The STEP 10 MWe sCO2 Pilot Demonstration Status Update

Abstract

The Gas Technology Institute (GTI®), Southwest Research Institute® (SwRI®) and General Electric Global Research (GE-GR) are executing the Supercritical Transformational Electric Power, “STEP” project, to design, construct, commission, and operate an integrated and reconfigurable 10 MWe sCO2 [supercritical CO2] Pilot Plant Test Facility. The $156* million project is funded $115 million by the US DOE’s National Energy Technology Laboratory (NETL Award Number DE-FE0028979) and $41* million by the team members, component suppliers, and Joint Industry Program (JIP) members. The facility is currently under final assembly and is located at SwRI’s San Antonio, Texas, USA campus. This project is a significant step toward sCO2 cycle based power generation commercialization and is informing the performance, operability, and scale-up to commercial plants. Significant progress has been made on this STEP project. The design phase is complete (Phase 1) and included procurements of long-lead time delivery components. Now well into Phase 2, a ground-breaking was held in 2018, and civil work and the construction of a dedicated 22,000 ft2 building was completed in 2020. Most major equipment is in final fabrication or delivered to site as of the end of 2021. These efforts have already provided valuable project learnings for technology commercialization. At time of paper writing most equipment has been received and installed, and commissioning will begin in the first half of 2022. An update on commissioning and experience with sCO2 equipment is given here-in.

A review of research on turbines for supercritical carbon dioxide power systems

“…Moore et al designed a high-temperature and high-pressure S-CO2 flow circuit with a flow rate equivalent to 1 MWe [27]. The STEP project executed by Gas Technology Institute (GTI), Southwest Research Institute (SwRI) and General Electric Global Research (GEGR), was to design, construct, commission and operate a 10 MWe pilot plant [28]. Xi'an Thermal Power Research Institute (TPRI) designed and constructed a megawatt-level integral test facility, which was operated for more than 1000 hours [29] [30].…”

“…Experimental research on MW level turbines has also been carried out. A 10 MWe S-CO2 turbine was manufactured by SwRI(Southwest Research Institute) and GE(General Electric) and tested at 715 ℃ and 27,000 rpm [28]. The rotor life increased from 20000 hours to 100000 hours.…”

Supercritical CO2 Power Technology: Strengths but Challenges

“…The second key advantage of sCO 2 cycles is the dramatic reduction in size of cycle components, which is again correlated to the high density of supercritical CO 2 [29,30].…”

“…These difficulties, not anticipated by the precursors of the technology, are linked to marked specificities of sCO 2 cycles, in particular their high pressures but low-pressure ratios, the difficulty of controlling CO 2 leaks and the unusually small dimensions of certain components, which require unconventional designs. That technology is therefore still in the engineering and testing phase, with the most consistent and active program being currently the so-called "Supercritical Transformational Electric Power" (STEP), funded by the US Department of Energy (DOE) [1,2].…”

Processing, Microstructure, and Properties of Bimetallic Steel-Ni Alloy Powder HIP

“…A high-temperature supercritical carbon dioxide (sCO 2 ) power cycle is being developed for concentrating solar-thermal power (CSP) application, providing more compact size and higher efficiency than a conventional steam power cycle [1]. A sCO 2 turbine that operates above 700 • C will require the use of γ ′ strengthened Ni-based superalloys for turbomachinery components at hot sections, leading to higher component cost than the lower temperature cycles that use structural steels.…”