't respond to just any pilot beam, however. The pilot beam is modulated with pseudo-random noise in a pattern that's known to the transmitter and receiver, but no one else. That makes the pilot beam impossible to mimic, and very hard to jam. If the pilot beam were to fail, or be successfully jammed, the result would be that the phased transmitting elements at the SPS would immediately lose coherence, and the transmitted power, instead of being focused on the earthside receiving antenna, would be radiated into space.
Whether to use concentration, and what degree of concentration to use, were somewhat controversial among the authors. I believe the reference design that was settled on, for purposes of the study, did employ a very modest degree of concentration. I think it was only about 3 suns, but I don't have a copy of the report handy to check. It wasn't felt that the cost of the solar cells, themselves, would be a gating item. Simplicity, reliability, and suitability for robotic assembly were higher priorities. In any case, it's likely that the cells used would not be the expensive thinned cells manufactured on earth for aerospace use. More likely, rolls of paper-thin amophorous silicon would be shipped to orbit, and processed there into high-efficiency solar cells. The high vacuum microgravity environment in orbit enables some very interesting options for processing silicon PC cells.
I could go on and address each of your questions at some length, but I don't have nearly the time or space to do it here. Maybe I'll come back later and post some references. Unfortunately, the most interesting references don't exist. They would be references to the ideas for "enhancements" to the system that I tried to foist upon the study authors. Gordon Woodcock, the manager in charge, was very tolerant, but rejected my ideas on the practical basis that the whole concept was wild enough as it was, and would be a hard sell. The things I wanted to do would make the system impossible for most engineers to understand. Or trust.
As it happens, the gist of my suggestions were later re-invented by David Chriswell and his team (at the University of Texas?). They're the folks pushing the idea of power transmission from the moon. In doing so, they've probably vindicated Gordon's rejection of my ideas for the SPS study. Almost nobody who isn't a physicist understands how power transmission from the moon could work, or takes the idea seriously.
But then, in the end, nobody took Gordon's "basic" SPS reference design very seriously either. What's the phrase? "Might as well be hanged for a sheep as a lamb".
Len Gould 6.23.06
The last design document I saw was battling with the problem of electrical transmission on the spaceship. Turns out that trying to collect all that electricity together to the transmission amplifiers requires either a) very heavy low-voltage conductors b) very heavy DC - DC voltage step-up-down electronics c) high-temp superconductors with heavy refrigeration equipment. Most efficient result, if I recall, was the superconductors, provided a couple of breakthu's in refrigeration.
Roger's post certainly helps clear up my questions re- aiming of transmitters. kudos.
Seems to me that given eg. the US spent $1/4 billion in 2000 on a single military exercise, just for practice, it might be time instead to start learning this technolgy.
Darel Preble 6.23.06
Thanks for the great discussion!! May I add a few more details.
The choice of photovoltaic (PV) cells revolves heavily around trasnportation costs to orbit. As the photovoltaic chapter at the website discusses, the leading PV contender today may be United Solar, “now developing a-Si solar cells using a 1-2 mil thick kapton substrate which could result in a specific power density exceeding 2000 Watts/kg." They have shown 1254 Watts/kg already. Their cells which flew on MIR showed minimal (virtually no) change in performance during 19 months. Apparently a “re-annealing” process was taking place, which has also been observed on earth, quelling some concerns about EOL. Most GSO sats are decommissioned because they run out of station keeping fuel - after perhaps 15 years. They now can be refueled. You get about ten times the energy per day per watt of PV at GSO compared to an average US site.
The leading Wireless Power Transmission (WPT ) candidate today is 5.8 Ghz microwave, the beam coupling efficiency from the phased arrays to the rectennas is estimated at 87%. Tapered Gaussian beam is the typical choice. Maxwell says that the transmission efficiency E for Gaussian beams is related to the aperture sizes of the transmitting and receiving antennas: E ~ 1 - exp((pi Dt * Dr/(4L*R)) **2) where Dt is the transmitting array diameter, Dr is the receiving array diameter, L is the transmission wavelength and R is the range of transmission. Sorry for the equation.
Solar pumped lasers are rapidly improving, but their cooling and efficiency problems leave 2.45 Ghz microwave probably in second place. 2.45 has less rain attenuation, but results in a larger rectenna than 5.8. The end customer’s local regulatory; land use, etc., rectenna preferences would be the ultimate arbiter.
National microwave limits would be stringently observed. Maximum power density at the rectenna fence would be the same as at a 100,000 watt FM radio tower fence - shall not exceed 1 mW per square cm. Under the rectenna it would be much lower, for occasional farm equipment operation. Top of the rectenna, center of the beam would be around 114 mW per square cm. Cell phones would have questionable operation near the fence.
Roger’s beam explanation is excellent.
At GSO, outages occur for up to 70 minutes at midnight during the spring and fall equinoxes – about a 99% capacity factor. I don’t think there is a better time for an outage than an hour at midnight in the spring and fall equinoxes - minimum loads, etc., Utilities can easily address those brief outages with peaking units, etc.,.
I hope you take some time to read over the SSPW website chapters. Listen to Burt Rutan at http://video.google.com/videoplay?docid=-2343976776379780431&q=NASA+2005
SSP repair, like construction, would be telerobotic. Telerobotic surgery and mining have pioneered these techniques. People are too expensive and radiation too high for them to work at GSO. (The ISS is inside the Van Allen Belts.) GSO is actually a fairly benign place for equipment, looking at historical operational records. Different risks, not greater.
Roger Arnold 6.23.06
I wrote the following offline, in reply to Len's last comment, before I saw Darel's response above. I'll go ahead and post it as is, since I don't think it overlaps much with what Darel wrote. - RA
Len,
Yes, the solar arrays in the reference design were so large that getting power to the central transmitter became a major issue.
The parameters of the reference design were the result of optimization following from a few key design decisions / requirements:
* peak beam power at the rectenna must be less than 25% of noon sunlight; * frequency selected for the power beam was 2.45 GHz; * DC to RF power conversion would be via klystron tubes; * slotted waveguides distribute power from klystrons to radiating elements; * inherent safety of a phase-conjugated return of a pilot beam was mandatory;
The last point guaranteed that, by design, the SPS could not be turned into a weapon and could not endanger anything outside the perimeter of the receiving antenna. But, in conjuction with the other points, it gave rise to some of the economically less appealing aspects of the design. E.g., its huge size.
Basic optics imposes a reciprocal relationship between the size of a transmitting aperture and the size of the receiving aperture. The received power from the beam in the reference design was 5 gigawatts. That's 5 nuclear plants worth, and inconveniently large. Especially when it all blinks off shortly around midnight each night near the spring and fall equinoxes. But for a smaller receiving antenna, you'd need a larger transmitting antenna with a much lower average power density. Bad news for system economics.
I had a way to get around that. It's not simple to describe, however. I'll write about it if I get time. In the meantime, I found this link that gives a good summay of the 1979 SPS reference design. --------- P.S. - transmitting at 5.8 GHz, as Darel suggest, would shift the optimum size toward a smaller rectenna and lower beam power. The frequency, though, is less important in the tradeoff analysis than the transmiter technology. The klystrons and slotted waveguides of the reference design had a high mass per square meter of transmitter array, but could handle a high power density. That drove the system optimum toward larger sizes. A transmitter technology with lower mass per square meter of aperture and lower power density would favor smaller systems.
Roger Arnold 6.23.06
Oops! Forgot that this system ignores single line breaks. That list of key design decisions should have looked like this (if I can get my embedded HTML right):
peak beam power at the rectenna must be less than 25% of noon sunlight;
frequency selected for the power beam was 2.45 GHz;
DC to RF power conversion would be via klystron tubes;
slotted waveguides distribute power from klystrons to radiating elements;
inherent safety of a phase-conjugated return of a pilot beam was mandatory
Len Gould 6.23.06
Excellent information, both Darel and Roger. Thanks. BTW, I'm willing to donate my claim to the "Gould Orbit" for SPS's, which defines an orbit which is slightly eliptical and tilted, sufficient so that the SPS satellite crosses the Clark orbit path a short distance below it at perihelion and the same short distance above it at apehelion. It is possible to define a large number of such orbit paths, each one of which can have as many satellites as the Clark orbit. Each satellite in a Gould orbit will appear esentially geo-stationary from earth, appearing to do only a slight north-south wobble. Ideally the orbit is timed so that when the SPS satellite is above the Clark orbit, it is half way between the two nearest communications satellites in the Clarh orbit to avoid toasting them. To an observer on a geo-stationary satellite in the current Clark orbit, an SPS in this orbit would appear to follow along exactly, but rotate around the observer at afixed distance above, to the sides, and below once per day.
It enables choosing your ideal orbit slot without needing to negotiate with currently allocated owners of slots in the Clark orbit.
And if the "slight distance above / below" were eg. 1/2 earth diameter (4000 km) you could even avoid those power interruptions at equinox, though that might be too much of a daily north-south shift in position. Minimum interval currently in the Clark orbit appears to be 400 km, so safe to assume that might also be used as the minimum crossing separation of these orbits around the Clark orbit.
Len Gould 6.24.06
BTW, these orbits begin to get interesting when you start to design "clouds" of synchronous reflectors travelling with an SPS and increasing their insolation to multiple "suns", though required manouvering might make it not worth it.
Graham Cowan 6.24.06
There may be Earth-like planets where big rockets were developed before nuclear reactors, and at the moment in their history analogous to this world here and now, solar power satellites are annually preventing billions of tonnes of CO2 emission, and in so doing, cancelling hundreds of billions in fossil fuel tax revenue. Perhaps one or more freak accidents have occurred; airliners crashing after flying into a microwave beam and having it interact in a more or less unanticipated way with engine electronics, or some such thing.
Despite this, they have an obviously lifesaving record in comparison to the fossil fuel energy, with its many non-freak accidents. No mass medium acknowledge this, nor the public's awareness of it, because the publically funded, who profit hugely from fossil fuels, don't like that kind of talk.
So it seems to me fission and SPS are very parallel cases, and in this world, fission got established first.
Analogous to the putative nuclear waste issue in this world might be the putative issue of kilotonnes of stuff in high orbits that may eventually decay. If nothing is being done about it now, surely that must be evidence that no-one knows what to do!
For a relatively objective history of a NASA administered space launch vehicle try: "Taming Liquid Hydrogen: The Centaur Upper Stage Rocket 1958 - 2002" by Virginia P. Dawson and Mark D. Bowles at www.nasa.gov/centers/glenn/about/history/centaur.html.
Don Giegler 6.28.06
Atlas Featured on The History Channel See the Mega Movers follow transport of Atlas V launch vehicle
A new show on The History Channel’s, Mega Movers series follows the transport of the powerful and large 191-foot Lockheed Martin Atlas V rocket from production facilities in Denver, Colo., to the launch site at Cape Canaveral Air Force Station (CCAFS), Fla. The show is scheduled to air July 11 at 10 p.m. EDT (check local listings). Mega Movers follows the relocation of the biggest, heaviest and least mobile structures imaginable. Episodes have shown the move of a 500-ton oil rig, giant locomotives and an historic Victorian mansion. The Mega Movers film crew was given close access to the delivery of Atlas vehicle components for the most recent launch of the Astra 1KR commercial satellite April 20. The show begins with packing of the Atlas booster at Lockheed Martin Space Systems in Denver, loading onto a Russian Antonov An-124 transport aircraft at Denver International Airport and unloading at the CCAFS Skid Strip. A second trip is required to transport the Centaur upper stage. The film crew follows the major processing milestones as the Atlas team prepares the vehicle for launch including stacking operations and rollout to the launch pad. Throughout the program, interviews with Lockheed Martin employees describe the careful planning and extraordinary attention to detail that goes into the handling of complex flight hardware. The program culminates in the ultimate mega move – a successful Atlas V launch of Astra 1KR on April 20. For more information on Mega Movers featuring Atlas, contact Julie Andrews at (321) 853-1567, e-mail julie.c.andrews@lmco.com.
Kevin Reed 11.18.06
Hi Darel,
I have spoken to a few people on Sunsat Council and they are all good people. Problematic is a good stepwise business method to put together the Gigawatt yearly capacity solar cells manufacturing facilities. No existing manufacturing can make these large space Solar Power Satellites in the Gigawatt range.
Only 1.6 Gigawatts of solar cells are made worldwide each year. A very small percentage of these are solar cells for space applications. Even if they gave free payloads to space they could not make the arrays.
I make record 4300 Watt/kg power density space applications solar cells and deployed the power is about 2 kW/kg. Most space applications solar cells are more like 65 Watts/kg for state of the art deployed array systems. Most with our cells as the exception are much too heavy for feasible SPS based on space launch cost alone. Using current SOA solar cells you will have to make new arrays in 10 to 15 years as they will only last this long in the space environment. Our last longer but even ours have limitations on the lifetime against micromeorites, radiation, AO and the like.
I suggest free payload does not much except give those already making large money from NASA more money to develop products for SPS as they have nothing suitable now. While good work for the future, this is not solving any real problem now.
Key is making thin film solar cells on dual use equipment for space solar and terrestrial solar cells. No government subsidizes space solar cell production. One must therefore address increasing manufacturing capacity within the context of terrestrial cell government incentives and then use this increased manufacturing capcity for space applications including SPS.
The very high ROI for space solar cells, average price of $1000 per Watt deployed in space, could be used to subsidize the full cost of terrestrial modules at $6 per Watt (deployed on your roof). If the internally subsidized cost of terrestrial modules is equal to government subsidy (say $3 per Watt) then one could break even and price these terrestrial modules essentially free to consumers at the government subsidy price.
Free to consumer solar module will definately stimulate the need for more available product and manufacturing capacity that can be used to address even larger high return on investment space solar projects. Very large manufacturing capacity has a great deal of impact on cost savings of scale. Cheaper cells for terrestrial and space use ... lower internal and government subsidy to provide free cells and best of all more overall profit for the business while they take a bite out of global warming.
Can not talk about government subsidized payloads unless you have a payload to launch. Best is a stepwise business program that put free solar on your house and increases manufacturing capacity and infrastructure for space solar power at the same time. Free would be an acceptable electric bill for me and global warming begins slowing faster as we work towards the space solar power we know will comes.
Every once in a while History takes a deep breath and decides what to do next ... (Terry Prachett) Perhaps one of those times is now.
