July 2009 – Page 6 – a sibilant intake of breath

Diet for nerds and computer programmers

John Walker, the founder of Autodesk, has written an interesting guide on health and weight loss, which is available for free online: The Hacker’s Diet.

Basically, the book focuses on the fundamental mathematical issues associated with weight loss and gain, and describes some useful techniques for transitioning to a lower weight. In particular, the moving average approach to measurement described seems quite valuable, insofar as it helps to separate the ‘signal’ of actual weight from the ‘noise’ of variation in things like water retention. The moving average generates a trend line that seems like it should provide more meaningful guidance than a scatterplot of individual data points, or even a simple curve fit to them.

The book also describes a 15-minute health regimen that ramps up in difficulty and is intended to serve as a minimum level of exercise for life.

The book is quite an unusual one, as health books go. For instance, it endorses frozen microwave dinners as a convenient way to get a predetermined number of calories. It also insists that exercise is not a critical weight loss strategy, and that some degree of suffering inevitably accompanies efforts to move closer to one’s ideal healthy weight. While I am sure people could take exception to this approach, it is good to have variety out there, and encouraging that tools are being created for the ever-larger number of people worldwide that are overweight or obese, and likely to suffer significant health risks as a consequence. Those who don’t want to mess around with Walker’s custom Excel files can use a web-based version of Walker’s approach at PhysicsDiet.com

Sustainable Energy – Without the Hot Air

David MacKay’s Sustainable Energy – Without the Hot Air is a remarkably engaging book; it has certainly kicked off and contributed to some very energetic discussions here. The book, which was written by a physics professor at Cambridge and is available for free online, is essentially a detailed numerical consideration of renewable forms of power generation, as well as technologies to support it, and to reduce total power demand. MacKay concludes that the effort required to produce sustainable energy systems is enormous, and that one of the most viable options is to build huge solar facilities in the world’s deserts, and use that to provide an acceptable amount of energy to everyone.

The book has a physics and engineering perspective, rather than one focused on politics or business. MacKay considers the limits of what is physically possible, given the character of the world and the physical laws that govern it. Given that he does not take economics into consideration much, his conclusions demonstrate the high water mark of what is possible, with unlimited funds. In the real world, renewable deployment will be even more challenging than it is in his physics-only model.

Here are some of the posts in which the book has already been discussed:

I have added relevant information from the book to the comment sections of a great many other posts, on everything from wind power to biofuels.

Even if you don’t agree with MacKay’s analysis, reading his book will provide some useful figures, graphs, and equations, as well as prompt a lot of thought. It is certainly one of the books that I would recommend most forcefully to policy makers, analysts, politicians, and those interested in deepening their understanding of what a sustainable energy future would involve.

Pumped and multi-lagoon tidal systems

Many forms of renewable power generation, such as wind and solar, suffer from differing power output depending on how intense the natural energy source is at any particular point in time. One neat exception to this is a tidal barrage with multiple lagoons. By managing the water level in each, it is possible to smooth out power generation between tides, as well as make output constant between days with bigger tides and those with smaller tides. It is also possible to use such systems to store excess energy from other renewable generation sites (such as winds farms running at full power during times of low demand) and to release energy at times of maximum demand, or when output from other renewable options is flagging.

With two lagoons and pumps for both, there are a huge number of options. You can maintain one pool at a ‘high’ level, and the other at a ‘low’ level, topping up the former using natural high tides or pumping and drawing down the latter in the same ways. When the tide is high, you can generate power by letting water flow into the low pool from the sea, or by letting water flow into the low pool from the high pool. When the tide is low, you can generate power by letting water flow from the high pool out to sea, or from the high pool into the low pool. Whenever you are producing power, you can use it for any mixture of supplying the grid, pumping up the high pool, and pumping down the low pool.

The combination of pumping with tidal lagoons is even better than conventional pumped storage. This is because you can actually produce more energy letting the previously pumped water flow than it took to do the pumping. Wikipedia explains:

If water is raised 2 ft (61 cm) by pumping on a high tide of 10 ft (3 m), this will have been raised by 12 ft (3.7 m) at low tide. The cost of a 2 ft rise is returned by the benefits of a 12 ft rise. This is since the correlation between the potential energy is not a linear relationship, rather, is related by the square of the tidal height variation.

David MacKay’s book also has a detailed section on tidal pumping and two-lagoon arrangements.

Of course, tidal power is not without environmental consequences. It will certainly alter the marine ecosystems that exist wherever facilities are built, and may create consequences in river systems located behind the barrage. That being said, the many advantages of tidal power as an energy generation and energy storage option mean that it probably has an important role to play in building a sustainable global society.

Improving voicemail

While useful, voicemail is a flawed technology that can be improved in many ways. Three recent examples come to mind:

First, there is Apple’s visual voicemail. The improvement here is like the improvement between cassette tapes and compact discs: each message is an independent ‘track’ that can be treated as a unit. That is nicer than just having a single audio string to deal with, since you can see right away who called and jump to any message.

Secondly, there is the voicemail system of my VoIP provider. The nicest thing they do is provide an option to email you MP3s of your messages, which include caller ID to let you know who they are from. Now, I only call the actual voicemail number to periodically delete all the messages accumulating there.

Third, and neatest of all, is the transcription feature in Google’s forthcoming ‘voice’ product. Not only do you get to see who called, but you get an automated transcript. I am sure the voice recognition is far from perfect, but people seem to find it good enough to evaluate which messages need to be listened to, and which ones are just ‘call me back’ requests. To some extent, this even makes voicemail searchable, which is a neat trick.

While sound has character and authenticity to it, it is really a degraded form of communication, when it comes to simple searching and management. It is nice to see innovative ways to overcome the limitations of sound-based messages, while still retaining the original format, for those situations where you actually want to hear the message.

Preserving plastic history

Over at Slate, there is an interesting article about art and chemistry: specifically, about the challenges involved in preserving artwork and historical objects that were made from fundamentally unstable plastics. As the article points out, this is an odd reversal of what most of the world is trying to do, namely eliminate plastic wastes that are proving far more durable than would be ideal. For instance, there is the worrisome North Pacific Gyre: a huge garbage patch in the deep ocean.

One interesting aspect of the Slate article is the assertion that some microorganisms can now digest plastics. This claim contradicts those made in Alan Weisman’s excellent book The World Without Us, in which he claims that such metabolic pathways had not yet evolved.

The overall question of materials over long spans of time is certainly an interesting one. They have a huge impact on what we do and can know about history. For instance, much of what we know about ancient peoples comes from examinations of the garbage and artifacts they left behind: clues that can give insights into diet, contact with other groups, and much else besides.

The the amount of material and information being accumulated in the modern world is unprecedented, the plight of the plastics curator is another example of how much of it is ephemeral. Perhaps that is more true of information than anything else. When the plastics and metals and dyes of our optical disks, hard drives, and flash memory systems start to degrade and fail, an unprecedented amount of information is likely to be lost, from baby and wedding photos to documentation of historical events.

What does 5% of global GDP mean?

Over at FiveThirtyEight.com (the pollster site made famous by the Obama election), there is an interesting response to Jim Manzi’s opposition to climate change action. Manzi argues that climate change will ‘only’ cost 5% of global GDP, 100 years from now, so we shouldn’t worry too much about this. The obvious responses to this are that the consequences of business-as-usual emissions will be much more severe than that, profoundly threatening our current way of life. The FiveThirtyEight post takes a different approach, enumerating what the loss of 5% of global GDP would mean, if concentrated in relatively poor states.

Eliminating 4.99997% of global GDP is akin to eliminating 81 countries, with a total population of 2,865,623,000 – 43% of the world’s total:

We’ve gotten rid of almost all of Sub-Saharan Africa, destroyed the entire Indian subcontinent, created a big lake in South America, turned El Salvador into an island, and solved a lot of our problems in the Middle East. I suspect we could also have nuked North Korea, by the way, except that the IMF didn’t publish information for them.

There are, of course, flaws with this way of looking at things. That being said, it is a nice illustration of how abstract economic figures can become disconnected from the real world consequences they represent. As the post’s illustration demonstrates, even climate change that only cost 5% of global GDP could still be an extremely serious problem.

Artificial geothermal and earthquakes

Apparently, artificial ‘enhanced’ geothermal sites may cause earthquakes. The concept (mentioned here before) is to drill shafts down into hot rock formations, pump in cold water, and generate steam to drive turbines. It would considerably increase the number of regions where geothermal power could be used.

According to Swiss government seismologists and officials on the Basel project, an artificial geothermal project caused an earthquake in Basel in 2006 and was subsequently shut down. Even after the shutdown, thousands of smaller earthquakes occurred in the following years. Now, there are concerns about a project that AltaRock Energy wants to undertake in California. Google’s philanthropic arm is investing $6.25 million in the project. The proposed site already experiences as many as a thousand small earthquakes per year. This video has some further details.

Obviously, the earthquake risk needs to be assessed and managed. It may be that not as many sites are suitable for enhanced geothermal as previously assumed. Perhaps such projects will only prove viable in sparsely populated regions. In any case, it is an unfortunate blow to an otherwise promising looking type of renewable generation.