Quantifying Community Garden Crop Yields

An informal study looking at the urban farming yields, by Mara Gittleman67 gardens, with a total area of 1.7 acres in NYC generated 87,000 lbs of food, with a market value of roughly $200k in 2010.  This is equivalent to about $3/square foot.  Just looking at the financial aspect, if we’re talking about land which could be developed, the net present value, discounting at 5%, of $3/sq ft, is (even if we go out 100 years) only about $60/sq ft. If you build a 5 story building, then property values need only be greater than $12/sq ft for the urban farming not to make (economic) sense, and I’m going to go out on a limb, and guess that property values in most of NYC are, um, substantially higher than $12/sq ft.

Energy Intensity and Boulder’s Climate Action Framework

With this year’s expiration of the Kyoto Protocol and our Climate Action Plan (CAP) tax, the city of Boulder is looking to the future, trying to come up with an appropriate longer term climate action framework, and the necessary funding to support it.  To this end there’s going to be a measure on the ballot this fall to extend the CAP tax.  I’m glad that we’re talking about this within the city (and county), because at the state and national level, the issue seems to have faded into the background.  Unfortunately, that doesn’t mean the problem has gone away.  This year’s wildfires, the continuing drought that’s decimating the corn and soybean harvests, and the phenomenal 2012 arctic melt season are just appetizers.  If the last decade’s trend holds true, we’ll have an ice-free arctic ocean some September between 2015 and 2020.

The major sources of emissions, broadly, are electricity generation, transportation, the built environment (space heating, cooling, hot water, lighting), agriculture, and industry (the embodied energy of all the stuff we buy, use, and then frequently discard).  The extent to which local government can impact these areas varies.  We interface with embodied energy most directly when it comes to disposal and at that point, the materials have already been made.  Similarly, most of our food comes from outside the region.  Our most ambitious project so far has been the exploration of creating a low-carbon municipal utility.  We’ve also potentially got significant leverage when it comes to transportation, land use, and the built environment, since cities and counties are largely responsible for regulating those domains in the US.

Continue reading Energy Intensity and Boulder’s Climate Action Framework

The Next Wave of Urban Growth

Where the Next Wave of Urban Growth Will Come From, the Harvard Business Review looks at a study from McKinsey, detailing the economic centrality of cities, vs. national economies.  Large cities and modest countries are now of the same scale, and cities are growing much much faster, economically.  If you’re going where the market is, most likely, it’s in a bunch of towns you’ve never heard of, each with a population of several million.  Mad change.

Google Street View for building energy efficiency

Essess is doing drive-by thermal imaging in high density urban areas across the US, hoping to target possible building energy efficiency opportunities.  Another company is using urban satellite imagery to choose the best rooftops for solar energy siting.  Big Brother may be watching you… but at least occasionally he’s got the right idea.

Alex Steffen’s SXSW Eco Keynote

Alex Steffen gave one of the keynotes, at the first SXSW Eco Conference this fall, talking about good cities as the single best leverage point we have in reducing GHG emissions.  It’s broadly the same collection of ideas as his forthcoming crowdfunded book Carbon Zero: A Short Tour of Your City’s Future.  Looking forward to its eventual release.

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?

Location Efficiency and Housing Type

According to this EPA study, regardless of the type of housing, living in an area with good transit access saves more energy than building a “green home”. Of course, living in a mixed use, transit accessible apartment that’s also energy efficient uses the least energy, but it’s important to realize how limited the potential for cost-effective energy efficiency is in a sprawling suburban context.