The annals of wind energy are filled with examples of arrogance, hubris, and hype about products that failed to deliver on their promoter’s promise. One long forgotten example is the Schachle wind turbine. However, unlike the Internet wonders that bedevil us today, the Schachle wind turbine was a real piece of hardware not merely electrons floating in the ether.
Charles Schachle installed his prototype wind turbine at the Moses Lake, Washington airport and connected his machine to the Grant County Public Utility Service District in May 1977. Schachle claimed he was an aeronautical engineer and had designed the novel highly-cambered airfoil that was manufactured out of laminated wood. The tower too was unusual. It was a mass of steel tubing forming a tripod, presumably so that it could be erected without a crane. The tower rotated on a circular track, a method not seen on electricity-generating wind turbines since the 1930s. But to top it all off, the wind turbine used a hydraulic transmission.
I visited the site in 1977 on a cross-country trip. The turbine was not operating when I was there. Why it wasn’t running I will never know.
For a privately funded wind turbine, it was a large machine for the time. The only comparable design, WTG Energy Systems’ MP-200, was only slightly larger, but was a far more conventional wind turbine. (See WTG Energy Systems’ MP-200 (1975-1982)).
Schachle Moses Lake Unit
- Three blades, upwind
- 72-foot (22 meters) diameter
- Full-blade pitch control
- 80-foot (24 meters) rigid, tripod tower
- Rated Power: 140 kW
- Rated Wind Speed: 26 mph (11.6 m/s)
- Specific Power: 370 W/m²
- Specific Area: 2.7 m²/kW
- Yaw on circular track a la the Soviet’s Balaklava turbine in 1931
The capacity rating of the turbine relative to its rotor area was comparable to other turbines of the period, but it was a far cry from the designs of Ulrich Hütter.
By the end of 1977 Schachle and his sons were promoting “commercial” versions of his design 275 kW, 600 kW, and 2,700 kW in capacity. This was an extremely short period of “testing” even for the day when everyone was rushing to the field. Schachle claimed that the 600 kW version was ready for “immediate mass production.”[1]
It would be an understatement to say that others in the budding wind industry were, shall we say, skeptical of the design and Schachle’s claims. We were especially curious about his odd airfoil and his choice of a hydraulic transmission.
For historical comparison, there were several of NASA’s Mod-0As then in operation in the US and GE’s Mod-1 was under construction near Boone, North Carolina. Most significantly, students and faculty at Tvind in Denmark’s northwest Jutland peninsula were building a giant, Tvindkraft, a monster machine that was 54 meters in diameter—one meter larger than the famed Smith-Putnam machine of the 1940s. Tvindkrat went into operation in 1978.
Bendix Enters the Mix
- Three blades, upwind
- 165-foot (50 meters) in diameter
- Full-blade-pitch control
- 100-foot (30-meter) rigid, tripod tower
- Rated Power: 3,000 kW
- Rated Wind Speed: 40 mph (17.8 m/s)
- Specific Power: 1,500 W/m²
- Specific Area: 0.66 m²/kW
- Yaw on circular track 78.5 feet (24 meters) in diameter
- Hydraulic transmission driving a synchronous generator
Despite the circular track, the tower could not rotate a full 360 degrees. It was limited to 330 degrees.
The hydraulic transmission used fourteen fixed-displacement pumps to drive a synchronous generator at variable speed.
Surprisingly for a machine of this size, it used slip rings![2]
Timing is everything in business as it is in life. About this time Bendix wanted to get in the wind business and was looking for a design they could adopt. Schachle was peddling his design. Bendix and Schachle found each other.
Meanwhile, Southern California Edison (SCE), one of the California’s two major electric utilities, wanted to put their stamp on the industry, following the growing interest of private developers in the winds of the San Gorgonio Pass in Southern California.[3]
SCE ordered a 3 MW version of the Bendix-Schachle turbine, planning to invest $2 million in the project. SCE installed the unit at its Devers substation in the heart of the San Gorgonio Pass in December 1980.
This was a very short time line from the first unit in early 1977. There are no digital records of how well the Moses Lake unit worked; if in fact it did work.
Despite the fanfare, SCE’s deployment of the Bendix-Schachle turbine did not go well.
Here’s how one report described testing.
“The proprietary blade design and tip speed control are expected to yield high rotor wind energy conversion efficiencies. Fixed displacement pumps and variable displacement motors are used to maintain a constant 1200 rpm generator speed.
. . . The WTG was first operated on-line on December 15, 1980. A gearbox bearing failure and low winds prevented operations until March 3, 1981. The bearing failure was caused by a lack of lubrication traced to the omission of an oil line.
. . . To date, power levels in excess of 1 MW have been reached.”[4]
From this we can tell that SCE bought the idea that Schachle’s “proprietary” blade design would provide high yields.
In another report, SCE wrote that the “unit will operate unattended and is expected to produce 6,000,000 kW hr/year in the winds present at the test site.”[5]
The Bendix-Schachle machine swept nearly 2,000 m² of the wind stream. If the wind turbine generated as much electricity as SCE claimed, it would deliver 3,000 kWh/m² per year. This isn’t rocket science. This is basic math. While this claim isn’t as outlandish of those by many internet hucksters, it’s largely on the outer edge of reasonable. Most wind turbines then being installed in the San Gorgonio Pass performed far, far worse. One of the best performers of later years, the Windane 34 delivered 1,500 kWh/m²/yr in 1992.[6] (See Photos of 1990s Windane Added to Site.) Most wind turbines then were producing less than 1,000 kWh/m²/yr and often less than 500 kWh/m²/yr. So Bendix-Schachle and SCE were promoting a turbine with claims three to six times what it was likely to achieve—if it worked. And it didn’t.
The tip off should have been the large generator (3 MW) relative to the rotor swept area. It is the rotor after all that captures the wind. The Moses Lake unit fell well within what others had done before. The specific area of the Moses Lake unit was 2.7 m²/kW. This was comparable to the WTG MP-200 and Tvindkraft that were being built at the same time. But the Bendix-Schachle turbine had a specific area of 0.7 m²/kW or one-thirteenth that of Ulrich Hütter’s machine of the late 1950s and one-eight of the Mod-0A, and one-fourth it’s previous design. This was a recipe for disappointment at least.
Tellingly, SCE began hedging their bets on the decision to use a hydraulic transmission.
“We don’t know the exact number, but we are looking at possibly a 25 percent loss in the hydraulic portion of the system. That matter will be evaluated in very strict detail during the operational testing program. The prototype utilized some off-the-shelf equipment not optimized for the WTG. I think the losses there are somewhat greater than the 25% value expected for the 3 MW unit.”[7]
That turned out to be extremely optimistic. The turbine never delivered more than 1.1 MW in part because of severe losses (75%) in the hydraulic system. According to one SCE report the turbine only operated 50-60 hours. Of course that beats the abysmal failure of GE’s Mod-1 that didn’t record any “operating” hours at all.
Paul Vosburgh in his 1983 book noted that Bendix and SCE had planned to dump the hydraulic drive train and replace it with the gearbox out of GE’s failed Mod-1 and using it to drive a 1.3 MW induction generator.[8] For whatever reason, that didn’t happen and the machine was dismantled in 1982.[9]
Eventually, Wind Power Products dismantled the Moses Lake prototype and shipped it to New Mexico Engineering Research Institute (now New Mexico Tech).[10] There the trail turns cold.
In contrast to SCE’s failure with the Bendix-Schachle design, the wind turbine at the Tvind school is still in operation in northwest Denmark, though it was never operated at its initial 2 MW rating. One blade failed in 1993, the rotor replaced, and the turbine continues to operate to this day.
[1] “Small Groups, Big Windmills,” Rain, January 1978, page 12.
[2] S.C. Rybak, “DESCRIPTION OF THE 3 MW SWT-3 WIND TURBINE AT SAN GORGONIO PASS CALIFORNIA,” in Large Horizontal-Axis Wind Turbines (Cleveland, Ohio: NASA/DOE, 1981), 575–91, (Bendix-Schachle), https://ntrs.nasa.gov/api/citations/19830010987/downloads/19830010987.pdf.
[3] California’s other major utility, Pacific Gas & Electric Co. (PG&E) also wanted in the game and contracted with Boeing to install one of their Mod-2s in the Altamont Pass.
[4] M. C. Wehrey, “Utility Experience with Two Demonstration Wind Turbine Generators,” 1982, 12, https://ntrs.nasa.gov/citations/19830010995.
[5] R. L. Scheffler, “Status of the Southern California Edison Company 3 MW Wind Turbine Generator (WTG) Demonstration Project,” 1979, 355–62, https://ntrs.nasa.gov/citations/19800008218.
[6] “Results from the Wind Project Performance Reporting System: 1993 Annual Report” (Sacramento, California: California Energy Commission, January 1995), https://web.archive.org/web/20150906082018/http://www.energy.ca.gov/wind/documents/1985-1993_reports/WPRS_1993_P500-95-001.pdf.
[7] Scheffler, 1979.
[8] Paul N. Vosburgh, Commercial Applications of Wind Power (New York : Van Nostrand Reinhold Co., 1983), http://archive.org/details/commercialapplic0000vosb.
[9] Loni Perry et al., “Wind Energy Development In California: Status Report,” Staff Report (California Energy Commission, April 1985).
[10] Vosburgh, 1983.
