Drilling advances

	Vol. 229 No.8
LES SKINNER, PE, CONTRIBUTING EDITOR, LSKINNER@SBCGLOBAL.NET

Wind power

Recently, I visited a wind power generating installation in north-central Texas where there are several hundred wind turbines turning slowly in the gentle breeze. What I saw was part of the Horse Hollow Wind Energy Center with 427 wind turbines spread over 47,000 acres of scrub oak and mesquite-covered ranch land. The facility produces about 40% of the total wind-generated power for the state of Texas. This wind farm is located near Abilene, where energy development is the norm-there are also thousands of oil and gas wells in the area. And there is a connection with oil and gas operations, which I will explain.

Wind, like water in lakes, streams and rivers, cannot be severed from the surface owner. In the US, the surface and mineral estates are not necessarily owned by the same entity. In fact, in most areas, the surface has one owner and the minerals have another depending on what was transferred when the land was sold. So wind power generation provides a means for surface owners to earn some much-needed income from a naturally occurring phenomenon. Most wind turbines generate from 1 to 3 megawatts of electricity in a year’s time. Generally, the surface owner receives a 3% royalty, providing an income of around $4,000/MW, with the developer retaining the balance. Still, for sizeable landowners, the income can be significant.

The turbines are huge. The towers are around 260-300 ft (79-107 m) tall and are erected in three sections. On top of each tower is what appears to be a small room that houses the gear reducer and generator. The entire machinery and blade package rotates automatically about the tower centerline, keeping the blades oriented perpendicular to the wind. The machinery room looks tiny from the ground. I wondered how people could inspect and maintain the machinery until I saw one of the gear reducers. It is the size of a small car. I quickly concluded that the little room at the top of the tower was actually the size of a small school bus.

The towers are 16 ft in diameter at the base and taper to 8 ft in diameter at the top. Access to the machinery room is through a series of vertical ladders. There are decks every 20 ft or so with the ladders staggered around the inside of the tower. The farthest a person could fall would be about 20 ft, but climbing up 250 ft of ladders several times a day to inspect gear might cause a bit of fatigue. It was bad enough going up a 126-ft derrick to service the crown block when I worked on rigs.

The fiberglass blades are a little over half the tower height in length (around 145 ft) and their pitch is computer controlled to provide a steady rotational speed of 21 rpm. On the day of my visit, there was a gentle breeze blowing from the south. Two of the turbines were down for repairs, but all the others were busily putting electrons into the grid using just the velocity of the wind at 260 ft above the surface.

One thing I quickly noticed is the noise these things generate. The machinery whines a bit, but that noise is suppressed by the distance from the source to the ground. There is a constant “swish” from each blade as it passes by. I was told that the tips of the blades are moving at a velocity of around 100 mph (160 kph). Environmentalists have pointed out that this constitutes a considerable threat to birds flying innocently through the blade path. Maybe it does. I doubt that they could find a similar threat from moving blocks on a drilling rig, although I have seen some crews that like to trip pipe at about that speed.

I did not see any birds the day I was at the wind farm, except for one covey of blue quail. Blue quail are ground feeders that move together in groups. Like politicians, they scatter and run at the first sign of any threat. The turbines seem to have no effect on the quail.

The cost of each turbine, including installation using the tallest crane I have ever seen, is just over $1 million. The units are fairly reliable, needing only minimal maintenance. It was necessary to build a new power collection system with step-up transformers to put the power into the Ercot grid. At an average of 1.82 MW/turbine (from the Alternative Energy Institute of West Texas A&M University) each unit should clear around $200,000/yr after taxes, royalty and operating cost. So it’s going to take a while to pay out these units even with favorable tax incentives. Apparently, the projects are economic at current power rates-there are more wind farms going up every day around the world.

Standing under one of these turbines is a truly eye-opening experience. The size and speed of the rotating blades coupled with the mass of the tower is mind-boggling. Knowing that this monster is turning just using wind alone blew me away (no pun intended). What was more impressive is that present wind turbines in the US generate 16,819 MW of power.

The real winner in wind-generated power, however, is Germany with 22,247 MW. Other countries with sizeable wind farms include Spain with 15,145 MW, India with 7,850 MW and China with 5,899 MW.

So why is this important to the drilling industry? The power generated by wind turbines is expensive to store, usually accomplished by pumped water, but there are other methods. Power enters the grid and is used when it is generated, but there are some days when the wind simply doesn’t blow. Also, if wind velocity is too high, the turbines are shut down to protect the machinery.

To maintain a constant supply, power generated by wind turbines must be backed up by a predictable power generating station burning a fuel such as natural gas, the fuel of choice. The power companies must build and maintain these plants and provide them with a reliable gas source that can be called upon immediately to take the swings out of the power grid. So the oil and gas industry is faced with continually finding new gas sources and providing them to the pipeline systems, while making a profit to ensure that all of the users, including power plants, have sufficient fuel.

Even if the present covey of the world’s politicians tells us that the answer to all of our energy needs can be supplied by wind turbines, the drillers still must get gas wells to TD, while completing them wisely and economically, or the public simply will not have enough power at all times. Who wants brownouts and blackouts?

Odd, isn’t it, that a publicly perceived solution to the energy crisis, wind power, relies on the oil and gas industry to make it run smoothly.