Overpopulation isn’t the Problem

Some folks in Boulder like to make analogies to exponential global population growth in discussions about our local land use decisions (see for example Frosty WoolridgeFrosty Woolridge again, Robert Baker, David Brandt, or the venerable Al Bartlett himself). These analogies are inappropriate in multiple ways.

First, steep declines in fertility worldwide have largely defused the population bomb. Second, even if the bomb were still ticking, the population changes we see in Boulder, and more generally the Front Range of Colorado, the US and the booming megacities of Asia aren’t about population growth per se, they’re about migration.  In the developing world, it’s migration from rural areas to cities. In the already rich countries, it’s mostly migration between cities, often from low-wage regions to areas with better jobs and higher quality of life. Or it would be anyway, if we actually let people build housing in those places.

How we choose to build and rebuild cities to accommodate these migrations and humanity’s peak population later this century will largely determine our ultimate impact on the Earth’s climate and biosphere, and the quality of life that humanity has access to.  Contrary to many “population bomb” narratives, the main problem here as it relates to climate isn’t the impact of large numbers of poor people, because small numbers of rich people are responsible for the overwhelming majority of current greenhouse gas emissions.  How we accommodate those wealthy, high emissions populations makes a big difference, both directly, and through the example it sets for the rapidly expanding global middle class.

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Less Than Revolutionary Finance



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Sustainable Energy Without the Hot Air

Sustainable Energy, without the Hot Air by David MacKay, is a book (available in its entirety online) looking at the sources of energy available, and the ways in which we use it today.  There are lots of options, but any real discussion has to, at the very least, use numbers that add up.

Industrial Scale Urban Farming in NYC

TED fellow Viraj Puri talks about his Brooklyn rooftop farming startup.  Gotham Greens has ~1500 square meters of hydroponic greenhouses producing herbs and salad greens in a very controlled environment… somewhere between a farm and a manufacturing facility.  The system is solar powered, and can operate all year long.  They currently produce ~100 tons of food a year, and they believe the business is viable at least in the urban foodie context.  I was happy to see Puri readily (repeatedly) admitting (or even pointing out) that the system cannot scale up sufficiently to provide a large proportion of the city’s overall food requirements.  This is in stark contrast to the idea of Vertical Farming, which is clearly bunkum — once you’ve covered the roofs with greens, there’s no more farming to be done unless you pipe in light somehow, which is much less efficient than simply farming where the light is naturally.

Just out of curiosity… I wonder how much food could be produced in Brooklyn at full capacity?  And roughly how much does the city eat?  The land area of the borough is 183 km^2 and it has 2,500,000 residents, or roughly 75 m^2 per person.  Their production of 100 tons/1500 m^2 is roughly 66 kg/m^2 per year.  So if the entire area of Brooklyn were producing like this greenhouse, you’d get nearly 5000 kg of food per person per year.  The average American consumes about 1000 kg of food per year, so if you were able to use 20% of the borough’s area, you’d be close to meeting demand… at least by mass.  Gotham’s 59kW solar array probably takes up ~590 m^2 (100 W/m^2 is typical of solar cell power production) and only provides part of the operation’s power.  Probably there’s other infrastructure too that’s not actively producing food, so say they’ve got about half their total area dedicated to actual plants… then you’d need to get up to 40% of the land area being utilized to get 1000 kg of greens per resident per year.  However, most of the 1000 kg that we actually eat is a lot more energy dense than lettuce.  I wonder how many calories per m^2 one can get out of these setups, and what the most productive crops would be?  Honestly I’m surprised at how large the potential production is.  I wonder what the actually available rooftop area is?

Why I Won’t Be Turning Off Any Lights for Earth Hour

A GOOD (Magazine) summary of why Earth Hour is lame.  First, it’s symbolic — turning lights off for an hour has a negligible effect on your (and the globe’s) energy consumption.  Second, the symbolism (which is all it’s got) totally sucks!  Want to be environmentally sound?  Then sit shivering in the dark.  Great.  Widely publicizing an action which is both unnecessary and turns people off (ha!), isn’t gonna win any hearts or minds.  It just reinforces the needlessly “hair shirt” vision of “green” that most people have.

This is what a closed-loop economy looks like today

A great series on the recycling industry in China from the writer of Shanghai Scrap.  We need to build a closed-loop material economy, and there are pieces of it around today.  This is one of them.  Mountains of fist-sized shards of shredded cars, sorted manually by women who are earning more than your average Chinese college grad.  Amazing photos.

Green Manhattan

A good piece from The New Yorker on what makes dense urban areas intrinsically better for the environment than suburbia or back-to-the-land fantasies.  More people closer together need less transportation to go about their daily lives.  High density buildings need less energy to stay comfortable inside because they have less surface area for the enclosed useful space.  More resources can be effectively shared when lots of people are close together.  The author, David Owen, has a whole book on the topic, entitled Green Metropolis: Why Living Smaller, Living Closer, and Driving Less Are the Keys to Sustainability. Cities have their problems, but often they aren’t the result of density directly. Poor air quality in cities, for instance, is almost entirely the fault of motor vehicles.

Toward a Zero Energy Home by David Johnston and Scott Gibson

I’ve been looking, apparently in vain, for a good book (that’s not in German!) detailing Passive House building and modeling techniques.  The best I’ve been able to do so far is Toward a Zero Energy Home, and it must have been pretty good, since I read it cover-to-cover in less than 24 hours.  It’s not particularly dense or detailed, but it was a nice quick overview of low energy building systems, with lots of pretty pictures, and a dozen case studies from all over North America, including a couple right here in Boulder.

Refurbished with passive house components, kindergarten in Estonia Valga

The goal that the authors have chosen to highlight — “Net Zero” — means that the buildings in question produce as much energy as they consume on an annually averaged basis.  This necessarily means that they all have some on-site production, wind, PV, solar-thermal hot water, etc.  However, to keep such projects reasonably cost effective, it’s necessary to focus first on energy efficiency measures.  Most important among these is a very tight building envelope, much more insulation than code requires, and appropriate glazing for passive solar gain.  Then the internal power loads need to be minimized, by using energy efficient appliances and LED or CFL lighting.  Only after doing all that is it financially worthwhile to start adding on-site renewable generation, capable of meeting the overall annual energy demands of the dwelling.  Financially worthwhile, that is, if you have already decided that you want to create a Net Zero building.

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