No commentary, just numbers.
In advance, here's my results:
| capacity | capacity factor | average output | % of total | |
| Natural gas/"bio"diesel | 7.6 MW | 77% | 5.84 MW | 98.5% |
| Solar panels | 0.5 MW | 14.5% | 0.073 MW | 1.2% |
| Vertical wind turbines | 0.36 MW | 5% | 0.018 MW | 0.3% |
[Philadelphia Inquirer] Eagles aim to turn Lincoln Financial Field into world's greenest stadium
In the parking lot - not where the fans park - the Eagles will build a cogeneration power plant that can run on biodiesel or natural gas.
The capacity of the plant will be 7.6 megawatts; the solar and wind together will add only .86 of a megawatt.
In short, natural gas.
The Eagles have contracted with Orlando FL-based SolarBlue, a renewable energy and energy conservation company, to install approximately 80 20-foot spiral-shaped wind turbines on the top rim of the stadium...
No source explicitly names these turbines, but I fairly sure they are these ones (S594 -- the 19.8-foot model):
http://www.helixwind.com/en/product.php
http://www.helixwind.com/en/S594.php
Under this assumption, 80*4.5 kW = 360 kW of wind turbines, so the remainder (860 kW - 360 kW = 500 kW) is the solar panels.
How much wind power? The most optimistic number is the manufacturer's advertised figure: 3,362 kWh/year per turbine. Out of 4.5 kW nameplate capacity, this is a pitiable 8.5% capacity factor -- but that's the optimistic figure. In the footnote it mentions the assumed conditions: 7 m/s annual average wind speed (15.7 mph). Wildly optimistic.
The Philadelphia Inquirer article reported the average sustained winds as 8 - 10.9 mph, or 3.6 - 4.9 m/s (I think these numbers are at weather station elevation, 10 meters (33 feet)):
National Weather Service statistics show that monthly average wind speeds at nearby Philadelphia International Airport ranged from 8 miles an hour in August to 10.9 miles an hour in March.
Likewise, NREL statistics put Philadelphia in the worst wind category, 0 - 5.6 m/s (0 - 12.5 mph) annual average at 50 meters (164 feet) above ground level.
Compare with the manufacturers' power curves:
Even at the upper limit of Philly 50-meter winds (5.6 m/s average), the range of expected output is from only 2,000 kWh/year down to roughly zero. The highest figure corresponds to 5% capacity factor, though, seeing the ranges involved, this is still wildly optimistic.
2,000 kWh/year per turbine * 80 turbines = 160,000 kWh/year = 18 kW average. Hilariously, this costs $1.28 million at retail price.
On to solar. NREL maps say this place gets roughly 4.5 kWh/year/m^2 for optimally-oriented flat plate (i.e. not sun-following) solar panels. (This is under "PV Solar Radiation (Flat Plate, Facing South, Latitude Tilt)—Static Maps" > "Annual")
Note that solar nameplate capacities are measured at 1 kW/m^2 irradiance (standard test conditions), so that assuming linear power/irradiance (very reasonable) 4.5 kWh/day/m^2 represents a capacity factor of 18.8%. Or close; this is the module's best-case DC output -- as NREL details, AC output would be around 0.77 of this (the "performance ratio"). So the capacity factor is around 14.5%.
(As a sanity check, the E.C. has a more sophisticated European map which does exactly the same calculation -- they assume a performance ratio of 0.75)
So in all: 14% * 500 kW = 614 kWh/year = 70 kW average output.
The surprisingly high capacity factor of the gas generator (why?) comes from this figure:
The Eagles and SolarBlue estimate that over the 20-year horizon, the on-site energy sources at Lincoln Financial Field will provide 1.039 billion kilowatt hours of electricity
Subtracting off the solar+wind generation, this leaves 1.024 billion kWh (basically all of it) to the 7.6 MW gas generator -- 77% capacity factor.
Superb work as usual, uvdiv. So the question is, what proportion of the cogen plant fuel will be biodiesel? I read elsewhere that the 'renewable' part of this is supposed to produce "an impressive 4 MW", which will be supplied the grid to save the plant even more money. That implies two things: one, the sun will never set and the wind will never cease, and two, the cogen plant will be running on biodiesel 40-50% of the time.
ReplyDeleteI really hope they publish their statistics to show the world how great their initiative is. Those types of data are so fun to look at. Like Bonneville Power Admin's real-time wind data, and Germany's solar output (that one is hilarious right now since it's winter).
http://www.sma.de/en/news-information/pv-electricity-produced-in-germany.html
It's fun to watch it inch up to 10% capacity factor at noon.