[Cold Iron]

The 20th, on Dec 12 2008, 11:40 AM, said:

Yes, I'm actually Shinrei. Since I was using my mask avatar, I counted the lines and decided to change my name for a bit.

Good post CI, the only part you know I'll take issue with is "private companies are irresponsible by nature" which is a weird blanket statement.

If you'd said "governments are irresponsible by nature" I would be more inclined to agree.

I can agree with that too, but the difference, as I'm sure you are aware, is that governments do not have the same motivations for cost cutting. And there is transparency with government as well.

I'm not saying that government would necessarily do a better job than private enterprise, just that I'm more comfortable with a public system when it comes to something this hazardous.

[cerveza_fiesta]

. There was a cool report given to the government of Canada (see attached) that I'd urge somebody interested in climate analysis to read. I know it's long, but it's a good example of a thorough analysis and it's very well researched. It talks about the various Canadian sectors in relation to GHG emissions, current trends and renewable energy.

Anyways, I found a couple new technologies lately that I thought I'd run by the thoughtful contributors to the Climate Change thread:

======================================

Never having been a fan of large scale wind turbine farms as a source of electricity, I like when something innovative comes along in this field. The report I attached mentions (chapter 7 or 8 I think) that even if every viable location in the entire of Canada was tapped for wind energy, it could produce no more than 11% of the country's energy needs. Though that's a large percentage at face value, it means you literally have to populate every viable piece of land with wind turbines to achieve it. Of course that's not economically viable and the amounts of materials needed would be plain ol' ridiculous. This Selsam guy www.selsam.com has come up with multi-bladed single shaft wind turbines that work extremely well. The theory is that multiple propellors turning the same shaft produce more electrical energy than two side-by-side single propellor turbines, each turning a separate shaft. He's extended his idea to 2,3,4 and 7 bladed production versions, one producing upwards of 4KW in a good location. That's a lot! The multi propellors also means you only need one tower to carry a pair or trio of turbines (reducing overall cost). The other good thing is that small-bladed light turbines are very good at operating in low winds on short towers, making them more accessible for single-home use. The standard twin-prop version can produce about 2KW in steady wind. This is more than enough to power the standby electronics in a home (fridge, freezer, water pump, computers, furnaces, ventilators....ie stuff that just runs all the time instead of only during peak hours). The twin system is about 2000 bucks and if you put it in a good location, it would pay itself off within 5 years easily.

Here's a pic



Anyway, my point is that these massive wind power projects look nice on paper, but maintenance and construction wise they aren't economically viable as a power source on a national level. This is the main reason why huge wind turbines aren't getting built as fast as green energy advocates would like. They just cost too damn much! Wind power IMO after researching it quite a bit is much better when used on a small scale to power individual homes or small groups of homes, rather than trying to market the electricity to the national grid. Makes more sense economically and materials wise.

==========

Another cool technology



The aeroscraft ML866. This thing impresses the hell out of me since I've kind of always been a fan of airships as a means of cargo hauling and passenger travel.

At first glance, blimps seem to be a good answer to air travel problems and a means of achieving huge fuel savings for equivalent distances traveled. I mean, kilometer for kilometer a blimp uses an almost negligible amount of fuel compared to a propellor driven plane or a jet. This is because you don't need to pay (fuel wise) to create the lift. With an airship, you only pay for forward propulsion and manoeuvring. This was perfectly true until they stopped using hydrogen as a lifting gas. Early airships used hydrogen, which is the lightest gas available. It has great lifting power for a given volume and if it were still in use today would probably mean we'd have cargo blimps flying everywhere. Hydrogen has the unfortunate side effect of being highly flammable however and as the hindenburgh taught us, it can suck when your blimp catches fire (OH THE HUGE MANATEE). Modern airships use helium which, while not flammable, is twice as heavy as hydrogen and has only half the lifting potential. This makes a helium blimp inappropriate for cargo transportation since even a large one can scarcely lift itself and a small crew off the ground.

Then along comes the aeroscraft. It's an ingenious take on the airship idea. It's an entirely new class of aircraft that uses both static buoyancy (helium lifting power) and forward propulsion with small stubby wings to stay aloft. About 2/3 of the lifting power comes from the helium and the last 1/3 comes from lift on the wings. In fact, the shape of the blimp is also a fat wing, so the whole body of the blimp in addition to the wings is helping to lift to some extent. Anyway, what you get is a blimp with the lifting power of a cargo plane that uses only a tiny fraction of the fuel to get from A to B. The coolest part of the whole thing is the takeoff and landing. The designers decided they didn't want to sacrifice the blimp's ability to perform vertical takeoffs and landings, so they incorporated 6 vertically mounted jet engines. Basically it uses these to substitute for the wings' lifing power when forward motion is stopped. This enables the craft to rocket straight up and down. For example, during a takeoff, the jets fire to lift up the areoscraft directly from the runway. Upon achieving a safe altitude, it turns on the forward propulsion, the wings take over and the vertical jets are shut off for the duration of the flight.

Anyhoo, the Aeros company has been working on this for years now and they were finally granted FAA approval to go ahead with prototype testing. They've got one in construction now and it's expected to be tested sometime in 2010. I am ridiculously excited for this to happen and I really think it could revolutionize air travel. Jets are going to become extinct as fuel costs rise, but air travel is too dang awesome to let go entirely. The only solution is to develop a flying machine that uses way less fuel and the aeroscraft looks to be just that thing. We'll have to accept lower flight speeds and longer transit times along with this. Estimates are that a transcontinental N.American trip (NY to LA) would take about 18 hours. That's a long time, but might not be too bad for cargo carrying. It's a heck of a lot faster than a transport truck and (if it ever comes to production) their cargo version could be as good as the rail system for getting stuff across long distances. Their commercial models boast carrying capacities up to 500 people with space to move around and lay down.

=========================

Anyways, what do you think of these two techologies? Discuss!

Attached File(s)

•  parliament03_04.pdf (1.58MB)
  Number of downloads: 23

[Cold Iron]

Cool post cf. i'll try to have a closer look at that report later. Now on to the technologies!

Firsty, I'd like to challenge your statement that "multiple propellors turning the same shaft produce more electrical energy than two side-by-side single propellor turbines, each turning a separate shaft". I looked around the website and couldn't find this anywhere. Per unit of materials you are going to get more output certainly, but even with a perfect design I can only see you approaching an equal amount of energy with the double as with two singles, but not more.

Also this development, while a genuine contender as a solution to the cost of materials problem, solves none of the other problems of wind power. Space is still a problem as I don't see these being able to produce a significant amount more watts per square meter of land (or sea). Total output is still a problem as even doubling or trippling the output will still not even come close to meeting the power needs of a country like Canada, which is huge and has a small population. Consider countries with a way higher power demand and way smaller land size.

And finally, noise. Noise is the reason you will not see urban adoption of wind technology. Even tiny ones are noisy and adding blades will just add to the noise. God forbid you be standing somewhere where the reverberation from the two blades were reaching you slightly out of phase with each other. Ever had your car window open just the wrong amount? You can literally mess with brain waves with sound, induce headaches, seisures or (on the plus side) trance-like states (no I have not seen examples of wind turbines causing trance-states, but i'm sure it could be done).


Ok on to the fat plane. Fat plane is fat. This seems to me to be a good way to transition away from fuel as a source of flight, like hybrid cars they are marrying an alternative technology with the existing status quo in order to mitigate some of the disadvantages. However, this is likely going to have the same problems with adoption as hybrids. It's dependent on the cost of the fuel. While fuel prices stay low, there's not enough motivation to pursue this stuff. And if cap and trade systems around the world are going to be as patheric as the one that was released by our gloriously green government yesterday for a 2010 roll out, this is not going to happen fast enough.

Get over your whining about your lost retirement funds people, you still have a house and a car, you are lucky. Don't be selfish, vote green

[cerveza_fiesta]

Cold Iron, on Dec 15 2008, 07:39 PM, said:

Cool post cf. i'll try to have a closer look at that report later. Now on to the technologies!

Firsty, I'd like to challenge your statement that "multiple propellors turning the same shaft produce more electrical energy than two side-by-side single propellor turbines, each turning a separate shaft". I looked around the website and couldn't find this anywhere. Per unit of materials you are going to get more output certainly, but even with a perfect design I can only see you approaching an equal amount of energy with the double as with two singles, but not more.

Also this development, while a genuine contender as a solution to the cost of materials problem, solves none of the other problems of wind power. Space is still a problem as I don't see these being able to produce a significant amount more watts per square meter of land (or sea). Total output is still a problem as even doubling or trippling the output will still not even come close to meeting the power needs of a country like Canada, which is huge and has a small population. Consider countries with a way higher power demand and way smaller land size.

And finally, noise. Noise is the reason you will not see urban adoption of wind technology. Even tiny ones are noisy and adding blades will just add to the noise. God forbid you be standing somewhere where the reverberation from the two blades were reaching you slightly out of phase with each other. Ever had your car window open just the wrong amount? You can literally mess with brain waves with sound, induce headaches, seisures or (on the plus side) trance-like states (no I have not seen examples of wind turbines causing trance-states, but i'm sure it could be done).


Ok on to the fat plane. Fat plane is fat. This seems to me to be a good way to transition away from fuel as a source of flight, like hybrid cars they are marrying an alternative technology with the existing status quo in order to mitigate some of the disadvantages. However, this is likely going to have the same problems with adoption as hybrids. It's dependent on the cost of the fuel. While fuel prices stay low, there's not enough motivation to pursue this stuff. And if cap and trade systems around the world are going to be as patheric as the one that was released by our gloriously green government yesterday for a 2010 roll out, this is not going to happen fast enough.

Get over your whining about your lost retirement funds people, you still have a house and a car, you are lucky. Don't be selfish, vote green

Thanks for the thoughtful response CI. Definitely have a gander at that pdf. It's a long dry read but I thought it was very interesting. Kind of shocked me as to the distribution and sources of carbon emissions. Anyways, your post above made me think more about the two technologies.

=====================================

The efficiency gain comes from the mechanics of the thing. Even if 2 props on one shaft is able to extract equal amounts of energy from the air as 1 prop on each of 2 parallel shafts, you have less running gear in the single-shafted version. 2 or 3 less bearings to create friction and 1 less generator to turn.

THere are several other advantages as well.

-High speed, low-torque props mean you use a high-speed, low-torque generator in the turbine's nacelle. These are much cheaper to produce pound for pound than the high-torque low-speed generators used in larger wind turbine installations. Larger turbines also often have gearboxes to adjust the rotor speed to something more suitable for power generation. These are a large source of friction and energy loss.

-The shaft is designed to be flexible and it's able to limit its rotation in high winds because of this. On a normal turbine, there is a mechanism at the base of the blades that feathers the blades (turns them) to be less efficient in high winds, reducing the overall rotational speed of the turbine. Makes for more maintenance and more cost, plus there is a hefty response time between blade feathering and rotational speed change...which means there are times when generation capacity isn't at a peak. On selsam's rig, the whole shaft flexes in high winds so that the downwind props get shadowed in behind the upwind props. This causes a decrease in overall energy extraction efficiency, and slows rotation. No feathering mechanism makes the whole thing much cheaper, and you have a much lower response time between speed changes because the props are smaller and don't require as much force to accelerate up to speed.

-The key to Selsam's design is density, how much energy can be extracted from the wind in a given cross section. Remember that energy extraction potential is proportional to the area of the blade cross section, not the length of the blades themselves. So, take a single prop turbine with 10 foot blades. It has an area of about 314 square feet for a total width of 20 feet. Next, take blades half the length. That gives us about 78 square feet of extraction area for a total width of 10 feet. Put 4 props like that on the same shaft and it equals 314 square feet at the same width. Now bring it to the reasonable limits of shaft and bearing design and you can get about 7 props like that on a shaft. Now you're up to 550 square feet of extraction area at exactly half the "footprint" of the larger turbine. That means more energy can be extracted on a smaller footprint than the larger turbine, using cheaper easier to maintain materials. Additionally, the lighter props mean you can operate in a lighter wind and therefore be closer to the ground. Lower tower means less materials and reduced installation costs.

All that said, they are noisy little fuckers. In fact they buzz like crazy and really wouldn't be suitable for widespread use in, say, a residential neighborhood. Where the multi turbine idea would shine is in rural areas (powering farms, unmanned research stations and whatnot) or someplace like a city where you have lots of high buildings. Noise from small turbines is miniscule compared to the overall noise at street level in a city so it would be viable from a human comfort point of view.

The idea of wind turbines on high city buildings has been an environmentalist's dream for years. However you can't build a big turbine on top of a building because the arerodynamic forces involved would rip a building to pieces. Take your standard 30-50 storey building in any large city. Chances are its structure was designed for supporting its weight, supporting the wind loading on its sides and some overdesign for seismic activity. Now put a 30 foot tower on the roof and a turbine with 20 foot blades. Unless specifically designed for it, there's no way the building could handle the weight of the turbine, let alone the forces required to hold it upright in a strong wind. Compare that to a multibladed turbine at a third the height and a fraction of the weight. Though the overall sideways force bearing on the turbine from the wind might be equal to the larger turbine, the lever arm that it's acting on is much smaller. Now you have something that is much more feasible for installation on pre-existing structures but maintains a useful generation capacity. It's something a large building operator might consider for some energy savings.

======================================

I dont' know if you can compare fatplane to the hybrid model. Hybrids are a fundamentally flawed design because they don't actually provide fuel savings on the whole. When you consider the emissions from manufacturing the whole thing, including the battery, they aren't much better emmissions-wise than trucks. Plus many people that have them don't use them in an efficient manner. The hybrid is only useful when you're doing frequent acceleration and braking...ie driving around a city on surface streets. All the people that own them and use them for commutes on freeways are wasting gas. If you're not stopping and starting your prius every few minutes (proven by research) you literally driving around a gas powered vehicle with about 500lbs extra weight tacked onto it. In fact, for highway driving, hybrids get worse gas mileage than some actually fuel efficient full size sedans (civic for example) entirely owing to the extra weight they carry. If you want to truly save gas, get a small fuel efficient gas fueled car. Hybrids are bullshit unless you're a cab driver. Small exception with the plugin hybrid, but they're still shitty.
[/rant on hybrids...goddamn I hate them]

Anyways, back to fatplane. Comparing it to a hybrid (ugh) isn't entirely accurate. Adoption of car hybrids is slow unless fuel prices are high because you need to pay a premium to own a hybrid (and its a significant premium). The whole idea behind fatplane is density...like selsam's wind turbine design. It uses so much less fuel and can transport so many passengers comfortably (compared to a jet) that right off the bat, passengers are charged significantly less for an equal distance traveled. Same goes for cargos. It doesn't matter what fuel prices are, it's going to be cheaper to fly fatplane than to fly on a jet no matter what. This massive economic saving will help with adoption regardless of fuel prices too since the thing can actually be made more cheaply than a jet plane. The fatplane just has a really good equation going for it.

More passengers per trip + novelty factor + green image - several $millions on purchase - several $millions on yearly fuel consumption = totally good idea.

EDIT: Low fuel prices are very temporary too and heavily related to the economic instability right now. Once shit levels out in another year or so, gas prices will go right back up again...mark my words. There's no way in the modern age that $40/barrel oil is going to stick around for long.

==================
[/essay]

This post has been edited by cerveza_fiesta: 16 December 2008 - 01:22 PM

[Cold Iron]

cerveza_fiesta, on Dec 17 2008, 12:11 AM, said:

Kind of shocked me as to the distribution and sources of carbon emissions.

Care to elaborate? Looks like you canukes just can't put on an extra jumper and turn down the heat (yeah, i looked at the pie graphs)

cerveza_fiesta, on Dec 17 2008, 12:11 AM, said:

The efficiency gain comes from the mechanics of the thing. Even if 2 props on one shaft is able to extract equal amounts of energy from the air as 1 prop on each of 2 parallel shafts, you have less running gear in the single-shafted version. 2 or 3 less bearings to create friction and 1 less generator to turn.

Ball bearing losses at low rotation speeds are actually really low. And as long as you service your gears, friction losses in gearboxes are also quite low. Also the turbulance caused by the other props and the shaft being in direct or peripheral proximity will also cause losses.

cerveza_fiesta, on Dec 17 2008, 12:11 AM, said:

Put 4 props like that on the same shaft and it equals 314 square feet at the same width.

Woh, hold on. The pics I'm looking at have a laterally mounted shaft with props along it's length, and the distance between each is easily larger than it's diameter. The only way to do what you're saying is to mount the props vertically along the tower, which is going to give them vastly different wind exposures, meaning the faster props are going to be losing power by dragging the slower props. As I said, I don't see how you are going to get more power per square meter out of this design, just lower materials cost.

cerveza_fiesta, on Dec 17 2008, 12:11 AM, said:

All that said, they are noisy little fuckers. In fact they buzz like crazy and really wouldn't be suitable for widespread use in, say, a residential neighborhood. Where the multi turbine idea would shine is in rural areas (powering farms, unmanned research stations and whatnot) or someplace like a city where you have lots of high buildings. Noise from small turbines is miniscule compared to the overall noise at street level in a city so it would be viable from a human comfort point of view.

Wind turbines in cities is simply not happening, not only do you have noise problems and structural problems, you also have vastly increased construction costs and really no gain. Cities cover a very small percentage of most countries total land, there is just no reason to build them there. Where the multi turbine idea would shine is in rural areas where farm owners can afford these due to the (potentially) significantly lower cost of materials and installation. I still see little advantage in this design for large scale installations for generating significant amounts of power.

cerveza_fiesta, on Dec 17 2008, 12:11 AM, said:

Anyways, back to fatplane. Comparing it to a hybrid (ugh) isn't entirely accurate. Adoption of car hybrids is slow unless fuel prices are high because you need to pay a premium to own a hybrid (and its a significant premium).

They aren't going to be cheap right off the bat. New technologies always come with a high price, there's a curve. The fuel costs of air transport, while significant, are not yet high enough that this technology would cause a significant reduction in price, even for long haul flights. More passengers is good but 500 is about the same capacity as an A380.

Think about what the saving would have to be to cause you to go for the 18hour haul over the 6 hour haul. Let's say a ticket from LAX to JFK costs around US$500 incl. tax. How much of this is fuel? Would you be surprised to hear that the cost per available seat mile on a 747-400 or a 777 is around 1.5c? At 2462 miles, you're talking about a total cost for the airline per passenger for a full flight at just under $37. How much of this is fuel? 20%? 50%? Hell lets go nuts and say it's 90%. That means the fuel cost per person equates to just over $33. Nice number for our calcs as the fat plane is going to use a third of this amount of fuel. $11 worth. So we have saved a grand total of $22 off our $500 ticket. Is this enough to get you to sit on the plane for an extra 12 hours? I don't think so. Hell let's go ahead and say the flights are only going to be half full, so we double the per person cost to $74. And lets say that the savings from shipping more passengers at once is huge, like 50% of of the total cost. So the saving now is not a lowly $22 but a whopping $59! Now we are TALKING!

cerveza_fiesta, on Dec 17 2008, 12:11 AM, said:

EDIT: Low fuel prices are very temporary too and heavily related to the economic instability right now. Once shit levels out in another year or so, gas prices will go right back up again...mark my words. There's no way in the modern age that $40/barrel oil is going to stick around for long.

We can only hope

This post has been edited by Cold Iron: 16 December 2008 - 11:45 PM

[cerveza_fiesta]

Cold Iron, on Dec 16 2008, 08:42 PM, said:

cerveza_fiesta, on Dec 17 2008, 12:11 AM, said:

Kind of shocked me as to the distribution and sources of carbon emissions.

Care to elaborate? Looks like you canukes just can't put on an extra jumper and turn down the heat (yeah, i looked at the pie graphs)

cerveza_fiesta, on Dec 17 2008, 12:11 AM, said:

The efficiency gain comes from the mechanics of the thing. Even if 2 props on one shaft is able to extract equal amounts of energy from the air as 1 prop on each of 2 parallel shafts, you have less running gear in the single-shafted version. 2 or 3 less bearings to create friction and 1 less generator to turn.

Ball bearing losses at low rotation speeds are actually really low. And as long as you service your gears, friction losses in gearboxes are also quite low. Also the turbulance caused by the other props and the shaft being in direct or peripheral proximity will also cause losses.

cerveza_fiesta, on Dec 17 2008, 12:11 AM, said:

Put 4 props like that on the same shaft and it equals 314 square feet at the same width.

Woh, hold on. The pics I'm looking at have a laterally mounted shaft with props along it's length, and the distance between each is easily larger than it's diameter. The only way to do what you're saying is to mount the props vertically along the tower, which is going to give them vastly different wind exposures, meaning the faster props are going to be losing power by dragging the slower props. As I said, I don't see how you are going to get more power per square meter out of this design, just lower materials cost.

cerveza_fiesta, on Dec 17 2008, 12:11 AM, said:

All that said, they are noisy little fuckers. In fact they buzz like crazy and really wouldn't be suitable for widespread use in, say, a residential neighborhood. Where the multi turbine idea would shine is in rural areas (powering farms, unmanned research stations and whatnot) or someplace like a city where you have lots of high buildings. Noise from small turbines is miniscule compared to the overall noise at street level in a city so it would be viable from a human comfort point of view.

Wind turbines in cities is simply not happening, not only do you have noise problems and structural problems, you also have vastly increased construction costs and really no gain. Cities cover a very small percentage of most countries total land, there is just no reason to build them there. Where the multi turbine idea would shine is in rural areas where farm owners can afford these due to the (potentially) significantly lower cost of materials and installation. I still see little advantage in this design for large scale installations for generating significant amounts of power.

cerveza_fiesta, on Dec 17 2008, 12:11 AM, said:

Anyways, back to fatplane. Comparing it to a hybrid (ugh) isn't entirely accurate. Adoption of car hybrids is slow unless fuel prices are high because you need to pay a premium to own a hybrid (and its a significant premium).

They aren't going to be cheap right off the bat. New technologies always come with a high price, there's a curve. The fuel costs of air transport, while significant, are not yet high enough that this technology would cause a significant reduction in price, even for long haul flights. More passengers is good but 500 is about the same capacity as an A380.

Think about what the saving would have to be to cause you to go for the 18hour haul over the 6 hour haul. Let's say a ticket from LAX to JFK costs around US$500 incl. tax. How much of this is fuel? Would you be surprised to hear that the cost per available seat mile on a 747-400 or a 777 is around 1.5c? At 2462 miles, you're talking about a total cost for the airline per passenger for a full flight at just under $37. How much of this is fuel? 20%? 50%? Hell lets go nuts and say it's 90%. That means the fuel cost per person equates to just over $33. Nice number for our calcs as the fat plane is going to use a third of this amount of fuel. $11 worth. So we have saved a grand total of $22 off our $500 ticket. Is this enough to get you to sit on the plane for an extra 12 hours? I don't think so. Hell let's go ahead and say the flights are only going to be half full, so we double the per person cost to $74. And lets say that the savings from shipping more passengers at once is huge, like 50% of of the total cost. So the saving now is not a lowly $22 but a whopping $59! Now we are TALKING!

cerveza_fiesta, on Dec 17 2008, 12:11 AM, said:

EDIT: Low fuel prices are very temporary too and heavily related to the economic instability right now. Once shit levels out in another year or so, gas prices will go right back up again...mark my words. There's no way in the modern age that $40/barrel oil is going to stick around for long.

We can only hope

Longquote is long.

Sorry I forgot to reply to this CI...I meant to and then it slipped my mind.

Anyways, to address your concerns:

• Gearbox efficiency is in the range of 95%. This is good, but is still an inhibitor in the wind power industry. Turbines are now being installed with direct drive generators to get around the gearbox. I'm not sure if they adjust turbine speed to regulate power output or if its handled in the electronics side of things. I'll have to ask my fiancee...she's an elec. engineer and would know better than I.
  
• They actually have a 7 bladed version of the turbines on Selsam's page...all mounted on the same shaft in-line. I know it sounds weird, but its doable with a carbon fiber reinforced shaft. The thing looks flimsy as all hell and flexes like a noodle in heavy winds but it holds together. Selsam's turbines actually outlast single-bladed turbines of the same diameter because of the advanced materials he puts into their construction. A key point of the small turbines is the light-weightedness. Because the blades on the props are so short, you can afford to make them out of lighter and weaker materials (like plastic). This in turn leads to lighter duty bearings, a smaller shaft size requirement, and a much less robust tower (all reducing cost significantly over the larger versions)
  
• You raised a concern about one prop "shading" the one behind it. Actually, the props aren't strictly in-line with the wind direction. The common shaft is inclined so that the upwind props are at a lower elevation than the upwind props. Each prop along the line is higher than the one in front of it and so is exposed to mostly undisturbed wind. The distance between the blades along the shaft is can be optimized to keep the shaft length reasonable without sacrificing too much power loss in the downwind prop. Speed regulation comes from flexure in the shaft. In a heavy wind or gust, the downwind part of the shaft flexes downward, reducing the elevation of the downwind props relative to the upwind ones, putting them behind the ones in front. This causes the overall efficiency of the system to decrease and the speed decreases accordingly. This is where the lightness of the system comes in. If you have everything built out of lightweight materials, you have very little rotating mass, which means the rotational speed is able to adapt quickly to changes in wind speed. On a larger prop, the blades have a huge rotational mass and can't adapt quickly to changing wind conditions without active control like braking.
  
• Agree with your statement about using them in cities. Its not really practical unless a company or building owner wants to make some kind of environmental statemnt. If it were for power generation alone, a vertical turbine would be a vastly superior choice in a city where wind direction is constantly perturbed by large obstructions (the buildings themselves). Vertical turbines are much less dependent on wind direction and don't make nearly as much noise. Here's another idea that would work reasonably well in a city due to its ability to get above the disturbed airflow, though it would look stupid.
  
• You're also right that rural use is the only reasonable application of the selsam turbine. I wasn't really trying to compare it to large turbines for a wind-farm type usage cos its not really the indended application. If you live someplace rural and want to generate energy for your home (and maybe to feed back into the grid), you're only probably going to erect a single tower. For the cost of the tower and turbine, it makes sense to double or triple the energy output at the same initial cost is all I'm saying.

================================

Fatplane,

Found this linke to an airline fuel cost calculator

http://www.darinlee....uel_widget.html

And got current fuel costs from

http://www.iata.org/whatwedo/economics/fue...nitor/index.htm

So, using LAX to NY, I chose the 767-200 (the one they actually fly you on), and the Feb2009 fuel price of US$ 1.25/usgal, and a round trip cost of $270 from American Airlines, we have a cost of about $130/passenger going straight to fuel.

Say with your assumption that paying for only 1/3 of the lift equals only 1/3 of the fuel (which is perfectly reasonable) we're looking at 86 bucks in savings off that ticket price from fuel.

Not that much, and certainly not enough to justify the extra 12 hours or whatever it would take for the fatplane to make the trip.

Now, going back to 2008 prices (which are a more reasonable assumption for 2-3 years from now) at $2.25/usgal, you have $235 on of the ticket price going toward fuel, which means fatplane saves you $156...still not great but starting to look more attractive.

Add to this the other factors in ticket price, which include depreciation of the airplane, pilot salary, support staff salary, maintenance and parts. Pilot and support staff portions aren't going to change much. Depreciation and maintenance are where Aeroscraft claims they'll make more savings. They claim 30% less capital to build the thing / tonne of payload and 50% less maintenance cost. Don't ask me where that comes from exactly...the source is the company's website, so we can assume that would be a best-case scenario. At any rate, those savings translate directly into a reduction of ticket price since the fatplane simply doesn't cost as much to purchase and run overall.

All that said, the long-haul flight isn't where the aeroscraft is expected to shine. In fact its being marketed (commuter-wise) to the short-haul flight market. Large jet airliners simply aren't profitable to run unless you're going a long ways because of the way they use fuel. Whether you're going trans-continental or on a 1 hour flight, a 737 still needs to reach cruising altitude to operate efficiently, at 38000-41000 feet. The problem is that a 737 uses half to 60% its fuel just getting to that altitude, so no matter how far you're going in a 737, it costs you at least half a tank of fuel. This is why short-haul flights can be the same cost or more expensive than a trans-continental flight. Once at cruise, the plane really doesn't use much fuel at all and on the descent it uses even less.

Its for this reason, you see a lot of airlines (like Air Canada) use turboprop airplanes for short haul flights. The Dash-8 has a cruise altitude of only 25000 feet and its propulsion is more efficient per gal of jet fuel than a turbofan (737 engine). The aeroscraft is designed for only about 8000 feet cruising altitude and it also uses turboprop engines, making it ideal for short-haul commuting. In the short haul, the speed difference doesn't translate into such a huge time difference either, making that $100 savings (or whatever it happens to be) on the ticket more attractive.

That's my best explanation to justify the aeroscraft. Makes sense to me. I mean, for a JFK-LAX trip, I'd pay an extra 100 bucks to save myself the extra half-day sitting on an airplane. For a Fredericton to Toronto trip, I might consider it. Then when you get into transporting cargo, unless its sameday courier stuff, who cares if it takes 18 hours to go JFK-LAX? If its cheaper, the courier companies will spring for it since they aren't as concerned with stuff like passenger comfort and occupant boredom.

EDIT: http://science.howst.../aeroscraft.htm

thats' a pretty good rundown on the aeroscraft. It references the official site so they aren't just making shit up.

The only thing that's for sure BS on there is the fuel-cell powered props. I can't see fuel cells giving enough power, they just suck too bad.

This post has been edited by cerveza_fiesta: 09 March 2009 - 01:32 PM

[Cold Iron]

cerveza_fiesta, on Mar 10 2009, 12:19 AM, said:

• Gearbox efficiency is in the range of 95%. This is good, but is still an inhibitor in the wind power industry. Turbines are now being installed with direct drive generators to get around the gearbox. I'm not sure if they adjust turbine speed to regulate power output or if its handled in the electronics side of things. I'll have to ask my fiancee...she's an elec. engineer and would know better than I.

Comparison of direct-drive and geared generator concepts for wind turbines said:

The objective of this paper is to compare five different generator systems for wind turbines, namely the electrically-excited and the permanent-magnet excited direct-drive generator system, the permanent-magnet and the doubly-fed induction generator system with single-stage gearbox and the doubly-fed induction generator system with three-stage gearbox. The comparison is based on cost and annual energy yield for a given wind climate. The doubly-fed induction generator with single-stage gearbox seems the most attractive in terms of energy yield divided by cost. The doubly-fed induction generator with three-stage gearbox is a cheap solution using standard components. The permanent-magnet direct-drive generator has the highest energy yield, but although it is cheaper than the electrically-excited direct-drive generator, it is more expensive than the generator systems with gearbox.
http://ieeexplore.ieee.org/Xplore/login.js...1394.pdf?temp=x

cerveza_fiesta, on Mar 10 2009, 12:19 AM, said:

• You're also right that rural use is the only reasonable application of the selsam turbine. I wasn't really trying to compare it to large turbines for a wind-farm type usage cos its not really the indended application. If you live someplace rural and want to generate energy for your home (and maybe to feed back into the grid), you're only probably going to erect a single tower. For the cost of the tower and turbine, it makes sense to double or triple the energy output at the same initial cost is all I'm saying.

Agreed!

cerveza_fiesta, on Mar 10 2009, 12:19 AM, said:

Fatplane,

Found this linke to an airline fuel cost calculator

http://www.darinlee....uel_widget.html

And got current fuel costs from

http://www.iata.org/whatwedo/economics/fue...nitor/index.htm

Just googled for mine and used the first crap i found, so I'm happy to admit your numbers are more realistic.

cerveza_fiesta, on Mar 10 2009, 12:19 AM, said:

The aeroscraft is designed for only about 8000 feet cruising altitude and it also uses turboprop engines, making it ideal for short-haul commuting. In the short haul, the speed difference doesn't translate into such a huge time difference either, making that $100 savings (or whatever it happens to be) on the ticket more attractive.

That's my best explanation to justify the aeroscraft. Makes sense to me. I mean, for a JFK-LAX trip, I'd pay an extra 100 bucks to save myself the extra half-day sitting on an airplane. For a Fredericton to Toronto trip, I might consider it. Then when you get into transporting cargo, unless its sameday courier stuff, who cares if it takes 18 hours to go JFK-LAX? If its cheaper, the courier companies will spring for it since they aren't as concerned with stuff like passenger comfort and occupant boredom.

Depending on the geographic layout you are starting to compete with rail and road in the short haul stuff, especially when you take into account that an airport is never the final destination. If you have a very short busy route over a body of water or mountains I can see fat plane competing. Perhaps London to Dublin or Singapore to Hong Kong.

This post has been edited by Cold Iron: 10 March 2009 - 10:58 PM

[cerveza_fiesta]

I wish I was still at the university so I could access IEEE for free. It was pretty badass being able to access all that stuff for no money. It's damned expensive to do research on your own.

Quote

Depending on the geographic layout you are starting to compete with rail and road in the short haul stuff, especially when you take into account that an airport is never the final destination. If you have a very short busy route over a body of water or mountains I can see fat plane competing. Perhaps London to Dublin or Singapore to Hong Kong

Very much agreed. The reason I used Fredericton to Toronto for an example is because of Fredericton's remoteness from Toronto by road/rail.

In a personal vehicle, the trip can be done in 15-16 hours, on a bus/train its in the vicinity of 20-24 hours. I used to make the trip lots, but they've completed several major sections of divided highway since then so my numbers might be a bit high.

Regardless, a trip from fredericton to toronto, even in a dash-8 turboprop plane, is only about 1.5 hours, making it a very attractive commuter option even when you include the transit time and general airport / taxi fuckaroundedness on either end. Say the fatplane does that trip in 3 hours (based a cruise velocity of 275km/h -- half that of the Dash-8), its still competitive with road and rail timewise.

I don't know if you're in N. America or not Cold Iron. If you're not and haven't been here, we have an unbelievably shitty rail system compared to the developed parts of europe and asia. Flying in N. America is often a cost and time effective means of travel compared to just about anything else. I see the fatplane being of great use in the US and Canada to passengers. Fatplane's primary market is going to be goods transport anyway...I doubt the commuter division of aeroscraft will ever be its mainstay.

This post has been edited by cerveza_fiesta: 17 March 2009 - 12:43 PM

[cerveza_fiesta]

Double POST!

Since we mostly agree on Fatplane and Selsam turbines (or at least have discussed them to death) let me raise a new question?

Has anybody seen a rigorous carbon emission or energy consumption comparison of electric-only cars vs. gasoline-only cars? I was looking for a bit but couldn't really find anything overly specific.

Not just talking about something on some guy's blog either...I would like to know definitively which is truly more efficient when you consider all the factors. The gas side is pretty basic, you start with crude oil and then multiply in:

• bulk transportation efficiency from the middle east (or whatever), related to the energy used by a tanker ship for example.
  
• refining efficiency
  
• distribution efficiency, including transportation and storage
  
• engine/drivetrain efficiency of the end-user's car.

on the electric side there's several more factors, starting with crude oil (for comparison's sake assume no hydroelectric)

• bulk transportation efficiency
  
• refining efficiency
  
• bulk refined fuel distribution efficiency
  
• combustion efficiency
  
• generation efficiency
  
• losses during transmission and transformation at high voltage
  
• losses during distribution and transformation to household voltage
  
• charging efficiency of the battery (which I've read is really really good now compared to 10 years ago)
  
• discharging efficiency
  
• motor/drivetrain efficiency

I suppose we can figure this out for ourselves. Anybody (CI perhaps) care to hazard a percentage on one or more of the points and cite sources? Could be an interesting excercise. Afterward we can compare that to electricity from hydro/nuclear or something.

Oh yeah, and suggest any points I might be missing.

This post has been edited by cerveza_fiesta: 17 March 2009 - 01:17 PM

[Cold Iron]

CF this depends on way too many factors to safely make generalised comments. In Australia, for example (where I'm from) most of our power (80%) comes from coal that is mined in close proximity to the power station, so we don't have significant losses from transporting fuel, however, this means that the quality of the coal isn't always great, so we have higher combustion losses than if you were to import high quality coal. Most of the rest of the 20% comes from hydro, which is also by nature local to the source, and we have a huge country, so by far and away the biggest losses for us is transmission. For these reasons, electric cars that use the grid to charge would be far less efficient and more carbon intensive here than regular internal combustion. This is why hybrids are really good here, I'd like to see hybrids with regen braking, PV roof and thermocoupled exhaust.

It really depends on your coutry's topography and energy scheme. I'd say places with high percentage of low carbon electricity grids like France and Iceland would do very well with plug in electrics. New world countries like Aus, Canada and US not so much.

[cerveza_fiesta]

Cold Iron, on Mar 17 2009, 08:38 PM, said:

CF this depends on way too many factors to safely make generalised comments. In Australia, for example (where I'm from) most of our power (80%) comes from coal that is mined in close proximity to the power station, so we don't have significant losses from transporting fuel, however, this means that the quality of the coal isn't always great, so we have higher combustion losses than if you were to import high quality coal. Most of the rest of the 20% comes from hydro, which is also by nature local to the source, and we have a huge country, so by far and away the biggest losses for us is transmission. For these reasons, electric cars that use the grid to charge would be far less efficient and more carbon intensive here than regular internal combustion. This is why hybrids are really good here, I'd like to see hybrids with regen braking, PV roof and thermocoupled exhaust.

It really depends on your coutry's topography and energy scheme. I'd say places with high percentage of low carbon electricity grids like France and Iceland would do very well with plug in electrics. New world countries like Aus, Canada and US not so much.

You've got a point there in the first line, but the rest of your post is exactly the thinking you need to do one of these analyses.

Make assumptions (location, distance of fuel to generator, etc...) and state them clearly so that everybody knows where the number came from. Then when you want to extend the analysis to another set of assumptions, you have a starting point.

For starters, do you think it would be logical to invent a hypothetical location where the IC engines and the powerplants use similar base fuel sources (crude oil in this case)? Kind of a worst-case scenario.

IMO it would be, because then you can more effectively compare the efficiency of the grid and transmission systems vs. transportation and combustion of refined gasoline. It would be a complex case that could easily be simplified later on to examine places where you have large percentages of your power coming from Hydroelectric...or nations with large oil reserves of their own....or any ofthe other things you mention above.

What you think?

[Cold Iron]

Even within one country it comes all the way down to individual location and habits, i would end up creating assumptions past the point of relevancy to anybody real. Given a lot of average data, you could feasibly make a world map of areas where electric cars would be less carbon intensive than IC. I'm not inclined to make an attempt at that just for this forum, however.

The bottom line is the way we generate electricity. I see no magic bullet. My current opinion is that like a human needs a healthy balanced diet, the best energy policy is to have spread and balanced generation. I'd like to see each energy generation method have it's own government body with it's own allocated budget. Part of the problem in Australia at the moment is that we still have state governments too tied up in what has now really become a federal issue.

[Gwynn ap Nudd]

Cold Iron, on Mar 17 2009, 03:38 PM, said:

It really depends on your coutry's topography and energy scheme. I'd say places with high percentage of low carbon electricity grids like France and Iceland would do very well with plug in electrics. New world countries like Aus, Canada and US not so much.

Just curious, but you seem to be lumping in Canada as having high carbon emitting electrical generation. Has cold climate hydro power suddenly been branded a high carbon emitter or is producing two thirds of the countyr's electrical power with hydro not enough to qualify as a lower emission grid?

[Cold Iron]

Apologies, you are right.

[cerveza_fiesta]

@CI

I guess what I'm getting at above is whether or not an electric car makes sense across the board. I've read that they're better carbon / energy use-wise regardless of the methods used to generate the electricity (even usng oil/coal power). I just wanted to do a calc and see if it was BS or not.

I don't think I've read a proper comparison of the 2 vehicle types before. I'm sure there's one out there anyway.


Back to the wind turbines:

My boss sent me this link

http://www.treehugge...icient_wind.php

on ducted wind turbines. The article is a piece of crap, but the idea seems like a good one.

Ducted fans are much more efficient at moving air / extracting energy from air than non-ducted fans since they reduce energy loss at the blade tips, enabling a much smaller fan to be used to generate the same amount of torque on the output shaft. From what I was able to find in a few quick searches however makes me think more about it

• Advantage - Ducted design accelerates flow entering the plane of the blades, allowing the turbine to operate at higher-than-ambient wind velocities
  
• Advantage - Ability to operate in lower wind speeds than conventional open-prop designs due to the increased velocity created by the duct
  
• Advantage - Reduced tip losses on the prop blades means smaller turbines can generate the same power as a larger open-prop turbine
  
• Advantage - Improved efficiency with stator fins in the duct that steer incoming / outgoing air to take maximum advantage of the blade aerodynamics and to reduce swirl on outgoing air (thereby reducing wasted energy).
  
• Advantage - lighter, smaller prop changes speed more quickly with changes in wind speed, making it more efficient in highly variable winds.
  
• Disadv - Duct is very heavy and needs beefy support structure
  
• Disadv - Duct design is critical to efficiency, and tolerance between the duct and blade tips must be very very close to maintain efficiency.
  
• Disadv - More directionally sensitive, meaning that the turbine performs poorly when the wind direction is shifting more rapidly than it can adjust its angle to the oncoming breeze
  
• Disadv - More cost in producing the shroud and the support structure.

Dunno if this is a good idea. What do you guys think? Read much about this?

[Cold Iron]

I can see this working in areas really consistent wind direction. Large tunnels with multiple turbines even.

[Cold Iron]

cerveza_fiesta, on Mar 23 2009, 10:44 PM, said:

I've read that they're better carbon / energy use-wise regardless of the methods used to generate the electricity (even usng oil/coal power). I just wanted to do a calc and see if it was BS or not.

I would lay money on this being bs.

[cerveza_fiesta]

Here's a PM sent to me by another forum member. I figured I'd post it in here along with my reply. Any thoughts?

Quote

Hey CF,

I figured you were the most likely person to know the answer to this (or at least point me in the right direction). Last year I recall reading a big write-up in the paper about 3-4 companies putting generators in the Bay of Fundy to try and harness the tidal power there. These were all prototypes, and whoever built the most effective one was liable to get the rights to produce more (if I'm remembering this correctly).

My question is, do you know what companies were involved in this project? I figure it might be a good project to invest in while it's still in the early stages (assuming it hasn't been benched 'til the economy picks up).

Much thanks!

-Ano (Chris)

Yo.

This is a project idea that's been going on since at least the late fifties. There was even a project where they thought of damming off the entire of Passamaquoddy bay (a small bay north of Grand Manan, off the bay of Fundy near its mouth) in an effort to harness the high-velocity tidal flow between the bay's barrier islands. It was squashed for obvious environmental reasons and because they figured silt buildup would fuck with the natural resonance of Fundy and cause a reduction in the tide height.

The same idea has been proposed for the smaller bays at the eastern end where the Bay of fundy forks...basically dam off a tine of the fork. AFAIK the dam idea was squashed for the same reasons as above.

http://www.cbc.ca/ne...idal-power.html
http://bayoffundy.blogspot.com/2007/10/bay...velopments.html
http://www.maritimet...technology.html

The above links are what's being proposed as an alternative to dams. Imagine long lines of these underwater wind turbines running along the mouths of smaller bays and coves along the shores of the Bay of Fundy. Much less efficient at energy extraction obviously, but the tidal currents are sufficient to push the blades around in a reliable, predictable fashion. As far as anybody knows you'd have to get them pretty densely packed to impact the overall resonance of the bay and they cause little sediment buildup.

The problem arises in the cost-benefit analysis. On the surface it seems a great idea, but you need to pound this gigantic shaft into the sea floor and mount a huge turbine to it all to get 300 measly KILOwatts of power (see the 3rd link), where your average coal combustor generates 300 MEGAwatts of power. Nice idea on the surface but you just can't generate enough energy at a high enough density to make it financially feasible. Hence why people concerned with "the bottom line" are more in favour of damming. Much better energy extraction efficiency. Damming has its own disastrous environmental consequences on the local wildlife habitat (not to mention potential permanent disruption of the tide cycle), and I sincerely doubt the canadian government would allow it.

Anyways, that's about all I've heard. You can find out lots more online.

CF

[cerveza_fiesta]

To resurrect what was IMO a cool thread

Was just reading about this new design for a wind turbine by Honeywell

http://www.gizmag.co...-turbine/11990/

It uses magnets at the blade tips which generate the electric potential inside the ring that encircles the fan.

Takes advantage of the higher tip velocity, removes the need for a central axle, gearing and separate generator.

It's designed for the small turbine market and claims to generate power with windspeeds down around 2mph. Not sure what it uses for wind direction sensing, but it must accomplish that somehow.

[Cold Iron]

Fuck that's pure unadulterated brilliance!

Meanwhile, I'm talking to people in the transmission and distribution business that are very unhappy about having current flowing back from household devices like these or PV panels - the power quality coming out of cheap inverters is pretty poor. I for one think man up and upgrade your grid, but it definitely means a lot of investment to do this. Lots of profit to be made by the big boys in more traditional products like var compensators and capacitor banks.

Also, 2000kWh should be more like half your annual household usage, not 15% as stated.

I'm looking to buy a house in about 2-5 years so it's a perfect time to kit it out with all this cool shit. We (finally) get a premium rate for renewable generation in my state, 60c/kWh, about 4 times what we pay, so electricity for me will be a revenue not an expense. Think of the profits when you go on holidays!!

This post has been edited by Cold Iron: 11 March 2010 - 10:10 PM