Arguably, there can be no cleaner source of energy than the sun. If you place a black container filled with water in the sun, you'll heat water at no cost and with no appreciable environmental impact. That's well and good, but impractical if you want to take a shower at 3AM, or need to boil water for cooking.
Ultimately, what we need is electricity, as our culture is based on electrical devices. So how does one turn solar power into electricity? While you could create a solar furnace that boiled water to produce steam that powered a generator, the cost and size are prohibitive. It's far more reasonable to use solar panels. But are they "green"?
That's a tough question to answer. Mac Life magazine recently ran this report by writer Jan Hughes, which offers a concise look at the pros and cons of solar. Pros: "free" energy, renewable, available anwhere there's sun. Cons: toxic waste being inresponsibly disposed of by makers, energy intensive creation, and the obvious 'doesnt work when it's dark' problem.
This article from Low Tech Magazine claims that solar actually produces more green house gases than even coal, and coal is a lot more convenient.
In Vermont, the Solar Bus is a common site. It's an old school bus that runs on bio-diesel (arguably a solar energy, [though so are fossil fuels]) covered with solar panels and filled with batteries. The bus travels around and powers events such as outdoor movies, concerts, etc. I applaud the ingenuity, but given the above two stories, is it a "green" idea? According to the solar bus site, it is.
So who do you listen to?
It's not easy, but you have to apply Carl Sagan's Baloney Detection Kit to the problem. Let's apply a bit of it to the Solar Bus:
Wherever possible there must be independent confirmation of the facts
Ok, so on the Solar Bus site, there is a link to an "independent" study that supports the claim that solar panels produce more energy than they require to be made. This study was conducted by a representative of Siemens Solar Industries, and here's a link to solar products sold by Siemens. Siemens is arguably an expert on the subject, but they have a built-in bias that must be considered. That's hardly "independent," and I have to say that the Solar Bus fails to defend their claim there.
Encourage substantive debate on the evidence by knowledgeable proponents of all points of view.
There is only the one study from Siemens. No dissenting view is presented, so again, the Solar Bus fails to make its case.
Arguments from authority carry little weight (in science there are no "authorities").
In this case, though the Solar Bus may claim authority on issues of solar power, that authority carries no weight as the evidence dictates the conclusion.
Spin more than one hypothesis - don't simply run with the first idea that caught your fancy.
This doesn't apply neatly in this case, but it's clear that the Solar Bus is convinced that solar is a good thing. Nothing on the site suggests that there may be reason to doubt that.
Try not to get overly attached to a hypothesis just because it's yours.
I think this is the biggest fault with the Solar Bus. The creator had an interesting idea, clearly invested a lot of time and money into it, and if the evidence points to his conclusion being wrong, he's going to be in a hard place. We have to consider the possibility that the Solar Bus will defends its opinion beyond reasonable limits.
Another thing that bothers me about the Solar Bus (and I have discussed this with them) is the politicized message of the site. Science isn't about politics, it's about evidence. And while the Solar Bus doesn't claim to be scientific, they are offering arguments that can be examined scientifically. Introducing politics clouds these arguments, and makes one question their motives.
In the end the Solar Bus is an advocate for solar power, but we're unsure why. They have failed to explain properly why solar power is better than any other form of energy, and though their conclusion may turn out to be correct, we shouldn't look to them as a resource.
And that's the thing with the Green Movement. Especially in Vermont, it's politically unacceptable to suggest that a "green" technology may not be what's best. I was once chastized harshly for throwing away a cheese-covered pizza box, as it was made of cardboard and could be recycled. The truth is that if it's covered with food, cardboard is prohibited from the recycling bin. Regardless of this easy-to-verify fact, I was permanently labeled as someone who didn't care about the environment.
This article will likely cause my neighbors to criticize me if they read it. "Why are you complaining about something good?" and "Don't you care about the environment?" are the imagined responses. So be it. I recognize and applaud the Solar Bus as a project, but I cannot get behind its mission because it's based on the unchallenged premise that solar power is "good," and that's not at all apparent.
I offer no apology for applying critical thinking, such that I'm able, to any subject. If solar power makes sense, I'll use it. If it doesn't, I won't. I'll decide if it makes sense or not based on the information I can gather, and sadly the information the Solar Bus provides is not enough.