Our Lady Help of Christians School Future City of Tecumseh

Our Lady Help of Christians School Future City of Tecumseh

Fuel Your Future

Founding Tecumseh

Tecumseh, Arkansas, population 65,000, is located on the banks of the Black River and in the shadows of the Ozark Mountains. As a regional headquarters for FEMA, it serves as a distribution site for disaster relief. Tecumseh is also home to the first Vertical Agricultural Solar Tower (VAST), which provides three vital services for Tecumseh: power, food, and water.

Choosing a Renewable Energy Source

Before designing and building the VAST, three sources of renewable energy were considered: wind, geothermal, and solar. Studies indicated that the wind velocity in southeastern United States was insufficient to meet energy demands. Similarly, use of a geothermal power plant was not feasible due to the lack of a nearby natural hydrothermal reservoir. Tecumseh does, however, use geothermal power for heating and air conditioning. Geothermal heat pumps transfer heat from the ground into buildings during winter, and return heat to the ground in the summer.

Because the use of wind and geothermal power plants was not advantageous, Tecumseh considered solar power. Initially, electrical engineers considered a city-wide system of photovoltaic panels. This system was extremely expensive and did not produce power at night or on overcast days. Also considered were reflective light towers which use a field of tracking mirrors to direct the sun’s rays to a solar receiver that converts the energy into electric power to be fed into a power grid. Though the maintenance cost of the reflective light tower is low, they are expensive to build, and like photovoltaic panels, they do not produce electricity when there is no sun.

A hybrid version of the reflective light tower that produces electricity during the evening has been developed. This hybrid was rejected by Tecumseh because it uses fossil fuels. Because neither reflective light towers nor photovoltaic solar panels were suitable, Tecumseh has engineered the Vertical Agricultural Solar Tower, or VAST, which harnesses the sun’s energy using a low maintenance solar updraft tower. This renewable energy power plant combines three proven technologies: the greenhouse effect, the chimney effect, and the wind turbine.

Generating Power

The VAST is comprised of three main parts: the collector, the updraft tower, and the turbines. The circular thermal collector, a greenhouse-like chamber at the base of the VAST, has a 300-meter diameter. The collector’s floor is covered with black, water-filled tubing. The collector’s roof, made of flexible polymeric glass, increases in height as it nears the center and funnels the heated air into the updraft tower with minimal friction.

The sun not only heats the air in the thermal collector, but also heats the water in the black tubing. Due to water’s ability to retain heat, the water-filled tubing continues to heat the air in the collector twenty-four hours a day.

The second part of the facility is the 200-meter updraft tower located in the center of the collector. Heated air from the collector rises through the cylinder. Because fluids increase velocity when passing through a restricted space, the top half of the tower narrows to accelerate the air.

The third part is the three turbine combinations which are rotated by the rising air to generate electricity. The first turbines, located on the perimeter of the collector, are turned by the air as it enters the facility. The second set of turbines is located where the collector meets the updraft tower. Here, the rising air spins multiple turbines. At the top, where air velocity is at a maximum, a final turbine generates the majority of the 150 megawatts produced by the VAST.

Distributing the power

The primary method of distributing electricity within Tecumseh includes underground wiring. These underground cables, which provide continuous electricity during high wind storms and tornadoes, are placed under the center of all roads, which minimizes the risk of stormwater damage. In response to the varying power demands, the electrical engineers of Tecumseh designed the SmartGrid, which uses communication and control capabilities to optimize an electrical grid which spans the United States.

Impacting the environment

Building the VAST required about the same amount of building materials and resources as any other power plant and has a relatively low operating cost. Because the VAST uses no fossil fuels, there are no emissions of CO2 or methane.

The largest impact on the environment was the amount of land required to build the VAST. Because the collector requires almost 71,000 square meters (18 acres) of land, the site chosen for the VAST was an area where the soil was depleted due to excessive cultivation and inadequatesoil management.

VAST Benefits

The VAST more than compensates for the lost farming acreage because a vertical farming system encases the lower half of the updraft tower. The VAST provides thirty floors, equivalent to 16 acres, of hydroponic farming and makes seasonal growing patterns obsolete. Furthermore, the hydroponic gardens have been designed to double as a water treatment facility that purifies gray water into potable water. Perhaps the best benefit of the VAST is its simple structure; the plant never needs to go offline for maintenance.

Reducing Associated Risks

With increased wind speeds at higher elevations, building these tall structures is a challenge. Therefore, structural engineers limited the height of the VAST structure to 200 meters. Furthermore, because construction of the updraft tower was based on aerospace technology, using lightweight aluminum, graphite, and titanium, the tower withstands extremely powerful winds.

Because of Tecumseh’s location near the New Madrid Fault, the structural engineers used spring-with-damper isolators, as well as lead-rubber bearings, on the VAST and many of Tecumseh’s buildings. Additionally, the VAST utilizes an Intelligent Building Designs system. These systems use sensors to measure the building’s response to seismic activity or high winds. Based on this information, computers calculate appropriate actions to damper the negative effects of the seismic activity or wind.

By combining proven technologies in an innovative manner and thoroughly analyzing all available options, Tecumseh engineers have designed an effective, sustainable solution to age-old problems.

Word Count with diagram words: 992

Works Cited

Bosschaert, Tom. "Solar Updraft Towers: Variations and Research." Renewable Energy World - Renewable Energy News, Jobs, Events, Companies, and More. Siemens, 7 Oct. 2008. Web. 18 Dec. 2011. <http://www.renewableenergyworld.com>.

“Electrical Engineer: What is This Job Like?” 18 Dec. 2011

<http://www.bls.gov/k12/math02.htm>

Gennaro, Julie. Interview with Structural Engineer employed at URS, Washington Division. 18 Dec. 2011.

Gruestein, Elizabeth. “Solar Tower Technology.” Bryn Mawr College, 13 Dec. 2011. <http:// www.brynmawr.edu/geology/206/gruenstein2.htm>.

Lefier, James P.E.: “Mitigating Terrorist Attacks and Earthquake Risk, International building Code Revisions Can Provide Solutions.” Structure Magazine. June, 2010. Page 49-50

Nationalatlas.gov. "Renewable Energy Sources in the United States." National Atlas Home Page. USA.gov Take Pride in America, 26 Jan. 2011. Web. 18 Dec. 2011. <http://nationalatlas.gov/articles/people/a_energy.html>.

Patel-Predd, Prachi. "The Tide Seems to Be Turining in Favor of Geothermal Energy in the US." Discover Apr. 2008: 22. Web.

Schlaich, Jorg, Rudolf Bergermann, Wolfgag Schiel, and Gerhard Weinrebe. "Design of Commercial Solar Updraft Tower Systems—Utilization of Solar Induced Convective Flows for Power Generation." Microsoft Academic Search. Schlaich Bergermann Und Partner. Web. 18 Dec. 2011. <http://academic.research.microsoft.com/Paper/11092961>.

“Solar Undraft Tower Variations and Research.” EXCEPT Animations & Visualizations. 13 Dec. 2011. <http:www.except.l/consult/SolarUpdraftTower/solar_updraft_Research.html.>

1