Tilting at Windmills
May 4th, 2008The attraction of using Wind to produce electricity is obvious: you put up a tower, you get endless free power with no environmental negatives.
Unfortunately it’s a mirage: there’s no free lunch and the unhappy reality is that windmills (installed, grid connected, single tower assemblies) are affected by three groups of problems that together make them among the most polluting, environmentally damaging, and highest cost forms of public power generation available.
The first group involves direct environmental or public health impacts. These range from trivial concerns over scene pollution and the opening up of otherwise protected lands to abuse through the construction and maintainance of the roads needed to emplace and maintain the windmills; to the bird, bat, and bee deaths traceable mostly to rotor turbulence.
Among these, the effects on protected species are the most politically important because governments in both Canada and the United States routinely jail people for killing individual birds while simualtaneously subsidizing wind farms known to kill them at wholesale rates.
It seems likely, however, that the most environmentally important impacts will ultimately be found among those which are currently least understood and least studied. For example, the health effects of microscopic abrasion products carried down wind from wind farms have not, I believe, been explored, and yet many of the materials involved are individually known to be highly toxic.
The second group of issues focuses on the greenhouse gas production caused by the decision to buy, emplace, and use a windmill. In its debt form, the question is under what circumstances the greenhouse gases not produced because a windmill is used to generate energy exceed the total greenhouse gas produced during its manufacture and placement.
The key thing to remember in this context is that commercial windmills are big: very big. Seen from a highway as you drive through Alberta’s Crownest Pass they may look like rows of child size whirlygigs, but in reality typical rotor wings could lift a Boeing 747, weigh up to forty tons, and give you, up close, the feel of three highway tractor-trailer combinations attached to a hub by their front bumbers and then whirled over your head.
A windmill’s energy (or greenhouse gas) debt is expressed through the bill of materials going into it from raw material through to eventual decommissioning.
Consider, for example, the fact that the typical 90 meter tower needs a 160 cubic meter foundation with each of the 140 or so cubic yards of concrete going into it containing about 700 pounds of portland cement. Making that cement took a lot of energy, and released a lot of CO2 - depending on process and source materials this means that the windmill starts out more than about 100,000 pounds of CO2 and 50,000KWH in debt before the concrete for the tower foundation even gets mixed and trucked out to the site.
The rest of that foundation is even more energy intensive - nearly twenty tons of rebar, a four ton steel mounting sleeve, high strength bolts - the list goes on and the power debt mounts. Add it all up, convert CO2 debt to KWHs of generated power at the 2:1 rate appropriate to the average 20 year old coal fired power plant, and you get rough estimates in the range of 1200 MWH for smaller assemblies rated at or below 200KW, and something like 3,200MWH for assemblies in the 1MW range - and all of that is before considering site construction, long term maintainance, and power distribution.
Since windmills rarely average more than 70% of rated capacity one third of the time, what these numbers mean is that smaller units almost never reach break-even and should be regarded simply as batteries for stored pollution, while larger units will usually breakeven before distribution costs in just over two years - or, in other words, whether they ever break even depends most directly on how far they are from the power consumer.
That’s bad - but the second form of CO2/Power debt is worse. The problems here are the effects of power displacement and the need for standby power.
Consider a simple scenario: imagine a public power grid fed from one coal fired generating plant to which enough windmills are added to reduce the coal plant’s output by enough to take it out of its efficient range - typically plus or minus about 3%.
Two things happen in that situation: first, because coal fired generation is designed to operate most efficiently at capacity, the decrease in CO2 output from the coal plant is less than the decrease in the number of KWH it puts on the grid - meaning that the use of wind power makes every KWH in the baseload dirtier.
Second, because it takes from hours to days to bring a coal fired generator back up to capacity but customers don’t want their air conditioners dying when the wind falters, the utility has to provide alternate sources of standby power - and that usually means gas fired generators.
Since all of the combustion products from the alternate power source are incremental to those produced by the coal plant, the net effect of adding wind power to the system is always to increase total emissions - by how much depends on many factors including plant efficiencies, utilization rates, and the utility’s ability to manage demand by cutting deliveries to some customers - but the result is always to add both more cost and net new greenhouse gas emissions to the system.
The question of how much cost it adds brings us to the third set of problems with wind power.
Because wind power is expensive and unreliable, utilities invest in it only in response to external presures - almost always in the form of government mandates expressed through some trade-off between the regulatory and tax systems.
The largest and most common component in these saw-offs, in both Canada and the United States, is the separation of power distribution costs from power generation costs - something that allows the green power advocates driving this at the political level to completely hide the single biggest cost of windpower from the customer.
Consider, on this issue, this bit from a recent NRO article by Drew Thornley:
Robust wind power expansion is expected, as Texas Senate Bill 20 (2005) mandated 5,880 MW of renewable energy by 2015 and set a 10,000-MW target for 2025. To this end, $700 million went into new wind Texas farms in January, thanks in part to government subsidies.
In addition to generous federal assistance - namely a 2 cents/kWh production tax credit and five-year, double-declining balance accelerated depreciation for wind-generating equipment - the state of Texas entices wind developers with a franchise tax exemption to manufacturers, sellers, or installers of wind devices; a corporate deduction from the state’s franchise tax for renewable energy sources; and a 100-percent property tax exemption on the appraised value of an on-site wind power generating device. But even with these federal and state subsidies, electricity from wind is more expensive per kilowatt-hour than that generated by fossil fuels.
ERCOT’s [Electric Reliability Council of Texas] estimates for transmitting West Texas wind energy, under four different scenarios, range from $3.78 billion to $6.28 billion. ERCOT estimated costs by using as-the-crow-flies distances for transmission cables. Thus, transmission costs were estimated using a best-case-scenario approach and, as such, should be considered the absolute (and unlikely) minimums. Add to this ERCOT’s estimates of $410 million to $1.03 billion for connecting wind generation to the new collection substations.
Additionally, ERCOT’s transmission-cost estimates do not include right-of-way costs or the costs of building transmission stations, which will be passed through to consumers, in the form of higher electric bills.
The second most significant of the accomodations typically reached between regulators, tax authorities, and utilities is one in which the official blended average price for output power comes closer to reflecting the nominal capacity of the windfarm than its actual power production.
To see how this works imagine that a system has one coal fired plant producing 100MW of continuous power at a cost of $0.032/KWH and a 22MW rated capacity windfarm that, on average, puts 3MW on the grid at a unit cost of $0.176/KWH. On the numbers, the blended price should be $0.0373/KWH (= 3.2 + 3 x 17.6/100) but the utility’s interest in maximimizing cost recognition can combine with the regulator’s interest in claiming the name plate capacity of the wind farm to produce negotiated pricing much closer to $0.071/KWH ( = (3.2 + 22 x 17.6/100).
The details on how both major forms of price manipulation are implemented vary by jurisdiction, but any complex financial system that can be gamed, will be gamed; especially if, as is the case with politically mandated wind power, both sides win by doing so - and the inherent complexities involved mean that everything can be done completely in the open with very little risk that the consumer will ever understand what’s happening.
So what’s the bottom line? Add it all up, and what you find is that the immediate bottom line on windpower is on everyone’s power bill - and the long term environmental bottom line is unknown, but just on greenhouse gases they’re dirtier than almost any other form of power generation.