And the profits grow

[kandrathe]

The reason photosynthesis isn't efficient is because 90% of the energy being stored is in turn used to maintain the survivability of the organism doing the storing. Non biological photosynthesis, as technologies advance, will circumvent this limitation. The "huge breakthroughs" you speak of still assumes a linear technology advancement path when technologies advance on exponential curves (or more accurately multiple exponential curves). The question isn't "even if we can increase the efficiency *this much*" it's a question of how accurately we can predict where we are on the technology curve for solar power (or hydrogen fuel cells, etc. etc. etc.). The efficiency is going to get better, I'm confident in making that prediction. Thinking about technology in a linear fashion tends to lead to two falacies: we overestimate tech advancements in the short term, and we vastly underestimate tech advances in the long term.

The dilute nature of solar power is not due to limitations in technology. It is due to the amount of solar power hitting the Earth at a given area over a measure of time. I believe we are well beyond the point of being able to replace our current consumption of petrol fuel with the amount of energy hitting the earth from the sun. I believe the current optimum of solar capture on Earth is around 1000 watts per square meter. At space with 100% capture the ratio is 1340 watts per square meter. The amount of loss is due to atmosphere, dust, distance, etc. Usually, at most points on Earth the solar capture capability is far, far less. For comparison, a gallon of gasoline contains about 1,300,000,000 joules of energy. For electric power comparison, 1 joule = 1 watt second.

1000 watts is 1.34 Horsepower. The curb weight of a Volkswagen is 1,090kg. Add four slim passengers at 55kg each, and we have 1310Kg to move. Assuming we are just accelerating on a flat plane, we can use the formula KE (joules) = 1/2 Mass * Velocity ^2, or 1/2 * 1310 Kg * 24.5872 Meters/Sec ^2. So, to accelerate our VW with passengers to 55 mph (or 24.5872 M/s) it will take 395967.41 joules. Remember that 1 joule = 1 watt second, so we can calculate the watts or seconds required to move our vehicle. I'm guessing that our vehicle has around 2.5 meters width x 4 meters length. Also assuming it is directly pointed at full sun gives us 10 meters^2 * 1000 watts, or 10,000 watts per second. Solving 395967.41 joules / 10,000 watt seconds potential gives a theoretical minimum time to achieve zero to 55 mph on a flat surface, or 39.6 seconds. Now add some hills, some additional resistance from snow, loss of energy from stopping and starting, and you'll need much more than the 10Kw potential. But, if we can reduce the weight, or store some energy in compact batteries then it has a chance. The issue is still energy density, and solar (including bio-fuels) will not do it alone.

[Chesspiece_face]

The dilute nature of solar power is not due to limitations in technology. It is due to the amount of solar power hitting the Earth at a given area over a measure of time.

actually present research shows that we would only need to "harvest" 1/10000th of the amount of solar energy that comes to earth to be able to meet all of our energy requirements. Most recently a panal of scientists and engineers including Ray Kurzweil, whom i mentioned earlier, convened by the American Association of Engineers gave their findings at the 2008 annual meeting of the American Association for the Advancement of Science. In it they, not only, describe how the use of Solar Power Cells are doubling every two years but how advancements in nanotechnology will increase the efficiency while creating smaller and lighter panals and how the use of concentrators using parabolic mirrors can focus large amounts of solar energy onto small sections of Power Cells.

[Occhidiangela]

Seems this thread is invaded by a legion of supreme right-winged nut huggers turning this into a "lets-bend over- for the-oil-companies- and take it in the (insert expletive in here)-fest"

*hums a few bars of old cowboy song "The Streets of Laredo"*

"I see by your posting
That you are a moron"
These words he did post
As he calmly dropped by
"Go sit on a fire plug
And rotate, not slowly,
'Cos your dead in the brain
Since the cells up and died."

See also the immortal quip of General Honore. They fit you like a glove.

Occhi

[kandrathe]

actually present research shows that we would only need to "harvest" 1/10000th of the amount of solar energy that comes to earth to be able to meet all of our energy requirements. Most recently a panal of scientists and engineers including Ray Kurzweil, whom i mentioned earlier, convened by the American Association of Engineers gave their findings at the 2008 annual meeting of the American Association for the Advancement of Science. In it they, not only, describe how the use of Solar Power Cells are doubling every two years but how advancements in nanotechnology will increase the efficiency while creating smaller and lighter panals and how the use of concentrators using parabolic mirrors can focus large amounts of solar energy onto small sections of Power Cells.

I'm sorry, how do concentrators change the equation? You still need to intercept 1m^2 to get theoretically 1000 watts. If the 1m^2 at the edge of space with 100% collection yields 1366 watts per square meter, then how do you use nano-technology or smoke and mirrors to increase anything beyond your research budget? We can use parabolic mirrors and lenses to concentrate solar energy now to melt salt. This sounds like the proverbial Mr. Barnum selling the suckers (who are born every minute) with deep pockets on the merits of buying into phantom energy.

Think of it another way. The average home uses about 877 kWh per month. Divide that by 30 days and 8 hours of decent sun a day giving 240 hours to possibly generate the 877 kWh meaning that every day every home must generate 29.23 kWh (877kWh / 30 days) over that eight hour period (29.23 kWh / 8 hours) is 3654.167 watts. This means about 18 or 19 solar panels of about 200 watts. This requires about 30 square meters per home, or 30 square meters x 114,317,700 households in the US is 3429531000 square meters of solar panels. That is equivalent of 1,324.15 square miles covered with solar panels. For comparison, Rhode Island is 1,545 square miles. Using the Sanyo Model from below, solar panels costing 656.25$ /square meter means 3,429,531,000 square meters x 656.25$/sq meter = $2,250,629,718,750. Of course, there would be some discounts in buying them in bulk.

That's a lot of infrastructure my friend. Add to that another huge amount of energy needed for transportation and industry. I'm not saying solar won't help. I'm saying it is too dilute to be the magic bullet that will solve our energy problems. Hoping that endless investment into technology can undo the laws of physics (solar constant) is not the answer either.

Edit: Fixed a math issue called out by Zenda. I was off by two decimal places in one conversion.

[eppie]

That's a lot of infrastructure my friend. Add to that another huge amount of energy needed for transportation and industry. I'm not saying solar won't help. I'm saying it is too dilute to be the magic bullet that will solve our energy problems. Hoping that endless investment into technology can undo the laws of physics (solar constant) is not the answer either.

I agree with you that only solar will be enough, and further I have to believe the amounts you are mentioning, but I am not so negative. Highly likely everybody who loves in a house (so not apartment building) will have his whole roof decorated with cheap plastic solar panels in x years. Calculation on efficiency are always done using an average lightness during a day (so not calculated for the Sahara). Add a few small wind mills (the 50 cm diameter kinds), and energy saving, and we will for sure be able to be self sufficient (I mean connect the whole thing to a back up generator or batteries or simply use a switch to connect and disconnect to the main electricity grid. Solar power panels can also be combined with sun boilers, so that they can also use the heat from the sun directly.

I my street they are, as we speak, installing geothermal heating for our water...pretty neat (Sweden wants to be the first carbon neutral nation, whatever that may mean).

That solar power might also help a lot for cars we can see when looking at the solar power challenge that they have in Australia every year. Those cars drive 3000 miles with an average of over 80 km per hour. Of course they are not cars in which you sit comfortably but nevertheless quite impressive.

[Kevin]

I agree with you that only solar will be enough, and further I have to believe the amounts you are mentioning, but I am not so negative. Highly likely everybody who loves in a house (so not apartment building) will have his whole roof decorated with cheap plastic solar panels in x years. Calculation on efficiency are always done using an average lightness during a day (so not calculated for the Sahara). Add a few small wind mills (the 50 cm diameter kinds), and energy saving, and we will for sure be able to be self sufficient (I mean connect the whole thing to a back up generator or batteries or simply use a switch to connect and disconnect to the main electricity grid. Solar power panels can also be combined with sun boilers, so that they can also use the heat from the sun directly.

I my street they are, as we speak, installing geothermal heating for our water...pretty neat (Sweden wants to be the first carbon neutral nation, whatever that may mean).

That solar power might also help a lot for cars we can see when looking at the solar power challenge that they have in Australia every year. Those cars drive 3000 miles with an average of over 80 km per hour. Of course they are not cars in which you sit comfortably but nevertheless quite impressive.

Just as an FYI some good basics on generals of solar energy (including the numbers that Kandrathe is using) can be found here: http://www.ucsusa.org/clean_energy/renewab...ergy-works.html it's very pro solar source, but it covers terms and concepts nicely.


Now onto some personal anecdotes and information. UMR (my alma mater) won that race a few years back, and they've won the one held in the US several times as well. I know they won SunRayce (the US version) for the overall title one year, not just the University bracket. So I've seen the vehicles up close and personal, as a student I even did some work for the team one year.

It's pretty much a very lightweight foam, some electrical motors a bunch of batteries, and solar cells. I think it was in 2003 when they dominated and I know there were several times they were limited by the speed limits on the road, 55 MPH for most of the course length. They could have gone faster at many points, there were some great shots of them passing regular cars on I 44 with the solar car going 70 MPH, the speed limit, and the normal cars only doing 65 or so. There is a lot of time spent in those races, after you hit the check point, of taking the cells off the vehicle and holding it at best angle to get more charge into the batteries. But there were times in 2003, where they were running top speed and getting enough power to add charge to the batteries. But as you mentioned those vehicles are not something you could do much in at all.

One application of solar cells on vehicles I have seen that was nice was a 'trickle charger' on the military vehicles. It was a 6 inch by 6 inch panel connected to the batteries that would slowly add charge to them if it got any power. Not a big deal but made a huge difference in time between battery replacement and the vehicles that had the chargers could generally be counted on to start. Some of those vehicles sit for 2-6 months between usage. Having that trickle charger made a big difference on them. Not that this application made any difference in the amount of diesel the vehicles burned.

Solar water heaters are definitely something I'd like to see more widespread, they seem to be pretty effective. I'm a fan of doing more of the little stuff like that to help out. More intelligent dwelling design. As you mentioned, if things are economical, getting solar collectors up on houses to help generate power. You can already get devices that let you feed power into the grid if you have excess, and you can pull out of the grid like normal if you need it. Some people actually get a small check from the power company each month because they generated more power than they consumed. The initial set-up fees aren't unreasonable for stuff like that. But if you can get some solar collectors on your roof, and for folks that live in the country can get a windmill up it can help. Windmills on farmland, especially animal grazing land is becoming more popular as they don't take a lot of usable land up. The issues with birds and such still have to be dealt with, it's not a zero environment impact solution, but I'm a fan.

So yeah, a large amount of oil goes into generating electricity (same for coal and natural gas and cutting dependence on those fuels is a good thing too) so cutting that usage is good. I'm a fan of centralize the less clean power generation sources since you can be more effective in controlling the pollutants they produce, but the cleaner sources, like solar and wind, while there isn't a major issue with centralizing them, I don't see any major drawbacks to decentralizing them. 10,000 sources producing 1,000 watts each seems to be as good as one source production 10 Mega Watts. OK that's not entirely true. That single source can deal better with the changes in demands for power. Even with lots of folks producing small amounts of power and feeding it into the grid you'll still need your lager point sources, and they can be solar or wind so be it. If a few still need to be coal or oil, I'm alright with that too.

And yes you have to worry about economies of scale in these issues too, but I think the scales will be large enough for most all of them that using several solutions will still like provide a better answer than just trying to back a single option.

[Zenda]

"By the time it reaches Earth's surface, the energy in sunlight has fallen to about 1,000 watts per square meter at noon on a cloudless day. Averaged over the entire surface of the planet, 24 hours per day for a year, each square meter collects the approximate energy equivalent of almost a barrel of oil each year, or 4.2 kilowatt-hours of energy every day."

Assuming only 10% efficiency, that would be 0.42 kWh per day. To supply 877 kWh in 30 days, the required amount would then be 69.6 square meters. Small enough to fit easily on most roofs, I'd say.

"The average home uses about 877 kWh per month ... Each home would therefore require a solar panel covering about 365 square meters"

Is this how you come to your conclusions, Kandrathe?

[Frag]

Windmills on farmland, especially animal grazing land is becoming more popular as they don't take a lot of usable land up. The issues with birds and such still have to be dealt with, it's not a zero environment impact solution, but I'm a fan.

Bun would be proud, you nut hugger!:lol:

~Frag

[--Pete]

Hi,

One application of solar cells . . . was a 6 inch by 6 inch panel connected to the batteries that would slowly add charge to them . . .

Such panels are very commonly used on sailboats to recharge the batteries. Often the solar panel is attached to the hatch cover, so the batteries are charging when the boat is docked, and everything is out of the way when the boat is n use.

Solar water heaters are definitely something I'd like to see more widespread, they seem to be pretty effective.

Here in Seattle, a solar water heater would be iffy in the winter. And in Pullman (Eastern Washington) where I lived for about eleven years, you'd need a large amount of anti-freeze in that system in the winter. But in some places, it would work fine. About 100 feet (say 30 m) of black PVC pipe was our water heater for the showers in Nah Trang, Viet Nam. Except during the rainy season, we always had plenty of hot water.

I'm a fan of doing more of the little stuff like that to help out. More intelligent dwelling design.

That would require more intelligent dwellers. People want nine to twelve foot ceilings, many big windows, and complex home design in huge houses.

You can already get devices that let you feed power into the grid if you have excess, and you can pull out of the grid like normal if you need it. Some people actually get a small check from the power company each month because they generated more power than they consumed.

Co-generation can get the consumer a bit back if the local laws require the power companies to pay (or if the power company is progressive enough to pay without being forced to). Mostly, though, the return on the investment is from avoiding having to buy the power.

The initial set-up fees aren't unreasonable for stuff like that.

Initial costs are pretty well meaningless by themselves. The buzz phrase is "life cycle cost analysis". How much does it cost to install, maintain, and finally dispose of the old system when the upgrade goes in? How much power will you generate during the life of the system. That ratio gives you the number to compare to the power company's rate. You'd be surprised how seldom you can come out ahead.

Windmills on farmland, especially animal grazing land is becoming more popular as they don't take a lot of usable land up. The issues with birds and such still have to be dealt with, it's not a zero environment impact solution, but I'm a fan.

Actually, it's the windmill that's a fan;) Sorry, couldn't resist.

I'm a fan of centralize the less clean power generation sources since you can be more effective in controlling the pollutants they produce, . . .

Centralized or not, there really isn't any way to keep the carbon dioxide out of the atmosphere. You can't store it, and the energy required to convert it into something else is more than what you got from burning the stuff in the first place. First law: you can't win. Second: you can't even break even. So releasing that carbon is bad, even if the other pollutants are scrubbed.

. . . but the cleaner sources, like solar and wind, while there isn't a major issue with centralizing them, I don't see any major drawbacks to decentralizing them.

An often overlooked advantage is that small, local sources don't suffer from long distance transmission losses and from transformer losses.

. . . using several solutions will still like provide a better answer than just trying to back a single option.

Very true, but the total energy requirements for an industrial society are large and most of these solutions are small. Ideally, we need to stop burning fossil fuels to reduce the greenhouse gas emissions. Hydro is pretty well maxed out, and many hydro dams are becoming maintenance nightmares because of silt (not to mention the environmental effects). Of the proven technologies, only nuclear has the potential for meeting the needs. The more it is supplemented with secondary sources, the longer we can depend on it. But any non-nuclear long term solution is a pipe dream.

--Pete

[Zenda]

For those who think the sun cannot sustain the earth...

http://en.wikipedia.org/wiki/Photovoltaic_array:

"The unpopulated area of the Sahara desert is over 9 million km², which if covered with solar panels would provide 630 terawatts total power. The Earth's current energy consumption rate is around 13.5 TW at any given moment (including oil, gas, coal, nuclear, and hydroelectric)."

That's based on current technology, with 12% efficient solar panels.


For those who think that nuclear power is the answer to all problems...

http://en.wikipedia.org/wiki/Uranium:

"The ultimate supply of uranium is believed to be very large and sufficient for at least the next 85 years"

That's right. Only 85 years, according to optimistic sources (like http://www.iaea.org/NewsCenter/News/2006/u...resources.html). Hardly worth investing in, I'd say, considering all the risks.

http://en.wikipedia.org/wiki/Uranium:

"In other words, there is very little high grade ore and proportionately much more low grade ore."

In other words, it won't be long before nuclear power becomes expensive too.

[Jester]

I can't say that's a very convincing argument about the long term sustainability of nuclear power. At the very least, you run into this problem:

http://en.wikipedia.org/wiki/Thorium#Thori..._a_nuclear_fuel

Nuclear fuel sources are not just restricted to easily mined Uranium. Nuclear power is not the answer to all questions (it notably does not answer "how do we get lots of power quickly and cheaply") but it is (so far) our best answer to the most important questions.

Also, from your own link at the IAEA:

"Based on the 2004 nuclear electricity generation rate of demand the amount is sufficient for 85 years, the study states. Fast reactor technology would lengthen this period to over 2500 years."

85 years may not seem like a long time to you, but 2500 is about as long term as anyone could wish for.

-Jester

[Zenda]

How come you all believe that technological advance will solve all problems for nuclear power, but not for solar power?

Btw, notice how that 85 years is based on consumption in 2004? When taking progress into account, the article estimates supplies to be sufficient up to ... 2025. Anyone thinks we will have that super technology by then?

[kandrathe]

"By the time it reaches Earth's surface, the energy in sunlight has fallen to about 1,000 watts per square meter at noon on a cloudless day. Averaged over the entire surface of the planet, 24 hours per day for a year, each square meter collects the approximate energy equivalent of almost a barrel of oil each year, or 4.2 kilowatt-hours of energy every day."

Assuming only 10% efficiency, that would be 0.42 kWh per day. To supply 877 kWh in 30 days, the required amount would then be 69.6 square meters. Small enough to fit easily on most roofs, I'd say.

"The average home uses about 877 kWh per month ... Each home would therefore require a solar panel covering about 365 square meters"

Is this how you come to your conclusions, Kandrathe?

Sure. I'll check my math.

Let's look at a real solar panel.

Sanyo 200 watt solar panel for $1050. It's dimensions are 51.9" x 35.2" x 1.4" and in optimum conditions it will generate 200 watts. 1826.88 (square inches) = 1.1786299 square meters -- So 200 watts / 1.1786299 square meters is 169.69 watts per square meter per second of sun. Again let's optimistically assume 8 hours of sun per day, 8 hours x 360 seconds per hour = 2880 seconds in 8 hours. 200 watts x 2880 seconds = 576000 watt seconds (Joules) or 1.6 kWh for the 8 hour period. So, 4.2 kWh / square meter is overly optimistic with this model of solar panel.

Back to the example of our Sanyo 200 watt panel. Let's see how many of these solar panels we need to supply our 877 kWh per month. We have 30 days of bright 8 hour sunny days to work with, so 1.6 kWh per day x 30 days gives us 48 kWh per month, or 877/48 means we need 18 or 19 of these to power our home. Yes, 18 x 1.1786299 = 21.22 square meters. This doesn't jive with my number of 365 square meters, so I'll go back and find my math error. If only we had more places that gave 100% optimum solar conditions for 30 days a month.

[--Pete]

Hi,

How come you all believe that technological advance will solve all problems for nuclear power, but not for solar power?

We don't. The fact is that breeder reactors exist and have been in use for decades. The fact is that reclaiming fissionable fuel from spent rods is being done, has been done for decades (that's how you get plutonium). The fact is that disposal of the remaining waste is a solved problem, mostly solved by the French. The only 'problems' with nuclear are the restrictions based on non-proliferation treaties and the social problem of vast numbers of ignorant voters who piss their pants in fear of everything nuclear. Nuclear is *yesterday's* technology as witnessed by the percentage of the world's energy generated that way.

Solar? That may be the way of the future, but they've been playing with it almost as long as they've played with nuclear and it still has many unsolved problems.

So, yeah. Intelligent, informed people have more faith in an established and mature technology than they do in something that's still failing to prove itself after more than four decades of development.

Btw, notice how that 85 years is based on consumption in 2004? When taking progress into account, the article estimates supplies to be sufficient up to ... 2025. Anyone thinks we will have that super technology by then?

Gee, I don't know. We had it by the mid '50s, but maybe we lost it? No. I think they still have it at Hanford. Maybe we can get them to share.

--Pete

[kandrathe]

How come you all believe that technological advance will solve all problems for nuclear power, but not for solar power?

Btw, notice how that 85 years is based on consumption in 2004? When taking progress into account, the article estimates supplies to be sufficient up to ... 2025. Anyone thinks we will have that super technology by then?

Uranium is not the only fissile material, we might find other common materials that we can use as fuel. Back in 1932, Lord Rutherford demonstrated that power can be generated from Lithium decay. The ultimate result is a reaction that is clean, producing 2 helium atoms and 43 M.e.v. It is essentially the physics of the hydrogen bomb, which has not been explored as a viable commercial nuclear reactor. Fast breeder reactors have yet to be optimized commercially. And, with limited research in the field, we currently have a Fusion reactor has yielded 65% of input power. The ITER project hopes to have a working productive fusion reactor in place in France by 2016.

In contrast, there is nothing really we can do to increase the solar constant.

[Jester]

When taking progress into account, the article estimates supplies to be sufficient up to ... 2025.

Where does it say that? I only see 2025 mentioned a handful of times. First is in the title, which describes the length of time the "red book" takes into account, not the point at which we run out of Uranium. It also says that by 2025, Uranium needs will go up 44%, but that existing resources are "adequate to meet this expansion." The final time is when it tells us outright that the whole idea of the study is to predict fuel needs up until 2025.

As far as I can tell, the article doesn't say we're going to run out in 2025. Are you certain you're interpreting it correctly?

From the links right there next to the article: http://www.iaea.org/NewsCenter/Statements/...ov01062006.html

Mr. Sokolov sure doesn't seem concerned.

-Jester

[Kevin]

How come you all believe that technological advance will solve all problems for nuclear power, but not for solar power?

Btw, notice how that 85 years is based on consumption in 2004? When taking progress into account, the article estimates supplies to be sufficient up to ... 2025. Anyone thinks we will have that super technology by then?

I'm not turning away from solar. There is a 17 acre field of mirrors in California that concentrates the energy recieved on an 80 meter tower to boil water, producing steam and driving a 10 Megawatt generator. Total solar energy that 17 acres recieves is just over 68 Megawats.

And there are parabolic concentrator generator stations in the Mojave desert built between 85 adn 91 ranging from 14 to 80 Megawatt with a total capacity across them all of 354 Megawatts. Similar plants are being built in Arizona.

For some parts of the world you can certainly build larger scale solar power stations with minimal environmental impact. But it's not something that can happen everywhere and you still have the issue that the generation isn't constant. Fortunately power consumption is lower at night than during the day, so that isn't so bad.

But like Pete said there are nuclear processes that are proven to work and the waste can be dealt with. The sooner we get off fossil fuels and onto anything else the happier I'll be. You can put nuclear solutions in place today pretty much anywhere, you can't do that with solar. You can put solutions in place today with solar in some locations.

Of course neither solution really works for the transportation industry. Purely battery powered vehicles and rapid electric power charging stations don't exist yet. Nuclear or solar can't solve either anytime soon. Biofuels are available now and can sorta solve the problem. They are at least renewable, though of course you have density issues and you'll still have cost issues. I'm still very excited about the hydrogen fuel cell vehicles that are out there, but they need a bigger infrastructure overhaul than a biofuel change would take. It's actually possible to scrub existing gas and diesel tanks over a period of time and make them usable for biofuels. You can't do that for hydrogen fueling.

I'm very pro any research into any means of energy generation. If you have cheap and clean energy generation many of the other problems humanity faces are a lot easier to deal with.

[kandrathe]

...
Biofuels are available now and can sorta solve the problem. They are at least renewable, though of course you have density issues and you'll still have cost issues.
...

GG, I agree with everything you are saying. I have one other caveat with bio-fuel. I'm concerned about the impact of overlapping the energy market with the food market. There will be a tendency to use arable land for fuel, that would otherwise feed the third world. In that case, where will compassion fall? Will it side with starving humans and economic stability, or will we continue to prevent drilling for oil in otherwise off limits areas?

[eppie]

Sanyo 200 watt solar panel for $1050[/url].

1050 dollars?? That is about 14 euros!
:D

[eppie]

Sure. I'll check my math.

So this 877kWH per month includes water heating (normally done by gas) ?
If so, the previously mentioned sun boiler can take care of that in many place son this earth.....and heating our water is often a very large part of the total energy costs (especially when people don't use air conditioning)