Home Photovoltaic Systems for Physicists

Just in time for $150 per barrel oil, this is a fun and timely article by Tom Murphy in this month's issue of Physics Today. It deals with the setting up of a modest photovoltaic system to run a suite of appliances. But what is interesting is that it deals with it from the background of what a physicist know. We are not electrical engineers, and while we do know the physics of semiconductor, the practical aspect of setting up something that needs to work at this level isn't trivial.

It was with those concerns in mind that I decided to explore the practical side of photovoltaic energy: In 2007 I built a PV system to power my living room. Though reasonably well informed on the semiconductor physics of PV junctions, I felt unsuitably prepared to evaluate the practical realities of owning and operating a personal solar PV system. Because I believe physicists can play a role in our energy future that extends beyond the confines of advanced research, I want to share my experiences in the hope that others might develop home PV projects. What better way to motivate innovation in the alternative-energy sector than to get a talented pool of physicists engaged on a personal level?

A recommended reading if you don't get a subscription to Physics Today.

Zz.

Symposium Focuses on Energy Challenges

If you're in Chicago or near the Northwestern University campus, this might be something interesting to attend.

Steve Chu, who won the 1997 Nobel Prize in physics and is director of the Lawrence Berkeley National Laboratory of the U.S. Department of Energy, will deliver the keynote address at the Northwestern-Argonne Energy Symposium on Friday at Northwestern University.

The symposium, themed "Energy: The Challenge for the 21st Century," is free and open to the public. The program is from 8:30 a.m. to 5 p.m. in the Ryan Family Auditorium in the Technological Institute, 2145 Sheridan Rd., Evanston.

With the cost of gasoline here in the US rapidly approaching an average of $4 per gallon, this has become certainly a very hot topic.

Zz.

Saving Energy While Driving

So I don't remember which TV public service announcement that I heard this from. I think it was on one of the cable channels that was advising how you can make NY City more "green". In any case, that isn't relevant. What it did say was that you can save gas if you drive with your windows up, especially at high speed.

Of course, with everything being the equal, this is true. If you drive with your windows down, you create more drag, or air resistance, for your vehicle. Thus, you burn more fuel as you drive, especially when you're driving very fast.

HOWEVER (somehow, I think you were expecting that, weren't you? :)), let's consider the situation here of when you usually drive with your windows down. It is typically in the summer, or when the weather is warm. So, if you roll up your windows, you inevitably crank up the air-conditioning! So now, you've reduced air drag on your vehicles, but you're using up additional fuel due to the air conditioning.

So which one uses up more fuel - driving with the windows down but no air conditioning, or driving with the windows up but with air conditioning? I haven't looked into the calculations of how much power is used is a typical car air-conditioner, and I haven't looked into it yet on the amount of drag created when a car drives around at, say, 60 mph (yes, we still use mph here in the US). Does anyone have some rough estimates on what these might be? Off the top of my head, I would think that driving with the windows down instead of using air conditioning might be more energy efficient than the other alternative.

Of course, driving with the windows up and not using air conditioning is a no-brainer better option. But the PSA didn't say that. All they said was to drive with the windows up to save fuel. That is not the complete story.

Zz.

Argonne Tests Find Near-Zero Emissions for BMW Hydrogen 7

A while back, I mentioned about the Argonne Green Transportation event. It displayed several hybrid and hydrogen vehicles that supposedly have better millage and/or very little polluting emission. The star of that event were a number of BMW vehicles that ran on hydrogen.

These cars have been tested at Argonne, and it appears that it is the only public facility that can test vehicles with that low amount of emission. The testing project has now been summarized on video that's available on YouTube.



Zz.

The Hummer is NOT More Environmentally-Friendly Than a Prius

It's amazing how a report that is full of holes can gain such a foothold once some talking heads on TV adopted it.

A while back, there was a rather dubious report called "Dust to Dust" that essentially drew up a conclusion that the monstrous Hummer is more "environmentally friendly" than the Prius, based on all the energy accounting that is being used to research, manufacture, and run the vehicles. Slate.com has a brief synopsis of the whole thing. Luckily, they also tackled the validity of that claim and cited several prominent (and certainly, NOT dubious) research work. It essentially debunked that myth.

Moral of the story: never accept the validity of science/engineering issues from politicians, TV personalities, or popular news media.

Zz.

Nature Collections of Energy Papers

Nature has compiled a list of their papers and articles related to our Energy issues and problems. Most of these papers are being made available FREE online. So take a look if you're interested (not sure why you won't be since this affects all of us).

Zz.