Renewable Energy Corporation Silicon III Plant, United States of America

Renewable Energy Corporation's (REC) silicon plant at Moses Lake, Washington was started in August 2002 by REC Solar Grade Silicon (REC Silicon), a joint venture between REC group and Advanced Silicon Materials LLC (ASiMl, a subsidiary of the Japanese industrial group Komatsu Ltd). The silicon production unit was a former plant of ASiMl, which REC Silicon converted into a dedicated plant for solar-grade silicon production.

Production at the existing plant was started in November 2002. The plant came under the ownership of REC when the group fully acquired ASiMl and REC Silicon in 2005. REC has another silicon production plant in the US at Butte, Montana.

In May 2006 the group announced its decision to invest in a third silicon manufacturing plant (Silicon III) in Moses Lake, adjacent to its existing plant at the location. The plant was announced as a part of REC's plan to more than double its polysilicon production from 5,300MT (2005 production) to approximately 13,000MT. It would also be able to produce 9,000MT of silane gas.

The existing plant at Moses Lake employed about 400 people and the expansion was set to create 100 more jobs.

Construction of the new plant was completed and production commenced in March 2009. However after ten days of the initial production phase, on 2 April 2009 REC halted production during ramp-up for an undetermined time due to interruptions affecting process safety. The company has indicated that commercial production at the plant will resume in the third quarter of 2009.

"The existing plant at Moses Lake employed about 400 people and the expansion was set to create 100 more jobs."

Silicon III plant construction

Construction of the new Silicon III plant began on 26 August 2006. Front-end engineering and design work was taken up by REC Silicon in 2005, and the company tested its new technology in a single half-scale pilot reactor that generated satisfactory output to meet all of the quality and production criteria of the company.

The project team for the new plant construction comprised of those involved in building REC Silicon's Butte, Montana plant in 1996–98.

Refinery and chemical plant design and construction company Fluor Corporation was chosen as the primary contractor in the expansion project. Fluor was appointed as the engineering, procurement, construction and management assistant contractor.

Haskell Corporation was chosen as one of the mechanical contractors for the plant, and the scope of work included installation of 110,000 linear feet of process piping that is set over 1,500t of structural steel. It also incorporated 100 pieces of equipment including pumps, heaters, large transformers, vertical towers and tanks, and compressors.

IMCO General Construction carried out site preparation, underground storm and access roadworks at the plant site. As a part of the contract IMCO built approximately 2,600fto f ADS 24in pipe interconnecting pipe rack concrete foundations, retaining walls and sumps.

Delays and cost overruns

Mechanical completion of the Silicon III plant was initially expected by the end of the first quarter of 2008, and the final completion and ramp-up of production by the third quarter of 2008. The total cost of the expansion project was initially estimated at $600m and expected to add NOK1.8–2m of revenue per annum based on the silicon pricing in 2006.

"REC has indicated that commercial production at the plant will resume in the third quarter of 2009."

However, following the delays in equipment deliveries due to tight conditions in the engineering, procurement and construction market in 2007 and 2008, Fluor delayed the mechanical completion of the plant by two months, and the project cost was revised to $800m including engineering and construction.

The project was further delayed when REC found weld defects in certain standard prefabricated carbon steel pipes in final commissioning stages of the silane gas production area, during the first reactor test runs in December 2008. By February 2009 the weld repairs were completed and a final process of system check-up and start-up procedures were initiated.

The plant finally commenced production in the last week of March 2009, being delayed by almost half a year.

Incorporation of proprietary FBR technology

REC Silicon is incorporating its proprietary fluidised bed reactor (FBR) technology developed for granular polysilicon production into the plant. Developed at REC Advanced Silicon Material LLC, the new reactor technology was further developed and commercialised at REC Silicon, and carries proprietary intellectual property rights. The proprietary production technology has been claimed to significantly reduce the current capital and operating costs of the plant.

The group's CEO Erik Thorsen said "We have run FBR pilot production over the past year and have seen very encouraging results. REC is cost competitive in the industry and this investment will further strengthen our position. The feedback we have received from solar cell pilot customers is that the outcome is identical to cells made with regular polysilicon."

"REC Silicon is incorporating its proprietary fluidised bed reactor (FBR) technology developed for granular polysilicon production into the plant."

Solar-grade silicon is used as raw material in solar cell production, the demand for which has been increasing as alternative sources of energy are becoming more valuable. The company's new technology makes the plant highly energy conservative.

On operation, the solar cells made from the plant's polysilicon would generate eight times more electricity compared to normal polysilicon produced without this technology.

Manufacturing process

The normal process of manufacturing solar-grade silicon involves two stages. In the first stage of the manufacturing process, 98% pure metallurgical-grade silicon is first distilled into silane gas using several distillation processes.

Part of the silane gas produced is sold to the manufacturers of thin film solar cells, flat panel displays and semiconductors, while most of it is used by REC Silicon for in-house production of solar-grade silicon. In the second stage, at a high temperature the solidified silane gas forms as a deposit on slim silicon rods, which gradually grows into solar-grade silicon material.

The FBR technology uses small particles in place of the slim rods present in Siemens' reactors for the silane gas deposition. The particles provide a more than 100 times larger surface area than that in a traditional Siemens reactor and therefore help in energy conservation.