Thank god for physicists.
To maintain balance we have politicians and bureaucrats.
Balance along what spectrum? Rationality vs. Demagogy?
"Sustainable Energy - Without the Hot Air" by David JC MacKay
11–20 of 34 posts
Re: "Sustainable Energy - Without the Hot Air" by David JC MacKay
#12Re: "Sustainable Energy - Without the Hot Air" by David JC MacKay
#13I like how he dispenses with the fallacy of saving energy by unplugging DC adapters or TVs by focusing our attention on the high-energy cost activities (heating and transportation). 5 minute shower * (5 gal/min) * (440 BTU [to heat water 85 degrees]/gal ) = 11000 BTU or 3.223kWh or ~16 hours of 200-watt HDTV 1 gallon of gasoline = 115000 BTU or 33.7kWh or 10 5-minute hot showers
The ironic thing about bodily hygiene is that room temperature water is as good at killing bacteria as warm or hot water, incidentally its effect is negligible. Soap works better in warmer water, however as more and more people use liquid soaps and hand washes its meaningless as the added surfactants enable it to work just as well at lower temperatures. In fact many liquid soaps are better at removing grease and dirt at lower temperatures than standard soap is at better temperatures.
Then there's the whole problem that frequently washing your hands in warm water without a good liquid soap (which typically contain antibacterial agents too) can actually increase the bacteria on your hands due to the added moisture and temperature.
Dropping the temperature of your shower to room temperature will not only save you significant amounts of energy but will wash you just as well. In fact plumbing a cold water storage tank into your shower line and keeping it in a well insulated area of your house, you can spend virtually nothing on heating your shower water. Even adding a cold water storage tank to your shower line will likely cut the energy usage of your shower in half even if you take a hot shower. Most showers either run off a hot water tank (majorly inefficient) or an on-demand hot water system (either one that replaces the hot water tank, or a stand alone shower unit connected to your cold water line) and both ways end up heating ground temperature water: water lines stay at ~55F, room temp is between 68F-77F and a hot shower is 85F.
So even if you like a hot shower, simply adding a holding tank to the cold water intake of your shower can reduce the amount of energy you use phenomenally (potentially a 2/3 reduction). If you're in and out of a shower in 5 minutes, you likely only need a 25 gal tank, but for an average household I'd recommend perhaps a 100 gal tank, just in case.
Re: "Sustainable Energy - Without the Hot Air" by David JC MacKay
#14Incidentally, David Mackay's group came up with the Dasher eye-tracking user interface and a bunch of cool machine-learning stuff; and for further HN cred, one of his ex-postdocs is CTO of Songkick.
Re: "Sustainable Energy - Without the Hot Air" by David JC MacKay
#15This is the book to read if you want to understand sustainable energy issues. The only part where it's weak is discussing the economics; I would have liked more material on the costs and how to make sure they're manageable. And yes, it's refreshing to see a book on this subject written by someone who can do enough math not to fall for nonsense.
I know this guy and he's pretty approachable. He was always keen to improve the content of the book so get in touch if you've got comments.
Re: "Sustainable Energy - Without the Hot Air" by David JC MacKay
#16I'm a bit confused. This author makes the future sound bleak, with impossible choices. He makes it sound like wind, solar, geothermal, and hydro will never be enough.
But then, you read a quote like this from another source and the solution sounds almost easy:
"Less than 1% of the world's deserts, if covered with concentrating solar power plants, could produce as much electricity as the world now uses."
http://www.trec-uk.org.uk/images/CSP_map_squares2.jpg
What am I missing?
Re: "Sustainable Energy - Without the Hot Air" by David JC MacKay
#17I seriously like the numbers he's giving. He actually outright states what the theoretical max of certain technologies are, like if wind turbines covered the whole of the UK we would only extract 200kWh/d per person (which would involve the levelling of every city to blanket cover the country), and his estimate for the UK is 195kWh/d per person of usage. Even his best-case production estimate (which would basically t…
Perhaps "like" is too strong a word, but it's rather bracing to get an idea of how long high-energy civilization can last; barring some miracle like practical, cheap fusion power appearing in the next decade. If I were to make a comparison to a work of fiction, it wouldn't be to Mad Max or The Day After Tomorrow ; but to The Cold Equations , by Tom Godwin.
Nuclear can prolong us for a long time, uranium would basically be a stop gap to full on conversion to thorium reactors, as it's 3 times more abundant than uranium, but 550 times more abundant than U-235.
Basically nuclear would only be a stopgap to Fusion. Once fusion becomes available, you can begin replacing fission with fusion. Existing nuclear power plants have so much land reserved around them as a buffer zone that entire fusion plants can be built on them without the requirement of any new land as the old nuclear plants are decommissioned.
The ITER project currently puts the first commercial fusion plant in 2050, however that's based on current funding and research. As fusion increasingly becomes our only alternative I have a feeling the funding will begin going through the roof. I still wouldn't bet on anything closer than 2035 though.
Re: "Sustainable Energy - Without the Hot Air" by David JC MacKay
#18Another book of his on a different topic but with same great clarity of explanation is "Information Theory, Inference, and Learning Algorithms". The PDF is on his site at http://www.inference.phy.cam.ac.uk/mackay/itila/book.html.
Re: "Sustainable Energy - Without the Hot Air" by David JC MacKay
#19I'm a bit confused. This author makes the future sound bleak, with impossible choices. He makes it sound like wind, solar, geothermal, and hydro will never be enough. But then, you read a quote like this from another source and the solution sounds almost easy: "Less than 1% of the world's deserts, if covered with concentrating solar power plants, could produce as much electricity as the world now uses." http://www.tr…
What am I missing?
1) His general point is that no single energy source will be sufficient. We're going to need a combination of many different sources of power, combined with as much improvement in efficiency as we can muster. He concludes that it is very difficult, but not impossible, and that tradeoffs will be necessary.
2) Covering the electrical needs of the world is an easier task than covering the total energy needs, and even covering the current energy needs will not account for increasing demand by the developing world. Still, this is an approach worth exploring. It's covered in considerable detail in Chapter 25: http://www.inference.phy.cam.ac.uk/withouthotair/c25/page_17...
Re: "Sustainable Energy - Without the Hot Air" by David JC MacKay
#20I'm a bit confused. This author makes the future sound bleak, with impossible choices. He makes it sound like wind, solar, geothermal, and hydro will never be enough. But then, you read a quote like this from another source and the solution sounds almost easy: "Less than 1% of the world's deserts, if covered with concentrating solar power plants, could produce as much electricity as the world now uses." http://www.tr…
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