TCS Daily

A Long Row To Hoe

By Russell Seitz - February 16, 2006 12:00 AM

Proposals for an alcohol-fueled end to dependence on foreign oil do not sit lightly on the American landscape. Can they fit within our borders at all?

State Of The Union speeches tend to cross using figures with speaking figuratively, and this hybrid rhetoric can bear strange fruit, like the switchgrass mania spreading up K Street like kudzu. Math has never been the Beltway's strongest suit, and it will take a while for many in DC to realize that biofuel, like the solar and wind energy franchises already on offer, suffers from sheer lack of real estate.

Solar ranching translates into paving areas the size of Massachusetts with silicon panels. But farming out the fuel supply means putting multiples of Texas under the plough. Even corn as tall as an elephant's eye yields less than half a gallon of ethanol per acre per day. And biotech might, at best, wring another quart out of fertile farmland.

That's just not enough -- it takes hundreds of millions of gallons of gas a day to run America's cars, trucks and tractors. A switch grass combine's mileage makes an Escalade look like a Prius rolling downhill. It would take upwards of a billion extra acres -- a million square miles -- to fuel the nation's transport.

A billion mile furrow is a long row to hoe -- decades of Green evangelism have failed to make alternative fuel crops a reality. A Federal subsidy program could command their planting, but the President's SOTU proposal amounts to reducing oil imports by less than 0.7% a year.

Before we're taken for a rimde on the switch grass hay wagon, let's reexamine another sort of American biofuel -- the fossil biomass underfoot. It contains millions of times the solar energy agriculture can store in a year, and vastly more hydrogen than the nation's oil and gas reserves, ANWR included. It is called coal, and we can get energy out of it and into our gas tanks.

Remember the "Energy Crisis"? It evoked National Academy of Science reports that still hold lucidly detailed answers to most of the energy policy questions junior congressmen, and op-ed writers, are asking anew today. The information revolution hasn't changed the laws of thermodynamics or the facts of fossil fuel geology since the 1974 Oil Shock. Reading studies of real resources may not be as fashionable as donning Green sackcloth, but the fact remains that America already has a four-century fuel reserve that's organic and pesticide free. For those fearful of climate change, it's also completely invulnerable to weeds, blight, hail, drought and hurricanes: fossil sunshine is immune to foul weather.

Coal's environmentally sound conversion presents complex problems, but four decades of research have already solved at lot of them. Wade through the National Academy of Science reports arising from the original "Energy Crisis" and you'll find that while premature attempts to convert oil shale and high hydrogen coal to liquid fuel were doomed by the petroleum price collapse of the '80s, coal and shale based synfuels have been historically supplied at about half the petroleum prices prevailing today (prices that have also assured nuclear electricity's economic future). Fuel farming may have its hour in the spotlight, but it will gather more applause if summoned by the invisible hand of economics than shoved on stage by the White House and the Greens.

With the War on Terror in progress, 17% of our oil still comes from the Mideast. Gasohol could allay our dependence, but what of the prospect of oil states retaliating? If biofuels debut prematurely, OPEC could drown them in the cradle by turning on the pumps, because average world oil production costs remain well under $18 a barrel. Petroleum reserves are not yet so far depleted that OPEC could not wring another Oil Glut from them. The road downhill from Hubbert's Peak is a mighty long one, and while futures traders may perceive the world's oil storage tanks as half empty, some mighty large reserves remain half full.

Russell Seitz has written on energy policy alternatives in Nature, Physics Today, The National Interest, and Forbes.



Traveling the Long Road
“Petroleum reserves are not yet so far depleted that OPEC could not wring another Oil Glut from them.”
In the last couple of years, all of the oil that could be pumped has been pumped and sold. OPEC can only marginally influence prices in a downward direction. And they cannot prevent price spikes in the event of short/medium term disruptions (hurricanes, wars, etc…). Given the growth in demand for energy, the best the world energy markets can hope for in the immediate future is to hold world oil consumption steady…using alternatives to supply the increasing demand for energy.

“Solar ranching translates into paving areas the size of Massachusetts with silicon panels”
Solar generation facilities would be ideally located on non-used land tracts…such as exist in abundance in Nevada and other western states. In addition, silicon based solar power is not the only option…see for information on solar-thermal electricity generation.

The key to energy stability is diversity. Additional coal, solar and nuclear facilities could generate the incremental electricity required to charge 100 million+ Plug-In-Flexible-Fuel vehicles (PIFF’s). PIFF’s would run mostly on electricity and ethanol. While it will likely take 20-30 years to reach significant market penetration, the eventual impact would to transfer the auto fuel source from nearly 100% gasoline to 90%+ alternative sources…including biomass, coal, solar, nuclear and others.

The transition away from gasoline in inevitable…the only question is how it is handled.

1/2 an acre per 1/2 gallon per day?
Somehow a trip to any liquor store seems to make that contention a bit dubious.

Fiddling on the roof
"Solar ranching translates into paving areas the size of Massachusetts with silicon panels."

Not true at all -- single-family homes in many parts of the country could supply all their electricity needs with commercially available roof panels. True, such a system requires 15-20 years to break-even, but with advances in material science and nano-technology will lower that figure.

Konarka Raises $20M in Funds
Red Herring, February 16, 2006

...The Series D round brings Konarka's total venture funding to $60 million, including a $7-million line of venture debt the company announced in May from Lighthouse Capital Partners. Konarka, a Red Herring 100 company based in Lowell, Massachusetts, makes a flexible solar plastic that it says weighs less than traditional solar products and COSTS ONE-THIRD AS MUCH TO MAKE.

...Marko Maschek, a partner with 3i, said Konarka's technology is unique, with a form factor advantage, different materials, and innovative manufacturing and processes. "The company has brought proven coating and printing know-how from the chemical, photographic film, and flexible electronics industries to energy via a new class of nano-engineered materials," he said.

How it should be handled
As these new technologies become economically viable, either through increases in petroleum prices or decreases in their costs, they will be adopted.

Forcing them to be adopted any earlier is nothing but a waste of money.

1) Even hard liquor contains less than 10% alchohol.
2) We don't drink millions of gallons of alchoholic beverages per day.

break even
That's 15 to 20 years to recover the cost of purchase.
It doesn't cover the costs of the loan needed to buy the panels (or replace what could have been earned had the money been invested instead).
It doesn't cover the cost of maintenance over the life of the panels. (they have to be cleaned regurally, in order to keep producing their rated power) Places like Nevada have big problems with wind driven sand, which scratches glass surfaces.
It also assumes that the panels will continue to produce the same amount of power after 15 years, that they produced on day one. They don't. Due to thermal and radiation affects, the power output of these cells starts decreasing as soon as they are exposed to light.

In reality, even in the best of circumstances, solar will never pay for itself.

Calfornia Dreaming
Not to hone to fine a point, but I don't recall gasoline or diesel to power electrical generation other that back up generators. Puting up wind turbines or solar panels to generate for you house is fine. It seems to me the article was geared towards transportation.

Biofuels require that the lion's share of the required "work" to produce and distribute it be provided in the present by energy consuming machines. This is its weakness. Petroleum on the other hand has had a large portion of the "work" already completed on it by nature and time.

When a biofuel get to the point, if ever, that it takes less than a gallon of it to produce another gallon (so that there is a net gain) then it will become of age. Until then, its just another "non-fuel" fuel.

There's a relief
Considering that it has taken less than a gallon of fuel to produce a gallon of ethanol since around 1948 (widespread use of Seed Corn), we must have come of age some 58 years ago.

Now what Mr. Flyfisher?


Pump and splendor
"In the last couple of years, all of the oil that could be pumped has been pumped and sold. OPEC can only marginally influence prices in a downward direction."

Really ? Monday night, at the CFR, Prince Sultan announced the Kingdom of Saudi Arabia was raising its base capacity from 11 to 12.5 million Bbl a day.

Taking the Fifth
The basic US corn ethanol stat is 150 gallons / acre/ year. That's at 200 proof- don't try putting Jack Daniels in your tank-at 86 proof the tiger will get wet and the carburetor will drown

Maker's Mark.
"1) Even hard liquor contains less than 10% alchohol.
2) We don't drink millions of gallons of alchoholic beverages per day."

Mark, why don't you take five gasses of absinthe and call us in the morrning ?

1. 86 proof is 43% alchohol
2. If 21.2 of 300 million Americans have one beer today , that's 2 million gallons

What color is your spare roof
"Solar ranching translates into paving areas the size of Massachusetts with silicon panels.
Not true at all "

Sorry, Rhampton- It's all too true- do the integral and you will discover that even using the best cells available, the nation's rooftop area falls an order of magnitude short of the electricity supply- when the sun is shining. If photovoltaic costs fall, they sure can help, but to do the whole job of supplying electricty globally entails areas large enough to alter the Earth's albedo- climate change is where you find it .

Pave Nevada

Perhaps paving much of the badlands in the west wouldn't be much of a loss. However, to avoid excessive losses, electricity needs to be produced near to where it is used. Or we could all move to Nevada... and pave over New York?

Can't tell - My head is in the clouds
I don't epxect to see solar as a complete replacement within my lifetime -- but it's portion of the overall energy supply will grow continously, increasingly.

The thing is, solar has the advantage of being "leveragable." Today, a few manufacturers are experimenting with jackets and bookbags with embedded with flexible solar panels -- enough to charge/recharge portable devices. But that same technology in the future could be applied as a thin film to the tops hybrid/electric vehicles. So as gains are made in efficiency and profitability, market forces push solar's potential further. [The same thing will happen with battery technology]

Today, one rooftop can supply one home's worth of electricity. But in a decade that could double, and by 2025, many -- perhaps a majority -- of home will be energy producers and energy suppliers will compete to add their contribution to commericial grids.

I know it sounds far fetched, even absurd. But in 1906, few realized how transformative the car would become -- reshaping our homes and our very lives. The impact of alternative energy will be more profound.

[Incidentally, one of the important breakthrough in solar cell R&D has been expanding silicon's sensitivity to the spectrum -- UV receptive cells would reduce, possibly negate, the impact of cloud cover.]

No Subject
I'm all for squeezing the last drop of quantum efficiencyout of silicon- and appaud silicon valley for _ already_ harvesting the spectrun all the way from he band gap to the plasmon frequency. But w that's makes advanced cells almighty black- and hot running- hence the albedo problem if we were to deploy terawatt's worth.

Alas I can't help that the sun is only worth a kilowatt per M2 at best- and hence have scant hope any normal sized car can get as much as a half horsepower - on the equator.

Solar Constant
I'm pretty sure that kilowatt/m**2 is only available if you are outside the atmosphere. That was the whole point of the geosynchronous solar arrays that would beam energy back to earth using a low energy density microwave antenna system. Considering how people on this site seem to believe a space elevator will be constructed any day now, I'm surprised no one before me has revived that idea. That solves at least some of the albedo problem as well.

Some basic science on solar
Rhampton, one roof top will not provide electricity for that home, not even remotely close and never will because of basic physics. First, at 44 degrees latitude, the maximum summer solar insolation is 1 kW/square metre, while during winter, it's about 800 watts. More importantly, winter total insolation values are less than one third those in summer. Some basic earth geometry, the further north you go the worse it gets because of planetary curvature.

Next, the theoretical maximum efficiency of a photovoltaic panel is 29 per cent, because most photons do not have sufficient energy to release electrons, irrespective of what materials the solar cell is made. Reflection and refraction effects further degrade efficiency, and again, there is no technical fix. In fact, even very light scratching can have such a severe reflection effect as to destroy the cell completely. Also a photo cell has ohmic resistance from electrical heating, all of which means that the practical limit of conversion is 12 per cent. This number has never been achieved except under highly controlled laboratory conditions that cannot be duplicated in the field.

Now, in the best locations in the U.S. southwest, you can get 300 W/square metre. Today you can buy solar cells for about $5/peak watt. Installed, it costs about $16/watt or $16,000/kW. Typical house roof is about 50 square metres, so it will produce about 15 kW at 12% efficiency, equalling roughly 7800 kWh per year. Actually you halve that amount because on a peaked roof half of it will be useless, so call it 3900 kWh.

That's less than a quarter of home annual consumption. And in the best location in the U.S.
And with a system performing perfectly.
And with a houseroof paved with panels gutter to gutter.
And using a conversion rate never achieved by any commercial application.
And assuming a peak insolation value sustained for 12 hours (obviously an overestimate, the actual value is about one third to one tenth, depending upon season, latitude and climate).

And how much did it cost? Oh about $240,000.

It's very simple RH, the economics don't work, and because of basic physics, never will. As to the UV effect, it helps a bit, but any improved efficiency is trivial given the above considerations.

Some other considerations
Who cares about the improved efficiency of an orbital installation? You've just added a minimum of $5000/lb to the capital cost, not including orbital labour costs to assemble the thing.

Finally, low density? How big a collector do you plan to use? This is energy, not an information signal being transmitted. The microwaves will have a lot of energy if it's an energy source. One wrong move with the alignment and you just cooked off Chicago.

Would you trust the Russians or the Chinese with such a thing in orbit? I didn't think so.

Beaming energy to earth
A better route would be to deploy thin solar films in space, and beam the energy back to the surface in the form of microwaves or laser light. Even Nevada is too nice to waste on an energy field.

The engineering for such a project is do-able, and collector films are more efficient the thinner they are. All we need do is devise a self-constructing platform and put it into orbit with some raw materials.

Beam me up scotty
I worked with high power microwave tubes for 30 years, and there are 2 major problems.

(1) The weight of the hardware required to beam a gigawatt of energy to earth. Can we say thousands of shuttle launches?

(2) The inefficiency of microwave generation. Ballpark it takes 3 watts to generate 1 watt. If you beam a gigawatt of energy to earth, you've got 2 gigawatts heating your microwave equipment up. We're talking mega radiators.

I tried a spreadsheet for my house.
Using data from BP solar about my location and suggested optimum system, and a modified spreadsheet from a wind-power company, I checked out my location, S Wisconsin.

Bottom line, figuring in decay of panels, maintenance, inflation etc. payback time was over 30 years.

Energy payback time was even worse.

And of course, the sun doesn't shine at night. And we recently set a record for most consecutive cloudy days.

No such fuel
Actually it takes 70% more energy to produce a gallon of ethanol than is returned.

Where did you ever hear of the existence of something that produces more energy than it possesses? That would be provide a perpetual motion machine, the phantom dream of the ages.

No fuel produces more energy than it contains. The challenge has been to find ways to come ever more closely to 100% efficiency.

A minor correction
17 percent of U.S. oil IMPORTS come from the Middle East. Only 11 percent of the total amount of oil the U.S. consumes comes from the Middle East.

The very concept of reducing dependence on foreign oil is misguided. It can't be done, and even if we could we wouldn't want to. England is oil independent. Has that spared them from price spikes that arise from supply disruptions. Nope. This whole discussion is silly.

Science indeed
ColinH, the current generation of solar cells are about 15% efficient -- meaning there's HUGE room for improvements. Even so, given todays's economics what I said is true:

Solar Power Isn't for Tightwads
The Wall Street Journal, February 12, 2006

...For tax years 2006 and 2007, homeowners can get a federal tax credit equal to 30% of the cost of buying and installing solar photovoltaic paneling or a solar thermal water heater, up to $2,000 per upgrade ... A system of photovoltaic panels that convert solar radiation into a home's electricity often costs about $8,000 per kilowatt before incentives. That's a total investment of anywhere from $16,000 to $64,000, considering that most homes need between a two- and an eight-kilowatt system to REPLACE MOST OR ALL OF THEIR ELECTRICITY NEEDS. (The higher end of the range may include homes that use electricity to power their heating systems.)

Even with the new federal credit, it often takes 20 or more years to recoup the initial investment through energy-bill savings.

...California provides an upfront incentive of $2.80 per installed watt -- that is, $2,800 per kilowatt -- for photovoltaic systems under 30 kilowatts. That's about 35% of the overall cost. California accounts for 85% of the solar-gear market in the U.S. In New Jersey, the rebate is an even greater $4.95 to $5.20 per watt, or about a 60% savings. Among other states, Maine offers up to a $7,000 rebate on residential photovoltaic-system installations and $1,250 on solar thermal water heaters that runs through this year. Minnesota offers a $2 per watt -- or about 25% -- rebate. Sometimes utility companies offer their own rebate programs.

...How long it takes to recoup the investment costs also depends on energy prices. Those who live in regions with surging energy prices, such as California and the Northeast, will garner savings faster than those in areas with lower utility rates. To get an idea of how long it might take you to break even, check out "My Solar Estimator" at online. Homeowners can also usually get a free analysis done by a local installer, but be sure to double-check the assumptions used.

Like regenerative braking, the point of a solarfilm car top would be to use freely available energy to extend the filling/charging cycle.

Very High Efficiency Solar Cell (VHESC)
February 25, 2005

The Defense Advanced Research Projects Agency's (DARPA) Advanced Technology Office (ATO), in collaboration with the Defense Sciences Office (DSO), is soliciting proposals under this BAA for the Very High Efficiency Solar Cell program. The objective of the Very High Efficiency Solar Cell program is to demonstrate at least 50% efficiency in a photovoltaic (PV) device. Recent developments drawing on the use of engineered biomolecules to guide the assembly of inorganic materials offer the potential of a new process path for fabricating nanoscale, inorganic, three-dimensional meta-structures with dimensional and assembly control not achievable with current technologies. Combined, these independent advances suggest the potential for manufacturing a new type of high-efficiency, advanced PV solar power source.

The program requires that teams be formed to comprehensively address all aspects of the high-efficiency PV problem including the development of fabrication processes that are scaleable to industrial manufacturing and an affordable product. As such, it is envisioned that successful teams may include elements from industry, to include both large and small businesses, academia, and national laboratories, but must include elements from industry appropriate to the subsequent manufacture of successfully developed devices.

The VHESC program final deliverables will include a minimum of 1,000 units, 10 cm2 per device, producing at least 0.5 W each with the above minimum efficiency, assuming a standard solar fluence of 1 kW/m2...

Read it again
RH, you said, "the current generation of solar cells are about 15% efficient -- meaning there's HUGE room for improvements".

Go back and read my post again. This is basic physics here, unless you are proposing to change the fundamental nature of photons and electrons or the output of the sun, in which case there are a large number of physicists out there who want to talk to you about quantum mechanics and a number of other things. There is virtually no room for significant improvement, end of story.

And again
Are you suggesting that "basic science" says we will not be able to extract no more than 15% of the available energy from sunlight? If so, then you need a remedial course or two.

Now consider that in the future an affordable PV system might generate 1kW for every 40sqft of exposure (apx 50% effiency). That translates to a potential 15kw generating capacity for a 1200sqft ranch house with only half its roof (the sunnier side) so covered.

True and....
You are correct about the net energy return on ethanol, and the desire for greater efficiency extraction. That's why we moved 800 years ago from wood to coal, and 100 years ago from coal to oil.

However, another aspect of the energy source is to harness energy sources which would otherwise simply be wasted, irrespective of what the efficiencies are. That's the advantage of hydro. It's also an advantage of nuclear power; instead of allowing uranium to waste all of its potential in radioactive decay, fission harnesses a small part of it in a reactor. The conversion efficiency to electricity is about 30 per cent, but it means using a source of energy that would otherwise be completely untapped for any other purpose.

Key thing to understand is how the 2nd Law of thermodynamics applies, or doesn't apply. It is true that all harnessing of energy leads to a loss of potential. However, any energy source must produce more energy than what is invested to package it, and that as you point out is why ethanol is a huge loser. Methanol may not be so, because it uses materials which would otherwise be scrap.

It comes down to energy payback periods; for a gas turbine it's about 3 months, for a coal-fired plant it's about 3 years (including coal mining etc.) for a nuclear plant it's about 2 years (including uranium mining), for a wind mill it's more than a decade, and for solar and ethanol from corn, the net payback is negative.

Once more
The maximum efficiency is 29 per cent in theory because most photons do not have the energy to dislodge electrons. The practical maximum is much lower than that. That means most sunlight is and always will be wasted. So, you can't get 50% efficiency. 12% is the practical limit, now and likely to be for the foreseeable future. Add in refraction and reflection problems, and the efficiency goes down much more.

No Subject
That's where your understanding of Science fails you. See my post "Updates" about DARPA developing 50% effiency.

Failure to communicate
That's where your understanding of Science fails you. See my post "Updates" about DARPA developing 50% effiency.

By the way, where did you get that idea that of a 29% ceiling?

Basic physics
Try learning something about basic physics and quantum mechanics. Otherwise, don't waste my time.

As for DARPA
Who cares? It's a project tender, not a project. They may know nothing about physics, and given that it's the military, that would scarcely be surprising. I could put out a tender asking for a ladder to the Moon, but that wouldn't make it real. Your error lies in the presumption that if they ask for it, it will be built. Predicting outcomes in that fashion is witchcraft, not science.

Basic physics does not cap solar energy extraction at 29%.

No this is fact
Sorry, you're wrong. It does. Most of the photons just don't have enough mev's to do the job.

Technology based assumptions
Bear in mind that this study used current (2003) solar cells to derive its numbers...

Theoretical limits of thermophotovoltaic solar energy conversion
Semicond. Sci. Technol, Issue 5 (May 2003)

Theoretical efficiencies are derived in a detailed balance calculation for thermophotovoltaic solar energy conversion, where solar radiation is absorbed by an intermediate absorber, which emits radiation inside an evacuated housing towards a solar cell. For ideal components with no optical losses and only radiative recombination in the solar cell, maximal efficiencies are found of 85% for full concentration of the incident sunlight on a black absorber, and of 54% for no concentration and a selective absorber absorbing only for bar h? > 0.92 eV. This is considerably larger than the efficiency for directly illuminated solar cells with also only radiative recombination, the Shockley–Queisser limit, which is 41% for full concentration and 30% for no concentration.

In order to approach efficiency limits for real TPV systems, several non-idealities have been introduced: (a) realistic assumptions about the geometry of the intermediate absorber, (b) optical losses of 5% for photons with energy below the band gap of the solar cell and (c) non-radiative recombination in the solar cell of the same amount as radiative recombination. This reduces the efficiency for non-concentrated sunlight to only 32.8%, but for very high concentrations of 10000 and above suitable absorber geometries still seem to allow efficiencies close to 60%.

All too true and....
Since innumeracy is the ground state inside the Beltway, the hardest row to hoe is getting in into DC skulls that the conversion efficiency of photosythesis is an order of magnitude and change worse than photovoltaics.

Barring some real biotech Mojo, like a major improvement in C3 or C4 land plant metabolism, or kelp that walks out of the water and wrings itself dry before hurling itself into the boiler fire , the real estate problem is not going to go away

Quito Gas & Electric
It's 1360 W/M2 in space at 1 AU, 980 watts at nominal wet sea level, and thanx to reduced H2O in the atnmosphere at altitude and inland , a measured 1023 watts on a good dry day in Quito- I would not have said a kilowatt in JGR or Nature, but hey , this is a family website. and we have to make allownce for the neighbors columns .

Current technology
"the gallium indium phosphide (GaInP)/GaAs tandem cell has achieved an efficiency of 30% and is now commercially available for space applications."
Splitting photocells by wavelength overcomes the theoretical limitation you use. They aren't economically attractive, of course.

A few months ago, algae was being discussed as a source of raw material for conversion to ethanol. The claim was that 11,000 square miles of solar algae vats could produce enough fuel for the entire current energy requirements of the U.S.

That really doesn't sound like something I would want on my roof
"...but for very high concentrations of 10000 and above suitable absorber geometries still seem to allow efficiencies close to 60%."

I'm not interested in paying $30 to access the full article. Did you read the full text? Did it by any chance give a temperature range for the intermediate absorber? At a concentration factor of 10,000 and above, I'm guessing it's pretty hot. For a commercial plant, you would still need square miles of mirrors.

Hot stuff
Again, that article derives its figures with the assumption that solar cells will be developed with technology circa 2003.

However, if you read the DARPA proposal for Very High Efficiency Solar Cells (VHESC) I posted in the comment titled "Updates," then you would realize that the future for solar cells will not be more of the same.

Fat future for thin films
Solar cell developers look beyond silicon
EE Times, February 20, 2006

...HelioVolt Corp. (Austin, Texas) has developed a process based on rapid thermal annealing and anodic bonding that allows high-performance copper-indium-gallium-selinide (CIGS) films to be deposited on just about any substrate.

Founder and photovoltaic pioneer Billy Stanbery claims the process can dramatically shorten manufacturing time and reduce the thermal budget by a factor of 10 to 100. The process could allow a new class of materials for building integrated photovoltaics that serve, for example, as a robust coating on external building materials or on interior furnishings like curtains, to turn buildings into self-powered photovoltaic plants...

...Moreover, Stanbery said, "it's the most efficient of any photovoltaic thin-film technology and it's beginning to overlap with silicon in that area." Moreover, "All the other thin-film approaches have inherent instabilities, but CIS, like silicon, has no inherent degradation mechanism that has been identified," Stanbery said.

Perspective on Multiple Sources...and Uses...and Ultimate Markets
Maybe this is a good time to note that most of these energy sources being discussed are valuable and profitable in niche markets right now. Biodiesal from french fries and digesting steer manure for methane both reduce waste and can have cost advantages. Likewise, an off-grid house in the Mojave can be cheaper than paying for a power line.

With hard work (and continued high prices of the conventional alternatives), some of them might become significant contributors to the energy mix. Still, none of them are going to change the albedo of the planet any time soon. Even a few gigawatts of panels in Nevada to keep slot handles in Vegas cranking would be a small blip in the heat balance.

Back at the car roofs, built-in arrays could make a few percent difference in hydrocarbon use by hybrids--nice, but Exxon still does the heavy lifting. Back at the house roofs, photovoltaic panels built as part of original construction (retrofit is $$$$) could eventually supply a significant part of the electrical load--especially the peak daytime air-conditioning load. Solar supplying a majority of power would entail somebody investing in major storage facilities--that's another set of technologies and issues And it still wouldn't affect the albedo noticably.

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