Archive for June, 2011

Fully Renewable Grid

A couple of years ago, Dr William Moomaw of Tufts mentioned a regional scale experiment with an all-renewable grid in Germany. I’ve been curious about that project since then. Today, I did a little googling and found a seven-minute youtube called “Fully renewable: biogas + wind + solar”

Dr Jurgen Schmid at the University of Kassel, Department of Efficient Energy Conversion is the spokesperson from this December 2007 video. The system described is wind with pumped hydro storage and grid scale solar with methane from biomass (corn biofuels). When the sun isn’t out in the South, the wind may be blowing in the North. When there’s too much wind, it can be used to pump water into reservoirs that will provide hydroelectricity days or weeks later. When the sun isn’t shining and the wind isn’t blowing, biomass can be burned or converted to methane. They say Germany can have a 100% renewable grid by 2050. Dr Schmid, along with John Sievers, Stefan Faulstich, Mathias Puchta, Ingo Stadler, is the co-author of “Long-term perspectives for balancing fluctuating renewable energy sources” (pdf alert: details the steps necessary to get to a fully renewable grid.

If it can work in Germany, which has, on average, about as much sunlight as Seattle, it can work in the USA too. Maybe even in a city like New York.

The NYC Solar Map (, a collaboration between New York City, the City University of New York, and the Department of Energy, shows 66.4 percent of the city’s buildings have roof space suitable for solar panels and could generate up to 5,847 megawatts of energy, 14 percent of the city’s total annual use (taking typical weather conditions into account).

The data for the map was collected using a Lidar-equipped plane recorded the shape, angle, and size of the city rooftops and the shading provided from trees and structures around them. New Yorkers can use the map to discover the solar power potential of their own roof, the associated costs, rebates, and various financial incentives by entering their address.

Today in NYC, about 400 solar installations produce 6.5 megawatts, and existing solar power installations nationwide produce about 2,300 megawatts. If the NYC data is replicable in other cities, we are currently using a little more than a tenth of what we could get from sunlight alone. And that’s just counting electricity.
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