Thursday, October 21, 2010

Atlantic Wind Connection
Atlantic Wind Connection (AWC) is an electrical transmission backbone proposed by Trans-Elect Development Company that could be constructed starting in 2013 off the East Coast of the United States to service off-shore wind farms. Google, the investment firm Good Energies, and Japanese trading firm Marubeni are investing "tens of millions of dollars" in the initial development stage of what could become a $5 billion dollar project.
I stumbled upon this while reading Wikipedia during my English Comp class in a computer lab (I was reading the English Wikipedia though so it's ok).  The article is somewhat interesting, although brief.  However, there is a 10 page paper published in 2006 about offshore wind power in the mid Atlantic area that I found pretty interesting.

On the off chance that any of my readers know me personally, you probably already know I do not view wind power favorably.  Specifically, I think the cost per watt (that is actual average produced watt, not nameplate capacity) is simply too high.  Particularly when you factor in nuclear.

I will say though that this paper has made me reevaluate the specific case of off shore wind farms over a very large geographical area.  I still think wind is more expensive than nuclear, but at least it's feasible.  Unlike photovoltaics, which are still obscenely expensive.

I'll summarize what I found interesting, or feel warrants a response for the small percentage of you that won't be reading the original paper.

The study is from 2006, and covers the states from Mass to NC and the adjacent water up to a depth of 100m (which they term the "Middle-Atlantic Bight (MAB)").

They claim that the energy needs and potential energy from wind of that area are:
"We find that the MAB wind resource can produce 330 GW average electrical power, a resource exceeding the region’s current summed demand for 73 GW of electricity, 29 GW of light vehicle fuels (now gasoline), and 83 GW of building fuels (now distillate fuel oil and natural gas)."

They get wind speed data from a handful of NOAA buoys that have recorded hourly wind data for 21 years.  They found that:
"Wind speeds at all nine NOAA buoys in or near the MAB show a mean of 8.3 m/s ([extrapolated] at 80 m height) with [standard deviation] across buoys of only 0.8 m/s."

They take into account areas that would be unavailable for use for a wide variety of reasons.  They also include 10x5 blade-diameter spacing around each turbine to ensure they don't affect each other.

Using the published wind speed to energy curves, as well as their wind history data they calculate an average of 39% nameplate capacity over the long term.

They address the variable output of wind by suggesting multiple sites over a large geographical distance with high voltage transmission lines connecting them.  Specifically, they look at 1, 3, or 6 generation sites in the MAB, and calculate the percent of the year when the combined generation would be at x percent of capacity.
"for the single site, 13% of hours are at maximum output but 15% of hours are off (below cut-in speed of 3.5 m/s). For 3 and 6 connected sites, the power is off only 2% and 0.3% of the hours, respectively."
They conclude that this means wind power is not "intermediate" but rather that its generation fluctuations don't match up to the demand fluctuations.  They propose one possible solution to storing this excess power.  Convert 66% of cars to plug in electrics with individual capacities of 30 kWh (Tesla Roadster is 53 kWh, Chevy Volt is 16 kWh).  Assume that at any given time half these vehicles could provide half their storage to the grid.  That capacity would be adequate to supply the average electrical demand for two hours.  They claim this would be sufficient all but five times a year.  In order to guarantee supply during those periods fossil fuel backups would have to be maintained.

Overall an interesting read.  However, they do not address cost, and that is where wind really suffers.  In a table they give figures for number of turbines that would fill the MAB.  It would take 166 thousand 5 MW turbines to cover the MAB.  That would give an average output of 330 GW.  Pinning down a cost per turbine is difficult, but this very topical article gives a hint:
150 turbines for an estimated $1.6 billion.  That gives a per turbine cost of about $10.6 million.  To cover the MAB would cost about $1.77 trillion.  Using a rather high estimate for new nuclear construction of $5,000 per kW getting the same 330 GW capacity would cost $1.65 trillion.

This however, still ignores the variable nature of wind power.  Additional costs would arise from long distance transmission lines, as well as mass electric vehicle conversions.  Or, more realistically from backup natural gas plants.

So, it would appear that large scale off shore wind is at least within the realm of possibilities.  That being said, given that nuclear is still cheaper, even given a high estimate, and excluding the hidden costs of wind, what reason is there not to just go with nuclear?

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