Can this satisfy the world's energy needs? High-altitude wind power.

[Orefa]

Maybe accessory "wings" can be added between the generator and the ground just to help hold the weight of the conductors and/or tethers.

 

[Astronuc]

I guess one issue will be airspace - it will have to blackout and avoided - which might not be a problem if the area is limited out west some where.

I'll have to look at the details, but how much work/power has to be done to keep the generating system airborn vs how much energy is transmitted.

And what to do about storms and wind shear?

 

[Ivan Seeking]

I set it up knowing it would fail, but I didn't set it up to fail. It failed on its own. I chose aluminum because aluminum exists. Spider silk...spider silk?? We can't mass-produce spider silk (or carbon nanotubes, for that matter). Once you start requiring technology that doesn't exist just to make the numbers work, you've moved over into science fiction.

Even the rope that I linked can carry 181,000 Lbs, while presenting a 13,000 pound load, at 30,000 feet. And we haven't even talked about carbon fibers, Kevlar, etc.

Wings on the tether is an interesting idea. That's basically what is done with power lines.

I keep thinking that a flying wing, perhaps with a gyro assist, makes sense. I too am curious about the lift that must be generated. The high voltage generators should help to minimize the load but I couldn't find a data sheet that showed the weight. Still, I know that we can build really big beautiful wings that can carry a great deal of weight. This could make the energy demand for lift a moot point, less the drag load.

No answer from the company. If they don't respond within a few days I'll call.

So how about it aerospace engineers: What are the basic equation needed here to calculate the efficiency of the system as a function of the power needed for lift?

 

[joema]

The problem isn't the tether. You can easily find conventional materials of sufficient strength-to-weight ratio. At 115 kilovolts you can pump 10 MW across a #1 gauge aluminum wire, which weighs 77 lbs per 1000 ft. Or you could beam it to the ground with microwaves.

However, like many alternative energy concepts the problem isn't getting a few demonstration examples to work. The problem is scaling it to the huge industrial levels needed to make a major contribution.

It makes no difference if hydrogen fuel cells or FEGs or anything else works on a small scale, if it can't be scaled to the gigantic level required for world energy consumption. As the thread title says, could it satisfy WORLD energy need, not a few megawatt hours in a demonstration facility.

We tend to think if it works on a small scale, someone will figure out how to scale it up. That's backward. If it can't be scaled up, there's no need to even consider it.

To investigate ultimate feasibility, don't work numbers for tethers. Rather work backward and calculate what's required to supply 1.18E17 watt hours per year.

Doing that indicates FEGs are probably not feasible as the primary world energy supply.

 

[Ivan Seeking]

To investigate ultimate feasibility, don't work numbers for tethers. Rather work backward and calculate what's required to supply 1.18E17 watt hours per year.

Doing that indicates FEGs are probably not feasible as the primary world energy supply.

Why?

,,,,,,,,,,,,

 

[joema]

If you mean why examine whether an alternative energy source can scale upward to supply a significant fraction of world demand, the answer is obvious: if it can't, it's mainly an interesting curiosity.

If you mean why doing so implies FEGs likely can't supply the world's energy needs (the thread title), as I stated before the math and implications are very simple. It would require 18 million 1.5 MW FEGs.

The website mentions using 20 MW FEGs without any analysis of whether that's actually possible. The largest terrestrial wind turbine ever made is the REPower 5M, a 5 megawatt unit with a rotor diameter of 126 meters. It weighs 120 tons. Each rotor blade weighs 18 tons. You'd need something maybe TWICE that size -- flying overhead -- for a single 20 MW FEG (accounting for higher rotor disc areal efficiency).

Then to supply the world's energy needs, you'd need 792,371 of those -- 1.18E17 watt hrs/yr / 149E9 watt hr/yr/FEG. It's should be obvious that's not realistically possible.

 

[Ivan Seeking]

If you mean why doing so implies FEGs likely can't supply the world's energy needs (the thread title), as I stated before the math and implications are very simple. It would require 18 million 1.5 MW FEGs.

The website mentions using 20 MW FEGs without any analysis of whether that's actually possible. The largest terrestrial wind turbine ever made is the REPower 5M, a 5 megawatt unit with a rotor diameter of 126 meters. It weighs 120 tons. Each rotor blade weighs 18 tons. You'd need something maybe TWICE that size -- flying overhead -- for a single 20 MW FEG (accounting for higher rotor disc areal efficiency).

You are assuming the same wind conditions as for the land based design, but that is a great deal of weight.

According the web site, for a given amount of power, it would use relatively smaller turbines due to the increased wind velocity as compared to land based turbines. And at least on the face of things, there is no reason why many turbines couldn't be used on a single platform. Why not make a large wing with ten or twenty of them onboard?

I keep thinking of an old design by NASA intended for overseas flights which involved a large flying wing to which 747's would dock at 30,000 feet. The wing was designed to remain in constant flight and could service four or five passenger planes at any time. The passengers would deplane and relax in the football field sized lounge. Again, the point being that we are really good at building fantastically large wings.

Then to supply the world's energy needs, you'd need 792,371 of those -- 1.18E17 watt hrs/yr / 149E9 watt hr/yr/FEG. It's should be obvious that's not realistically possible.

I'm not so quick to give up. How many cars, planes, and ships do we build? How many nuclear power plants would be required to produce the same amount of power, ~20,000? What is the cost of a nuclear plant compared to a platform like this? What is the liability? How long will it take to build 20,000 nuclear plants? And what are the chances that they could ever be built given the political climate and terror concerns.

After all we are talking about the entire planet. The idea of 800,000 generators isn't really so striking to me. In fact no matter what we do for energy, we have many of the same problems.

 

[Ivan Seeking]

One more thought for perspective: We are talking about replacing the entire world's energy infrastructure with one shot. We have to be able to imagine what already exists - all other sources of energy, their distribution systems, and all of the related political and environmental issues that go along with it.

 

[Ivan Seeking]

4. Airbus A380F 1,305,000 lb L: 239'3";S: 261'8"

That's 650 Tons

I didn't spot the maximum take off speed, but it wouldn't be more than 200 MPH, I would think. At that point I would think that most of the lift is generated by the body and wings?

 

[joema]

You are assuming the same wind conditions as for the land based design, but that is a great deal of weight.

Higher winds aloft mean higher stress. That in turn means more complexity and development and production expense for the same power output. It's much harder and more expensive to make light sophisticated things (e.g, airplanes) than heavy things (e.g, cars).

According the web site, for a given amount of power, it would use relatively smaller turbines due to the increased wind velocity as compared to land based turbines.

I already factored that in, by allowing a 2x reduction in size. However you lose some because you expend lift holding the huge contraption up. 2x the areal efficiency of a terrestrial turbine probably isn't far off, and that still equates to gigantic mass overhead, vastly beyond anything ever conceived thus far.

And at least on the face of things, there is no reason why many turbines couldn't be used on a single platform. Why not make a large wing with ten or twenty of them onboard?

You could if you wanted 10 or 20 hundred foot diameter rotors spinning on the same structure. However that is vastly beyond any aerodynamic construction ever seriously considered.

...large flying wing to which 747's would dock at 30,000 feet. The wing was designed to remain in constant flight and could service four or five passenger planes at any time. The passengers would deplane and relax in the football field sized lounge. Again, the point being that we are really good at building fantastically large wings.

We are good at talking about it (and many other things) -- see Popular Science cover stories over the past 50 years. Most of those are never built and cannot ever be built.

I'm not so quick to give up. How many cars, planes, and ships do we build? How many nuclear power plants would be required to produce the same amount of power, ~20,000?

Using the Palos Verde nuclear plant mentioned on the SkyWindPower site, it would take 4,129 to supply the world's energy needs.

What is the cost of a nuclear plant compared to a platform like this? What is the liability? How long will it take to build 20,000 nuclear plants? And what are the chances that they could ever be built given the political climate and terror concerns.

I'm not saying a gigantic nuclear effort is clearly the answer, either. But just because there are problems with nuclear, or biofuel, etc, doesn't automatically mean some other alternative will work.

After all we are talking about the entire planet. The idea of 800,000 generators isn't really so striking to me. In fact no matter what we do for energy, we have many of the same problems.

That's exactly right -- there are problems with virtually all energy solutions, so picking one that's practically achievable is important.

 

[joema]

4. Airbus A380F 1,305,000 lb L: 239'3";S: 261'8"

That's 650 Tons

I didn't spot the maximum take off speed, but it wouldn't be more than 200 MPH, I would think. At that point I would think that most of the lift is generated by the body and wings?

You essentially need a gigantic helicopter, not a gigantic fixed-wing plane. As anybody familiar with aviation will corroborate, helicopters are much more expensive and complex than fixed-wing aircraft, and have much less lift capability.

E.g, the heaviest lift US plane, the C-5B Galaxy, can lift about 261,000 lbs. By contrast the heaviest lift US helicopter, the CH-53E, can lift about 30,000 lbs. Rotor-wing craft also also require far more maintenance than fixed wing. An FEG is much closer to a helicopter than a fixed-wing plane.

 

[Ivan Seeking]

Higher winds aloft mean higher stress. That in turn means more complexity and development and production expense for the same power output. It's much harder and more expensive to make light sophisticated things (e.g, airplanes) than heavy things (e.g, cars).

This may or may not be a significant issue. I don't think we can say at this point.

I already factored that in, by allowing a 2x reduction in size. However you lose some because you expend lift holding the huge contraption up. 2x the areal efficiency of a terrestrial turbine probably isn't far off, and that still equates to gigantic mass overhead, vastly beyond anything ever conceived thus far.

What I am saying is that we use a high-lift wing, not a gyro. The energy needed for lift then becomes a function of the wing size and not the turbine size. It becomes a tether and structure problem, and not an power problem.

You could if you wanted 10 or 20 hundred foot diameter rotors spinning on the same structure. However that is vastly beyond any aerodynamic construction ever seriously considered.

Well, at ten or twenty, I was talking about smaller turbines. But the point is that I have seen serious design concepts that were more radical. For now I'm thinking about something on the scale of the Airbus, and all we really need are the wings.

We are good at talking about it (and many other things) -- see Popular Science cover stories over the past 50 years. Most of those are never built and cannot ever be built.

same as above

Using the Palos Verde nuclear plant mentioned on the SkyWindPower site, it would take 4,129 to supply the world's energy needs.

Okay, I thought ~1 GW was the state of the art. But then we are still talking about plants that are five times larger.

I'm not saying a gigantic nuclear effort is clearly the answer, either. But just because there are problems with nuclear, or biofuel, etc, doesn't automatically mean some other alternative will work.

That's exactly right -- there are problems with virtually all energy solutions, so picking one that's practically achievable is important.

Well, obviously there are alternative that are competitive in some areas now, but until now, no alternative to oil were viable globally except nuclear, using existing technology. In principle we could probably start building FEGs tomorrow. And if we can completely eliminate the risk of nuclear power and all of the related problems, what are the potential savings - a city, maybe much more?

The FEG idea also creates an implicitly robust grid with many generators distributed over the system, rather than having a highly centralized system. This even speaks to issues such as national security beyond the immediate concerns of a nuclear disaster.

Again, the rotor idea doesn't make sense to me either. A tethered wing with at least two counter rotating turbines could make much more sense. And again, the Airbus can take off with a max weight of 650 tons. This easily could lift two of your turbines, the generators etc, at least at ground level, and at something close to high altitude wind speeds. So we are already in the ball park with an existing, off-the-shelf wing. Of course a better design is easy to imagine but the point is that scale is there.

 

[Ivan Seeking]

Can we talk Iran into FEGs?

 

[joema]

This may or may not be a significant issue. I don't think we can say at this point.

A terrestrial 5MW wind turbine weighs 120 tons. Building a flying version with equivalent output would be vastly more expensive. Ask any engineer experienced in the area -- reducing weight while maintaining capability is almost always very expensive and complex.

What I am saying is that we use a high-lift wing, not a gyro. The energy needed for lift then becomes a function of the wing size and not the turbine size. It becomes a tether and structure problem, and not an power problem.

You're right if you could depend on approx 150 mph lateral winds, a tethered flying wing the size of a C-5B could lift about 118 metric tons. You can only count the payload weight, not the entire vehicle weight, as the wings must also lift the vehicle.

Considering a C-5B-size wing alone (no turbines) with a 10:1 lift/drag ratio, the drag would be 11.8 metric tons. To this you must add the drag force of the turbines and associated structure. A 20 MW turbine might have a turbine airfoil area of 1512 m^2 (roughly 2x the above-mentioned 5 MW terrestrial turbine). Assuming 10 degree angle of attack, the blade frontal area would be about 276 m^2, and drag coefficient (Cd) would be about 0.1. More info: http://www.risoe.dk/rispubl/VEA/veapdf/ris-r-1024.pdf Equation for drag force is:

Fd = cd 1/2 rho v^2 A, where

Fd = drag force (Newtons)
cd = drag coefficient (0.1 for C6 Corvette)
rho = density of fluid in kg/m^3, 0.56 kg/m^3 at sea at 20k ft
v = velocity in m/sec (150 mph, or 67 m/s)
A = frontal area in sq. meters (roughly 276 square meters)

Fd = 0.1 * 0.5 * 0.56 * 67^2 * 276
Fd = 34690 Newtons (7798 lbs force)

So at least the drag force from the turbine blades themselves seems low.

However you'd need a tether capable of carrying itself plus a 11.8 metric ton load, plus an approx 2x safety margin, so call it 25 metric tons. That appears no problem, even using conventional ropes: http://www.samsonrope.com/home/newcommfish/gp-2in1superstrongnylon.cfm?ProdNum=158

A 20,000 ft tether constructed of the above 1.5 inch line could restrain 34 metric tons (inc'l its own weight), and would itself weigh 5.4 metric tons.

obviously there are alternative that are competitive in some areas now, but until now, no alternative to oil were viable globally except nuclear, using existing technology.

The initial post asked about satisfying world energy need, not world petroleum consumption. Petroleum only accounts for very roughly 40% of world energy consumption, but is by far the most time-critical energy issue since at current rates conventional oil will be depleted in about 35 years, and peak oil will happen far sooner. By contrast there's enough coal for a 200 years at current consumption rates.

There is an existing alternative to oil using current technology, which is biodiesel from high yield algae. In theory that could supply world petroleum energy consumption within available acreage and construction/maintenance costs. Obviously remaining research is needed, but it could use existing production, transportation, and vehicle technology: http://www.unh.edu/p2/biodiesel/article_alge.html

In principle we could probably start building FEGs tomorrow. And if we can completely eliminate the risk of nuclear power and all of the related problems, what are the potential savings - a city, maybe much more?

The most time critical energy issue is petroleum, not energy (nuclear, coal, etc) for utility generation. Even if FEGs worked, using them for transportation energy via hydrogen/fuel cells would take many decades and entirely new vehicle and distribution infrastructure. Oil would be depleted long before that transition could happen.

The FEG idea also creates an implicitly robust grid with many generators distributed over the system, rather than having a highly centralized system.

The current energy production and distribution system is already highly distributed, with many generators spread across the system.

 

[Ivan Seeking]

A terrestrial 5MW wind turbine weighs 120 tons. Building a flying version with equivalent output would be vastly more expensive. Ask any engineer experienced in the area -- reducing weight while maintaining capability is almost always very expensive and complex.

If you mean to say that this is proof that it can't work, no way. We can't possibly know. At most is a concern. But since we have been building wings with props for over a hundred years now, I tend to doubt that this is a serious issue. It obviously does represent a focal point of the design.

You're right if you could depend on approx 150 mph lateral winds, a tethered flying wing the size of a C-5B could lift about 118 metric tons. You can only count the payload weight, not the entire vehicle weight, as the wings must also lift the vehicle.

We wouldn't have to carry most the weight of the vehicle. We only need the wings void of fuel and engines. Also, we don't need the fuselage, wheels, AC, most flight controls, etc. And again, this was only for comparison with existing technology. We could easily come up with a more appropriate design for this application.

Considering a C-5B-size wing alone (no turbines) with a 10:1 lift/drag ratio, the drag would be 11.8 metric tons. To this you must add the drag force of the turbines and associated structure. A 20 MW turbine might have a turbine airfoil area of 1512 m^2 (roughly 2x the above-mentioned 5 MW terrestrial turbine).

Edit: Sorry, I guess I don't understand the point

... oh, okay, were you just working this through?

The initial post asked about satisfying world energy need, not world petroleum consumption. Petroleum only accounts for very roughly 40% of world energy consumption, but is by far the most time-critical energy issue since at current rates conventional oil will be depleted in about 35 years, and peak oil will happen far sooner. By contrast there's enough coal for a 200 years at current consumption rates.

We still don't have clean coal. Not really a viable solution as yet.

There is an existing alternative to oil using current technology, which is biodiesel from high yield algae. In theory that could supply world petroleum energy consumption within available acreage and construction/maintenance costs. Obviously remaining research is needed, but it could use existing production, transportation, and vehicle technology: http://www.unh.edu/p2/biodiesel/article_alge.html

Not yet viable. And we still have the problem of 100-200 watts per sq meter yield.

The most time critical energy issue is petroleum, not energy (nuclear, coal, etc) for utility generation. Even if FEGs worked, using them for transportation energy via hydrogen/fuel cells would take many decades and entirely new vehicle and distribution infrastructure. Oil would be depleted long before that transition could happen.

We have this problem no matter what we do.

 

[Ivan Seeking]

I want to stress that I have been and am a huge supporter of all sorts of energy alternatives, but something that is always frustrating is the fact that nothing is quite there yet. And even something like biodiesel is still dirty and problematic, but its definitely worth doing from all that I see.

As for Bio-Willy, a flukey thing: We once took his private bus for a 1000 mile joy ride, for a long weekend. Back then he had this cool King Tut theme going. Anyway, long story but it was pretty cool.

 

[joema]

If you mean to say that this is proof that it can't work, no way. We can't possibly know...we have been building wings with props for over a hundred years now...

Not saying it CAN'T work, but it's likely economically unfeasible. Howard Hughes built the largest ever prop plane, but you don't see prop planes of that size flying today. Just because it CAN be done doesn't mean it's economically and technically feasible to do on a vast industrial scale.

We still don't have clean coal. Not really a viable solution as yet.

Not a viable solution? Today coal provides 24% of world energy. It has already happened. You have to prioritize. The highest priority is transportation energy, not utility energy. If you allocate most resources now to developing new utility energy (when existing sources will last over 100 years) and transportation energy runs out in 30 years, what is the benefit?

Not yet viable. And we still have the problem of 100-200 watts per sq meter yield.

It's far more viable and less expensive than building a million 747-size wind turbines, hundreds of million new fuel cell cars, tens of millions new hydrogen fuel stations, etc. I have no idea what you mean by 100-200 watts/m^2 yield. If you read the web site, you'll see the yield is over 100x other common biofuel feedstocks, and the total acreage easily fits within available real estate.

We have this problem no matter what we do.

No -- the problem varies based on implementation time for the chosen technology. For hydrogen/fuel cells, every car, every engine in every car, every tanker truck, every pipeline, every service station -- EVERYTHING must change. That takes decades, even given huge economic support. Others like biofuels use the existing distribution and vehicle infrastructure, which means they can be implemented much faster and cheaper.

I can't stress strongly enough -- the issue isn't whether an individual FEG or solar panel or fuel cell car or biofuel car will work. Whatever technology is chosen must be economically scaleable to titanic industrial levels to have meaningful impact. Those are often two different things.

 

[Ivan Seeking]

Not saying it CAN'T work, but it's likely economically unfeasible.

I don't think so. In fact the review here implies just the opposite to me.

Not a viable solution? Today coal provides 24% of world energy. It has already happened. You have to prioritize. The highest priority is transportation energy, not utility energy. If you allocate most resources now to developing new utility energy (when existing sources will last over 100 years) and transportation energy runs out in 30 years, what is the benefit?

What good is coal for transportation? This is less viable for transportation than electric cars are now.

It's far more viable and less expensive than building a million 747-size wind turbines, hundreds of million new fuel cell cars, tens of millions new hydrogen fuel stations, etc. I have no idea what you mean by 100-200 watts/m^2 yield. If you read the web site, you'll see the yield is over 100x other common biofuel feedstocks, and the total acreage easily fits within available real estate.

Simple math. The total energy going to each square meter is limited to the energy from the sun. This is a theoretical max of 1300 watts per square meter, and then we factor in the eff of the system. Simply put, it can't replace oil. Especially if we want to eat.

No -- the problem varies based on implementation time for the chosen technology. For hydrogen/fuel cells, every car, every engine in every car, every tanker truck, every pipeline, every service station -- EVERYTHING must change. That takes decades, even given huge economic support. Others like biofuels use the existing distribution and vehicle infrastructure, which means they can be implemented much faster and cheaper.

I can't stress strongly enough -- the issue isn't whether an individual FEG or solar panel or fuel cell car or biofuel car will work. Whatever technology is chosen must be economically scaleable to titanic industrial levels to have meaningful impact. Those are often two different things.

However, if we can't find a complete solution, we're screwed, and bio-fuels can't do it. When do you propose that we begin on a real solution?

And we don't have clean coal technology yet, which is a huge problem.

The point is not whether or not FEGs should be used to replace everything, the question is, should we start building them given the proper design. Do they make sense? And so far I think they do. I also think when we talk about 1,000,000 generators or so, its simply a problem of recognizing the scale of what would be replaced. One generator every 2000 sq miles is not so hard to imagine as compared to the entire energy infrastructure.

 

[Ivan Seeking]

Correction, in order to replace oil with bio-fuel, I come up with something like 10¹⁰ sq meters if we assume 200 watts per sq meter. So that's not nearly as bad as I was thinking. 200 watts is probably way too generous, but even at 50 watts we are talking about something plausible, it seems.

We still need to look at the total energy of the process though. We haven't considered processing which I know requires harvesting, energy for separation and extraction, heat energy, and methanol. And we don't really know how efficient the system is for solar. It could easily be 1%, or worse. I was actually using the best case for solar cells as a number.

 

[Ivan Seeking]

Again, I am a bio-fuel fan, but my understanding is that serious issues still exist.

First of all, the author assumes that we could convert to B100 [100% biodiesel as opposed to a mix with petro-diesel]. My understanding is that in no way can most vehicles do this. In fact around here they recommend B2 - 2% Bio to 98% petro. The stuff is untenable at low temperatures and many standard engines have had problems with injector systems, filters, seals, etc. The advocates say that most of these problems are resolved but in no way have I found a consensus on this point.

When I started checking into this, due to all of the problems experienced, no diesel engine manufacturer would warranty an engine for use with bio-diesel. And of course all ignition vehicles would have to be replaced with diesel engines, and, I don't think this can be used for aviation fuel, which is never mentioned.

Creating new farmland is energy intensive. And we already are seeing issues with water shortages in places like california, Nevada, etc. The solution to clean water shortages is desalination, which requires energy. So water supplies alone could be an issue - and irrigation requires energy. This is what seemed to kill biodiesel crops in many areas, but your link offers a different twist.

NREL's research focused on the development of algae farms in desert regions, using shallow saltwater pools for growing the algae. Using saltwater eliminates the need for desalination, but could lead to problems as far as salt build-up in bonds. Building the ponds in deserts also leads to problems of high evaporation rates. There are solutions to these problems, but for the purpose of this paper, we will focus instead on the potential such ponds can promise, ignoring for the moment the methods of addressing the solvable challenges remaining when the Aquatic Species Program at NREL ended.

So they could escape some concerns by using salt water algae. That is good!

I will say this, I know where I would have rather put our $300,000,000,000, besides Iraq.

III. Cost

In "The Controlled Eutrophication process: Using Microalgae for CO2 Utilization and Agircultural Fertilizer Recycling"3, the authors estimated a cost per hectare of $40,000 for algal ponds. In their model, the algal ponds would be built around the Salton Sea (in the Sonora desert) feeding off of the agircultural waste streams that normally pollute the Salton Sea with over 10,000 tons of nitrogen and phosphate fertilizers each year. The estimate is based on fairly large ponds, 8 hectares in size each. To be conservative (since their estimate is fairly optimistic), we'll arbitrarily increase the cost per hectare by 100% as a margin of safety. That brings the cost per hectare to $80,000. Ponds equivalent to their design could be built around the country, using wastewater streams (human, animal, and agricultural) as feed sources. We found that at NREL's yield rates, 15,000 square miles (3.85 million hectares) of algae ponds would be needed to replace all petroleum transportation fuels with biodiesel. At the cost of $80,000 per hectare, that would work out to roughly $308 billion to build the farms.

The operating costs (including power consumption, labor, chemicals, and fixed capital costs (taxes, maintenance, insurance, depreciation, and return on investment) worked out to $12,000 per hectare. That would equate to $46.2 billion per year for all the algae farms, to yield all the oil feedstock necessary for the entire country. Compare that to the $100-150 billion the US spends each year just on purchasing crude oil from foreign countries, with all of that money leaving the US economy.

So according to this, for about the price of the Iraq war we could in principle end our dependence on petroleum altogether.

The biggest problem that I see here is that this is the usual problem; it's not ready to go. There is always the qualifier, "more research is needed". So at least it sounds like no one has actually farmed salt-water algae and used it for the practical production of bio-diesel.

The Office of Fuels Development, a division of the Department of Energy, funded a program from 1978 through 1996 under the National Renewable Energy Laboratory known as the "Aquatic Species Program". The focus of this program was to investigate high-oil algaes that could be grown specifically for the purpose of wide scale biodiesel production1. The research began as a project looking into using quick-growing algae to sequester carbon in CO2 emissions from coal power plants. Noticing that some algae have very high oil content, the project shifted its focus to growing algae for another purpose - producing biodiesel. Some species of algae are ideally suited to biodiesel production due to their high oil content (some well over 50% oil), and extremely fast growth rates. From the results of the Aquatic Species Program2, algae farms would let us supply enough biodiesel to completely replace petroleum as a transportation fuel in the US (as well as its other main use - home heating oil) - but we first have to solve a few of the problems they encountered along the way.

 

[Ivan Seeking]

I was curious about the solar efficiency of the algae. Using his numbers and these

http://www.nafa.org/Content/NavigationMenu/Resource_Center/Alternative_Fuels/Energy_Equivalents/Energy_Equivalents.htm

I show an average of about 80 watts per sq meter. That's pretty amazing if true!

 

[Cliff_J]

Ivan - some of the biggest problems with BioDiesel is in the implementation. The fuel acts as a very effective solvent that dislodges gunk that's in the fuel system and can attack older hoses and seals that aren't robust enough to handle the fuel. Unlike a gasoline engine, the typical mechanical injection diesel operates with the fuel under incredible pressures and the tolerances inside the parts leaves little room for any impurities. Also, the system is very intolerant of any moisture, and biofuels don't help in this area.

E85 has a similar downfall, according to Motorweek (as I recall) the biggest limitation of E85 (besides the limited distribution of FFV cars setup to handle the fuel) is that when E85 was sent down an existing gasoline pipeline that its solvent-like characterists removed enough varnish buildup on the pipes that it caused leaks. So its distribution method is solely by truck at the moment, and explains its regional availability.

There is also E95 for diesels, and biodiesel can be blended to help with its cold weather performance. So there are some more things to understand than just fillin' 'er up.

With an educated consumer base who understands how to respect the biofuels they are a great substitute and even a 20% reduction would be outstanding. I was reading a report on a test-drill scenario where %5 of the worlds oil supply was cut off, and the price of oil went to $120 a barrel. I think a little consumer education, and maybe a little more monitoring by manufacturers (similar to warning lights) to assist in proper use of biofuels, that we as a planet could switch this problem around. Once the economics happen, I think it will occur whether the Luddities would like it to or not.

 

[joema]

Any alternative energy source if EVER expected to supply much of the world's energy, must be scaleable to gigantic industrial levels. This entails several requirements:

- Must fit within the available real estate. Does no good if it requires 3/4 continent full of windmills or solar panels.

- Must have significantly positive net energy balance (energy in vs energy out). If it takes more energy to manufacture or harvest than it produces, it's not workable.

- Must be economically affordable to build, including ALL development costs, and any related distribution and technology changes. Even if the technology works, if it costs $50 trillion if scaled to world need, that's not affordable. E.g, solar power satellites clearly would work on a small basis, but can't economically be scaled upward to world need.

- Must be implementable within the time frame for exhaustion of conventional energy source. For replacing petroleum, this means the alternative must be completely on line within two decades at the outside. For utility energy we have longer.

While there are many alternatives that work on a small experimental basis, there are very few that can be scaled to the titanic level required for global energy needs.

We can eliminate most alternatives as totally impossible based on the above criteria. E.g, hydrogen/fuel cells for transportation energy via solar or wind power. You can't complete fuel cell development, build solar arrays the size of Australia, replace the entire distribution infrastructure and replace most road vehicles with new technology within 20 years. It's impossible. If it's doable in 50 years, that's irrelevant, since global commerce can't stop for 30 years to await availability.

Another example of an alternative that works on a small scale but not a global scale is ethanol from corn. The yield is just too low, plus there's insufficient unused acreage for global-level output.

I don't know if all issues related to biodiesel from high yield algae are solvable. However it at least it satisfies the areal efficiency, net energy efficiency required, implementation cost and timeframe requirements. It also mostly solves the CO2 problem, as it only emits CO2 it absorbed during growth.

If a biodiesel from high yield algae project was scaled up to global size, it might encounter unforeseen problems that preclude implementation. However there are no current known insurmountable problems By contrast most other alternative approaches have already visible insurmountable problems if scaled to that level.

All issues about biodiesel in diesel engines can be solved by minor modifications of current engine and fuel production technology. You have to distinguish between somebody making biodiesel in their back yard from waste vegetable oil vs a well engineered large production complex.

Extrapolating from the numbers on http://www.unh.edu/p2/biodiesel/article_alge.html (141E9 gal/yr to replace all US transportation energy), to replace all global energy, it would take roughly 22x that much: (400 quadrillion BTU / (141E9 gal * 130000 BTU/gal). Land area required would be somewhat larger than Texas, but it could be 100% in non-arable land (e.g, deserts) around the world. It would use essentially existing distribution, storage, and engine technology, unlike other approaches that require total replacment of all those.

 

[Ivan Seeking]

While we agree much more than not, a few additional comments.

Also, a good link
http://www.eia.doe.gov/emeu/international/total.html

Any alternative energy source if EVER expected to supply much of the world's energy, must be scaleable to gigantic industrial levels. This entails several requirements:

- Must fit within the available real estate. Does no good if it requires 3/4 continent full of windmills or solar panels.

This is a little unfair since it would take less acreage for solar cells to produce the same amount of power as biofuels. However, we don't really know the well-to-wheels efficiency of either approach, so it is possible that neither would yield a net positive when all is said and done. Since in both cases we are talking about future technlogies, large scale production of products like paint-on solar cells [currently in development] could prove viable and superior to biofuels as solar energy converters. And taken at face value, at about 100 watts per sq meter, they already are.

- Must have significantly positive net energy balance (energy in vs energy out). If it takes more energy to manufacture or harvest than it produces, it's not workable.

From what I see, this is still a problem for many alternatives. I'm not convinced that we have any net positive alternative yet.

- Must be economically affordable to build, including ALL development costs, and any related distribution and technology changes. Even if the technology works, if it costs $50 trillion if scaled to world need, that's not affordable. E.g, solar power satellites clearly would work on a small basis, but can't economically be scaled upward to world need.

True, however, most Joes-on-the-street expect far too much, and most engineers expect far too little. It doesn't pay to be cynical based on guesses. The economy of scale can be extreme and surprising.

- Must be implementable within the time frame for exhaustion of conventional energy source. For replacing petroleum, this means the alternative must be completely on line within two decades at the outside. For utility energy we have longer.

It means that a set of solutions must be online within some time that some claim is as little as two decades. My feeling is that if some technologies pan out, we could do this in a decade.

While there are many alternatives that work on a small experimental basis, there are very few that can be scaled to the titanic level required for global energy needs.

Your opinion and far too broad a statement to defend.

We can eliminate most alternatives as totally impossible based on the above criteria. E.g,

So you say.

hydrogen/fuel cells for transportation energy via solar or wind power. You can't complete fuel cell development, build solar arrays the size of Australia,

not an accurate statement. Also, fuel cells are hardly in their infancy. To me the big question with fuel cells is the lifetime efficiency. Some people argue that when taken in total, it makes more sense to run hydrogen in IC engines, than fuel cells in electric vehicles. And we could run H2 in regular cars as well. I think it is BMW that makes a car that goes from petro to H2 combustion with the flip of a switch, which is a great solution to the chicken and egg problem. And the distribution technology for H2 is well under way - Iceland is changing to H2 right now.

replace the entire distribution infrastructure and replace most road vehicles with new technology within 20 years. It's impossible. If it's doable in 50 years, that's irrelevant, since global commerce can't stop for 30 years to await availability.

I agree that we are running out of time.

Another example of an alternative that works on a small scale but not a global scale is ethanol from corn. The yield is just too low, plus there's insufficient unused acreage for global-level output.

It only makes sense to me to grow the most eff bio-fuel crops.

I don't know if all issues related to biodiesel from high yield algae are solvable.

Twenty years to figure it out? Already looking bad.

If a biodiesel from high yield algae project was scaled up to global size, it might encounter unforeseen problems that preclude implementation. However there are no current known insurmountable problems By contrast most other alternative approaches have already visible insurmountable problems if scaled to that level.

It has never really been done either. They need to move ahead with this program quickly and see if it really pays in joules. I can still imagine this ending up as a net loss.

All issues about biodiesel in diesel engines can be solved by minor modifications of current engine and fuel production technology. You have to distinguish between somebody making biodiesel in their back yard from waste vegetable oil vs a well engineered large production complex.

Extrapolating from the numbers on http://www.unh.edu/p2/biodiesel/article_alge.html (141E9 gal/yr to replace all US transportation energy), to replace all global energy, it would take roughly 22x that much: (400 quadrillion BTU / (141E9 gal * 130000 BTU/gal). Land area required would be somewhat larger than Texas, but it could be 100% in non-arable land (e.g, deserts) around the world. It would use essentially existing distribution, storage, and engine technology, unlike other approaches that require total replacment of all those.

I totally support the use of bio-fuels, and it sounds like they could free us of petro, however, it is still a dirty fuel that can't satisfy all of the worlds energy needs. As I said, no mention of aviation, for one. And the demand for water, which can be a large energy liability, also competes directly with the needs of people; thus biofuels put food into competition with energy on two fronts - for airable land, and for water, and of these, water being the most critical.

 

[Ivan Seeking]

The best current deal on new 50 watt solar panels is about $4.25 a watt--$212 for a 50 watt panel, in quantity.

http://www.otherpower.com/otherpower_solar.html

So right now, with a demand of 2.7E16 Watt-Hrs, it would cost about $10¹³ to replace US oil energy with off-the-shelf, solar panel energy. Not very practical right now.

One positive note: Given solutions such as $300,000,000,000 worth of algae farms, consider Iraq. We have spent $200,000,000,000 in just a few years. So given a clear and effective plan, large scale change could happen very quickly.

 

[Ivan Seeking]

If we assume that just the barebones wings from an Airbus 380 could be purchased at 5% of the total sales price of the vehicle, for 300 Billion, we could purchase 23,000 sets wings.

Again, sorry for all of the late edits but I'm just playing with the numbers here. Interestingly, if we built 10,000, 10 MW FEG platforms, 10¹² watts and 200 per state, the basic equipment costs would probably come in on the order of $300 billion, and this would produce about the same energy per year as is contained in all US oil - with an average demand of about 3X10¹² watts. Obviously these are just seat of the pants calculations, but the estimates seem reasonable.

whoops, off by ten, that would be 10¹¹ watts. So we need ten times as many for the same power.

 

[Ivan Seeking]

The website mentions using 20 MW FEGs without any analysis of whether that's actually possible. The largest terrestrial wind turbine ever made is the REPower 5M, a 5 megawatt unit with a rotor diameter of 126 meters. It weighs 120 tons. Each rotor blade weighs 18 tons. You'd need something maybe TWICE that size -- flying overhead -- for a single 20 MW FEG (accounting for higher rotor disc areal efficiency

I was looking over the wind data for this issue. For a 126 meter diameter [worth of] rotor at 35,000 feet, based on avg wind conditions at about 45 degree latitutde, we have an average of about 37 MW of wind power available. This assumes about 3KW per sq meter as is indicated in the data plots.

From what I am seeing, state of the art designs can run close to 50% efficient. So instead of expecting 5MW, for that amount of rotor swept area we might do as well as 15MW, correct?

 

[joema]

...it would take less acreage for solar cells to produce the same amount of power as biofuels. However, we don't really know the well-to-wheels efficiency of either approach, so it is possible that neither would yield a net positive when all is said and done. Since in both cases we are talking about future technlogies, large scale production of products like paint-on solar cells [currently in development] could prove viable and superior to biofuels as solar energy converters.

We know the approx. biodiesel via algae real estate required: I calculated it above, and it's based on real data, not paper hypothesis.

Solar PV real estate required is roughly the same size, but that area must be filled with solar arrays, not algae ponds. Solar PV acreage calculation:

Average solar insolation in US southwest: 5000 watt-hrs/m^2/day, or 1.8E6 watt-hrs/m^2/year
Overall PV efficiency: 10% (must include DC/AC conversion losses, cell aging, etc). Solar cell efficiency degrades at about 2% per year, so after 20 years, output has declined by 1/2.
Average actual useable annual solar PV energy output: 186,000 watt hrs per year per square meter.

Hydrogen electrolysis is about 70% efficient, transport about 90% efficient, vehicle/depot storage about 80% efficient, fuel cells about 70% efficient, electric motors about 92% efficient, for total end-to-end efficiency of about 32%. That's roughly the same end-to-end efficiency as biodiesel.

Solar PV acreage required for world energy demand (1.18E17 watt hrs/yr):

1.18E17 watt hrs/yr / 186,000 watt hrs/yr/m^2 = 634 billion square meters, or 245,000 square miles (roughly the size of Texas).

So the acreage requirements seem roughly the same, but solar/hydrogen/fuel cells require total replacement of the distribution infrastructure and totally new vehicle technology. That also assumes you can economically make solar PV arrays to cover 634 billion square meters, plus replace them about every 20-30 years.

A 10 MW FEG at 80% capacity factor produces about 70E9 watt hrs per year. The number of 10 MW FEGs required to handle world energy is:

1.18E17 watt hrs per yr / 70E9 watt hrs per FEG = 1.7 million 10 MW FEGs.

 

[Ivan Seeking]

The numbers that you cite are based on ideal conditions and lab testing conditions and not on data from real algae farms. We don't know how this will scale up. So my objection is not that we shouldn't try it, my objection is that it is still theoretical and may not prove as viable as it appears. 80 watts per sq meter does not leave a lot of room for the practical energy needs of irrigation, harvesting, processing, ect. And aside from price, solar cells have the same problem. We don't know the true energy investment in a solar panel. But, as I have been saying for thirty years, the technology coming along looks promising.

As for comparing FEGs to algae farms, we have no idea how large FEGs could be built or how many it would take, or the price, or the total efficiency, so it is premature to state the performance or costs of one approach over the other. But just playing with wild guesses of 30 million per 10MW unit, with as much in maintenance costs over a twenty year lifespan, I come up with 4 cents per KW-HR at 45 degrees latitude, and 35,000 feet, which is highly competitive now. And in the end, the price per kw-hr is the key test.

 

[Ivan Seeking]

Oh yes, and based on the weight estimates, given the increased power per unit rotor area, it would appear that something on the order to the Airbus 380 wings could lift enough equipment to produce 30 MW avg power, in ideal locations. So if we are going to shoot from the hip, you need to divide by three - 560,000 FEGs.

And I would bet a year's wages that we could do much better given a serious effort.