This blog takes an astrophysicist’s-eye view of societal issues relating to energy production, climate change, and economic growth. The approach is often playfully quantitative, with the aim of arriving at a fresh perspective on our world. Posts stress estimation over exactness, because in many cases a reasonably complete picture can be developed without lots of decimal places. Estimations of this type can be used to bring clarity to complex issues, or to evaluate the potential of proposed energy solutions. Hopefully, readers will gain the courage and techniques to start making valuable estimations of their own. The blog begins with a two-part assessment of the implications of continued growth, then settles down to tackle a variety of cute questions relating to energy storage, biofuels, home energy, transport, climate change, etc.
Many estimates will leave out small contributions to the problem, but these tend not to change the overall conclusions: ballpark is often all we need. Also, it is usually not hard to find thorough, detailed analyses of these same problems elsewhere. Part of the point is that we don’t always need thorough, detailed studies to arrive at a useful understanding. There is power in being able to assess the broad-brush aspects of a problem using things you already know, and putting relevant numbers together. We don’t have to rely on what experts tell us if we have the power of useful estimation at our disposal.
The content of this blog site does not represent the view of the UCSD physics department. Tom Murphy is responsible for the content, though may not himself share the views contributed within the discussions.
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Tom – thank you for starting this blog. I’ve bookmarked you and will share your url around. Your approach is refreshing and reminds me of Dr. David MacKay’s approach in Sustainable Energy Without The Hot Air. I’ve admire you physicists a lot; my own B.Sc. is in physics, and I made the unfortunate decision not to pursue it further. Thus missing out on the most exciting 40 years in the history of the science… Keep on writing and I’ll keep on reading.
Comparison to MacKay is a great compliment—thanks! I just added his site to the blogroll earlier today, in fact: I’m a big fan of his book.
Professor,
Thanks for the great articles you have written so far. I enjoy your “big picture” perspective. The article on galactic-scale energy should be mandatory reading for all high school and college students (and politicians).
Hi Tom,
Nice post. I went through a similar exercise myself when planning my electric car conversion. It has been running a bit under two years now. I noted you plan to look at ev’s in another post. Here’s a bit of data. My 2001 Suzuki Swift has an EPA rating of 32 mpg. Using the D.O.E. number of 33.7 kWh/gal gives about 1050 Wh/mile. As an electric car it has averaged about 216 Wh/mile for roughly half highway, half secondary road driving, or a bit more than 1/5 as much. The 3 phase AC motor and controller combined efficiency is around 80% (less of course for a several seconds during acceleration), so that buys a factor of about 4, the rest comes from the fact that the electric motor does not run while the car is stopped. The MPGe is about 156. At 40 mph it uses about 1 3/4 the power of a clothes dryer. The cost per mile doesn’t matter to me as it gets all its energy from solar panels on the roof of our house. Some info on the car is here: http://www.evalbum.com/3060.
Regards,
Tom