Turbine Whine

Rest easy, friend. Saskatoon’s $5 million public relations stunt is safe and economically viable, says the person responsible to ensure the safety and economic viability of Saskatoon’s $5 million public relations stunt.

Four reports on the tall wind turbine project were made public in order to satisfy citizens’ concerns about the safety and environmental impact of the project. These reports covered the impact on birds and bats, sound and shadow flicker, waste mechanics, and wind resource. City councillor Pat Lorje, who never met a constituency she couldn’t pander to, flexed her NIMBY bonafides and focused on the noise and shadow issue. Since the turbine is to be located half a mile from the nearest home atop the local landfill, this was never an issue. Sure, the 120-metre turbine would be a glaring eyesore, but considering the state of public art in this town, I think we can lay the aesthetic argument aside for the time being.

The biggest concern with the project, however, was and remains the economics. Since we are, bizarrely, not provided the economic analysis of the project, we are left with the wind resource assessment conducted by the Saskatchewan Research Council. It is with this assessment, however, that a few red flags emerge regarding the overall feasibility of the project.

For starters, the assessment only used data from September 2010 to September 2011, even though, “ideally, wind assessments would be two or more years.” This would be because the project sponsors, Stantec Engineering and Saskatoon Light & Power, requested a tight turnaround on the project, likely the result of heightened public scrutiny. One would argue that this work would have been completed far before the decision to move ahead on the project, considering that the success of the project would be the result of the available wind resource at the site. After all, a mine project would only move ahead once the available ore is sufficiently delineated; why would this be different for a wind turbine? The project authors do compare the one-year dataset to the long-term trends found at the Saskatoon John G. Diefenbaker International Airport, but the comparison is hardly scientific.

Another red flag occurs on the use of the tower installed to collect meteorological data. Due to concerns of collapse, the tower collected data at levels 30, 40, 50, and 60 meters from the ground, even though the hub of the turbine is to be set at 80 metres, with the blade span reaching 120 metres. Not to worry, “extrapolating wind speeds to higher elevation canbe done accurately by measuring wind at multiple heights along a tower” and “wind speed generally increases exponentially with height,” although no citation was provided for either statement. Regardless, the report fails to take into account that the elevation of the base of the turbine the top of the landfill — 515 metres above sea level — is about 15 metres higher than the regional elevation of 500 masl. This means the tower likely collected data at 45, 55, 65 and 75 metres above the surface, and that the turbine hub would be roughly 95 metres up.

Meterological data was collected atop of the landfill site

Why is this relevant? The report says that “wind speed is the most important factor to consider for the generation of electrical power from a wind turbine,” so we’ll look at the wind speed data. The next red flag illustrates how the data was used to extrapolate to the proposed height of the turbine. This is the data set of the velocities measured at the site as shown in Table B:

Level (m) Mean (m/s) Minimum (m/s) Maximum (m/s) Std. Dev
60 6.13 0.35 17.70 2.86
50 5.88 0.35 17.15 2.73
40 5.64 0.35 16.75 2.61
30 5.35 0.35 16.15 2.51

Again, the report says that “wind speed generally increases exponentially with height”. But look at that data set. The difference in average wind speed from 60 (or 75) meters to 50 (or 65) metres is 0.25 m/s, from 50 to 40 is 0.24 m/s, and from 40 to 30 metres is 0.28 m/s. This is hardly exponential growth. Linear, maybe, but of course we don’t have a long enough timeframe to collect sufficient samples to prove otherwise.

What’s more, the authors attempt to extrapolate the data out to 80 (or 95) metres through a pair of logarithmic functions:

Switch axes, please

Notice anything? Not long after noting that wind speed is a function of height, and exponentially so, they apply a log curve in which height is a function of wind speed. In fact, unless my math skills are more rusty than I realize, the graph shows that the acceleration in wind speed actually decreases logarithmically with respect to height. In other words, the wind appears to decelerate as you get higher.

What’s more, the function itself, which hardly matches up to observed data, ought to account for the 15 metres of height differential between the top of the landfill and the regional topographical trend.

What does this mean? Probably nothing. Or everything. The flags seem to suggest that the average wind speeds could be lower than what we would see over the life of the project, but that’s not the point. The flags also tell me this was likely a hastily conceived study that made some sloppy assumptions, limited scope, and was poorly reviewed, which leads me to wonder if the experts knew what they were doing with respect to the other main calculations found later in the report.

But let’s take it at their word that the final conclusions of the assessment were reasonably accurate enough. After all, “the data set was analyzed using … professional software packages designed for wind analysis and turbine power output predictions,” and we all know how well that has gone historically. Ultimately, however, the report concludes that the proposed site is considered “Wind Power Class 2” out of seven, or “marginal for supporting wind power generation.”

Yet Saskatoon’s “alternative energy engineer”, Kevin Hudson, is adamant that the project will make good on its $5 million investment over its 20-year lifespan, assuming that this investment is the net present value (though that might be too much to expect).

Leave aside the fact that, after 20 years, any large-scale energy project should return considerably more than its initial investment regardless of the source of fuel, why doesn’t the city provide the calculations they used to come up with their conclusions? What are their assumptions of electricity costs over the next two decades? Why are they saying that the wind turbine will power 500 homes and reduce greenhouse gas emissions by 3,000 tonnes? If this is a 2-MW project as they claim, how come a similar project in Toronto only powers approximately 100 homes and reduces greenhouse gas emissions by only 400 tonnes?

I’m not sure where to go with this. The city’s already approved the project, despite the fact that no reasonable person believes the project will (a) make money, (b) provide reliable power or (c) reduce greenhouse gases.

What a fucking waste.

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