Solar PV seems to be the current darling of the renewable energy world. But how much “resource” is really out there? How much should cities rely on the development of local solar resources to meet their climate and energy goals? What trade-offs should urban cities make between desirable things like tree canopy and maximizing solar energy resources? GIS tools and new data resources can help begin to answer that question.
Counties and states are beginning to produce LiDAR data more regularly, which provides the building block information needed to analyze solar resources on buildings and elsewhere (see my previous post for a brief intro to LiDAR, or see here). Minnesota happens to have LiDAR for the whole state, and Minneapolis has a climate action goal that references local renewable development, so I’ll focus there.
So how much solar electric potential does Minneapolis have? Enough to supply 773,000 megawatt-hours (MWHs) each year, at the upper bound. That would mean covering every piece of rooftop with good sun exposure and appropriate pitch (southeast to southwest facing or flat) with the best modern PV panels. It would also mean solar installations on 68,351 structures, consisting of over 2.3 million individual panels. Continue reading
With a short appearance by yours truly. Watch the video here. Unforunately, it won’t embed.
Boston, New York City, Denver, Cambridge and other cities have created solar potential maps to help their residents understand that solar photovoltaic systems are viable in dense urban areas, and to demonstrate the potential that exists on rooftops.
Of course, I had to try this myself.
Minnesota produces LiDAR data, which is basically micro-scale elevation data produced by flying a plane back and forth in a grid and shooting the ground with lasers a bajillion times. Skilled/obsessive GIS users can clean from this data information that can be used to make a fairly accurate model of everything on the ground (buildings, trees, etc). GIS software also makes it easy to produce daily, monthly or annual solar insolation maps. By taking the position of the buildings and trees, knowing the latitude, and projecting how the sun moves across the sky throughout the year, the software calculates a total amount of solar radiation that will hit a point after shading, angle and other factors are taken into account.
Solar insolation in January
After much tinkering, the Kingfield Solar Energy Potential map was born. The extreme density of the LiDAR data limits how large an area I could process (there were 4.9 million individual data points in this one small section of Minneapolis), but you get the idea. This map shows the area of each roof that might be appropriate for solar, how many panels could fit in that area, and an estimate of the annual production from those panels.
The Kingfield Solar Map
Some roofs are wholly inappropriate for solar, whether due to tree or building shading, orientation or size. But there is significant potential. If solar was installed on every appropriate piece of roof in this one-quarter square mile area, it would produce an estimated 2.2 megawatt hours of electricity each year, and avoid 2.9 million pounds of carbon dioxide emissions.
Over at streets.mn, I detail some of my first impressions of one of Minneapolis’ newest car-sharing options, Car2Go.
According to MPR, by 2014 there will be over 400 vehicles available to car-sharing customers.
The bulk of these will be in the fleet of Car2Go, which operates on a different business model than the rest, offerring “point to point” service. Walk to a car anywhere in Minneapolis, drive where you want to go, then park it at any curb space in Minneapolis (expect rush hour zones). Other companies require that you return their cars to a specified location at a specified time. The trade-off is that their rates are generally cheaper.
Read the rest.
For the last two years, I’ve mapped the flows of the Nice Ride bikes. I’ve always been slightly dissatisfied with the results, since bikes were obviously shown taking routes that any sane Nice Rider would never take (Hennepin Avenue between Lake and the bottleneck, for example). Try as I might, I could never get ArcGIS to prioritize trails, lanes and bike boulevards sufficiently.
Enter the good people at Cyclopath. Cyclopath is something like a bike route wiki, in that it is constantly updating it’s database of bike routes using ratings from users. So every street in their database has a rating from bad to awesome (actually 0 to 4). And this database includes the whole metro and beyond. Best of all, they were willing to share it!
The latest version of ArcGIS has a new “restriction preference” setting, meaning there are six levels of preference for a link from “Highly Avoid” to “Highly Prefer”. So I combined cyclopath’s street ratings with these preference settings and got a new and better route analyzer. Here are the results:
As a reminder, here is what the old version looked like:
A few changes of note:
- Hennepin is obviously not so popular anymore, save in downtown where there are more Nice Ride Stations.
- The Cedar Lake Trail got a little more popular, perhaps 500 trips in some locations, since it was a Highly Preferred route.
- West River Parkway south of the Washington Avenue bridge got a lot less popular (although crossings at Franklin stayed nearly the same).
- There is generally just a lot less jigging and jogging on small streets as trips tend to condense onto major routes (see the major difference on Summit Avenue in Saint Paul).
Here is a version with a base street map for orientation:
Over at streets.mn, I have a post about everyone’s favorite fictional urban transit revolution, the urban gondola (or aerial tram).
The case history on US urban gondolas doesn’t look good cost-wise, but the travel time savings look great. The Portland Aerial Tram, which could also be called an urban gondola (if you consider low-slung Portland urban), cost $57 million, or roughly $90 million per mile, if I calculated the hypotenuse correctly. The Portland Aerial Tram travels at a top speed of 22 mph, which could make an Uptown Transit Station to Hennepin-8th Street trip in 6.5 minutes. That’s about one-third the posted travel time for the #6 bus, and less than half the travel time of the limited-stop #12. 6 minutes is even less than half the travel time identified by Metro Transit for an upgraded arterial BRT on Hennepin.
Matt Yglesias, Slate writer and MOU (market-oriented urbanist), laments Minneapolis’ NIMBYs (emphasis mine):
…if each NIMBY group gets its way, then the “push the costs onto other people” plan becomes self-defeating. Others bear the costs of your NIMBY actions, but you bear the costs of their NIMBY actions. What’s needed is a citywide institutional framework that leads to a less-dysfunctional outcome where valuable projects are allowed to go forward.
Perhaps some sort of community visioning session that combines a look at projected growth, market forces, neighborhood desires, externalities of development, transportation impacts, and comes up with a mutually-agreed-upon document that can guide regulatory land use controls?
Or perhaps he means, as a friend emails, a comprehensive plan and zoning code that aren’t influenced by residents/stakeholders? 1) Good luck and 2) that kind of defeats the purpose.
See my early screed about MOU “solutions”. MOUs claim market forces can unlock better outcomes for our urban areas, but the big barrier is really one of better process and collaborative decision making, which gets short shrift or no shrift at all in these posts.