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Clean Energy

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‘Clean energy’ may have a specific definition in your mind — you may think it’s synonymous with ‘renewable energy’ (i.e. wind energy, solar energy, hydro energy, and geothermal energy). This is, generally, how I use the term.

–>Note: If you’re looking for the latest clean energy news, check out our clean energy category.

However, ‘clean energy’ is actually a rather nebulous term, since there is no agreed-upon, standard definition of it. To some, clean energy also means nuclear energy. To others, it may mean natural gas. And it can even include so-called ‘clean coal’ (if you let it). As many have noted, Obama is one such person who uses this term very broadly.

Nonetheless, despite its malleable nature, ‘clean energy’ is becoming an increasingly popular term. Indeed, I think I use it more than ‘renewable energy’ now (and, as I said, to discuss the same energy sources or technologies). So, I will briefly explain why I use it like this, and why I use it so much.

Why Use The Term ‘Clean Energy’?

I think ‘clean energy’ has become increasingly popular for two basic reasons,… or maybe three.

Firstly, ‘clean’ is a simple concept, and it’s easier to use simple concepts when speaking to the public (as politicians often are when they are using this term). It implies, rather clearly, that the use of these energy sources creates less pollution, is better for the environment. That’s a little simpler, perhaps, than the term ‘renewable’.

Secondly, people like ‘clean’ things. Generally, cleanliness is considered a good thing. And, in this context, ‘clean’ is the opposite of polluting, and pollution is widely considered too be bad. So, when speaking about whatever technologies you support (even if they are not clean in some people’s eyes, such as natural gas and nuclear energy), using a term that has a very positive connotation is popular.

Thirdly,.. well,.. with the term becoming more and more popular, it just makes sense to use it more (it’s a cycle).

Now, I think many people who use the term regularly would like to steer public opinion to using it for energy sources or technologies they support. And that gets us to the next section.

Why Use The Phrase ‘Clean Energy’ How We Do?

Basically, at, we do not see natural gas, nuclear, or ‘clean coal’ as truly clean energy.

Natural Gas

Natural gas has been documented to create all sorts of water quality problems. Natural gas production, as it occurs today, includes the pumping of massive amounts of toxic chemicals, carcinogens (that is, cancer-causing chemicals), into places they really shouldn’t go.

Leading energy and climate scientists have also specifically identified that using natural gas as a ‘transition fuel’ to get us off of coal power is a bad idea — it’s not going to be adequate enough to stop catastrophic global warming. That’s a big deal. Here’s one graphic from a recent study on the matter:

‘Clean Coal’

While I think it is important to develop carbon capture and sequestration technologies for coal, I don’ think coal could ever be considered clean. Coal is highly subsidized by you the taxpayer, and additionally costs the U.S. about $500 billion a year more than what is accounted for in its price, according to the former Director of the Harvard Medical School Center for Health and the Global Environment and 11 co-authors; the human cost of coal goes way beyond its impact on the climate, which is anything but negligible; and coal causes all sorts of other environmental problems. These days, we have gone the route of blowing up entire mountain ranges to extract coal, something that not only destroys mountains and mountain ecosystems, but also waterways and mountain communities.

Coal is not clean, even if we were someday able to capture the CO2 it emits and sequester it.


Nuclear comes the closest to being clean in my eyes. But it’s got one fatal flaw. One, it creates radioactive nuclear waste that lasts longer than humans are known to have existed for. I think it’s extreme arrogance to assume that we will be able to contain that for such a long period of time. There are other reasons for opposing nuclear energy (i.e. it’s an economic nightmare), but that’s why I don’t consider it ‘clean’.

What is Clean Energy?

So, with all that said, I do view renewable energy technologies as being clean, because they have a much, much lower contribution to global warming, and take from or harm the environment to a much, much smaller degree. I’ve seen many studies confirming this over the years.

So, basically, if you initially thought solar and wind energy when you thought of ‘clean energy’, I’m with you.

Top Image: wind turbines courtesy shutterstock.

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  • KjAndersson

    Strange how you treat bioenergy on your website – like almost not existing. Why is bioenergy not included among the renewable energy forms? What is so suspicious about using living plant systems to trap solar energy?
    I come from Sweden, where bioenergy today accounts for 33 percent of the final energy use. We have very little solar radiation for several months, but the trees can produce a lot of bioenergy during our sunny summers. This energy, stored in the wood, can be used during our cold and dark winters. To me this is truly renewable, and the cost is low compared to most other renewable energy systems.

    • Bob_Wallace

      Bioenergy is not as developed in the US as in parts of Europe.

      Many parts of the US no longer allow wood stoves or fireplaces due to the particulate release.

      We do have some biomass electricity production. And some of us do heat with wood, but we’re very much in the minority. (Warm night tonight, my stove is getting a rest.)

      • KjAndersson

        I am sitting on the train between Stockholm and Gothenburg – a beautiful spring morning. Every single town I pass has a heat plant using biomass as fuel (wood chips, bark, sawdust, SRC chips, etc) for district heating. Often located right by the train track. The bigger plants are CHP:s producing electricity as well. This is modern bioenergy. The forests and fields are efficient solar collectors. Bioenergy is as much renewable energy as solar, wind, hydro and geothermal. Include bioenergy in your website and on your charts!

        • Bob_Wallace

          Read the site more.

          Bioenergy is regularly covered.

          And we have electricity plants running on wood waste. One is about 30 miles from where I’m sitting right now.

  • Jef Franklin
    • Bob_Wallace

      No naked links, please.

      If it’s important then tell people why.

  • yu tube

    for me the article lost credibility the moment I saw the power circle chart. That huge circle representing solar is the total hitting the earth, now unless we cover the oceans with panels knock 70% off the total energy number. Then just look at the controversy of covering just a few tens of acres with solar panels and how it will devastate the desert tortoise. Imagine the opposition of covering old growth forests!
    When biased information like that is published it diminishes the ability to have a useful discussion of the benefits of solar power and how it can be incorporated into the power generation industry.

  • Bioleux

    I am aghast at your omission of renewable biowaste as Clean Energy.
    Despite the fact that you can actually get your hands dirty handling it, it is as clean as solar or wind, and actually helps getting our environment CLEANER.
    Not to mention more practical, as it can be generated 24/7 and stored.

  • Mukesh Bhati

    i m student of final year n my project is based on solar steam power plant n heat combustion method plzz give me me particular direction for working best in my project

  • Dinesh

    can we join OLED technology with OPV cells in mobile phones to develope a solar powered app for smartphones?

  • ukaway

    I’d be interested to know what readers think of this:

    • jimbo

      If you’re convinced your ideas are valid it should be easy enough to build a small scale test setup to verify.

  • ColinG

    Where does biomass/biofuel sit in the spectrum of “clean” energy?
    Renewable yes, but “clean”?

    • Bob_Wallace

      Clean in that the carbon released was already above ground.

      Could be some particulate problems like we have with diesel and gasoline.
      “Cleaner” is probably the best description.

      I doubt we can get people to give up intercontinental air travel and shipping. That probably locks us into some biofuels.

  • Jacques Bellange

    this is right and good

  • L’Obel Solar Power

    very nice vision

  • Meerwind7

    Largest Solar Photovoltaic (PV) Power Plants:

    Add Neuhardenberg (Germany) 145 MW
    Eberswalde/Finow / Schorfheide (Germany): 84,5 MW


    • Zachary Shahan

      Thanks. Not everything makes it to English sites. :D

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  • Jkolle

    What is a GWp

  • Mickelodian Ranks

    The primary problem with renewable energy was and still is the increased ‘use it or lose it’ issue. With coal, nuclear gas etc production can be halted or increased (within limits) to account for demand. This is also true with renewables but there are now two not one ‘use it’ bottlenecks. The elements provide the first…the sun does not always shine, the wind does not always blow…and this coupled with the fluctuations in demand requires somewhere for this energy to be stored…. So mass battery storage is required to remove that second bottleneck…and it will also aid in removing partly the first bottleneck. This ‘storage’ issue being solved is the one that will cut costs considerably. Thankfully there are people working on this very issue at an industrial storage level.

    • Zachary Shahan

      Yeah, the storage needs are growing, and it’s good news that a lot of folks are working on this issue.

  • Abdul_azim17

    India is a country where there is sunshine for more than 300 days in a year and hence has maximum potential to make use of solar pv power.But not much progress is made in India to harness the solar power except for the Gujarat plant credit for which must go to its CM Narendra mody.I would like to take up distribution and marketing of these products in India as I have an engineering background if Iam offered an agency by a suitable organisation

    • Abdul_azim17

      My email I’d may be corrected as

    • Zachary Shahan

      Good luck to you!

    • Bob_Wallace

      Jump the queue.

      Take your engineering background and start a program that brings solar to the people who live off the grid.  

      It shouldn’t take a lot of capital.  You need some very basic solar systems (small PV panels, controller, batteries, LED lights) to bring light and cell phone charging to a home now operating with kerosene.  

      They can pay you for your solar system with part of what they were paying for kerosene, you make money and they have better quality light and a bit more money in their pocket.

      A few years of hard work and treating people right and you’ll be a “suitable organization” and have the satisfaction of knowing that you made a lot of people’s lives better.

      Here’s a company already doing what I suggest.   India has room for many, many more companies like this one… 

  • Arjaytech

    Wow, that was pretty awesome.

  • Solare Solare

    Please update your Solar Growing Rapidly graph to show 2011′s data – 28GW installed. The graph becomes even more steep.

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  • Andrew R Long

    Wow – brilliant information. How much more price competitive would this be if we enacted fee and dividend like the Citizen’s Climate Lobby is proposing — charge a flat $10 on each ton of carbon emitted and gradually increase the price, and refund 100% of the money collected to the American people! Economist say that 2/3rds of households would get more money back than they pay in slightly increased energy costs ($0.13 per gallon of gas, initially).

    At this rate solar is going to be at grid parity with or without this law, but it’s still a law we ought to get passed.

    • Zachary Shahan


  • Dan8

    No matter how you spin the data and people will spin the data, the reality is that solar still has an approx 20 year return on your investment, 15 with the rebates. That’s the worst investment a person can make especially in a moving technology. If you have the money to throw away, fine, otherwise it’s a foolish venture. Wait until the ROI is 3 years or less.

    • Zachary Shahan

      Dan, there are plenty of places where its far less than 20/15. In some it has gotten down to a few years. There are also leasing options where you’re saving money from Day 1.

      • Dan8

        Well, I’m totally skeptical. Let’s be a little more to the point. Just to see what’s happening in the market I’ve gotten 2 bids each year for the last 3 years to totally solarize my So Cal home. My electric bill averages about $300 a month. I choose to go to only reputable vendors that have solid products, will be around for the next 20 years and guarantee their work and products. The price range quoted for the entire 3 years for all vendors is between $75,000 and $85,000 after rebates. You don’t do any better recouping your costs by leasing after you look at the fine details.
        Can you give us some similar concrete examples of what you say are a ‘few’ years and how many is a ‘few’ years. I do think the Dow product is good but I suspect the cost is even more prohibitive otherwise they would be posting their prices. Since there are some Dow installations already, why can’t you get some numbers for us otherwise this is all more hype. The devil is always in the actual numbers. Solid facts don’t lie.

        • Zachary Shahan

          “A recent report from the USA has found return on investment from solar power is higher than any other renewable energy source.

          The report entitled “Global Solar Inverter Markets”, released by SBI Energy,
          states the payback period for a typical solar PV-based project has reduced from 7-10 years to 3-5 years currently.”

          Estimate for a house in AZ with a 6.7 year ROI:

          We are planning a piece looking at solar leasing vs going solar on one’s own in more detail.

          • RobS

            Discussing specifics is difficult without a lot of info but here goes.
            $300/ month at an average Californian retail rate of 15c/kwh suggests you use about 2000 kwh per month, it should be noted at this point that is about 66kwh per day whilst Californian households average 24kwh/day consumption. It is inevitable that given you use 3 times the Californian average a system to supply all your needs will inevitably be unusually large, measures to significantly reduce that consumption including more efficient lighting etc would likely be cheaper than simply buying a bigger system, however for the purpose of this discussion let’s just continue with your current consumption.
   is the website I shall reference for system costs, they are based in California and have a large selection of grid tied systems. You will see that that you will need ~15kw system to produce 2000kwh per month. They have a range of systems between 14.5 and 15.5 kw ranging from $28,000 to $32,000. Add ~30% for installation taking you to ~$40,000 pre rebate, with the 30% rebate your looking at about $30,000. Now let’s ignore feed in tariffs which are usually generous in southern California and will significantly reduce payback time, even at your normal rate this system will save you ~$300 monthly so $30,000 will take 100 months or 8 years 4 months to pay itself back.

            Looking at this from the point of view of an investment as you initially framed it this $30,000 system generating $3,600 of power saved annually is returning 12% annually, however as that is cash saved rather then money earned it is tax free. To earn $3,600 after tax from $30,000 capital would require an investment return of ~$5,100 or a return of 17%. If you can show me in investment that consistently returns 17% with little to no risk as long as you have your system insured under your home insurance then I’ll happily admit you were right that solar is a poor performing investment. Remember the returns we have discussed thus far is the equivalent of dividends there are many studies showing that solar systems have a significant effect on your homes capital value which will further increase your return on investment.

          • Zachary Shahan

            Thanks for the breakdown, RobS — this is great! & worth a full repost. Any interested in changing/adding anything before I publish it as a full post?

          • Dan8

            As I said, the devil is always in the details. Those are DIY based numbers you quote, not from a full service dealer that will install and guarantee the system end to end for it’s lifetime. I talked to these DIY folks and they are providers for people that want to do it themselves, they can provide complete DIY kits but no installation or guarantee of the entire system. That makes the (large) investment high risk. That’s exactly what people need to avoid. My numbers from full service dealers stand. If I were capable to and adventurous, yes I would take on the project myself.
            This issue triggered a phone call to 2 more dealers to get a 2012 estimate. Will be interesting to see if things have gotten any better.

          • Zachary Shahan

            Let us know what you find out! Curious to see the details in your case.

          • Dan8

            Well I’m baaaack, a bit humbled by the way. The difference between the early and the latest solar quotes is and was amazing and I ended up with a system for about $35K using a reputable installer and a 6 year return on investment of 23%. My electric bill averages $1.50 a month. So I hope you all forgive my bone headed insistence about costs; I just had not updated my data.

          • Bob_Wallace

            That’s great news, Dan. Thanks for bringing it.

            What size system did you install? (Looking for a $/watt number.)

          • Dan8

            From the System Specs:
            $4.8/Watt DC

          • Matt

            “Add ~30% for installation” was for the installer

          • Dan8

            And if Zachary wants to post the info, he needs to point out all the facts, not just those favoring one side or the other.

          • Matt

            Thanks Rob

        • predrag raos

          By the way, for this kind of money you could buy 10-15 kW of nuclear generating capacity in USA, 20 kW in Korea and 50 kW in China (of constant power, of course). With useful life of 80-100 and not 30y. PV are good for niche applications, for providing isolated communities and even some of peak power, but for heavy industry and great conurbations… Well, give me a break.

          • Bob_Wallace

            Your right. Large industrial machines discard any electrons coming from solar panels and accept only electricity coming from coal and nuclear plants.

            Thanks for sharing your wisdom….

          • predrag raos

            Drink a glass of milk. It helps.

          • Zachary Shahan

            predrag, in all seriousness, we’ve dismantled all of your wild claims for why nuclear is the energy option of the future. no one here is being swayed by bad arguments. stop trolling the site with your nuclear propaganda.

          • Matt

            No Nuclear plant built to date has lasted 100 years and none have calmed they could.

          • Bob_Wallace

            Just adding some detail. No nuclear plant has operated for 50 years. The first one will reach 50 years in 2019, the year the plant is scheduled to close.

    • Tmar2

      Stand by to stand by. Even here in Fl. where FPL owns the state and our incentives are horrible comparatively, I now have a $42/mo. avg bill. Internal reduction of kWh needs is primary. solar water heater, leds and a few little things, bam I win. Sit on the fence and talk about it, the fence will turn to barbed wire.

    • Solare Solare

      Tier 3 is $0.30/kWh here in San Diego. To get a 3 year return you can afford $0.90 plus the $.20/W rebate plus the 30% ITC or about $1.50 in total. This is how much the components cost today, so go out and get a system and install it yourself.

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  • Bngautam16

    In our faith we worship as Sun God ,life sustainer life protector .Potentials of its energy r sufficient 2 meet energy reqirements of Earth.Former President APJ Abdul Kalam has proposed several energy projects predominantly Solar Sattelite in space 4 harnessing Solar Energy.During his Presidency our magificiant Rashtrpati Bhavan was powerwd by Solar Energy—–arole model 4 our planners

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  • Rajesh

    Sir, i want to construct some solar tree, please give me the suggestion ,what is the cost of a solar tree. thanks

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  • Rahul Iyer

    Sir can we connect! Rahul Iyer, Mumbai 9820540757

  • Karl

    Sure what sort of system do you want and have you the space for 4,500 panels requiring an area of approx 6,000 sq m. Are you doing a EPC project or hoping to do it all yourself? You may contact me on Hear from you soon.

  • RobS

    I should add that if there are companies trying to sell systems they have bought wholesale for ~$30,000 for $70,000+ then what a scam and no wonder US solar companies are struggling to survive the current competitive market. The new quotes you have sought will be interesting, solar panels wholesale prices have fallen more than 40% in the last year, I’m hoping you might find the $70,000 system last year will be closer to $50,000 currently. The other thing I would point out is that it is often unnecessary and inefficient to size a system to supply 100% of your power consumption, installing a solar system tends to increase awareness of power consumption and increased energy efficiency, buying a system that supplies 50-75% of your consumption will cost substantially less and you may find that within 12 months or so it may supply closer to 100% of your power needs.

    The other benefit of a smaller system is that most CA utilities have tiered electricity tariffs, for example if your 2000kwh per month were billed as follows, 14c/kwh for the first 750 kwh, 16c/kwh for the next 750 kwh and 18c/kwh for any beyond 1500kwh, giving you an average price of 15.7c/kwh. If you then installed a system that supplied 50% of your needs, that would shave off power being billed at the two highest rates, the offset power has an average cost of 17c/kwh. The implication of this is that the relative benefits of a smaller system can be higher if you are on a tiered pricing structure. A smaller cheaper system offsetting your most expensive power increases the economics substantially.

  • T. Lester

    You sound like what I call an exceptionalist: someone who looks for exceptions to point out flaws of a largely beneficial system. The vast majority of the above article is about m-a-s-s p-r-o-d-u-c-e-d solar energy and not DIY, individual use solar energy.
    But your point about $10,000 not being DIY is moot in that the cost of a home is far more than that. Also loan programs, buy back programs, grants, tax credits and leasing programs are not factored in to your sweeping generality.

    You will get the last word, as I won’t be hanging around to argue with you about this.

    Hopefully, you can spend as much time pointing out flaws of coal and nuclear energy production.

  • Brent

    Karl – your website is inoperable – however,
    all you need is 2564 Higher Efficiency Monochrystalline – 96 cell modules of our 390 W – good for about a 40% reduction in land footprint-hence only 3600 sq miles are needed…and all the associated costs, i.e. lugs, racking, wire, connectors, etc. are 38-41% less.

  • Zachary Shahan


  • Pavan

    Brent, I went through your website. We are in process of starting a solar power plant in India. I want to know details and quote for a 5MW and 10MW capacity plant from your company. Can you please mail me at

  • F-Alli

    I live in Nigeria and i am into Inverter and just starting Solar Projects .

    What info do you need in Nigeria, maybe we can work together.

  • F-Alli

    Solar Information in Nigeria, you can reach me on

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