Tucson adding solar capability at Sundt power plant

Tucson Electric Power (TEP) said Jan. 31 that it is partnering with AREVA Solar on a concentrated solar power (CSP) addition to Tucson Electric’s coal- and gas-fired H. Wilson Sundt plant in Tucson.

TEP’s Sundt Solar Boost Project will use AREVA Solar’s Compact Linear Fresnel Reflector (CLFR) solar steam generators to produce up to 5 MW of power during peak demand periods without added emissions. Over the course of a year, the system will allow Sundt Unit 4 to produce enough additional power to serve more than 600 Tucson homes, the utility noted.

Producing that same amount of power at the dual-fueled unit would otherwise require burning 46 million cubic feet of natural gas, or 3,600 tons of coal. So the Sundt project avoids the annual production of either 4,600 or 8,500 tons of CO2, depending on whether the unit is running on natural gas or coal.

The Sundt project is part of TEP’s plan to expand its solar generating capacity to more than 200 MW by the end of 2014. Its output will help TEP meet or exceed Arizona’s Renewable Energy Standard, which requires electric utilities to increase their use of renewable energy each year until it accounts for 15% of their power in 2025.

In addition to helping TEP meet its renewable energy goals cost-effectively, the Sundt project will allow the company to evaluate the potential integration of CSP additions at other power plants. The project will also further demonstrate AREVA’s high-pressure, superheated steam offering. Construction of the Sundt Solar Boost is scheduled to begin this spring, with the project expected to be operational by early 2013.

“AREVA Solar’s innovative solar boost technology gives us a cost-effective, environmentally responsible way to expand the output of our largest local power plant without increasing emissions,” said Paul Bonavia, Chairman and CEO of TEP and its parent company, UniSource Energy Corp. (NYSE: UNS).

“TEP is a national leader in solar energy, and we are pleased that they’ve selected our U.S.-designed and manufactured CLFR technology for this addition to their clean energy portfolio,” said Bill Gallo, CEO of AREVA Solar. “Solar booster projects like this are gaining momentum in the United States and around the world as a way to leverage existing power infrastructure to provide needed energy with no new emissions. AREVA Solar’s booster installation aims to do just that.”

In addition to augmenting coal-fired plants, AREVA’s solar steam generators can also easily integrate with natural gas-fired combined-cycle plants and can be used in standalone solar thermal and hybrid facilities, as well as industrial process steam applications. AREVA recently broke ground on a 44-MW solar booster project for a coal-fired power station in Australia and currently has more than 540 MW of CSP projects in operation, under construction or in advanced development.

AREVA Solar, headquartered in Mountain View, Calif., is a subsidiary of the AREVA Group that specializes in the design manufacture and installation of steam generating solar systems for its global power generation and industrial customers in a dependable, competitive and environmentally responsible manner.

Xcel’s Cameo project broke ground in the CSP area

A similar CSP system was demonstrated a couple of years ago at Xcel Energy’s (NYSE:XEL) coal-fired Cameo plant in Colorado. The project’s objective was to assess the technical feasibility of integrating concentrated solar thermal technology with conventional coal power generation. The project used solar thermal energy to supplement the steam cycle to reduce the use of fossil fuel in the production of electric power at the plant. This project was the first to supplement coal-fired electric generation with solar thermal heat input in the U.S., said Xcel in a final report on the project dated March 2011.

The Colorado Integrated Solar Project (CISP) at Cameo involved a parabolic-mirror-type concentrating solar thermal facility adjacent to the existing plant. The CISP provided supplemental heat to the Cameo Unit 2 heat exchanger to reduce the fossil fuel required by that generating unit to produce electrical power. The project installed solar thermal loop(s) to assist with heating the feedwater used in the production of steam.

Factors considered in the technical feasibility study of the project included: operational reliability, electric generation, reduction in coal usage, and reduction in emissions. “The installation demonstrated that this type of supplemental application to an existing fossil boiler will work and will not interfere with normal generation operations,” said the final project report.

Cameo Unit 2 was designed to generate 49 MW operating on coal or natural gas as an alternate fuel. The unit consisted of a two pressure steam turbine – high-pressure and low-pressure. It had two low-pressure feedwater heaters, a dearator, and two high-pressure feedwater heaters. The solar-powered heat exchanger provided additional feedwater heating in between the two high-pressure feedwater heaters.

Cameo Unit 2 was one of the smaller and older fossil fired units on the system of Xcel subsidiary Public Service Co. of Colorado. Cameo Unit 2 stopped generating electricity on Dec. 29, 2010. The use of this unit, already targeted for shutdown, for the demonstration project provided the company with an opportunity to conduct the testing with minimal disruption and risk to the rest of the system in case any problems arose during testing, the final report noted.

“The results of the integration were very positive,” said the Cameo final report. “There were no coal unit outages or derates caused by the solar thermal heating during the seven month test period. Unit 2’s impact on the solar field was also minimal. The coal unit availability was 98.4%. There were two days of forced outage and two days the unit did not operate because its generation was not needed due to wind generation.”

About Barry Cassell 20414 Articles
Barry Cassell is Chief Analyst for GenerationHub covering coal and emission controls issues, projects and policy. He has covered the coal and power generation industry for more than 24 years, beginning in November 2011 at GenerationHub and prior to that as editor of SNL Energy’s Coal Report. He was formerly with Coal Outlook for 15 years as the publication’s editor and contributing writer, and prior to that he was editor of Coal & Synfuels Technology and associate editor of The Energy Report. He has a bachelor’s degree from Central Michigan University.