The Texas Commission on Environmental Quality said in a notice issued on Jan. 9 that it intends to approve a wastewater permit for a compressed air power project.
“Apex Bethel Energy Center, LLC, 3200 Southwest Freeway, Suite 2210, Houston, Texas 77027, which proposes to operate the Bethel Energy Center, a compressed air energy storage facility, has applied to the Texas Commission on Environmental Quality (TCEQ) for a major amendment to Texas Pollutant Discharge Elimination System (TPDE) Permit No. WQ0005002000 to authorize low-volume wastewater (consisting of demineralizer blowdown and demineralizer cleaning wastewater) as an additional wastestream,” said the notice.
“The proposed facility is located approximately 2 miles south of the intersection of Farm-to-Market Road 2706 and United States Highway 287 South, at the southeast corner of the intersection of Farm-to-Market Road 2706 and County Road 2504, approximately 5 miles northwest of Tennessee Colony, Anderson County, Texas 75861,” the notice added. “The effluent will be discharged via pipeline to Trinity River Above Lake Livingston in Segment No. 0804 of the Trinity River Basin.”
The notice didn’t give any details about the power project itself.
Apex Bethel Energy Center in March 2014 got from EPA’s Region 6 office a final PSD permit for GHG emissions for the Bethel Energy Center in Anderson County at the described location. Apex received an permit for its non-GHG pollutants from the TCEQ in 2012.
The Bethel project developer proposes to use the compressed air energy storage (CAES) technology developed by Dresser-Rand to produce up to approximately 317 MW. The Bethel plant will consist of two expansion turbines/generating trains each rated at 158.34 MW. CAES technology involves two major processes:
- air compression and storage; and
- air release for electricity generation.
During the air compression and storage process, electric motor driven compressors are used to inject air into an underground cavern for storage under high pressure. Electricity is generated by releasing the high-pressure air, heating it with natural gas combustion and expanding the air through sequential turbines (i.e., expanders), which in turn drive an electrical generator.
The compressed air storage for APEX Bethel will be created by drilling a “cavern well” having a cemented well casing at a terminal depth of approximately 3,750 feet. Fresh water withdrawn from local groundwater wells will be pumped down the well to dissolve salt, creating the storage cavern. Salt brine withdrawn from the cavern during this “leaching” process will be injected into existing permitted brine disposal wells on nearby property. The cavern is expected to operate over a wellhead pressure range of approximately 1,900 to 2,830 psia (static pressure range). If full, the cavern will support approximately 100 hours of generation at near full rated output without recharge.
The Apex Bethel facility will be made up of two Dresser-Rand CAES compression trains, each consisting of a set of multi-stage compressors driven by a dedicated 150 MW (nominal rating) electric motor. Each compression train will be capable of producing up to 1.4 million pounds per hour of air at a compressor outlet pressure of up to 2,830 psia.