EnviroMission Limited Received Debt and Equity Finance from AGS Capital Group
EnviroMission Received financing facility from AGS Capital Group.
- (1888PressRelease) November 09, 2011 - EnviroMission is set to build the tallest structure in North America with its innovative solar updraft tower design, which provides baseload power. The solar updraft tower uses a solar energy collector canopy and a central tower to generate an updraft airflow that drives the rotation of pressure-staged turbines at the base of the tower and generates electricity.
The solar updraft technology
Although a full-scale commercial plant has not yet been built, Roger Davey is confident that the company's design will work because the design is entirely based on well-understood and tested engineering, without the use of extremely high temperatures or many moving parts. In addition, the German government funded a small-scale demonstration plant that operated in Manzanares, Spain, from 1982 to 1989, which proved that the technology works.
The solar updraft tower consists of three main parts, the canopy, the tower, and the turbines. The canopy is a large circular greenhouse collector area, about 5,500 acres. The canopy is 10 feet (~3 m) off the ground on the outside of the collector area and
slopes slightly upwards, to 50 feet (~15 m) off the
24 Sun & Wind Energy 10/2011
review updraft technology ground at the center. The canopy heats the air trapped under the canopy. The heated air rises and moves towards the center of the field. The canopy will be made from ETFE plastic, which was designed to withstand high temperatures while maintaining strength, among other light-absorbing materials, says Chris Davey.
The tower, which acts like a large chimney, is located at the center of the greenhouse canopy and is the thermal engine for the technology. The tower creates a temperature differential between the cool air at the top and the heated air at the bottom. This creates the chimney effect, which sucks air from the bottom of the tower out of the top. This suction creates a 35 mph (56 km/h) wind at the base of the tower, which powers 32 turbines and generates electricity. The turbines work just like well-understood Kaplan turbines commonly used in hydroelectric power plants.
EnviroMission plans to build its first commercial solar updraft tower on public lands in La Paz County, Arizona. "If you imagine a sunny day in Arizona, where the outside temperature would be 40 degrees Celsius, the temperature under the collector would be 80 to 90 degrees Celsius and the temperature at the top of the tower would be 32 degrees Celsius," says Roger Davey. This creates the ideal temperature differential that EnviroMission desires.
Benefits of the technology
Also like hydro plants, the solar updraft tower technology is a passive system, with very few moving parts, so there are minimal ways in which this technology could go wrong, says Chris Davey. If one turbine goes out, the system still works. "Consistency of operation is critical for power plants and ours is consistent," says Chris Davey.
In fact, consistent plant operation - a high capacity factor - is one of the main benefits of the solar updraft tower design. Solar towers provide maximum
output for 12-plus hours during the day, says Roger
Davey. It continues to produce power even at night because there is still a temperature differential that creates an updraft airflow, but it isn't as strong, says Roger Davey. "Our plant will get a 60 percent capacity factor, meaning it will operate at maximum power
60 percent of the time," says Roger Davey. A coal- fired plant operates at about 80 percent efficiency, while wind and PV are somewhere between 20 and
30 percent. The solar updraft tower will operate much more like a coal-fired plant by providing more reliable, base-load power.
"We have tried to make our technology as competitive as it can be in a very uncompetitive and unleveled playing field. Fossil fuels receive considerably more financial support from the government com- pared to renewable energy," he says. EnviroMission is trying to compete in an unlevel playing field by creating a renewable energy base-load power source. Because the solar updraft tower acts like a base-load power source, it does not require a natural gas back- up system like other renewable energy facilities such as wind and PV.
In addition to a high capacity factor, the solar up- draft tower uses absolutely no water in the production process. One of the main reasons that solar companies have trouble securing environmental permits for their power plant plans in the US Southwest, is water use. Because EnviroMission does not use any water, it hopes to be a more attractive technology to environmental groups interested in protecting fragile desert environments. "With this technology you don't have to worry about water use, costs of gas for back-up, or any other costs that a lot of other renewable energy technologies have to deal with," says Chris Davey. But the true cost of the tower will not be known until final designs and specifications have been completed for the first project.
The first solar updraft tower
Although site-specific designs have yet to be finalized, such as the exact tower and canopy dimensions,
The graphic displays how the solar canopy heats air, which creates a temperature differential that sucks air and passes through turbines to generate electricity.
The tower is slotted to deliver 200 MW to SCPPA in California, but is constructed in La Paz County. In order to deliver a large amount of power, the tower has to be tall, likely about 2,500 feet (762 m). "That's about twice the size of the Empire State Building in New York and the tallest structure in North America," says Chris Davey. The height of the tower provides the updraft necessary to drive turbines to produce the desired output. The taller the tower, the larger the temperature differential and the faster the turbines will spin.
Once the final designs are ready, by March to June of 2012, EnviroMission will begin working on securing financing, doing grid connection studies, and finalizing necessary permits. "We have done initial environmental, heritage, and transmission studies and everything appears to be fine," says Davey. The site is located close to the grid, so the company does not have to complete a large transmission project to get the power plant connected. Although the tower re- quires a lot of land to generate heat, the flora and fauna underneath the canopy are left largely untouched, which will help the company when getting environmental permits for the project.
If the planning stage goes smoothly, Davey hopes to begin construction of the first tower in 2012 and start producing power by the beginning of 2015. After the first tower is built, EnviroMission plans to build a second tower in the same area.
It has already secured some partnerships to ensure that this project gets completed. The company has partnered with ARUP, a global group of design engineers, as well as with the US construction company, Hensel Phelps, Colorado. EnviroMission has also secured debt and equity finances from AGS Capital Group, LLC in New York (www.agscapitalgroup.com)
The company could not say at this point how much the tower would cost because the final designs have not yet been finalized. It will be expensive, but Roger Davey is confident the company will secure the necessary financing. This first project will be more ex- pensive than future solar tower projects because there is a big learning curve on the first project, says Roger Davey. But despite the high costs of the first project, the internal rate of return for the project is attractive enough to put it on the queue for financial viability, he says. After the first project, costs will decrease due to improved construction methodology
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