How Green is Green?
October 14, 2005 1:40 PM Subscribe
Unexpected Downside of Wind Power - Wired reports on the shutdown of wind power turbines along Altamont Pass in California. Wind power is seen by some as an alternative to burning fossil fuels; yet these turbines are being shut down over environmental and ecological concerns. Some of the concerns about turbines are that they endanger bird migrations, yet others say that they are not a problem for bird migrations. It's not just a question of the ecological footprint, though. The entire environmental impact has to be assessed for any project. Hydroelectricity is not without its effect on ecosystems, either (Scroll down to "Ecosystems and Large Dams", about 40% of the way down).
If even green or renewable energy sources cannot be accessed without a significant adverse environmental impact, how can we meet our energy needs? Reducing consumption is only approaching the problem from one side. How do you properly gauge the environmental impact of a project and when is it okay to give it the green light? Or are we being oversensitive and should we let natural selection handle the birds that can't adapt?
If someone would just listen to me.....
Sterling (or Manson) engines in Death Valley (or any hot desert). Hot side above ground, cool side below. Free power, little impact on the landscape, all is good.
posted by Kickstart70 at 1:45 PM on October 14, 2005
Sterling (or Manson) engines in Death Valley (or any hot desert). Hot side above ground, cool side below. Free power, little impact on the landscape, all is good.
posted by Kickstart70 at 1:45 PM on October 14, 2005
Wind turbine at the wrong height equals = birdy cuisinart. Bummer.
I did find it quite interesting on the second page that someone claims cell phone towers kill alot more bird than wind turbines.
posted by fenriq at 1:49 PM on October 14, 2005
I did find it quite interesting on the second page that someone claims cell phone towers kill alot more bird than wind turbines.
posted by fenriq at 1:49 PM on October 14, 2005
We've made a lot of progress since 1970.
Altamont Pass in California has turbines placed both too low and in a spectacullarly bad spot. Not to surprising that these kinds of mistakes were made in this installation considering it was an early implementation.
posted by Mitheral at 2:00 PM on October 14, 2005
Altamont Pass in California has turbines placed both too low and in a spectacullarly bad spot. Not to surprising that these kinds of mistakes were made in this installation considering it was an early implementation.
posted by Mitheral at 2:00 PM on October 14, 2005
If you take the view that human intervention is part of natural selection, then the term becomes meaningless. Yes, we are part of nature, but we don't think of poodles or cows as having evolved naturally. Even if we invented a power source the size of a thimble that would supply a family's energy needs, the patio heater boom alone would change the climate. Kickstart (I'm listening) may have described something closer to a free lunch. In the meantime, put on a sweater, and turn off your goddamn 4x4 when you shop.
posted by weapons-grade pandemonium at 2:05 PM on October 14, 2005
posted by weapons-grade pandemonium at 2:05 PM on October 14, 2005
The wind turbines at the Altamont Pass are notorious for being poorly planned and sited. They really don't have any implications for the green energy movement other than that you shouldn't do really stupid things.
Generally speaking, window turbines built with existing technology and sited properly don't kill any more birds than a static tower in the same place. And they kill far, far fewer birds than are killed by structures with windows, like houses and skyscrapers.
posted by alms at 2:10 PM on October 14, 2005
Generally speaking, window turbines built with existing technology and sited properly don't kill any more birds than a static tower in the same place. And they kill far, far fewer birds than are killed by structures with windows, like houses and skyscrapers.
posted by alms at 2:10 PM on October 14, 2005
[mad-scientist]
Frankly, I'm more interested in Vortex Engines, though not as a power source. Basically, all weather is merely the result of varying rates of water evaporation and air pressure between distant areas. So I'd bet that careful worldwide placement of these artificial, controlled tornadoes/hurricanes would permit direct manipulation of said evaporation and pressure, altering the jetstream and paving the way for localized weather control. But who knows, on a large enough scale it might be a key to actually reversing global warming, instead of merely coping with it.
That is, if the darn things actually work in the first place.
[/mad-scientist]
Kickstart70:
Sterling (or Manson) engines in Death Valley (or any hot desert). Hot side above ground, cool side below. Free power, little impact on the landscape, all is good.
.
.
.
(smacks forehead) Holy crap, that's so obvious! Why aren't we doing that already?
posted by PsychoKick at 2:16 PM on October 14, 2005
Frankly, I'm more interested in Vortex Engines, though not as a power source. Basically, all weather is merely the result of varying rates of water evaporation and air pressure between distant areas. So I'd bet that careful worldwide placement of these artificial, controlled tornadoes/hurricanes would permit direct manipulation of said evaporation and pressure, altering the jetstream and paving the way for localized weather control. But who knows, on a large enough scale it might be a key to actually reversing global warming, instead of merely coping with it.
That is, if the darn things actually work in the first place.
[/mad-scientist]
Kickstart70:
Sterling (or Manson) engines in Death Valley (or any hot desert). Hot side above ground, cool side below. Free power, little impact on the landscape, all is good.
.
.
.
(smacks forehead) Holy crap, that's so obvious! Why aren't we doing that already?
posted by PsychoKick at 2:16 PM on October 14, 2005
odinsdream, thanks, I think I must have vaguely heard about the Stirling engine before as it was familiar but still kind of new. Very interesting stuff and it does make me wonder why these aren't being used right now?
The problems with the engines on the Wiki page don't really seem insurmountable.
posted by fenriq at 2:23 PM on October 14, 2005
The problems with the engines on the Wiki page don't really seem insurmountable.
posted by fenriq at 2:23 PM on October 14, 2005
A Compendium of Solar Dish/Stirling Technology
I'm in favor of protecting endangered species and opposed to killing wildlife willy-nilly. But this pro-bird, anti-turbine attitude seems extreme to me. The popularization of wind power is likely to have beneficial long-term network type effects (like spurring the development of flexible, alt-energy-friendly power grids, or getting Joe Citizen to think about eco/energy issues, etc) that ultimately could be more important than the clean energy a few turbines produce or the birds that they kill.
posted by Western Infidels at 2:24 PM on October 14, 2005
I'm in favor of protecting endangered species and opposed to killing wildlife willy-nilly. But this pro-bird, anti-turbine attitude seems extreme to me. The popularization of wind power is likely to have beneficial long-term network type effects (like spurring the development of flexible, alt-energy-friendly power grids, or getting Joe Citizen to think about eco/energy issues, etc) that ultimately could be more important than the clean energy a few turbines produce or the birds that they kill.
posted by Western Infidels at 2:24 PM on October 14, 2005
Stirling engines introduce many design problems that prevent them from reaching their maximum efficiency. Theoretically, it all sounds good, until you actually have to build a turbine that is both inexpensive and works on a daily basis. Rising energy prices may change the cost equation, but simple physics will always constrain the design.
posted by Rothko at 2:36 PM on October 14, 2005
posted by Rothko at 2:36 PM on October 14, 2005
*safe* nuclear is the only answer.
I agree that if we could somehow deal with the radioactive waste, nuclear becomes a pretty good proposition. What I think we really need is a space elevator on which we could send send the waste into orbit, then give it a nudge toward the sun. Cheap, safe and effective.
Of course, the moment a bird collides with the carbon nanotube tether, environmentalists would want this torn down too.
posted by darkness at 2:57 PM on October 14, 2005
I agree that if we could somehow deal with the radioactive waste, nuclear becomes a pretty good proposition. What I think we really need is a space elevator on which we could send send the waste into orbit, then give it a nudge toward the sun. Cheap, safe and effective.
Of course, the moment a bird collides with the carbon nanotube tether, environmentalists would want this torn down too.
posted by darkness at 2:57 PM on October 14, 2005
Kickstart70: The combination of high initial cost (in money and energy), low efficiency, high maintenance and desert-specific logistical problems make Stirling engines unusable. Solar cells would probably do better, and they are in turn not used for just these reasons. Such a plant would take forever to pay for itself.
posted by springload at 2:59 PM on October 14, 2005
posted by springload at 2:59 PM on October 14, 2005
Has any group ever assessed the impact of depleting a wind-current of the several thousand kilowatts of energy a wind-farm generates?
I mean, the wind is supposed to get from one point to another, but it won't make it as far if it's had 5% of it's energy removed, will it? And it'll be colder, or slower, or different in some quality or quantity when/if it gets there.
I guess I'm thinking about questions like, "Do wind-farms result in a change in downwind precipitation patterns?" "Do wind-farms result in changes in downwind erosion?"
Birds are fairly smart. They learn or evolve. Birds near a lot of wind-farms learned or adapted to fly around them or over them. Birds aren't the major issue. It's the potential of moving the usual rainfall over a rich cropland 200 miles west that I wonder about.
posted by Crosius at 3:12 PM on October 14, 2005
I mean, the wind is supposed to get from one point to another, but it won't make it as far if it's had 5% of it's energy removed, will it? And it'll be colder, or slower, or different in some quality or quantity when/if it gets there.
I guess I'm thinking about questions like, "Do wind-farms result in a change in downwind precipitation patterns?" "Do wind-farms result in changes in downwind erosion?"
Birds are fairly smart. They learn or evolve. Birds near a lot of wind-farms learned or adapted to fly around them or over them. Birds aren't the major issue. It's the potential of moving the usual rainfall over a rich cropland 200 miles west that I wonder about.
posted by Crosius at 3:12 PM on October 14, 2005
"green light" - that just kills me.
posted by FormlessOne at 3:28 PM on October 14, 2005
posted by FormlessOne at 3:28 PM on October 14, 2005
It's almost like there's no such thing as a free lunch, and any means of providing the massive amount of power required by a grossly wasteful industrial civilization will come at a significant environmental expense.
TANSTAAFL.
posted by freebird at 3:33 PM on October 14, 2005
TANSTAAFL.
posted by freebird at 3:33 PM on October 14, 2005
We will have to do something. And, I'm sorry, I'd trade a logger for the Spotted Owl any day of the week but not a potential power source for a bird that can't change direction.
I like the space elevator too, gotta get OFF this planet.
posted by Max Power at 3:58 PM on October 14, 2005
I like the space elevator too, gotta get OFF this planet.
posted by Max Power at 3:58 PM on October 14, 2005
I did find it quite interesting on the second page that someone claims cell phone towers kill alot more bird than wind turbines.
Between 5,000 - 10,000 Lapland Buntings were killed at three communications towers in kansas (PDF).
400 birds were killed flying into the WMTV tower in a single night last month.
posted by lilburne at 4:01 PM on October 14, 2005
Between 5,000 - 10,000 Lapland Buntings were killed at three communications towers in kansas (PDF).
400 birds were killed flying into the WMTV tower in a single night last month.
posted by lilburne at 4:01 PM on October 14, 2005
According to the American Wind Energy Association, wind farms in 34 states were generating 6,740 megawatts as of January, enough juice to power 1.6 million homes.
Wow, I had no idea the figure was that high. Also, the aforesaid American Wind Energy Association claims in its FAQ that "Avian deaths have become a concern at Altamont Pass in California, which is an area of extensive wind development and also high year-round raptor use. Detailed studies, and monitoring following construction, at other wind development areas indicate that this is a site-specific issue that will not be a problem at most potential wind sites."
posted by LarryC at 4:32 PM on October 14, 2005
Wow, I had no idea the figure was that high. Also, the aforesaid American Wind Energy Association claims in its FAQ that "Avian deaths have become a concern at Altamont Pass in California, which is an area of extensive wind development and also high year-round raptor use. Detailed studies, and monitoring following construction, at other wind development areas indicate that this is a site-specific issue that will not be a problem at most potential wind sites."
posted by LarryC at 4:32 PM on October 14, 2005
Birds flying into windturbines? YOU ARE THE WEAKEST LINK, GOODBYE!
There are tons of things out there that are man-made that kills things everyday, and birds as a species will be better of for it.
Yes, I do care for the environment, but cleaner air for all takes precedence over some birds flying into windturbines.
Birds fly into skyscrapers all the time, do those of you who want to remove the turbines also want to dismantle skyscrapers?
posted by LinemanBear at 5:22 PM on October 14, 2005
There are tons of things out there that are man-made that kills things everyday, and birds as a species will be better of for it.
Yes, I do care for the environment, but cleaner air for all takes precedence over some birds flying into windturbines.
Birds fly into skyscrapers all the time, do those of you who want to remove the turbines also want to dismantle skyscrapers?
posted by LinemanBear at 5:22 PM on October 14, 2005
In other news, government officials have announced that automobiles will be completely phased out of production and removed from roadways over the next five years.
"Roadways are the worst possible place for cars," say environmentalists, "and they have resulted in astronomical numbers of wildlife kills over the last five decades." Vehicle owners will be permitted to retain their vehicles, provided they remain stationary.
posted by mullingitover at 5:38 PM on October 14, 2005
"Roadways are the worst possible place for cars," say environmentalists, "and they have resulted in astronomical numbers of wildlife kills over the last five decades." Vehicle owners will be permitted to retain their vehicles, provided they remain stationary.
posted by mullingitover at 5:38 PM on October 14, 2005
LinemanbBear: I gotta agree with you. The first I heard about this 'problem' I thought, "You've gotta be kidding me.". Now that I've heard all the facts (I live in the Bay Area, and this is a somewhat-major news story here) I say, "You've gotta be kidding me."
I think, on balance, we're doing more good than harm for pretty much all flora and fauna by having gigantic bird-o-matics generating power, rather than burning fossil fuels or dirty nuclear power. But environmentalism is a religion nowadays, especially in California, and if the greenies can find something to bitch about they howl to the heavens about it. Even if it's wind power.
posted by wolftrouble at 6:01 PM on October 14, 2005
I think, on balance, we're doing more good than harm for pretty much all flora and fauna by having gigantic bird-o-matics generating power, rather than burning fossil fuels or dirty nuclear power. But environmentalism is a religion nowadays, especially in California, and if the greenies can find something to bitch about they howl to the heavens about it. Even if it's wind power.
posted by wolftrouble at 6:01 PM on October 14, 2005
I think wind farms are a good idea, especially if they're built within sight of Martha's Vineyard. Some bats, however, do not.
posted by Kirth Gerson at 6:26 PM on October 14, 2005
posted by Kirth Gerson at 6:26 PM on October 14, 2005
If the environment didn't want to get raped like this, it shouldn't have evolved us.
posted by delmoi at 6:28 PM on October 14, 2005
posted by delmoi at 6:28 PM on October 14, 2005
The combination of high initial cost (in money and energy), low efficiency, high maintenance and desert-specific logistical problems make Stirling engines unusable.
Much of that could be overcome with a little intelligent research. As well, variants like the Manson engine have much less of the problems that plague Sterling engines, and can easily be adapted from what we've learned from pistons in combustion engines. Basically, a lot of people keep finding fault with Sterling/Manson (especially the latter) that comes down to nothing more than resistance to change.
posted by Kickstart70 at 6:38 PM on October 14, 2005
Much of that could be overcome with a little intelligent research. As well, variants like the Manson engine have much less of the problems that plague Sterling engines, and can easily be adapted from what we've learned from pistons in combustion engines. Basically, a lot of people keep finding fault with Sterling/Manson (especially the latter) that comes down to nothing more than resistance to change.
posted by Kickstart70 at 6:38 PM on October 14, 2005
I'm a windfarm designer; possibly the only one on mefi. Most of the legacy windfarms in California are pretty much an embarrassment to the industry. They were built for tax-grab purposes, and consequently have about as much relevance to sustainability as does a sour-cream glazed donut.
The way you measure impact on birds is to check migration patterns, assess site predation levels (by placing dead birds on the site, and seeing if they get eaten), and then do the sums. It's a standard part of any environmental assessment, and is a process accepted by bird folks and wind folks alike. By this process, the Toronto wind turbine might kill two birds a year. The windows of my house -- a nondescript urban semi -- dispatched two birds within 10 minutes last Sunday morning.
Kickstart70, factor in the cost of running a powerline to these remote, hot places, and your Stirling engine plan is stillborn. Plus maintaining these fairly finicky things in an inhospitable climate isn't going to be fun, or cheap. Plus (on preview) Stirling-type engines have low theoretical cycle efficiency, which no amount of clever mechanics will fix.
darkness, nuclear waste is rather dense. To simply lift it to geostationary orbit would take a huge amount of energy. You're also relying on a solution which we don't yet have. I'd love to be able to do that in real life.
My biggest gripe with nuclear power is that it requires a huge petroleum-based infrastructure for it to work. Excavators, trucks and ships all run on oil, and it will take more and more oil to extract the ore as easier reserves are used up.
homunculus' solar towers might work, but again, none of any real size have ever been built. Plus there's the cost of those powerlines, which can run into the millions per kilometre.
Basically, thermodynamics doesn't like us one bit.
posted by scruss at 7:11 PM on October 14, 2005
The way you measure impact on birds is to check migration patterns, assess site predation levels (by placing dead birds on the site, and seeing if they get eaten), and then do the sums. It's a standard part of any environmental assessment, and is a process accepted by bird folks and wind folks alike. By this process, the Toronto wind turbine might kill two birds a year. The windows of my house -- a nondescript urban semi -- dispatched two birds within 10 minutes last Sunday morning.
Kickstart70, factor in the cost of running a powerline to these remote, hot places, and your Stirling engine plan is stillborn. Plus maintaining these fairly finicky things in an inhospitable climate isn't going to be fun, or cheap. Plus (on preview) Stirling-type engines have low theoretical cycle efficiency, which no amount of clever mechanics will fix.
darkness, nuclear waste is rather dense. To simply lift it to geostationary orbit would take a huge amount of energy. You're also relying on a solution which we don't yet have. I'd love to be able to do that in real life.
My biggest gripe with nuclear power is that it requires a huge petroleum-based infrastructure for it to work. Excavators, trucks and ships all run on oil, and it will take more and more oil to extract the ore as easier reserves are used up.
homunculus' solar towers might work, but again, none of any real size have ever been built. Plus there's the cost of those powerlines, which can run into the millions per kilometre.
Basically, thermodynamics doesn't like us one bit.
posted by scruss at 7:11 PM on October 14, 2005
If the environment didn't want to get raped like this, it shouldn't have evolved us.
I know that's my favorite comment, but it will take me some time to decide which of the many ways to interpret it I like best. Know, though, that I will be savoring it all weekend.
posted by freebird at 7:18 PM on October 14, 2005
I know that's my favorite comment, but it will take me some time to decide which of the many ways to interpret it I like best. Know, though, that I will be savoring it all weekend.
posted by freebird at 7:18 PM on October 14, 2005
Historical note: One of Christie Todd Whitman's first flaps as EPA chief was her comment that "Windmills kill birds, because they're in the flyway" -- which was part of a carefully built right-wing talking point. The Cato Institute used numbers from Altamont -- as discussed, an outlier -- to extrapolate "avian mortality" numbers for a nationwide network of wind farms.
posted by dhartung at 8:47 PM on October 14, 2005
posted by dhartung at 8:47 PM on October 14, 2005
from www.flap.org
This group collects stats on birds killed in collisions with office towers in Toronto. The counter on their site indicates they've counted some 28k dead in the last 10 years or so.
posted by bobloblaw at 8:53 PM on October 14, 2005
Like scruss, I'm involved in the wind energy business (not as a wind farm designer though, I work for a co-op developer of wind projects). scruss can probably comment on this in more detail, but FLAP was consulted as part of the siting of Toronto wind turbine project , and there was a study done in the US that compared deaths from wind turbines as compared to other manmade developments, and both seem to demonstrate that Altamont is an exception, not the rule. Due to the public awareness and feelings around Altamont, we as developers are extremely conscious of the need to site turbines to minimize the footprint and negative impacts. Even if we didn't care, the regulatory and legislative requirements here in Canada would make it extremely difficult to purposely site a wind turbine in a 'negative' location.
posted by Cyrie at 9:56 PM on October 14, 2005
posted by Cyrie at 9:56 PM on October 14, 2005
To reiterate the comment of several on this post :
The "bird kill" objection is about 20 years out of date. Turbine designs - and analysis of turbine placement - have dramatically mitigated the problem.
On the other hand, Global Warming will - unmitigated - decimate or destroy many avian species.
posted by troutfishing at 10:05 PM on October 14, 2005
The "bird kill" objection is about 20 years out of date. Turbine designs - and analysis of turbine placement - have dramatically mitigated the problem.
On the other hand, Global Warming will - unmitigated - decimate or destroy many avian species.
posted by troutfishing at 10:05 PM on October 14, 2005
i agree, the turbines at aliment pass also used a tower design that allowed birds to live in them, todays single pole towers help keep birds from landing on them...another thing is cats and building kill a lot more birds than turbines. i find it crazy that people use these isolated cases to say all wind power is bad. wind power in general is probly our best bet for short term renewable energy solutions.
posted by stilgar at 7:16 AM on October 15, 2005
posted by stilgar at 7:16 AM on October 15, 2005
Unexpected downside? That must be a contender for the most out of date headline ever award. The potential for bird deaths has been an issue with the installation of wind turbines for well over 2 decades, and particularly with regard to the Altamont Pass wind farms. Wind turbines picked up the name 'cuisinarts of the sky' sometime in the 1980s. Early developments in the Tarifa region of Spain also received criticism for being in the path of birds of prey. The fact is that all wind turbine developments now tend to take into account the positioning of farms as part of their consideration of environmental assessment. The cost of having a project rejected for planning or to the industry in general of having multiple rare bird deaths means due consideration is built into planning for new wind projects even where this isn't made compulsory by law.
Further, considerable research has been carried out to model how birds relate to operational wind turbines, how they approach them and how bird mortality can be minimised, even as to how offshore turbines can impact on bird feeding grounds and on migration.
posted by biffa at 7:33 AM on October 15, 2005
Further, considerable research has been carried out to model how birds relate to operational wind turbines, how they approach them and how bird mortality can be minimised, even as to how offshore turbines can impact on bird feeding grounds and on migration.
posted by biffa at 7:33 AM on October 15, 2005
This isn't meant as a challenge. I'm just an interested bystander who wants to learn more.
Rothko: Stirling engines introduce many design problems that prevent them from reaching their maximum efficiency.
scruss: Stirling-type engines have low theoretical cycle efficiency, which no amount of clever mechanics will fix.
This Sandia National Laboratories report says:
springload: The combination of high initial cost (in money and energy), low efficiency, high maintenance and desert-specific logistical problems make Stirling engines unusable.
200 years ago, steam engines had all of these problems. 100 years ago, internal combustion engines had all of these problems. 50 years ago, gas turbines had all of these problems. Is there some specific reason why Stirling engines in particular are unlikely to ever overcome these mundane engineering challenges?
posted by Western Infidels at 11:40 AM on October 15, 2005
Rothko: Stirling engines introduce many design problems that prevent them from reaching their maximum efficiency.
scruss: Stirling-type engines have low theoretical cycle efficiency, which no amount of clever mechanics will fix.
This Sandia National Laboratories report says:
Advanco Corporation (now defunct), building on the work done at the Jet Propulsion Laboratory (JPL), integrated the 25-kWe Vanguard dish/Stirling system in 1984. It produced the highest recorded net conversion of sunlight into electricity, 29.4% (including parasitic power) (Droher and Squier, 1986).I took this to mean that this (Stirling-based) system held the record for the most efficient conversion of sunlight to electricity, as of 20 years ago at least. That is, I took it to mean that it was more efficient than solar cells, solar convection towers, solar furnace-type boiler systems, etc. Is that not the case? If that level of efficiency is considered low (and it does seem a bit disappointing, but hey, the fuel is free) then what solar technology fares better?
springload: The combination of high initial cost (in money and energy), low efficiency, high maintenance and desert-specific logistical problems make Stirling engines unusable.
200 years ago, steam engines had all of these problems. 100 years ago, internal combustion engines had all of these problems. 50 years ago, gas turbines had all of these problems. Is there some specific reason why Stirling engines in particular are unlikely to ever overcome these mundane engineering challenges?
posted by Western Infidels at 11:40 AM on October 15, 2005
up with alt. NRG! but I'd put my $ on solar. unless your land is on a big windy hill side thats windy all the time it just sounds like a lot of infrastucture for wimpy pay off. The sun comes up every day. compared to solar, wind power blows.
Economically its easier to hook a prop to a generator - I think I could even fabricate something like that and solar (silicon) is $ costly. But that's got to change.
Here's an interesting company that want to make solar windows
posted by celerystick at 10:16 PM on October 15, 2005
Economically its easier to hook a prop to a generator - I think I could even fabricate something like that and solar (silicon) is $ costly. But that's got to change.
Here's an interesting company that want to make solar windows
posted by celerystick at 10:16 PM on October 15, 2005
Western Infidels: It's because they're pushing towards a hard limit. When steam engines and car engines emerged, they did so from a strong position, since anything was better than some moody old horse.
The Stirling engine has a maximum theoretical efficiency of 1-Tc/Th, where Th and Tc are the temperatures of the hot and cold end, respectively. As an example, the temperature difference between ice and boiling water can be utilized to a mere 27%, in a perfect machine. To increase the efficiency, the solar rays must be concentrated, which requires big mirrors or lenses. These have to withstand sand storms without losing focus, and they have to follow the sun across the sky, which requires some advanced support structures.
In a real engine, mechanical and electrical losses are inevitable, and there isn't as great a room for improvement as there was for car engines. All the knowledge of efficiency that goes into a car engine also goes into a Stirling engine, and the further things improve, the smaller are the consecutive improvements. We're not waiting for a major breakthrough in engine technology, but merely grinding the pistons a bit better to get less friction. Apart from being small, such improvements tend to be easily reversed by small quantities of sand.
posted by springload at 4:23 AM on October 16, 2005
The Stirling engine has a maximum theoretical efficiency of 1-Tc/Th, where Th and Tc are the temperatures of the hot and cold end, respectively. As an example, the temperature difference between ice and boiling water can be utilized to a mere 27%, in a perfect machine. To increase the efficiency, the solar rays must be concentrated, which requires big mirrors or lenses. These have to withstand sand storms without losing focus, and they have to follow the sun across the sky, which requires some advanced support structures.
In a real engine, mechanical and electrical losses are inevitable, and there isn't as great a room for improvement as there was for car engines. All the knowledge of efficiency that goes into a car engine also goes into a Stirling engine, and the further things improve, the smaller are the consecutive improvements. We're not waiting for a major breakthrough in engine technology, but merely grinding the pistons a bit better to get less friction. Apart from being small, such improvements tend to be easily reversed by small quantities of sand.
posted by springload at 4:23 AM on October 16, 2005
springload: Thanks for answering. It's certainly true that other engines were more different from their contemporary alternatives.
But the more I read about Stirlings, the more perfect they seem for a "solar power in the desert" application. They must be hermetically sealed to operate at all, so I imagine sand in the works isn't much of an issue. Mechanically, they're quite a bit simpler than internal combustion engines and even slightly simpler than steam engines - the engines themselves should require very little attention. The Carnot limit (1 - Tc/Th) applies to all heat engines, not just Stirling engines - but Stirling engines can actually operate at low temperature differentials other engines can't use.
It looks like the concept is undergoing some important developments this year. It's likely that piece suffers from a bit of "enthusiastic booster" syndrome, but if the basic facts are right, then quite a few people seem to think it's worth a trial run on a megawatt scale.
posted by Western Infidels at 2:42 AM on October 17, 2005
But the more I read about Stirlings, the more perfect they seem for a "solar power in the desert" application. They must be hermetically sealed to operate at all, so I imagine sand in the works isn't much of an issue. Mechanically, they're quite a bit simpler than internal combustion engines and even slightly simpler than steam engines - the engines themselves should require very little attention. The Carnot limit (1 - Tc/Th) applies to all heat engines, not just Stirling engines - but Stirling engines can actually operate at low temperature differentials other engines can't use.
It looks like the concept is undergoing some important developments this year. It's likely that piece suffers from a bit of "enthusiastic booster" syndrome, but if the basic facts are right, then quite a few people seem to think it's worth a trial run on a megawatt scale.
posted by Western Infidels at 2:42 AM on October 17, 2005
Western Infidels: Yes, my scepticism is not limited to Stirlings, but applies equally to all heat engines. The California project looks interesting though, and has better prospects than the Sahara plant I had in mind, but a brief look at the page leaves some questions unanswered:
Is 25kW peak power, averaged over 24h, or over a year or an expected device lifetime? Does it include downtime, cloudtime, and times when the mirror is out of optimum position? From the previous link, 25kWe appears to be peak peformance. If so, multiplying 25kW with 20000 stations to give 500MW is insincere. They also don't like to talk much about the cost, which leaves me sceptical. Thanks for the link though - it's interesting to see that people are trying to bring it to production scale.
posted by springload at 6:17 AM on October 17, 2005
Is 25kW peak power, averaged over 24h, or over a year or an expected device lifetime? Does it include downtime, cloudtime, and times when the mirror is out of optimum position? From the previous link, 25kWe appears to be peak peformance. If so, multiplying 25kW with 20000 stations to give 500MW is insincere. They also don't like to talk much about the cost, which leaves me sceptical. Thanks for the link though - it's interesting to see that people are trying to bring it to production scale.
posted by springload at 6:17 AM on October 17, 2005
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posted by Eideteker at 1:42 PM on October 14, 2005