Net Zero Electricity for less than $700

A few months ago, I wrote a blog comparing the number of negawatts you could produce by giving away Compact fluorescent Light bulbs (CFLs) to the amount of electricity you can produce with a rooftop photovoltaic system.  The CFLs had photovoltaics beat six ways from Sunday, and I concluded that you could do better by putting the money you were considering investing in a PV system in a Bank CD, and using the interest to give away CFLs.  Since I actually believe my own calculations, I set out to do just that.


I offered a $2 a bulb rebate (up to $5) for anyone who bought CFLs and sent me a receipt.  Apparently, $5 is not enough money to get most people off the couch, and I did not get a single receipt sent to me (the offer is still on, by the way.)  However, I also give away CFLs (usually something interesting like an outdoor spot or a candelabra bulb… most of my prospects have already replaced everything they can with the twisty type) to potential clients who come by my office, and the blog started making the rounds of the internet, eventually making it to Marc Dreyfors, who is on the board of the Environmental Educators of North Carolina (EENC).  EENC was planning their annual conference, and they usually offset the carbon from their conference by giving away CFLs, and Marc had the bright idea of asking me to fund it.


They calculated (with the help of Clean Air Community Trust) of
Asheville, that they needed to replace 51 60-watt incandescents with CFLs to offset the 16.7 tons of Carbon their conference was expected to produce.  My thought was: “we need to think bigger than that!” because I wanted to offset some of my own carbon as well.  They were fine with that, they just didn’t want to be greedy.


In the end, I funded the replacement of 320 60-watt bulbs (with 11w CFLs) and 80 100-watt bulbs (with 25w CFLs).  After the tax deduction, that cost me about $600, and EENC was able to use my grant to persuade Progress Energy (their local utility) to stump up a $500 donation to expand the program further.


I arbitrarily decided that EENC would get half the carbon offsets from my donation for their work, and I’d get the other half for coming up with the cash.  Assuming the bulbs we gave away are used just 1 hour a day, that means that all my CFL giveaways are saving someone over 12 kWh of electricity each and every day, which is more than my wife and I use.   With the help of a programmer-friend, I’m tracking the progress on my website. (on the right hand side.)  Note that the offsets cost only about half a cent per kWh over the lifetime of the bulbs, about a third of the cost of buying green tags from someone like Sterling Planet.   If I tried to produce 12kWh a day with a PV system here in Colorado, it would cost about $12,000 after all the rebates, and I’d save about $170 a year on my electricity bill.

Now I just have to do the calculations to figure out how many bulbs I need to give away to offset my use of natural gas, gasoline for my wife’s Prius, and biodiesel for my Jeep. 


  1. This is a cool idea. Nicholas Kristof mentions something similar in his Jan. 30 2007 column in the NYT, only there, the carbon credits finance the giveaway. This is
    going on in Australia. Does it really help with emissions if the carbon credits are sold?
    Maybe. It gets people into the habit of using the more efficient light bulbs and they
    should see the savings on their electric bill.

    With carbon trading at $3.75/ton on the Chicago Climate Exchange you’re up to about
    $0.70 a bulb, if they did an avoided emissions credit.

    Did you just declare the emissions avoided to handle the needs of the conference or
    is there are formal method to get your bulb giveaway registered?

  2. tomkonrad said

    I hadn’t thought of selling the carbon credits, since I want them for myself.

    I would say that, if you give away the bulb and sell the carbon credit, you are still doing good, because you are also offsetting other types of emissions (SOx,NOx, Mercury, and particulates) as well as reducing the amount of necessary coal mining, even if you are not offsetting carbon. Combine that with the spillover effect of possibly encouraging the purchase of CFLs, and you have something real.

    I don’t know if there is some way to register my bulb giveaways… but I also don’t feel the need. When you buy RECs or green tags or carbon credits, you basically are doing it to feel like you are making a difference. Giving away CFLs makes me feel that I am making a difference, and that’s all I really want for it.

    By the way, I also recently signed up for Xcel’s Windsource program, so my CFL giveaways are now working to offset my natural gas and fuel for my cars… my wife and I are probably pretty close to carbon neutral at this point… at a cost somewhere north of $1000.

    But I see no reason to stop at carbon neutrality. I wasn’t anywhere close to carbon neutral for the previous several decades; I’ve got some cathching up to do.

  3. In some places, Texas is one, the wind enegy contracts people have taken
    have ended up saving them money. CFLs also save money. It seems to me
    that we are not all that far from renewables and efficiency making substantial
    financial sense. If we get to such a tipping point, what do you think will
    happen to the sunk costs in the fossil fuel infrastructure? Do investors
    just not get the expected return on investment or would you think that
    there would be a bail out with even larger subsidies for fossil fuels?

    I some ways I see cap and trade schemes as just a soft landing for investors
    and the big build efforts for new coal plants to be a way to establish a big
    emissions portfolio to trade on. I wonder what your thoughts are?

  4. Tom said

    I was one of those Texans who was getting wind power fro less than fossil fuel power, back in 2001. Then I moved 😦

    Efficiency has made substantial financial sense for a long time… and some renewables (wind, landfill gas, geothermal) can currently compete even without internalizing the costs of emissions from fossil fuels. Beyond that, some renewables are on the cusp of competitiveness (CSP with thermal storage, PV facing west in congested areas of the grid… but others are a long way from competitiveness, or only work in very special locations.

    So we are passing over the “tipping point” now… but it is not a point, it’s a wide, smooth hill. And when we say “wind is competitive with coal” what we really mean is that “new wind is competitive with new coal.” If you’re talking about scrapping an existing plant, you have to have the comparable renewables be competitive with the cost of only fuel and maintenance. In the case of coal, this number is only 1-2 cents per kWh, which is less than half the cost of comparable wind power (and even competitive with many energy efficiency measures. Add this to the fact that it takes time to build RE generation or implement EE programs, and you see that the role of renewables and energy efficiency will be (at best) simply supplying power ot meet growing demand and (maybe) replacing old fossil plants as they come online. Talking about scrapping fossil plants before they have reached the end of their useful lives goes beyond what even the most ambitious planners are considering currently.

  5. […] December 13, 2006 at 12:44 am · Filed under photovoltaics, Nonprofits, solar energy, Renewable Energy Many of us would like to have put solar photovoltaic (PV) panels on our home, and generate our own electricity.  Until now, I’ve always told people that they have better uses for their money.  Even with the recent extension of the federal tax credit until the end of  2008, and (in Colorado) the rebates being offered by Xcel Energy in order to meet their Amendment 37 requirements for customer sited solar electric, the return on investment for the electricity generated at current prices (about $8 per watt for the panels & system; $4.50 per watt rebates from Xcel, and a $2000 federal energy credit), a 4 kW system only returns 1.4% per year in electricity savings.  (I got these numbers from a workshop presented by Jeff Lyng, who will be vice-chair of The American Solar Energy Society next year, and calculated the return from those.  Jeff was speaking as a consultant for Xcel on their solar rebates program.)   To me, it makes more sense to invest in renewable energy or energy efficiency companies, which are likely to yield a higher return (or put the money in a CD and use the interest to buy RECs or give away CFLs). […]

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