Joined: May 19, 2004 Posts: 892 Location: San Francisco, California
Posted: Wed Oct 06, 2004 2:14 pm Post subject: statistics on energy used in manufacturing
I'm interested in finding out how much energy is actually used to produce items like laptops, bicycles, automobiles, solar panels, et cetera. And what is the source of this energy?
To boil it down to specific questions:
1. How much energy is required to manufacture a bicycle/laptop/automobile/solar panel? Are we talking about oil or electricity?
2. What is the basis of the assertion that in the future, we won't have enough energy to manufacture solar panels? How much oil is used in their manufacture? Could that oil be replaced with something else?
3. What's the EROEI of a solar panel?
If you have statistics on this stuff, I'd like to know your sources.
Posted: Wed Oct 06, 2004 2:31 pm Post subject: Re: statistics on energy used in manufacturing
johnmarkos wrote:
1. How much energy is required to manufacture a bicycle/laptop/automobile/solar panel? Are we talking about oil or electricity?
which production methods? factory assembly?
Quote:
2. What is the basis of the assertion that in the future, we won't have enough energy to manufacture solar panels? How much oil is used in their manufacture? Could that oil be replaced with something else?
scale of the amount of panels we need to produce in the amount of time there is oil to produce them. Plus we need to switch to produce a huge amount pretty fast.
Quote:
3. What's the EROEI of a solar panel?
according to heinberg's the party's over --> solar --> photovoltaics EROEI 1.7 to 10
According to BP solar ( i emailed them) the output energy in the total lifespan of the panel is 20 times as big as the production energy. This is only the factory production energy. So you have to count in production of basic needed elements, movement of elements to factory and movement of solar panel to house.
As far as i know the basic panel lies somewhere around an Eroei of 4 in the beginning degrading to less then 2 in a matter of years. You have better panels ofcourse
The problem is that no one really knows. This is a large scale problem, and with solar panels and lap tops, you are not looking at a 'cottage' industry. You need so much stuff that goes into that. that any EROIE given for any technology is questionable. The thermodynamic limit is 27%. That is that if you invest 100%, the most you get out of it is 27%, if the manufacture and delivery and conversion to new energy is based on a technological process, and it goes downward by about 70% for every step you have. So, if you do something and it requires transportation, mining, factories, you look at downward spiral, unless you get energy from somewhere that has been accumulated/stored for a long time, such as coal, oil, uranium.
Hope that helps, the rule of thumb is 1/3 of what you put in you get.
Joined: May 19, 2004 Posts: 892 Location: San Francisco, California
Posted: Sun Oct 10, 2004 11:24 am Post subject:
I wrote,
Quote:
1. How much energy is required to manufacture a bicycle/laptop/automobile/solar panel? Are we talking about oil or electricity?
Rembrandt responded,
Quote:
which production methods? factory assembly?
I suppose it varies between products. For a laptop, I would say factory manufacture of the parts. I (or my wife, who is more talented at putting those little bits back together -- she fixed her own powerbook once) could put the parts together at home. For a bicycle, I'd also say factory manufacture of the parts. For an automobile, I guess you need the whole thing -- some people know how to assemble autos from kits but most people aren't willing to invest the time. For a solar panel? I have no idea.
At any rate, the factories could be right here in California so transportation could be minimized. They already make cars here -- it wasn't too long ago that all of those other things were built here as well. Also, California (and much of the U.S.) has a great culture of restoration -- of cars, bicycles, et cetera. Some people love to do it themselves, even when they don't need to. Maybe part of the transition to the future economy will involve a renaissance in that culture.
BTW, I've been reading the book, "Prosperous Way Down," by Howard T. Odum and Elisabeth C. Odum. Fascinating stuff. I don't think I fully grok the way emergy works but it's definitely an interesting idea.
I'm trying to visualize the San Francisco Bay Area economy (not Mad Max, I hope) of twenty or thirty years from now.
Joined: May 19, 2004 Posts: 892 Location: San Francisco, California
Posted: Wed Oct 27, 2004 12:05 pm Post subject:
Quote:
According to BP solar ( i emailed them) the output energy in the total lifespan of the panel is 20 times as big as the production energy. This is only the factory production energy. So you have to count in production of basic needed elements, movement of elements to factory and movement of solar panel to house.
So could BP Solar sprinkle the world with solar powered solar panel factories (thus reducing movement of solar panel to house)? What basic elements are needed for manufacture, other than sand and iron?
Joined: Dec 15, 2004 Posts: 2 Location: Sausalito,California
Posted: Wed Dec 15, 2004 2:38 pm Post subject: solar eroei "standard"
I am also interested in finding the total eroei on anything manufactured. Is there a standard for calculating the total eroei? from mining of raw material to disposal in landfill. all the steps in between should be considered. with a solar panel should the wire and battery be considered along with the energy to assemble the solar package. deep cycle batteries last only 5 years so for the lifespan of a solar panel, typically 20-25 years, 4 or 5 new batteries must be purchased. i think with any product the eroei should also include the building of the factory and the tooling for production. i can only think that the true eroei on any product is very low when all factors are considered.
can anyone explain in laymens terms what "thermodynamic limit" is?[I]
Posted: Wed Dec 15, 2004 8:31 pm Post subject: Painting processes
One thing that used to astound me years ago in the auto industry was the amount of energy consumed to put on that combined 3 mil layer of paint primer and top coat. To start with, the capital investment in the paint shops of auto makers is usually about half the total investment of an assembly plant, so a corresponing huge amount of energy to go into fabricating that structure. We are talking here about a monster amount of steel that goes into paint booths and the long snaking ovens, held at about 220 C, typically 1 km long for each paint bake stage. A succession of 50 hp electric motors to drive the fans used to suck outside air in and then heat it to 22 degrees C and then blast it all out again a couple of minutes later with the flashed off solvents. They do use water borne paints now to avoid environmental problems with hydrocarbons, a big improvement.
I think if technology could come with a better coating method there could be big energy reductions. I know many years ago, there were Gleaner farm combines with were not top coat painted just galvanized steel, but they did look real ugly.
Maybe some type of shrink wrap vinyul decal material?
Joined: Jul 21, 2004 Posts: 1282 Location: Suburban tar sands
Posted: Thu Dec 16, 2004 1:53 am Post subject: Re: Painting processes
Denny wrote:
I think if technology could come with a better coating method there could be big energy reductions. I know many years ago, there were Gleaner farm combines with were not top coat painted just galvanized steel, but they did look real ugly.
Joined: Jul 21, 2004 Posts: 1282 Location: Suburban tar sands
Posted: Sun Dec 26, 2004 1:31 am Post subject: Re: statistics on energy used in manufacturing
johnmarkos wrote:
I'm interested in finding out how much energy is actually used to produce items like laptops, bicycles, automobiles, solar panels, et cetera. And what is the source of this energy?
2. What is the basis of the assertion that in the future, we won't have enough energy to manufacture solar panels? How much oil is used in their manufacture? Could that oil be replaced with something else?
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