Friday, March 14, 2008

Solar Energy - Not the mythical beast afterall?

These days there is a hot debate going on as to whether the human contributions to global warming can be reversed, or even slowed, by employing alternative energy technologies. On the one side, those who deny humans have any impact on global climate thus say there should be no concerted effort to change our energy sources. Even staunch supporters of human induced global climate change fear that there isn’t enough alternative energy to meet our needs.

What neither side has done, which irks the scientist in me, is a study on generating capacity of any of the alternatives. Everyone just assumes that if we switch to anything other then coal, natural gas, oil, and nuclear, our economy will tank and our energy supplies will go down. These impacts will lead, they all agree, to a lowered standard of living.

So I did a simple study tonight that should point to a different answer. First, I looked up the area around my office on Google Earth. Essentially I created a viewscape in two dimensions that runs about ¼ mile or so out from the building. It’s really what I see out my window. Zoomed in enough, one can count individual buildings, and differentiate the residential structures from the commercial ones. With the proliferation of condominium buildings around the Washington DC area this calculation gets a bit difficult, but once I had an image I liked, I just called the condos commercial buildings to make the math easier.

Then I got out the multicolored crayon pack and colored the residences one color, and the commercial buildings another. Then I counted them – twice. I got 181 houses and 114 commercial buildings.

Now, the math gets a bit tricky. Assuming the residences had solar systems that generate 2 kilowatts (kW) and the commercial buildings averaged 5kW each (they would probably do more, especially the high rises with large roofs), these 295 buildings can generate at least 932kW at one time from roof mounted Photovoltaic (PV) systems. That’s 932kW each day, for anywhere between 6 and 10 hours a day, 365 days a year.

How does this help meet our energy needs – and reduce anthropogenic global warming? Simple really. The US Department of Energy estimates that in 2006, the US had a peak demand of 706, 108 megawatts (mW). So the few buildings I counted generate nearly 1 mW, thus reducing our nations energy needs measurably. Imagine what would happen if we expanded this to include, say, the 1500 federal buildings owned by the General Services Administration? What if those buildings had enough PV on the roof to reduce their daytime load by 30% on weekdays – when they are occupied – and they actually put hundreds of kW into the grid on weekends? Even better, what if every building in the DC area had the maximum PV system its structure could handle? Where would that put us for electricity generation? I don’t have the numbers, but I bet some enterprising engineering student hopped up on Jolt cola (or Red Bull) could figure it out.

Now I admit, the energy savings these PV systems create cease once the sun goes down, and that is a problem. Still, if we burn significantly fewer hydrocarbons during the day to make our computers runs, keep our coffee pots warm, and make sure our laundry gets cleaned, the fewer total hydrocarbons we have to burn period. I’ll admit that current thinking suggest that major reductions now may not take effect for many years, but why should that stop us?

My point in all this fuzzy math is this – we can say it can’t be done. We can say there isn’t enough capacity. We can say it’s too expensive. Those are easy statements to make when you haven’t taken the time to find out if it is possible. Unfortunately, our climate, our ecosystems, and our economy can’t wait for us to exhaust the excuses and then decide we should see if it is possible. After all, if Americans had taken a similar attitude in the 1950’s and 1960’s Neil Armstrong would never have set foot on the moon; August Picard would never have plumbed the depths of the Marianas trench; America would never have passed the Civil Rights Act and begun to rid our nation of the scourge of racism. But you are all probably right – switching to alternative energy sources probably won’t help us solve the problem.