Slashdot Mirror
(Solar) Power to the Masses
D3 writes "This report on a solar power tower (pdf) looks extremely interesting. Maybe one day we can have international power lines where all the countries with lots of sunshine provide power to the rest of the world? How cool would that be?" The NY Times has a good article on solar power in Japan.
It requires a complete re-think of the utilities infrastructure and removal of idiots that run them.
If a normal neighborhood had 2 stationary panels on each home's roof pointed south that backfed to the utility power and they did the storage, it could be a reality right now.
but it's easier to keep that 1929 Coal plant running and those power commisioners that have no fricking clue or care outside their pocket or circle of power than to change to current technology.
Anyone here can easily reduce their power consumption to 1/10th of what they use now. Couple that with a city wide solar network with some wind plants like in Macinaw city or out west and you can easily have clean power.
it's changing government, and the wasteful companies (running 1500 horse power pumps from 1955-1957 instead of buying noew high efficency pumps) that will be nearly impossible...
Changing to non polluting power will be more difficult than getting bill gates to embrace and use linux.
Do not look at laser with remaining good eye.
Another obvious stirling use is as part of your home heating plant.
British Gas to launch individual CHP boiler for homes
British Gas has announced that it is developing a household boiler that generates both heat and electricity, which will increase energy efficiency and cut costs for customers, allowing them to sell excess electricity back to the Grid.
The new combined heat and power (CHP) boilers, developed by MicroGen Energy
Think about it. You burn gas to stay warm. (if you don't have a heating season....then you don't) Why not burn the gas to do work? You still get your heat. And the work can make electricity.
According to http://www.humboldt1.com/~michael.welch/pvpayback. pdf photovoltaic payback in all energy costs associated with manufacture is anywhere from 3-7 years, depending on photovoltaic type (CIS or SC-SI) and assuming 5 hours/day of direct sunlight. Interesting read. --M
Solar insolation is about 1kW/m^2.. Well, except for the earths rotation. Assuming a non-tracking system, we have to divide by a factor of pi, so thats 300 W/m^2.. Well, except that the average efficiency of solar cells is under 15%, so thats 45W/m^2. Now, the average home has what? 2 people in it, and the per-capita electrical usage, averaged over the course of a year is 1kW. So, you need 2kW for that home, and only get 45W/m^2. So, you need 50 square meters of solar cell, correctly angled south. And this is the best case.
Now account for clouds and dirty cells. Unless you clean the cells every few days and pressure wash them biweekly, better increase the square meters of solar cells another 50%. So, thats 60-80 square meters of cell/house..
Now the next question. Where do you store all the energy you'll use at night? If you don't store it, where does it come from? Fancy burying a few ton flywheel in your backyard? How about aa closet filled with lead and sulpheric acid batteries? If you're going to use hydrogen to store it, better double or triple the square meters of solar cell for those inefficiencies.
The same problem applies to 'Solar 2'. You need about 1000 of them to equal the average energy of a nuclear power plant. And another 299000 to equal the mean energy used by the US. To replace all energy used in the US requires about a million Solar 2's.
Let's assume we want to provide all of the world's energy needs by solar power. If I recall correctly, the world currently uses about 500 exajoules of primary energy per year, or about 16 terawatts. The sun provides about 1000 watts/m^2 at our distance. However, the overall system efficiency would be somewhere around 1% of that (say 20% solar cell efficiency, 75% loss from night/day/latitude geometry , 40% weather loss, 70% storage conversion and transmission loss). That gives 10W/m^2 average output, so we need 1.6 million square kilometers, about the size of Alaska.
That sounds bad, but it's actually only 0.3% of the earth's surface area. I would guess that the best way to implement that much collector would be to develop plastic based collectors in huge sheets that are floated on the oceans. Convert the energy to hydrogen on site and pipe it to the consuming countries. By eliminating fossil fuel usage, you free up huge sources of raw materials to make all of that plastic.
You could argue that that much area would screw with the earth's climate by changing reflectivity. However, at least it's not generating a layer of greenhouse insulator. Moreover, current agriculture practices alter the reflectivity of a much larger percentage of the earth's surface.
(Don't bother replying to suggest outer space collectors. Say they were 30X more efficient than earth-based systems. Nobody's going to launch satellites with a surface area 3% the size of Alaska. We've been trying to put up a space station the size of my back yard for 20 years now, and still haven't finished.)
Very good questions, as it happens, I have answers!
In California it costs around $15-$20K to refit a house with solar panels. Due to recent legislation the power company MUST pay the wholesale price to any of their customers who generate power. It takes around 20 years for the cost of the panels to be recouped.
Note that these numbers assume that the cost of power stays stable, which is fairly unlikely. If the cost per kilowatthour increases then it will take proprotionately less time for the panels to pay for themselves. A long term investment, but ultimately worthwhile.
In terms of pure energy costs (neverminding money) it takes a typical solar panel about three years to generate the amount of energy it took to produce. Some panels are made from recycled wafers (typically wafers which were rejected for chip manufacture) these take about 3 months to make the electricity that went into their production.
"Mission Accomplished" -- George W. Bush May 1, 2003
Looking at our electrical bills over the last year averaging between $100 and $150 a month, I decided to look into putting in solar panels and here is what I found out.
For 7K out of pocket (after tax credits, rebates, etc.), I can get a 2KW solar panel system with grid tie installed. This would give me, conservatively, about 496 KW hours a month in production. This would cut my usage by 2/3s. For 12K out of pocket, I can get a 3KW system which would give me about 720 KW hours a month in production and would completely clear my needs.
With a grid tie system, I run my meter backwards when my production is greater than my demand. This means that any electricity that I generate is credited against my bill at the rate in play (I believe you also get peak pricing withi this setup) at the time I generate it.
Bottom line, is that for a 12K investment, I can clear an average bill of $150 a month. This means that in a little over 6 1/2 years I have paid off the system. Or you can think of this as giving me an annual return of 12.5% on my initial investment. That is pretty damn good!
Well, There's always a chance someone on Slashdot doesn't know this, but... Global Warming / Cooling is junk science. The proponents have blocked appropriate measures of earth's temperatures, which involve measuring the ocean's aggregate temperature, and have done so for about a decade now. The measurement would have involved a solitary underwater explosion, and the sound wave would determine the ocean's temperature (although salinity has an effect, it is far from a trivial science). This would be a tremendous mass of ocean water.
The "Save the whales" crowd resurfaced decrying the untold damage to aquatic life by doing this, which is ridiculous compared to doing nothing to find out what is happening to our planet.
Air temperature measurements are a waste of time, especially in urban areas, which have an elevated measure of heat because of the asphalt roofs, roads, etc. Measuring the ice caps is also silly, because their size changes seasonally, like with weather cycles. Everyone remembers the Halloween blizzard in Minnesota. And the 65 degree day in late December 15 years later. The only useful measurement would be of a volume of water (not a tiny pocket of air) the size of the ocean, at the equator. But that's being blocked bye environmental activists; they must have something to hide; what's a few deaf gray whales if it will save the planet?
Did you bother to mention that the various "greenhouse gasses" are mere precursors to tropospheric ozone, which is the hazardous smog that is discussed at the Weather Underground ? All of the sudden, ozone is bad and good.
I read a statistic once that in order to be entirely solar with our power, we would cover the earth 11% over with the dumb cells. Considering the nasty chemicals involved in the manufacture of solar cells, and that solar cells are not simply recycled, and fail in a decade or so (fragile materials), I can't imagine why any earth-first crowd would want yet another major source of toxic waste.
I have long thought that the only solar cells of any use on our planet (since the stuff in space is pretty handy, I'll admit) are the green ones in my lawn and garden. They produce oxygen, which every living animal needs. If you live in a newly developed neighborhood (like in suburban USA), the best thing you can do for your environment is plant plenty of trees on your lawn. Sure, it means raking, but in my neighborhood, I have 100+ year-old oak trees, and they are positively enchanting. They keep the sun off my lawn so I don't have to water, and they keep the sun off my roof (remember, these are mature oak trees) which reduces my AC costs. McDonalds passes out seedling trees on Earth Day, so it really doesn't cost you anything. Sure, it'd make more sense if they passed them out on Arbor Day, but no one remembers when that is, despite it being the more venerable day of commemoration by a good century or more.