From http://www.dailycamera.com/news/2009/apr/30/30elet/
Photovoltaic arrays for energy efficiency
I was inspired by the photo in the paper (April 16) about the extensive 98-kilowatt photovoltaic (PV) solar system installed by SolSource of Denver on the roof of Blue Mountain Arts. When I think of all the acres of flat rooftops available in Boulder, imagine how much renewable energy we could produce if we placed photovoltaics on nonresidential rooftops throughout the city.
It’s estimated that for every acre of rooftop, we can generate as much as 0.7 megawatts of electrical power and supply energy to anywhere from 72 to 200 homes per year (depending on the system). Tapping into unused real estate on top of city buildings to generate renewable energy makes sense instead of covering up our open space with solar arrays (land, which we could better use for growing food). Urban rooftop solar systems will also help cool buildings further increasing the structure’s energy use. In the SolSource installation, the PV panels kept the roof intact and will prevent over 257,000 pounds of CO2 carbon emissions from entering the atmosphere every year.
By using the roofs of Boulder’s big box stores, city recreation centers, manufacturing plants and large office and municipal buildings for PV arrays, we can create local electrical generation centers across Boulder and make a noticeable dent in reducing our use of fossil fuels for energy production. Given the combined and unprecedented challenges of climate change and peak oil, Boulder’s citizens are increasingly aware that we need to transition as quickly as possible to renewable energy sources.
Boulder, we have the talent and knowledge to reduce our city’s contribution to global warming and be a leader nationwide for innovative environmental ideas. Let’s make rooftop PV arrays on nonresidential rooftops a long-term sustainable solution that one day, when we look back, we’ll say “well done!”
To which I replied
Posted by RalphShnelvar on April 30, 2009 at 2:44 a.m.
NESHAMA ABRAHAM: “Boulder, we have the talent and knowledge to reduce our city’s contribution to global warming and be a leader nationwide for innovative environmental ideas. Let’s make rooftop PV arrays on nonresidential rooftops a long-term sustainable solution that one day, when we look back, we’ll say ‘well done!’”
One good rule of thumb measure for how much energy something consumes to make is how much it costs.
Assuming that you think that CO2 is the evil that I think that it isn’t, and …
If it costs $40,000 (not some phony subsidized price) to produce enough electricity to run the average home …
You have to ask yourself, is it worth the carbon footprint to produce that $40,000 device compared to the carbon used to generate that same electricity for 25 years?
$40K is, at high market prices, 10,000 gallons of gasoline.
The average household in the United States uses about 8,900 kilowatt-hours of electricity each year. (http://hypertextbook.com/facts/2003/B…)
10,000 gallons of gasoline is roughly equivalent to 366,000 kilowatt-hours. (http://www.convertunits.com/from/gall…)
Over the current 25-year useful life of a PV systems, the average American home would consume 222,500 kilowatt-hours. (25 x 8900).
Thus … a PV system costs the environment 366,000 gallons of gasoline versus 222,500 gallons for a conventional electric grid.
One can, of course, redo the numbers for coal or natural gas but it remains that PV is NOT a panacea.
Thus it costs the environment AND the economy about twice as much (in CO2 _and_ dollars) to install PV than to simply use the current grid (which, presumably, uses gasoline-equivalents).
Assuming that my computations are correct,
NESHAMA ABRAHAM, do you want to change your mind about PV?
More to the point … if it is _proved_ that the carbon footprint associated with the production and installation of PV is worse than simply using the current power grid, will you change your mind?
Ralph Shnelvar
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I also replied to another poster in the same day’s blog:
gilbysm: Go tour a PV manufacturing facility. They all have big PV arrays on the roof, which they use to power their manufacturing equipment, which means that PV panels are made using solar electricity.
As others have said, you simply cannot run a plant on the power produced on the roof of a building.
Just go to Home Depot and look at the roughly one square meter panel the sells for about $300. It produces a whopping 45 watts of power.
From: http://solarpowerauthority.com/how-much-does-it-cost-to-install-solar-on-an-average-us-house/
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A conservative value to use for a solar panel’s generating capacity is 10 watts/sq. ft. This represents a panel conversion efficiency of about 12% which is typical. That means that for every kW you need to generate, you’d need about 100 sq. ft. of solar panels.
One kilowatt doesn’t even run a hair dryer. Do you really think you can run an entire plant if you cover the roof?
And, if you were producing wind towers, wouldn’t you put a wind tower(s) on your property as an example of what you are producing?
gilbysm: Furthermore, equating dollars to gallons of gasoline is asinine. It’s like saying a dollar spent on Coors coal-powered beer in an aluminum can is the same as a dollar spent on an apple at the farmer’s market. Surely with all of your vast knowledge of markets and the evils of market distortion, you know that fossil fuel prices exclude the vast majority of their real costs.
Of course it is. That dollar that goes into the apple represents: the energy cost of the fertilizer, the harvester, the transportation. What else is involved?
gilbysm: Add to that the fact that PV panels generate more electric energy than the total energy used in their construction (the same cannot be said of fossil fuel plants, which merely deplete existing stocks of energy-dense material very inefficiently), and your comment makes even less sense.
As others have asked … please prove that. I will cite an article I wrote showing that I _did_ do the research and that PV is net energy negative: www.dailycamera.com/blogs/letters-editor-blog/2007/sep/12/shnelvar/
gilbysm : Just admit that you love cheaply priced fossil fuels and the privileges they afford you at the expense of everyone else, already. Your grandkids will sure love you for burning over half the fossil fuels ever created in your lifetime, so they can tell each other stories about how you wasted so many precious, non-renewable resources while they struggle to subsist on the leftovers 50 years from now.
gilbysm , you are not paying attention. I am delighted when there is a technology that will efficiently convert solar power to electricity in an economically reasonable way.
What you are doing when you promote PV _now_ is to make a bad problem worse. It is you that is spending precious nonrenewable resources in an ideological quest for clean power.
Just because it looks green does not make it so.
Ralph Shnelvar
Ralph–in your commentary about ditch diggers and a $15 per hour excavator, that ain't how it is.
Backhoe's can cost $75/hr or more. And the ditch diggers usually do other useful stuff, like form and finish concrete, landscaping, framing, painting, roofing, siding, drywalling etc. Backhoe doesn't do that.
I don't deny that there is a threshold over which the prevailing wage will push contractors into using using alternatives. But we are diameterically opposed in relation to how things work in the economy. I won't pretend to be a capable debater, so no repsonse is expected.
gunsandnoses – You're commenting to a guy who is neither a Libertarian or involved. Hasn't posted anything in 8 months. Never a comment about local or state politics in all that time. He's not listening, which is why you can't debate him. The DC should remove this blogger and let an active Libertarian take his place.
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