Halloween Special - Energy Payback and Bats

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Introduction
One way to measure the effect of adding various types of renewable energy is to do a Life Cycle Analysis (LCA) on the product. These add up all of the energy (some or a lot of which involves CO2 pollution) that goes into making the product, as well as doing other evaluations (how much water gets consumed, does it contribute to Ozone depletion, water pollution, are there toxicity issues associated with the manufacture of the product as well as the intermediate parts/components used to make the product). Many of these can become a very long and involved analysis.

One example of an LCA for a commercial scale wind turbine is one done for the Vestas V112 x 3 MW product - see http://www.vestas.com/Files/Filer/EN/Sustainability/LCA/LCA_V112_Study_Report_2011.pdf, which is an 84 page (and summarized one at that, too) paper on the product. In their example, a wind farm with 99 MW capacity in a windy location (average wind speed is 8 m/s) with an average net output of around 43.3% would have an 8 month energy payback, while one operating in a slower wind speed region (7 m/s, with a net output of 34%) at 84 meters above the ground would have a payback time of 10 months. This is about as good as it gets for renewable energy these days, and almost an order of magnitude better than photovoltaic panels (around 6 years for them to hit "payback").

Summary
A payback of 8 months for a turbine lasting 20 years means that one unit of pollution sourced energy (mostly for steel and concrete manufacture) would provide 30 units of renewable electricity over that 20 year period. If the turbine lasts for 24 years (quite likely), the payback is 36:1. With the lower wind speed region examined, the paybacks become 24:1 and 28.8:1. Many of these turbines should be able to outlast reasonably modern wind turbines, and certainly outlast the very primitive ones installed in the early 1980's.

Another important aspect in the life of a wind turbine is recycling. Up to 80% of the V112 x 84 meter tower can be recycled - especially the steel, copper and aluminum. Most of the plastics (paint, wire insulation, nacelle enclosure and especially blades) would need to be incinerated. The concrete foundation can also be recycled as road or roadbed. The greater the amounts that can be recycled, the better the LCA becomes, and the quicker the energy payback becomes for a given wind resource.

The V112 is an example of the latest "medium speed" wind turbine generation. The 56 meter rotor gives a swept rotor to generator capacity ratio (power ratio) of 3.28m m^2/kw, so this is not designed for low wind speed regions (wind speed less than 7 m/s). With an 84 meter tower, the tip of the wind turbine blade is at most 140 meters above the ground (and at minimum 28 meters); this is about as big a single piece blade (54.6 meters) as can be transported by rail and truck. Taller towers (95 and 119 meters, the latter being a hybrid with a lower concrete and an upper steel section) can also be used, which allow faster winds (and produce greater power production) to be tapped. Due to the slow rotation rate that comes with a larger turbine, this unit comes with a four speed gear reducer, and a choice of permanent magnet or traditional doubly fed induction style generator.

Over 1 GW of wind turbine capacity of the V112 for onshore uses (334 wind turbines) has been ordered to date; the first ones to be installed were recently shipped from Denmark to Australia. This turbine also was designed for "moderate" offshore winds - not the blazing gales in much of the North Sea, for example, where turbines with a power ratio of less than 2.5 m^2/kw are used). Very recently, 89 of these (267 MW) in total were ordered for a pair of wind farms in Sweden and Great Britain - see http://www.offshorewind.biz/2011/10/28/vestas-shares-up-after-offshore-wind-turbine-order-announcement-denmark/. These would have been ideal for the Great Lakes, and in which case they would have been made in Colorado.

Bat Development (announced near Halloween, too):
A competitor of Vestas is Nordex, which also has a manufacturing facility in the U.S. - in this case, Arkansas. Nordex recently announced development a software system that minimizes bat mortality near wind turbines - they claim up to an 80% reduction in bat injuries can be obtained. The system uses knowledge of local weather, time of day and other local factors to calculate when the greatest probability of bats coming near wind turbines is likely to take place. Bats can get injured from damage to lungs via the air pressure variations/pressure waves that develop near moving wind turbine blades and unless they are feeding they don't sense the proximity of the blades via their sonar (which is only "on" when feeding on insects). When a certain high probability level for nearby bats is calculated, the turbine gets shut down and then gets restarted when the bats "retire" and/or wind speeds speed up. Bats are unlikely to be feeding when winds exceed 6.5 m/s - too hard to track down food. The developer of the product, Biotope, claims that power production is only likely to be affected by about 0.2 % - see http://www.nordex-online.com/fileadmin/MEDIA/Kundenzeitschrift/EN/Nordex_WPU_33_en.pdf.

Conclusion
So, a less scary world for bats, and a less scary world with respect to Greenhouse Gas pollution, all on Halloween. The only really scary thing is that NY does not really have a sane electricity pricing system - see here for some of the 2008 numbers, when, for example, the owners of the Dunkirk and Huntley coal burners got an 81% return on their investment: http://www.scribd.com/doc/22323398/New-York-State-Electricity-Plants’-Profitability-Results. So not only can pollution based energy producers "chow down" on their consumers ignorance of the complexity of the NYISO system, we also can't afford to install wind turbines without really significant "incentives". For example, the 74 MW Hardscrabble wind farm, NY's newest, could use up to $160 million in Federal grants (Section 1603) and tax deductions (MACRS, interest paid on loans), and it could also be the beneficiary of $42 million in NY's RPS (Renewable Portfolio Standard) awards form NY State, meaning that the Iberdola Corporation might get the wind farm for free, after a convoluted 10 year process.

Bottom line: essentially no wind turbine manufacturing so far in NY State despite 1349 MW of installations, representing an investment of roughly $2.7 billion. Obviously, that leaves a lot of room for improvement. And it is roughly 10% cheaper to make them and install them nearby, as long distance transportation can add 10% onto the installed cost. That's worth close to 1 c/kw-hr....

To me, that's scarier than what the candy-searchers are dressed up to be.