Some Solar Power Considerations

Bleg: Thin Film Solar Modules on Aging Barn Roof

A quick question: I'm starting to research installing solar at our place near Ithaca (always my intention from when we bought it, but other projects had to happen first).

It seems to me appealing to put the solar power on the barn rather than the house:

• It has a much larger area (ie more power)
• The cosmetic impact from the road will be lower

Since the barn roof structure is not that heavy, it probably makes a lot more sense to apply flexible CIGs modules (eg like these Global Solar modules) than to use conventional modules.  These flexible modules are generally glued to a metal roof (eg with mastic).  So one question is whether folks have experience with these modules and prefer one brand to another?

Secondly - the sheet metal on the barn roof is a few decades old.  While the roof isn't in imminent danger of failing, about 50% of the roof area now looks rusty and about 50% still has the galvanized surface.  I've already had a contractor offer to cover the roof with an aluminized asphalt product to extend the life of the metal.  Clearly, it's not desirable to attach solar modules to metal with a noticeably shorter life than the modules.

One idea that occurs to me is to use an aluminized asphalt product to adhere the modules to the metal, and cover the whole roof at the same time in the interests of preserving it.

Does anyone have any experience with a similar situation?

Total Available Renewable Resource

Several commenters questioned Friday's post on the grounds that the total amount of solar and wind power potentially available is insufficient to power modern civilization

This is incorrect.

Total available wind power available on land and near shore has been estimated at 72TW.   This is close to five times current total primary energy consumption, and still more than twice as large as energy consumption in 2040 (extrapolating at the 2.7% growth rate of the last decade).

Of course, not all technically and economically feasible wind sites are politically feasible.  Thus it's important that total incoming solar radiation is also very large.  Top of the atmosphere incoming solar radiation is 174000TW.  If we just look at the world's desert areas, they represent about a third of the global land area, itself about 30% of the total surface.  Allowing 30% losses in the atmosphere over deserts, and throwing out something for Antarctica (a desert, but not a very useful one for solar power), we end up with something in the ballpark of 7000TW of available solar energy from deserts alone.  This is hundreds of times larger than current civilizational energy consumption.

Therefore, constraints on our ability to utilize renewables are political and economic, not ultimate physical ones; there is plenty of renewable energy out there.

Climate Change Action is Not Hopeless

Global Solar Growth Continued Strong in 2011

Wind and Solar Global Stats

Global Solar Capacity Grew 73% in 2010

Carbon Neutrality with PVs

Photo credit: Dow Chemical

Robots vs Relocalists

One of the great things about the Archdruid is that even when I believe he's wrong, he's rarely wrong in a dull, predictable way.  Instead, if he's going to be in error, it's often in an interesting and thought-provoking way.  So it is with this week's essay, The Twilight of the Machine. In it, he argues that, well, let's have him say it in his own words:

The end of the age of cheap abundant energy, as last week’s Archdruid Report argued, brings with it an unavoidable reshaping of our most basic ideas about economics and, in particular, economic development. For the last three centuries or so, the effective meaning of this phrase has centered on the replacement of human labor by machines. All the other measures of development – and of course plenty of them have been offered down through the years – either reflect or presuppose that basic economic shift.

The replacement of labor with mechanical energy has even come to play a potent role in the popular imagination. From the machine-assisted living of The Jetsons to the darker image of reality itself as a machine-created illusion in The Matrix, the future has come to be defined as a place where people do even less work with their own muscles than they do today. All this is the product of what an earlier post called the logic of abundance: the notion, rooted right down in the core of the contemporary worldview of industrial society, that there will always be enough resources to let people have whatever it is that they think they want.

Abandon that comfortable but unjustifiable assumption, and the future takes on a very different shape. In a world where everything but human beings will be in short supply, it makes no sense whatever to deploy increasingly scarce resources to build, maintain, and power machines to do jobs that human labor can do equally well. An example may be useful here, so let’s take Rosie the Riveter, the iconic woman factory worker of Second World War fame, and match her up against one of the computer-guided assembly line robots that have replaced so many workers in production lines in the industrial world; we might as well pit icon against icon and call the robot HAL 9000.

He goes on to make a variety of non-quantitative arguments for why Rosy will win this contest. I won't rehearse them here. Instead, this affords me an opportunity to present a simple hypothetical calculation that has been at the back of my mind for a year or two, the conclusion of which bothers me a lot:

Archdruids and Net Energy

This week's Archdruid Essay is an improvement on the ones I discussed last week, but although he's retreated a little onto higher and more defensible ground, I still think his position has some poorly defended salients that he should abandon.  In particular, I think he's still too hung up on energy concentration, and is still trying to argue that there's something physically difficult or impossible about transitioning to a renewable powered civilization.  In my view, there's nothing physically impossible about that (though I'm perfectly willing to concede that the total cultural inertia of western civilization is enormous and that worries me a lot).  The Archdruid makes two main arguments in his post, and in this post I'm going to take on the first of them (hopefully coming back to the other at some point in the future when time and interest allows).

Limits on the Thermodynamic Potential of Archdruids

I often read John Michael Greer, the Archdruid. He's a smart and thoughtful guy who worries about some of the same things I worry about, though he tends to have decided they are all hopeless, whereas I tend to see society as having a lot more options than he perceives.  He has read very widely and often comes up with interesting historical analogies that hadn't occurred to me, so he's well worth the spot in my reader.

Where he tends to go horribly wrong, and why I think his overall take on the subject is too negative, is when he tries to talk about physics. In a recent series of three posts:

• Energy Follows It's Bliss
• An Exergy Crisis
• Barbarism and Good Brandy

He has been trying to argue that there are fundamental physical barriers to society surviving the transition away from fossil fuels, and getting horribly snarled up.

Now, I am not a working physicist, but I may well be the nearest thing that will admit to reading the Archdruid - I trained in Physics, have a PhD in the subject, and then went into Computer Science.  But the points at issue are pretty elementary here, so let me try to straighten the Archdruid out, and at least place something in the record for anyone that might be confused by his arguments.

In short, there are no fundamental physical barriers to a non-fossil-fuel based economy - the main problems are social, economic, and practical, not issues of physical law.