Wind, water and sun beat biofuels, nuclear and coal for clean energy, researcher says

Dec 10, 2008
Wind power is the most promising alternative source of energy, according to Mark Jacobson.

(PhysOrg.com) -- The best ways to improve energy security, mitigate global warming and reduce the number of deaths caused by air pollution are blowing in the wind and rippling in the water, not growing on prairies or glowing inside nuclear power plants, says Mark Z. Jacobson, a professor of civil and environmental engineering at Stanford.

And "clean coal," which involves capturing carbon emissions and sequestering them in the earth, is not clean at all, he asserts.

Jacobson has conducted the first quantitative, scientific evaluation of the proposed, major, energy-related solutions by assessing not only their potential for delivering energy for electricity and vehicles, but also their impacts on global warming, human health, energy security, water supply, space requirements, wildlife, water pollution, reliability and sustainability. His findings indicate that the options that are getting the most attention are between 25 to 1,000 times more polluting than the best available options.

"The energy alternatives that are good are not the ones that people have been talking about the most. And some options that have been proposed are just downright awful," Jacobson said. "Ethanol-based biofuels will actually cause more harm to human health, wildlife, water supply and land use than current fossil fuels." He added that ethanol may also emit more global-warming pollutants than fossil fuels, according to the latest scientific studies.

The raw energy sources that Jacobson found to be the most promising are, in order, wind, concentrated solar (the use of mirrors to heat a fluid), geothermal, tidal, solar photovoltaics (rooftop solar panels), wave and hydroelectric. He recommends against nuclear, coal with carbon capture and sequestration, corn ethanol and cellulosic ethanol, which is made of prairie grass. In fact, he found cellulosic ethanol was worse than corn ethanol because it results in more air pollution, requires more land to produce and causes more damage to wildlife. The paper with his findings will be published in the next issue of Energy and Environmental Science but is available online now. Jacobson is also director of the Atmosphere/Energy Program at Stanford.

To place the various alternatives on an equal footing, Jacobson first made his comparisons among the energy sources by calculating the impacts as if each alternative alone were used to power all the vehicles in the United States, assuming only "new-technology" vehicles were being used. Such vehicles include battery electric vehicles (BEVs), hydrogen fuel cell vehicles (HFCVs), and "flex-fuel" vehicles that could run on a high blend of ethanol called E85.

Wind was by far the most promising, Jacobson said, owing to a better-than 99 percent reduction in carbon and air pollution emissions; the consumption of less than 3 square kilometers of land for the turbine footprints to run the entire U.S. vehicle fleet (given the fleet is composed of battery-electric vehicles);l the savings of about 15,000 lives per year from premature air-pollution-related deaths from vehicle exhaust in the United States; and virtually no water consumption. By contrast, corn and cellulosic ethanol will continue to cause more than 15,000 air pollution-related deaths in the country per year, Jacobson asserted.

Because the wind turbines would require a modest amount of spacing between them to allow room for the blades to spin, wind farms would occupy about 0.5 percent of all U.S. land, but this amount is more than 30 times less than that required for growing corn or grasses for ethanol. Land between turbines on wind farms would be simultaneously available as farmland or pasture or could be left as open space.

Indeed, a battery-powered U.S. vehicle fleet could be charged by 73,000 to 144,000 5-megawatt wind turbines, fewer than the 300,000 airplanes the U.S. produced during World War II and far easier to build. Additional turbines could provide electricity for other energy needs.

"There is a lot of talk among politicians that we need a massive jobs program to pull the economy out of the current recession," Jacobson said. "Well, putting people to work building wind turbines, solar plants, geothermal plants, electric vehicles and transmission lines would not only create jobs but would also reduce costs due to health care, crop damage and climate damage from current vehicle and electric power pollution, as well as provide the world with a truly unlimited supply of clean power."

Jacobson said that while some people are under the impression that wind and wave power are too variable to provide steady amounts of electricity, his research group has already shown in previous research that by properly coordinating the energy output from wind farms in different locations, the potential problem with variability can be overcome and a steady supply of baseline power delivered to users.

Jacobson's research is particularly timely in light of the growing push to develop biofuels, which he calculated to be the worst of the available alternatives. In their effort to obtain a federal bailout, the Big Three Detroit automakers are increasingly touting their efforts and programs in the biofuels realm, and federal research dollars have been supporting a growing number of biofuel-research efforts.

"That is exactly the wrong place to be spending our money. Biofuels are the most damaging choice we could make in our efforts to move away from using fossil fuels," Jacobson said. "We should be spending to promote energy technologies that cause significant reductions in carbon emissions and air-pollution mortality, not technologies that have either marginal benefits or no benefits at all".

"Obviously, wind alone isn't the solution," Jacobson said. "It's got to be a package deal, with energy also being produced by other sources such as solar, tidal, wave and geothermal power."

During the recent presidential campaign, nuclear power and clean coal were often touted as energy solutions that should be pursued, but nuclear power and coal with carbon capture and sequestration were Jacobson's lowest-ranked choices after biofuels. "Coal with carbon sequestration emits 60- to 110-times more carbon and air pollution than wind energy, and nuclear emits about 25-times more carbon and air pollution than wind energy," Jacobson said. Although carbon-capture equipment reduces 85-90 percent of the carbon exhaust from a coal-fired power plant, it has no impact on the carbon resulting from the mining or transport of the coal or on the exhaust of other air pollutants. In fact, because carbon capture requires a roughly 25-percent increase in energy from the coal plant, about 25 percent more coal is needed, increasing mountaintop removal and increasing non-carbon air pollution from power plants, he said.

Nuclear power poses other risks. Jacobson said it is likely that if the United States were to move more heavily into nuclear power, then other nations would demand to be able to use that option.

"Once you have a nuclear energy facility, it's straightforward to start refining uranium in that facility, which is what Iran is doing and Venezuela is planning to do," Jacobson said. "The potential for terrorists to obtain a nuclear weapon or for states to develop nuclear weapons that could be used in limited regional wars will certainly increase with an increase in the number of nuclear energy facilities worldwide." Jacobson calculated that if one small nuclear bomb exploded, the carbon emissions from the burning of a large city would be modest, but the death rate for one such event would be twice as large as the current vehicle air pollution death rate summed over 30 years.

Finally, both coal and nuclear energy plants take much longer to plan, permit and construct than do most of the other new energy sources that Jacobson's study recommends. The result would be even more emissions from existing nuclear and coal power sources as people continue to use comparatively "dirty" electricity while waiting for the new energy sources to come online, Jacobson said.

Jacobson received no funding from any interest group, company or government agency.

Energy and vehicle options, from best to worst, according to Jacobson's calculations:

Best to worst electric power sources:

1. Wind power 2. concentrated solar power (CSP) 3. geothermal power 4. tidal power 5. solar photovoltaics (PV) 6. wave power 7. hydroelectric power 8. a tie between nuclear power and coal with carbon capture and sequestration (CCS).

Best to worst vehicle options:

1. Wind-BEVs (battery electric vehicles) 2. wind-HFCVs (hydrogen fuel cell vehicles) 3.CSP-BEVs 4. geothermal-BEVs 5. tidal-BEVs 6. solar PV-BEVs 7. Wave-BEVs 8.hydroelectric-BEVs 9. a tie between nuclear-BEVs and coal-CCS-BEVs 11. corn-E85 12.cellulosic-E85.

Hydrogen fuel cell vehicles were examined only when powered by wind energy, but they could be combined with other electric power sources. Although HFCVs require about three times more energy than do BEVs (BEVs are very efficient), HFCVs are still very clean and more efficient than pure gasoline, and wind-HFCVs still resulted in the second-highest overall ranking. HFCVs have an advantage in that they can be refueled faster than can BEVs (although BEV charging is getting faster). Thus, HFCVs may be useful for long trips (more than 250 miles) while BEVs more useful for trips less than 250 miles. An ideal combination may be a BEV-HFCV hybrid.

More information: Mark Z. Jacobson, Energy Environ. Sci., 2009, DOI: 10.1039/b809990c
www.rsc.org/Publishing/Journal… cle.asp?doi=b809990c

Provided by Stanford University

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Doug_Huffman
3 / 5 (21) Dec 10, 2008
Solar energy is low quality energy limited to 1350 Watts per square meter.
thermodynamics
3.2 / 5 (18) Dec 10, 2008
Doug is right about the energy density of solar. The same is true of wind. The idea that either source could be put in place to replace fossil fuels within the next 20 years is not credible (even with a massive push through work projects).

If there is a real reason to reduce the accelerating rate of CO2 increase in the atmosphere (at least accelerating before the recession set in and probably accelerating after the recession is over) then there has to be some mechanism for capturing and sequestering CO2 from stationary sources. There is high-quality research related to capture and sequestration going on right now that indicates that the numbers cited by the author of this paper are not correct and the capture and sequestration of CO2 from coal and oil fired plants is possible at much less of a penalty than he is allowing.
theophys
4.2 / 5 (19) Dec 10, 2008
I volunteer Nevada to be the energy production state of the country. We have large amounts of geothermal energy waiting to be tapped, the northern part of the state gets quite a bit of wind, and our entiore state is very sunny. As for nuclear, well, we have several hundred square miles that used to be used for nuclear weapon testing. Most of it isn't being used for anything important, just about everything is dead already, and we have a bunch of military bases so security shouldn't be a huge problem.
Besides, we need something going for us other than gambling and prostitution.
svenkesd
3.3 / 5 (20) Dec 10, 2008
Strange, he doesn't talk about things like breeder reactors that reuse nuclear fuel and render any potential bomb material as useless.

Acording to his quote the possibility of a nuclear attack is factored into his assessment of energy sources? Are you kidding me?

Where is the information coming from determining the amount of deaths due to air pollution? Those are estimates at best, wild guesses at worst.

All around bad science. I am dissapointed this found its way onto physorg.com.
Damon
3.5 / 5 (13) Dec 10, 2008
Doug, you said 1350w per sq meter, but the article is talking about concentrated solar plants, which I believe have a much higher return on size- the Nevada Solar One is one example. 65MW on 1.2km of plant size.
axemaster
3.3 / 5 (17) Dec 10, 2008
"Ethanol-based biofuels will actually cause more harm to human health, wildlife, water supply and land use than current fossil fuels."

Right on. I'm always surprised by how few people know about this, when the data has been out there for years and years...

"Strange, he doesn't talk about things like breeder reactors that reuse nuclear fuel and render any potential bomb material as useless. "

You're ignoring the fact that they still produce copious amounts of deadly nuclear waste, which CANNOT be disposed of in any reasonable way. I attended a talk by a prominent nuclear physicist a few weeks ago who said, without any hesitation, that nuclear power plants - his job - were completely unsustainable. He said, in a very knowledgable and professional way, that nuclear waste is one of the biggest environmental dangers of the next century, and one that is nearly impossible to fix. We do NOT need any more of this stuff.

Why do you think there was that big stink about the Yucca Mountain nuclear waste dump? They still haven't finished it, and meanwhile the stuff is leaking out all over the place in 30-50 year old rusty/cracked containers around the country. Plus, how can they ensure that a train hauling it doesn't cause a spill? Can you even comprehend the consequences of something like that? Nuclear waste, traveling into the water table, down rivers?

That's why nuclear is not an option.
Bill_2077
2.5 / 5 (15) Dec 10, 2008
Nice article. I am surprised that geothermal energy is not at the top of the list given the work being done in Australia on Hot Fractured Rock geothermal energy but it has not been completely proven yet. If the tests over the next few months are successful (and there is every reason to believe that they will be) this is the ultimate clean baseload electricity source.
Anybody who suggests nuclear as an option is insulting our intelligence when you consider that the entire industry arose from the need to make bombs after WW2 and the power is just a side effect. Nuclear power plants are not economical without weapons grade material production (even without taking the disposal of waste into account).
theophys
2.6 / 5 (16) Dec 10, 2008
I think nuclear would be a perfectly reasonable option if we were to develope safe, non-violent, uses for the waste. I remember reading an adrticle a few years back that said some group was working on geneticaly engineering an insect that fed on the waste. Maybe we could genetically engineer plants that use the waste for fuel and returned a safe (non-radioactive) crop.
Lord_jag
2.2 / 5 (13) Dec 10, 2008
"Indeed, a battery-powered U.S. vehicle fleet could be charged by 73,000 to 144,000 5-megawatt wind turbines, fewer than the 300,000 airplanes the U.S. produced during World War II and far easier to build."

Sweet! I say we declare war on the electron! The only way to defeat them is to rip them away from their valence shell. The weapon? Wind turbines.

Screw the auto industry. Put all the out of shape and overpaid autoworkers back building wind turbines.
Lord_jag
3.8 / 5 (15) Dec 10, 2008
Nuclear waste safety:

http://en.wikiped...ar_flask

"The crashworthiness of the flask was demonstrated publicly when a British Rail Class 46 locomotive was forcibly driven into a derailed flask (containing water and steel rods in place of radioactive material) at 100 mph, the flask sustaining minimal superficial damage without compromising its integrity, while both the flatbed wagon carrying it and the locomotive were more-or-less destroyed."

So... you can hit it with a steel locomotive and it will survive intact.

Google videos of it. Awesome to see!!!
MikeB
3.6 / 5 (17) Dec 10, 2008
If France can do Nuclear, we can do it... 75% of their power is from Nuclear Energy. They have a very safe way to handle the waste. Their process produces about one teaspoon, yes one teaspoon of waste per family per year.

Don't tell me that France, France!! is better than America.

http://www.world-...f40.html
Gush10
3.1 / 5 (14) Dec 10, 2008
If France can do Nuclear, we can do it... 75% of their power is from Nuclear Energy. They have a very safe way to handle the waste. Their process produces about one teaspoon, yes one teaspoon of waste per family per year.

But that is still 65,000 litres of radioactive waste EVERY YEAR (not including any growth rate)! Nuclear is too expensive and too dangerous.
MikeB
3.2 / 5 (12) Dec 10, 2008
"But that is still 65,000 litres of radioactive waste EVERY YEAR (not including any growth rate)! Nuclear is too expensive and too dangerous."

Ok I figure that the USA could provide 75,000,000 families with energy for a year, leaving app 3,100 bbl US of waste, if we use the same scheme as France.
That doesn't seem insurmountable to me.
MikeB
4.1 / 5 (14) Dec 10, 2008
"You're ignoring the fact that they still produce copious amounts of deadly nuclear waste, which CANNOT be disposed of in any reasonable way. I attended a talk by a prominent nuclear physicist a few weeks ago who said, without any hesitation, that nuclear power plants - his job - were completely unsustainable. He said, in a very knowledgable and professional way, that nuclear waste is one of the biggest environmental dangers of the next century, and one that is nearly impossible to fix."

Who is this prominent nuclear physicist? Does he have a name?
Arikin
4.4 / 5 (17) Dec 10, 2008
I don't believe coal is good at all but the logic presented here is a little off.

"carbon capture requires a roughly 25-percent increase in energy from the coal plant, about 25 percent more coal is needed..."

With the stated assumption of one type energy being used 100% for everything:
Is he assuming running the mining trucks off coal??? You can't use oil or diesel in the 100% assumption. Or is he calculating steam powered vehicles? You can't measure correctly unless you stick to your assumptions completely.

Hopefully the full article explains this logic.

And why is he using emotional adjectives?
"just downright awful"
Just quantify and that will justify the conclusions!
phlipper
4.3 / 5 (19) Dec 10, 2008
I believe thorium power is the way to go.
Ten Essential Facts about Thorium
1. Thorium is a naturally occurring, slightly radioactive metal, and it has been considered as an alternative nuclear fuel to
uranium.
2. Unlike uranium, thorium is non-proliferative: The key advantage of the thorium fuel cycle is that it does NOT produce
plutonium and is non-proliferative for that reason.
3. The energy contained in one kilogram of thorium equals that of four thousand tons of coal.
4. The energy stored in the earth's thorium reserves is thought to be greater than that available from all other conventional
(fossil) and nuclear fuels combined.
5. Thorium is cheaper and more abundant than uranium (approx three times more abundant in the Earth's crust than all
forms of uranium combined).
6. The thorium fuel cycle produces less radioactive waste than uranium (1,000 to 10,000 times less than in conventional
reactors).
7. Unlike natural uranium where only the 0.7% sliver of isotope 235 is fissionable, thorium is fully used in the fuel cycle.
8. Unlike uranium, thorium can burn plutonium waste from traditional nuclear reactors with additional energy output.
9. Unlike uranium, thorium is not suitable for the production of weapons-grade materials.
10. Global reserves of thorium (India, Australia, Norway and the U.S. possess the largest reserves) could cover the world's
energy needs for thousands of years.
http://www.thoriu...rium.pdf
magpies
1.1 / 5 (17) Dec 10, 2008
The best energy sorce is fun. If you can have fun you can do anything. Science and God working together sense 2000bc.
twango
3.1 / 5 (10) Dec 11, 2008
Universal comparisons like this are sorely needed ... good to see someone doing one. We need to be able to see quantitative comparisons looking at cradle-to-grave for everything, and then have it all examined by highly-qualiified professionals. There's too much bias coming from various interest groups otherwise, making it hard for people to reach an informed consensus.
Bill_2077
3.4 / 5 (7) Dec 11, 2008
lord_jag - sorry but just because you can put something in an incredibly heavy and expensive container for transport doesn't make it safe. Unless you are proposing that all waste is kept in those shipping containers for ever?
phlliper - I would like to see a costing of a Thorium reactor if it does not have weapons grade material to offset the dollars required to build and operate a plant. And it still produces waste! And your link doesn't work...
Soylent
3.5 / 5 (13) Dec 11, 2008
Why do you think there was that big stink about the Yucca Mountain nuclear waste dump?


Because pretending that there's a problem and trying to forestall any use for as long as possible is a good way for competing sources(AKA coal and it's useful idiots in the environmental movement) to forestall having to change their business model for as long as possible.
Soylent
3.6 / 5 (13) Dec 11, 2008
As usual, the article doesn't even make a mention of the real problem with wind energy. Generating power is the easy part, getting it to where and when it's needed is not.

If wind energy is ever going to get rid of it's hideous dependency on natural gas turbines and coal spinning reserve it necessitates a continent-wide Rube Goldberg machine that can't possibly be built within any reasonable period of time or at any reasonable cost.
Velanarris
4 / 5 (14) Dec 11, 2008
Strange, he doesn't talk about things like breeder reactors that reuse nuclear fuel and render any potential bomb material as useless.

One of the main reasons you won't hear much about breeder reactors is due to the fact the US outlawed them under the carter administration as part of a big oil bill funded bill.

The US views on nuclear are almost archaic. Nuclear is a viable energy source that can fit perfectly as a stop gap until we find something better.

Those of you pushing wind power are far off base. The average wind farm does not produce that much electricity and in turn require electricity when the wind isn't blowing to prevent mechanical failure. Unfortunately, the best energy idea that is realistic, (other than nuclear), is solar, but we face hard limits on what that can generate.

I'm really hoping to see fusion in the near future but as the addage goes, fusion will always be the technology of the future, never of the present.
Roach
4.4 / 5 (10) Dec 11, 2008
I'm all for a fair comparison, but where does he discuss the dioxin relese from the manufacture of PV cells, or the arsenic from the mirros, and let's not even discuss the cocktail of chemicals of the production of really efficient wind turbine blades, plus the need for high temperature silicon or lithium based grease at solar mirrors, or the impeiment that wave generation farms make for aquatic life, or the acreage that would have to be damed up to produce sufficient lakes to feed hydro.

I agree biofuels are the wrong approch. All we need is to divert farmland from food to fuel and then add just one more direct tie between fuel cost and food cost.

Also while in the land of the lotus eaters it's fine to suggest that zero impact energy is great for everyone, he essential wants to damn major portions of the population into no electricity. Just a question, how much of New York State and the nearby coastal areas would need to be utilized to provide energy for all the buildings, vehicles, boilers, lawnmowers, weedeaters, fire trucks, buses, police cars boats, etc. that just NYC and the surounding suburbs use? Do we need to evacuate Pennslyvania also? Maybe close the Hudson so we don't have to worry about shipping traffic damaging the wave generators. Or maybe we could make one source for all the country's power, dam up the Mississippi and make Lake Missouriindianaillinoiskentuckyarkansastennesseelouisianamississipi. Sure some people would have to drown to death and we'd lose countless species, but we'd be green right?

And for thouse who like wind farms so much just remember too many turbines in a concentrated area you actually create a laminar flow region where the wind circumvents the turbines, that's why they are so spaced out on wind farms. How about if we evict the few residents between Fargo and Austin and the Mississippi river and Denver. Shouldn't be too many people. I realize the Champ here is discussing a combination of sources, but we go back to the earlier question of how many combined power sources does NYC need, or the population dense New England states if you can figure out NYC. What about oh, Alabama, Kentucky, Georgia, Tennessee, West Virgina where None of the above would be sufficient even in combination? Oh that's right most of them will be under water, never mind.

None of this still addresses the fact that while fusion is still far off, so are room temperature super conductors or low loss high retention time clean safe energy storage. Don't feed me some BS about how LithPoly is safe, that's worse than burning tires in a pile in your backyard for fun, and hydrogen, anyone here want to know what a massive hydrogen explosion looks like? Picture a mushroom as the hydrogen procedes to burn the oxygen out of the area until it burns out. Or maybe not an explosion picture a giant shuttle engine burning for the next week with enough force to change weather patterns over a major portion of the globe.

Once again I want cheap sustainable power. But if it were as easy as these people claimed, it would already have been done, yes yes big oil blah blah, but if they could make the same money for less capital expenditure they would have already done it. Duh.
lengould100
3.9 / 5 (8) Dec 11, 2008
Some reality, please. This "article" presents mostly non-scientific nonsense. I agree that sustainable energy resources need to be developed at max. asap, but based on my own investigations believe that solar thermal is far superior to wind (eg. can do a given job with typically only 1/3 or less the transmission capacity of wind). The "scientist" has also cherry-picked the application. Only charging of BEV's or HFCEV's can make wind look good as a generating resource vs. solar thermal or geothermal, because the auto's provide the storage. Start trying to figure out how to run industry, commercial and residential (much larger loads with typically fixed schedule requirements) and the wind starts costing a fortune for backup.

Several smart ways to mitigate problems, (smart grid load management, diversify mix of generation used) but definitely needs a huge chunk of absolutely reliable baseload which wind simply cannot provide.

Again, please get it straight people. This article is nonsense, written apparently by someone who knows nothing about how to operate a grid.
Velanarris
3 / 5 (4) Dec 11, 2008
There was an article I read recently provided by the US Dept of Energy stating that the only true sustainable energy source that has any possibility of providing enough energy for civilization is solar. He went into far more detail than I can on the relevant math and processes however the main point he made involved the amount of available energy produced by each source if 50% capture and transmission were not an issue across the board.

His figures on potentials and space requirements were rather enlightening. For instance, in order to produce as much as 2% of the projected future (year 2070) needs of the world we would have to build wind farms that inhabit an area as large as the entire North American landmass. Nuclear would require the construction of reactors at a pace of 40 per day for the next 8 years. If I can find the article online I'll link it. It was a rather effective push for solar development.
agg
3.4 / 5 (5) Dec 11, 2008
not a single word about tooling costs

when I say cost I mean energy available to do work

that means lots of energy to retool not even discussed, factored or otherwise accounted

sorry I see it as just another pie in the sky analysis that neglects the bottom line

I wonder if we had all that technology available to us and chose to use it, and our twin society chose to slurp up hydrocarbons that bubble from the surface, then who would be more advanced 100 years down the line? Use Hamilton's principle and follow the least action integral and arrive at hydrocarbon based industry that can only now consider higher barrier technology.
Xorays7
3 / 5 (4) Dec 11, 2008
I was reading there may be an impact from solar power. Nitrogen trifluoride (a GHG 17,000 times more potent than a similar mass of CO2) used used during the manufacture of liquid crystal flat-panel displays, thin-film solar cells and microcircuits:
http://www.nasa.g...gas.html
lengould100
4 / 5 (5) Dec 11, 2008
I was reading there may be an impact from solar power. Nitrogen trifluoride (a GHG 17,000 times more potent than a similar mass of CO2) used used during the manufacture of liquid crystal flat-panel displays, thin-film solar cells and microcircuits:
http://www.nasa.g...gas.html


In all discussions, please distinguish between solar photovoltaic and solar thermal. The ONLY thing the two have in common is the immediate energy source (which BTW averages 150 watts delivered on every sq. meter of earth continuous. Wind, not so much, about 0.1 watt per sq. meter for the entire vertical column of atmosphere)
Xorays7
5 / 5 (3) Dec 11, 2008
Solar Voltaic then. Thanks for the info comparing wind and solar (very illuminating).
Roach
4.2 / 5 (5) Dec 11, 2008
Lengould,
I agree the confusion between solarthermal and PV is very important, but solar thermal is limited to conventional heat engine efficiencies which pretty much moves you to 40% of carnot, roughly. PV will only give an ideal 18 or 20%(to my knowledge no-one has ever pulled this off), but either way the limiting factor is the conversion. Just on my limited reading, the theoretical cap to thermionics is much better for a long term solar solution. Some estimates are as high as 80% of carnot with the right tunneling insulator. Then we're right back to manufacturing process chemicals. Admittedly someone would need to spend the money on the research for it to advance, and other than space probes, which can make assumptions we can't on earth like, who cares about radioactive leaks, or we don't have to dispose or repair this, no one seams willing to devote the time or energy. Oh well.
lengould100
3.5 / 5 (4) Dec 11, 2008
It is misleading to compare a theoretical future 80% efficiency and who knows what price / kw (which I agree is probably possible eventually, though via optical rectenna not thermionics) to solar thermal's NOW AVAILABLE IN LARGE UNITS 15% efficiency at prices cheaper than Natural Gas. When a relatively tiny proportion of world deserts covered with mirrors could supply ALL world energy requirements plus provide sufficient power for supplying desalinated drinking and irrigation water to all people who now lack it, we need to stop this stupid DEBATING.

We need to get on solar thermal right now.
Roach
3.7 / 5 (6) Dec 12, 2008
I really don't understand the desert theory, even if we could turn the sahara, the mohave and, and the kalahari, and Produce 500% of the worlds energy needs, we'd still have the issue that the power is there and not where we need it and efficient superconductors to move that energy to where it is needed is at least as far off and theoretical as Thermionics or the rectenna. Desalination at the desert is even more distant, want to take a guess at the headloss over 10,000miles of pipe? We could probably do it, but it'd take a new type of pump which as yet has not been invented. Of course if we had the supper conductors we could decentralize the desalination, but again here we are and no one has a superconductor that will work at room temperature much less the 100F plus in the desert, and then remain stable and keep working at the desert night time lows. Solar thermal only works in high temperature low precipitation areas so the desert route is right, except it's just as far out as any other suggestion.

And for the record, while neat and not a typical arangment, Optical Rectenna is a form of Thermionics. Anything that uses heat/light to run a diode is Thermionics. So at least in a round about way we agree on this point. Plus better diode development could revolutionize geothermal(forget water tables, go for the magma), which would provide the solution to regions where solar isn't feasible.
lengould100
2 / 5 (5) Dec 12, 2008
Roach: "efficient superconductors" ?? What do superconductors presently have to do with electricity transmission? Bringing that up is a diversion. Hydro Quebec (Canada) presently transmits large amounts of electricity over quite long distances using HVDC and standard conductors, as do many other utilities in the world outside the USA.

"Anything that uses heat/light to run a diode is Thermionics." -- definition -- "In physics, thermionics is a branch of electronics dealing with the emission of electrons from matter under the influence of heat. (Wiki)" -- "thermionics the science or study of the emission of electrons from substances at high temperatures. (theFreeDictionary)" So is your car's radio reciever recieving the radio signals using thermionics? That vacuume tube unit must be a classic at least.

At any rate, ignoring the wordage microdefinitions, Optical rectenna solar energy systems are a different animal from classic photovoltaic solar energy systems. Whereas traditional photocells depend on individual molecules in a crystal structure to receive photons, knocking off an electron which is then captured and conducted to a load, Optical Rectenna sets up a resonant antenna which recieves the light wave packets just like a radio or radar receiver, with a diode rectifier at one end of the antenna. And yes, I know, there are several different phenomena exploited commercially in "photocells" but none so far has used the Optical Rectenna, which WILL BE a breakthrough some time in the future (and probably the ONLY way you'll ever see the above proposed levels of efficiency).
Velanarris
4.3 / 5 (6) Dec 12, 2008
Roach: "efficient superconductors" ?? What do superconductors presently have to do with electricity transmission? Bringing that up is a diversion.

Simple. The only way to beat current losses in power due to transmission, and to surmount current transmission restrictions is to go into super conductors. This is a known element in the field of energy and grid management. If you can generate 500 terawatts of juice but can't transmit it further than 100 miles then some or all of that power is wasted.
Velanarris
2.3 / 5 (3) Dec 12, 2008
Grow up SH.
Roach
4 / 5 (4) Dec 12, 2008
Thank you Vel,

Lengould, yes from your deffinition "emission of electrons from substances at high temperatures." How do you thing that Diode Rectifier works? Look it up.

And for your comments about Hydro Quebec, sorry, you're wrong, They can transmit it all the way to the far end of the Yukon Territory and it still isn't far. If they can push their electricity to Hawaii from Quebec then I'd be interested, but it still wouldn't matter because that's still less that the distance from the Sahara to Ontario. You do understand we aren't talking about some short push of a few thousand miles or even the half circumnavigation of 10,000miles, after manuevering the world your into millions of miles of power lines and that still doesn't get you to the house level. No one can make that work with current tech.

Line resistance = (resistivity/cross-sectional area)* Length

You can cheat this without superconductors but to make up for a 1,000 fold increase in length you need to have wires with 20 times their current diameter. At 10,000 which will be more likely under your system, we'd need cables with 56times the current diameter. that means on a single 53 foot trailer you could haul possibly up to 53 feet of power line. of course that's only one branch so really it would take 3 truckloads for every 53 feet of powerline. for easy numbers that puts us at 300 truck deliveries a mile, 300,000,000 trucks for a million miles of transmission lines. lets assume the have the optimal location for this new facility that can make such a wire, the average distance for these trucks is lets say 5000 miles per drop discounting oceans, 5 miles to the gallon on diesal fuel, 1000 gallons per segment, 300,000,000,000 gallons of diesal fuel. Just for truck delivery of this wire, not counting ocean shiping or construction equipment, escavation, unless you want to try to put these things over head. Congrats, you trucking bill just passed a trillion dollars and you haven't made the first thing with that money. Now to find the copper, that's easy pull all the copper out of Kennecott, now you're to the edge of the Sahara. Take all the pennies and unused copper lines in the US... and you still haven't crossed the Atlantic.

If physics didn't work against us we wouldn't have to look for good energy sources, they'd all be good.
Thadieus
1 / 5 (6) Dec 12, 2008
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theophys
4.3 / 5 (3) Dec 13, 2008
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Methanol and ethonal are bad ideas. They increase the required amount of farm land while simulatneously decreasing food production. WE already explored that route and there's a reason why we stopped. Disregarding environmental impact and going soley off the need for energy independence, biofuels are a bad choice for our economy and we're probably better off buying oil from OPEC and hoping they don't decide to skyrocket the prices again.
v_g
3 / 5 (1) Dec 13, 2008
@the first posts about the amount of solar energy.

The wind hasn't the same strength everywhere. You can't place a wind turbine at the bottom of a valley, but you could find there a factory which rooftop is not used and could be good for PV solar.
The only thing the article said I agree with is that the only solution is a mix of solutions, we must make the best of all the available space
v_g
2 / 5 (3) Dec 13, 2008
It is typical of an american to say that corn based or cellulosic based ethanol are not efficient and then rule out all the biofuels.
Rapeseed combined with diesel engine has a good energy balance, not all the biofuel solutions are idi0t as the choice you made.
Sometimes I think you got in the biofuel sector to kill it.
Adam
4.2 / 5 (5) Dec 13, 2008
Wind and ocean movements transport, together, about 10 Petawatts from the equatorial regions to the Poles. Humans currently use ~15 Terawatts and could live in comfort using ~90 Terawatts (when population peaks - hopefully - at 9 billion) thus if we could tap ~1% of those natural flows our energy problems would be solved.

Problem is... actually doing it. Covering 1% of the earth in wind-turbines seems rather excessive, and clogging the oceans with wave-machines and current-turbines is perhaps counter-productive.

So what's wrong with nukes? Not the obscene "use 0.7% and throw the rest away" approach to Uranium that currently dominates, but developed Fast Reactors that can burn straight natural uranium and thorium, and produce 1% the waste, which decays to safe levels in just ~300 years.

Best thing about Fast Reactors is they can BURN UP all the present waste and old bomb Plutonium, and they're next to impossible to divert bomb-grade material from. But the present nuclear economy is too tied up with bomb-making for the shift to be welcomed with open arms by Governments and Greens... but not for long. When the downside of wind and similar nonsense becomes blatantly obvious - as it is too more informed commentators - then Fast Reactor power will have its day.
Alizee
Dec 13, 2008
This comment has been removed by a moderator.
GrayMouser
not rated yet Dec 15, 2008
Doug, you said 1350w per sq meter, but the article is talking about concentrated solar plants, which I believe have a much higher return on size- the Nevada Solar One is one example. 65MW on 1.2km of plant size.


1.3KW/m^2 is the maximum energy density at the surface of the Earth due to solar radiation. The Solar One collector covers 300 acres and generates a (nominal) 64MW. That comes out to about 52W/m^2. About 4% efficiency it would appear.
Quantum_Conundrum
3 / 5 (3) Dec 15, 2008
Doug, you said 1350w per sq meter, but the article is talking about concentrated solar plants, which I believe have a much higher return on size- the Nevada Solar One is one example. 65MW on 1.2km of plant size.


Dude, if you actually do the math, that only equals 54.16 Watts per square meter...which is a joke.
lengould100
4.7 / 5 (3) Dec 15, 2008
Man, sure would help if a lot more people with opinions on energy were a lot more educated on energy (or vice versa).
Quantum_Conundrum
2.7 / 5 (3) Dec 15, 2008
1.3KW/m^2 is the maximum energy density at the surface of the Earth due to solar radiation. The Solar One collector covers 300 acres and generates a (nominal) 64MW. That comes out to about 52W/m^2. About 4% efficiency it would appear.



Exactly. Solar power is definitely a resource we should pursue as appropriate, but believing it can support the entire population is purely fantasy. Solar Power CAN provide a significant portion of the total energy, but you have to figure how much energy used in harvesting the raw materials and manufacturing and installation. Do they really even pay for themselves in their lifetime? Not just in terms of "money," but in terms of real energy produced vs spent.

I calculated it would take 12,500 solar towers like the one in spain to power all the residential needs of America for 13 of 24 hours per day.

However, this does not cover transportation, industrial, or commercial energy needs.

This ~12,500 towers ONLY covers the energy needs of homes and apartments, and ONLY for about 13 hours per day. During the 12 hours of daylight, you can store enough energy for making about one more hour of electricty.

The average worker in America uses 2-3 gallons of gasoline every day to drive to work and back home. Then there is the gasoline used for transporting students to school or college, driving to the grocery store, computer store, clothing store, etc. This means that the average household in America is probably using a total of about 8-10 gallons of gasoline per day for transportation.

Even if everyone did away with gas guzzlers and drove electric or hybrid cars no larger than a golf cart, you would still need several thousand additional towers to supply the power for recharging those tiny cars. And besides, all of this energy is peanuts compared to industrial and commercial energy use.
lengould100
2.8 / 5 (4) Dec 15, 2008
You're WAY off, Quantum. See report by Sargent & Lundys Engineering to NREL, "Assessment of Parabolic Trough and Power Tower Solar Technology - Cost and Performance Forecasts - Sargent & Lundy LLC Consulting Group Chicago, Illinois"

http://www.nrel.g...4440.pdf

or The DESERTEC Concept for Energy, Water and Climate Security - Club of Rome (energy invested in installations is about 1% of energy provided).

http://www.terraw...aper.pdf
Velanarris
3 / 5 (2) Dec 16, 2008
It is typical of an american to say that corn based or cellulosic based ethanol are not efficient and then rule out all the biofuels.
Rapeseed combined with diesel engine has a good energy balance, not all the biofuel solutions are idi0t as the choice you made.
Sometimes I think you got in the biofuel sector to kill it.
Problem with Rapeseed is you can't continually grow in on the same land year after year, it also requires land that would be rather productive as food crop land. It won't grow on marginal land well. Secondly, biodiesel, especially rapeseed biodiesel, is incredibly dirty.

Wind and ocean movements transport, together, about 10 Petawatts from the equatorial regions to the Poles. Humans currently use ~15 Terawatts and could live in comfort using ~90 Terawatts (when population peaks - hopefully - at 9 billion) thus if we could tap ~1% of those natural flows our energy problems would be solved.
Except for the fact that now since you're perturbing the natural currents of the planet, normal heat transport will be greatly affected resulting in climate changes for multiple regions.
GrayMouser
3 / 5 (2) Dec 16, 2008
You're WAY off, Quantum. See report by Sargent & Lundys Engineering to NREL, "Assessment of Parabolic Trough and Power Tower Solar Technology - Cost and Performance Forecasts - Sargent & Lundy LLC Consulting Group Chicago, Illinois"

http://www.nrel.g...4440.pdf

or The DESERTEC Concept for Energy, Water and Climate Security - Club of Rome (energy invested in installations is about 1% of energy provided).

http://www.terraw...aper.pdf


The S&L study requires heat storage technology that does not currently exist:
"Without thermal storage, the annual capacity factor of the solar plant is limited to approximately 20% to 25%. To provide generation during non-solar periods and thereby increase the plant capacity factor, thermal storage is required."

Your also looking at plants on the order of a three quarters to one half million m^2 (120 to 190 acres) per 100MW.

The Club of Rome is a political organization with a track record of disaster predictions that never come true. Look up their "Limits of Growth" study.
Velanarris
1 / 5 (1) Dec 17, 2008
The CoR has never been successful in doing anything other than causing mischief and attempting population control of groups they deem "unsavory"
Roach
5 / 5 (2) Dec 17, 2008
Wind and ocean movements transport, together, about 10 Petawatts from the equatorial regions to the Poles.


Time out, just did the math on that one, I might be wrong, but that works out to less than 20 Watts per square meter over the surface of the Earth. That's a big chunk of area even at 0.1% coverage your talking half a million square kilometers of coverage for the power collection system. 1% puts it at 5 mil.
twango
5 / 5 (1) Dec 20, 2008
I'm not sure how you did your math, but compare to this chart: average annual PV insolation in the US is about 5kWh/m^2/day

http://en.wikiped...2004.jpg

As I commented earlier: We need to be able to see quantitative comparisons for everything. Without all the my-dog's-bigger bickering and PR-flack hand-waving glimpses presented in this caterwauling 'discussion'.
twango
5 / 5 (1) Dec 20, 2008
I'm not sure how you did your math, but compare to this chart: average annual PV insolation in the US is about 5kWh/m^2/day

http://en.wikiped...2004.jpg

As I commented earlier - and this 'discussion' demonstrates it completely: We need to be able to see professional quantitative comparisons for everything. The last eight years proved that the time for religion is past.

Doug_Huffman
1 / 5 (1) Dec 27, 2008
The 1350 Watt meter^-2 Solar Constant is defined outside the atmosphere to remove variables in insolation.

All bio-renewables are so limited, even fossil fuel on a time scale beyond the human age. To utilize renewables at a greater (area) rate indebts the future even as dino-fuel has done.

Nuclear power is secure power.
Velanarris
1 / 5 (1) Dec 27, 2008
The 1350 Watt meter^-2 Solar Constant is defined outside the atmosphere to remove variables in insolation.
The solar constant is a misnomer, it's more like the solar average.

Nuclear power is secure power.
Until you realize that nuclear fusion is currently the power of the future, and will most likely remain so. As for fission, standard fission reactor fuel, enriched and enrichable uranium, is also rather limited. Thorium and other breeder type reactors are secure, but the legality of these power sources is non existant in some countries, namely the US, which has banned them since the 70's.

We need new tech or adaptation of old tech to new purpose.