VESTAS ENERGY AUDIT

You might want to go to youtube to see what a small country is doing with wind energy.

Some of the energy built in to the typical system is obvious and explicit, the heat used to smelt the iron ore, for example. The BTUs required to process a ton of ore is a matter of record. This energy is embedded in the final product, no room for argument or opinion. The energy used to mine and transport the ore to the smelter is not as easy to find. I suppose we could make an educated guess about the embedded energy in the ore, but that would leave room for arguments and opinions. I won't include these implied energies that we know are there and are quite significant but are hard to pin down. The totals, therefore will be very conservative. The energies shown as "typical" are industry standards for estimating similiar products, for instance, I have assumed that the energy to fabricate a tower is about the same as the energy to fabricate a very simliar steel pipe.

Energy In

The tower weighs 125 tons, the nacelle 52 tons, probably 50 tons of steel and 2 tons of machinery, we'll get to the machinery later, and the rotor weighs 43 tons, probably 40 of that steel, we'll get to the other 3 tons later. That's 215 tons of steel. Using the steel industrys optimistic numbers it takes 12,600,000 BTUs to refine a ton of steel. That equates to 3962 KWH

215 tons X 3962 KWH = 851,830 KWH

The 2 tons of machinery is a precision gear box, the electrical generator, control for the turbine blades and electric transformers and controls. The energy into these items is typically at least 10 times the energy in the raw materials.

2 tons X 3,9620 = 79,240 KWH

The 3 tons that isn't steel in the rotor is fiberglass and/or carbon fiber and epoxy resins. We would be very generous assigning only the same energy in as the machinery.

3 tons X 3,9620 = 118,860 KWH

The energy to fabricate most consumer products is about 10 times that of the raw materials. That works for an automobile or a refrigerator. Using that for the towers and other components.

851,830 KWH X 10 = 8,518,300 KWH

The plant in Pueblo that will build the towers is projected to cost 271 million dollars and take a year to build. The energy embedded in the plant is more difficult to estimate. Assume a plant and machinery life of 20 years, that's better than most, that's 13 million dollars a year invested in plant and machinery that is used up and has to be accounted for. With 1000 towers a year that's 13 thousand dollars a tower. The tower plant in South Korea may be more cost efficient but let's assume the energy investment is comparable to the new plant. Thirteen thousand dollars would buy about 16 tons of steel. Building material steel has about 15,000 KWH embedded energy per ton. That converts:

16 tons X 15,000 = 240,000 KWH

Using the same information for the rotor plant in Colorado and the nacelle plant in Scotland is probably also justified. The economics may be different but the energy stays about the same. This adds another:

Very conservative 240,000 KWH

They say the plant in Pueblo will build 1000 towers a year and employ 500 workers. The nacelle and blade plants north of Denver will employ another 1950 for a total of 2450 workers. That means it takes about 2.5 workers a year to build one system. The human being is about a one quarter horsepower device, about 180 watts. Each day every employee adds 180 X 8hrs = 1440 watt/hours to the system. For a five day work week that's 250 days X 1400 = 360 KWH

2.5 employees X 360 = 900 KWH

The energy it takes to keep the employees healthy and get them to work also goes into the product, but about the only thing we can document is the electrical power. The average household uses 8900 KWH of electricity a year.

Extremely conservative 2.5 X 8900 KWH = 22,250 KWH

There are many other factors adding energy to these systems but the ones shown here are facts. All this information is available to anyone. The truth is out there.

The system is now ready for transport. Let's assume the site in Colorado. In a couple of years the tower will be local, but right now the tower is shipped about 4600 miles from Busan South Korea on a special ship to a special dock at Longview Washington. Sea freight is quite efficient, only consuming about 225 watts per ton mile. 225 watts = .066 KWH, and 125 tons X 4600 miles = 575,000 ton/miles

.066 KWH X 575,000 = 37,950 KWH

The tower is then loaded directly on a special railroad car and taken about 1080 miles to Pueblo, and it's probably not that short or simple. Railroad freight is much more efficient than truck bur it still takes 800 watts per ton mile. 800 watts =.234 KWH and 125 tons X 1080 miles = 135,000 ton/miles

.235 KWH X 135,000 = 31,725 KWH

The nacelle is shipped from Campbelltown Scotland about 3600 sea miles to Houston X 52 tons = 187,200 ton/miles.

.066 KWH X 187,200 = 12,355 KWH

Rail freight Houston to Pueblo = 830 miles X 52 tons = 43,160 ton/miles

.235 KWH X 43,160 = 10,142 KWH

The rotor comes about 80 miles from Brighton Colorado to Pueblo, 80 miles X 43 tons = 3440 ton/miles.

.66 KWH X 3440 = 2270 KWH

Then assume the whole 220 tons is trucked to a site 120 miles away. Many sites could be much farther from a railroad. 120 miles X 220 = 26,400 ton/miles.

.66 X 26,400 = 17,424 KWH

There are places where the energy expended getting the system built and on site could be a great deal more than this.

Total Embedded Energy = 11,609,566 KWH

Now comes the installation. But first, a foundation has to be prepared for the tower. The installation crew, numbering over 200 workers at one site, builds a road to accomodate the large equipment. They blast and dig a hole 14 feet in diameter and about 30 feet deep. Some forms and a whole lot of big long bolts are carefully positioned in the hole and then about 85 yards of concrete is poured. This ends up as a concrete cylinder with the center backfilled. It takes about 500 KWH to produce a yard of average concrete.

85 X 500 = 42,000 KWH

The site preparation includes digging trenches, laying electrical cables. and locating the cranes. The tower is erected with cranes capable of lifing 50 tons 200 feet with precision control. The complete process takes a lot of men many days. A very significant amount of enegy is embedded in the system here but any estimate could be questioned. The copper in the electrical system contains huge amounts of embedded energy. The offshore systems being proposed for the East coast are another installation problem. You can go to offshore and guess how many KWH the system has to produce to break even. If we only count the concrete in the foundation we have:

Verifiable embedded energy = 11,845,108 KWH

Energy Out

The rated output of the generator is at maximun allowable wind speed. The manufacturer claims a 30% "Avalability", meaning the generator is generating 30% of the time, not at rated output, but generating some. I think we would be generous assuming rated output 10 % of the time. That's a 25-30 MPH wind two and a half hours every day. 365 days X 2.5 hrs = 912 hours.

912 hrs X 2 mw = 1,824,000 KWH per year

Conclusion

If the iron ore was delivered to the smelter free of embedded energy, if the coal was delivered to the mill free of embedded energy, if the installation and electrical transmission lines were free of embedded energy, if all the very real implied energy were not added, it would take almost 7 years to break even. Just the required monitoring and periodic maintenence would take the system to a net energy loss over the expected life of the rotor and electrical components.