Posts Tagged by physics
Sustainability — It's About Physics, not Politics
| January 16, 2011 | Posted by Craig Shields under Sustainability |
A reader whose political sensibilities obviously do not parallel those in “The Story of Stuff” writes in:
As for “Stuff,” I don’t doubt that most of what [Annie Leonard] says is true and it certainly is deplorable, but I missed her solutions unless she proposes an anti-consuming society, which wouldn’t work here or anyplace else.
Thanks for your observations.
I see that you and she diverge on the issues. But even as wide as the gap there may be, I’m sure a common meeting ground is the notion of sustainability itself. Read More
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Renewable Energy — Facts and Fantasies: Tales from Launch Day
| November 7, 2010 | Posted by Craig Shields under Renewables - Business |
A funny thing happened when we launched Renewable Energy Facts and Fantasies last week. Of course, I was hoping it would do well in the categories to which Amazon.com had assigned it: energy, engineering, and physics. And while it went to number one for a few days in both energy and engineering, it got massacred in physics.
It seems that Steven Hawking, by far the most famous physicist on Earth, had just launched his new book. And was there any controversy that may have spurred his book sales even higher than they otherwise would have been? Read More
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An Engineer Comments on "Renewable Energy and Basic Physics"
| November 21, 2009 | Posted by Craig Shields under Renewables - Science |
![](http://i708.photobucket.com/albums/ww83/craigshields/Parabolic_trough_solar_thermal_elec.jpg "An Engineer Comments on "Renewable Energy and Basic Physics"")
My friend Geoffrey Nicholson comments my post “Renewable Energy and Basic Physics”:
Craig, I couldn’t agree more.
Other than geothermal energy, all the other sources of energy available to us originally came from solar energy and with a rather lossy process. Petrochemical from solar growing primordial goo. Hydrokenetic from solar driven convection. Wind from solar convection with a bit of coriolis effect. Water from lightning from solar convection. Wood and alcohol from solar energized green growy things.
Gas turbines can be around 50% efficient burning fuel but, again, how efficient is the production and transportation of the fuel?
Steam turbines a bit more efficient.
Gasoline engines about half as efficient as turbines with Diesels a bit more efficient that gasoline.
Stirling engines are quite efficient but pound for pound don’t produce much work.
Interestingly, hydrogen fueled aircraft could be more efficient than kerosine since the specific weight of hydrogen is less than gas but the design of the aircraft would have to change dramatically since the specific volume of hydrogen is greater. Fat planes would result that would probably fly slower than today’s aircraft. Again, how would the hydrogen be produced?
The idea of collecting solar energy from the upper surfaces of already constructed buildings seems like the least intrusive and most efficient method to utilized light, in my opinion. It doesn’t shade the natural ecosystem and collects/distributes the energy where humans need it.
What do you think?”
To which I respond:
Thanks, Geoff. Everything you write here is true, as far as I understand. PV on rooftops makes a great deal of sense. The costs and coming down, the efficiencies are going up, and the overall engineering is getting increasing clever. See my post on California-based Solyndra as an example.
The only piece you’re missing, I feel, is solar thermal / concentrated solar power (CSP) as described at the bottom of the post.
Thanks for writing!
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Renewable Energy and Basic Physics
| November 20, 2009 | Posted by Craig Shields under Renewables - Science |
My old friend Peter Buzzard commented on my post “Molten Salt Energy Storage“:
“Craig, do you know if a Stirling engine would be more efficient than making steam for a turbine?”
To which I reply:
I don’t know know much about Stirling engines; I need to learn about these. But it sounds like you may be comparing apples and oranges.
I’m sure you’re aware that devices that simply store energy (e.g., molten salt, batteries, capacitors) and devices that convert energy form one form to another (e.g., motors, turbines) are two different things. And as far as the latter is are concerned, electric motors, even using the technology of the very first ones 120+ years ago, are quite efficient; in fact, the AC induction motors that are used in today’s electric vehicles are close to 90% efficient. What’s not to like about that?
Thus, it seems to me that the real question is how to generate, store, and distribute the electricity. Coincidentally, I was writing my book’s chapter on basic physics last night, in which I noted the following about the conservation of energy:
Once one really wraps his wits these basic ideas, one is in a terrific position to understand most discussions of energy. Here are two examples to make this clear:
Hydrokinetics: Every day, the energy from the sun evaporates water into steam that is later condensed into clouds, the precipitation from which forms rivers, some of which are in high altitudes. The kinetic energy of the water flowing back downhill can be converted into electrical energy. But the conservation of energy tells us that the most electricity one can possibly hope to generate from this water is the potential energy it had before it started to flow (which equals the weight of the water times the height of the elevation from which it fell). This is for this reason that hydrokinetics cannot provide a significant amount to the overall energy picture, regardless of how many dams, how efficient the turbines, etc.
Solar: On the other hand, the earth receives 6000 times more energy from the sun every day than mankind currently uses for all its purposes: transportation, heating, air conditioning, etc. Put another way, if we had the capability of capturing and distributing 1/6000th of the sun’s energy, we would not need to burn another lump of coal, spilt another atom, or pump another ounce of gasoline. This fact alone forms the rationale for our interest in solar energy.
I encourage readers to review all assertions about different forms of power generation — renewable or otherwise – to this discussion on the conservation of energy. When someone says, “This car runs on water,” ask yourself: water? Isn’t water already “burned” hydrogen and oxygen, i.e., the result after these two elements release energy by joining together? That’s like saying, “Let’s build a fire using those ashes for fuel.” Sorry, they’ve already been burned, meaning that the chemical energy that was once stored in the carbon bonds of the wood has already been converted into the heat, light, and sound of a fire. The ashes are the low-energy result of that process.
I got an email from a friend announcing a miracle car that runs on air. As it turns out, it actually runs on compressed air. The energy required to compress the air is stored in a tank and converted into kinetic energy. Trust me, there is not one bit of energy delivered to that car’s wheels that didn’t going into compressing the air in the first place.
At the end of the day, I think the energy direction of the planet is very clear:
Generation: solar, especially concentrated solar power (CSP).
Storage: molten salt (Note that storage is somewhat less important for solar than say, wind, as solar tends to be generated in congruity with times of peak need). Note also that solar it’s already heat energy; there is no need to convert it to something else.
Transmission: High voltage direct current (HVDC). This requires a build-out of our ancient power grid, but we need to do that anyway.
Thanks again for writing, Peter. I hope this was useful.
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Renewables and Cutting-Edge Physics
| November 12, 2009 | Posted by Craig Shields under Renewables - Science |
Given the realities of our time, most of us are short-term focused – even those in renewable energy R&D. We tend to want to know what can we do NOW to lower our carbon footprint and lessen our dependence on foreign oil. I’m not saying that this thinking is flawed, but occasionally I like to ask questions that attempt to get at the long-term answers as well.
To that end, in preparing my book on renewables, I’ve conducted a few interviews with extremely senior physicists, and asked questions about the theories and experiments in the lab right now that may change the may we power our world 100 years hence.
One such interview was yesterday’s, featuring Martin Perl, Nobel Laureate in particle physics – a man so brimming with warmth and kindness (not to mention overwhelming intelligence) that I really hated to leave when the interview was over. We sat just a few feet from the Stanford Linear Particle Accelerator — a device that speeds up particles – normally electrons – to velocities just under the speed of light – and then subjects them to various conditions, e.g., strong magnetic fields. Suffice it to say that wild things happen under those conditions.
The reason I traveled those 300+ round-trip miles was my belief that:
- the point of cutting-edge physics is to understand the ultimate building blocks of the universe,
- depending on whom you believe, we as a civilization are somewhat close to achieving that understanding, and
- with that understanding will come (somehow) an endless supply of clean energy
But surprise! Dr. Perl’s beliefs are 180 degrees opposed to these points. Summarizing an hour-long conversation, one that was both fascinating and disappointing at the same time, he believes that we’re nowhere close to understanding those building blocks and mechanics of the universe, and, even if we were, there is no indication that clean, useful, and inexpensive energy would ever come as a result. (Having said that, there are some extremely powerful implications of Dr. Perl’s work that will be a true boon to mankind in other areas, e.g., medical science.)
So what’s the take-away from all this for us fans of renewables? I suppose it’s this: If you believe Dr. Perl – and it’s hard not to given his credentials – we’ll have to look elsewhere for a long-term answer to our energy challenge. In a way, I suppose, that ratchets up the pressure to find answers using today’s technology that work within the confines of the law of conservation of energy as we know it. And is that impossible, when the sun bestows 6000 times more energy each day on the earth that all 6.8 billion of us consume? Hardly.
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OK, the Conservation of Energy Isn't a "Law." But Can I See a Working Model of a Counter-Example?
| September 20, 2009 | Posted by Craig Shields under Renewables - Science |
Steele Braden responds:
I know this is hard for us guys schooled in the “old” physics thinking, but the longer I investigate and experiment, the more anomalies I turn up regarding accepted physics “laws.” Remember, it was impossible for man to fly with his own body power — until somome flew accross the English channel. Remember the sound “barrier”? Travelling to the moon was a permanent science fiction.
Great points, all. It’s funny; I had just written a piece advising the authors of business plans to “keep it real,” in which I explain: if you’re going to challenge conventional wisdom, do it convincingly. I review submissions for what are essentially perpetual motion machines at the rate of about one per week. And by the way, I read each of them carefully and with no derision, because I’m sure that eventually, mankind will come to an understanding of the cosmos that will make all us 2009 people look quite foolish, as paradigmatic breakthroughs have been doing since the dawn of civilization. Having said that, understand that if your invention suggests 1 Watt in and 2 Watts out, you’re presenting this idea to people who have been taught since they were babies that you’re a liar or a fool.
I believe that many of the so-called laws will, in fact, be broken. Yet I have trouble believing that somewhere, right now, there is a machine that is running above 1.0 efficiency, based on a principle that no one can explain. Sorry to sound cynical, but I need to see it.
I’ll make you a deal: If you can give me clear reason for hope that I can see the first working model of such a device, I’ll take my wattmeter (to support my skepticism) and a bottle of really good champagne (to celebrate the gift to the world if I’m wrong) anywhere in the world for the demonstration.
Again, I hope we can keep the dialog open. I know that there are many people who are far more ardent scientists than I who will be thrilled to know that legimate science has broken yet another “law.” Please keep me informed.
