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Thread: Solar Powered Tools

  1. #1
    Join Date
    Dec 2006
    Melbourne, FL

    Solar Powered Tools

    Yesterday watched a little of "Invention Nation" on TV.

    They had a "Green" Homebuilder who was building a home completly with solar power.

    He had a box van full of standard tools plus 800 pounds of lead acid batteries with inverter and solar panels on the roof.

    I know I am biased (many years at Nuclear Power Plant ) and my calculation may be wrong BUT....

    They had maybe 1 - 2 sq meters of Solar Collectors Total on the roof of the van.

    As I understand it the good old earth recieves about 500 watts of energy per sq meter. This is a generous alotment as the numbers only decrease (distance from equator, atmosphere density, collector eff, time of day). I will be very generous and give them 100% conversion (that is about a factor of 10 generosity).

    Build the whole house - I Do Not Think So! - maybe run a saw for 1-2 hours per day.

    I would expect things to run well on a daily basis to film the show and you can thank the large battery bank for that.

    I would be very surprised if they were not plugging the van into good old AC power at night to get a little help.

    I would love to do a MythBuster type follow up to shows like these.

    They just falsely lead people to believe that a couple of solar cells on the roof in bright sunny upstate New York can power the whole house.

    Did I forget to mention huge additional LOSSES from the inverter and the charge/discharge cycle of the batteries.

    And if Mr Green construction can get over all those problems lets discuss the energy required to build the batteries and the solar cells. After that we can start on the chemical mess of disposal of the batteries and chemicals used in the construction of the solar cells and the batteries.

    To bad many of the good intentioned people who want to help our environment do not look at the bigger picture of how their "Clean Green System" really works.

  2. #2
    Join Date
    Jan 2007
    Sacramento CA
    I have noticed on that program that they tend to ignore things that would negate what they are trying to "sell." Not that I don't enjoy watching once in a while.

    Specifically I noticed when they need fuel for their bus they go the the nearest Mexican restaurant and "just pour the grease in the tank." Wrong! There are several critical steps between grease and fuel they don't bother to mention and the equipment to do it is rather large. It don't fit in the back of the bus.

  3. #3
    Join Date
    Jul 2007
    DSM, IA
    I've always been a fan of solar dad was/is a big fan/invovater in solar heat. The houses I grew up in had/have solar heating systems he designed and built which help my parents spend much less on natural gas to heat their house. Solar power was stifled back in the 80's, not sure why possibly a topic for another time...I think it has a great future, why not try to capture energy that should always be available...but you are right, there are bad trade offs, battery cost/disposal etc.

    Heck, I live in Iowa and I don't think ethanol is all that great of idea because of the same reasons. It's not that efficient to produce, drives up food cost(milk, meat, etc because of increased feed prices for farmers) and many other factors...but we do have cheaper gas prices here.
    A man is rich in proportion to the number of things he can afford to let alone. -Henry David Thoreau
    My Website

  4. #4
    Join Date
    Dec 2006
    Quote Originally Posted by Hubert Carle View Post
    Specifically I noticed when they need fuel for their bus they go the the nearest Mexican restaurant and "just pour the grease in the tank." Wrong! There are several critical steps between grease and fuel they don't bother to mention and the equipment to do it is rather large. It don't fit in the back of the bus.
    Actually, it can be done, just not such a great idea. Properly filtered (a BIG if ) and on a warm engine this will work ok. Most SVO (straight vegetable oil) vehicles have a higher pressure fuel pump to deal with the higher fuel viscosity, and many have a switchable fuel system to start the vehicle on regular fuel and switch over to SVO once its warmed up. The dual system is mostly the reason its not as popular to run a diesel on oil as to make fuel out of the oil.

    As to the solar shop.... I don't think I'd believe it, just due to the arithmetic that Pete outlined. Takes a lot of juice to cut stuff up. Smartest way to do it would be using cordless tools and direct DC charging of the batteries. Why fool around with wet cells and inverters when there's already all the cordless technology to take advantage of? I bet it'd still take a lot of collector area to charge them up though.

  5. #5
    When ever I switch channels and find a "green" program, I just keep on switching.

  6. #6
    Join Date
    Dec 2006
    Melbourne, FL

    I am all for using Solar Also!

    Do not get me wrong. I am all for using solar.

    I live in Fl and I know with a small solar collector we could easily get all of our hot water. Very few homes down here have Solar Hot Water. Many homes here heat their pool with solar collectors.

    Not sure why we do not use solar here in Fl for domestic hot water. Must be the higher initial cost that few builders would want to add to the price tag.

    I get asked often about alternate forms of energy (people know I worked for a Utility ) I know there are many noble efforts out there trying to capture some energy from the sun or other natural source but most (maybe all) just cost to much per watt.

    The real problem with most alternate energy methods is the $0.10/KW energy available from the Utilities.

    I also know there are many energy scams out there and that is what bothers me.

  7. #7
    Join Date
    May 2007
    Kansas City, Missouri
    The following site actually sells a system to use straight veggie oil. The system starts the engine using regular diesel fuel, preheats the oil (filtered) and then switches over to run the veggie grease. When the engine is shut down it keeps running, and switches back to diesel to clear out the injectors for the next startup...then shuts down.

    To a small child, the perfect granddad is unafraid of big dogs and fierce storms but absolutely terrified of the word “boo.” – Robert Brault

  8. #8
    Join Date
    Oct 2006
    Tokyo Japan
    Just for fun, watch this video............

    The pessimist complains about the wind; the optimist expects it to change; the realist adjusts the sails.
    William Arthur Ward

  9. #9
    Join Date
    Dec 2006
    I have found that with the tree huggers and the greenies, people buy what thier are selling whether it is truth or a bunch of you know what. People just want to believe what they say and never check anything to see if it is fact or a little fact and a big bunch of half truths, it is just eaiser that way.

  10. #10
    The company I work for builds small solar collectors to power appliances in emergencies. They decided that since they had the expertise in the collectors and electronics for building yachts, had the fiberglass people to lay up the shells, and had the electricians to do the wiring...why not make a small portable device that can be helicoptered into disaster areas for FEMA. So that is what they do now, make these unit. You can check them out on this website, by clicking the Solar generator link at the top right hand side of the page.

    As for being green, I am only green when it comes to saving green. Unfortunately I married a woman with a degree in Environmental Science and Marine Biology so this long time certified logger often spars with the Mrs over green issues.

    I still can't diffuse the idea of heating my woodworking shop with compost heat, and am in hopes to get that idea up and running sometime this Spring.

    As for powering an entire shop with solar most people quickly find out, power from the grid is VERY cheap. My uncle has a windmill and by the time the thing is paid back by energy savings...even at Maine's high 15 cents a kw will be 12 years down the road...and time for a new windmill.
    I have no intention of traveling from birth to the grave in a manicured and well preserved body; but rather I will skid in sideways, totally beat up, completely worn out, utterly exhausted and jump off my tractor and loudly yell, "Wow, this is what it took to feed a nation!"

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