Transmission, Distribution, & Refining
Novel Process to Use Salt Caverns to Receive Ship Borne LNG


The goal of this project was to develop a new, cost-effective process for receipt and storage of LNG that will lead to increased U.S. import capacity and greater storage flexibility. This project will design, construct, and field test a commercial-scale system for re-gasification of LNG directly from ocean tankers for storage in underground salt caverns. The novel Bishop Process™ includes a high capacity and energy efficient LNG heat exchanger, a high pressure LNG pump, and offshore LNG ship mooring and product transfer systems. The project will examine all critical elements of the proposed process for both onshore and offshore LNG receiving applications.

The "Bishop Process" - re-gasification of LNG directly from ocean tankers for storage in underground salt caverns

The United States faces an increasing natural gas domestic supply/demand imbalance. Most experts agree that significant growth in LNG imports will be required, in part, to effectively address the deficit. For the U.S. to increase LNG imports, existing facilities will have to be expanded and new onshore and offshore import terminals constructed. In 2004, the United States used about 600 Billion cubic feet (Bcf) of LNG and the rising demand for natural gas is expected to increase U.S. LNG imports to more than six (6) Tcf by 2025.

With the onset of a large LNG import increase seeming inevitable, numerous new LNG facilities have been planned and announced throughout the U.S. The majority of these, with only a few exceptions, have been land-based conventional LNG storage tank terminals. Several of the announced projects have been met by local community opposition.

Unlike traditional heat exchanger systems, which use natural gas, the Bishop Process™ uses low cost seawater to warm the LNG. The heat exchanger is a critical component of the Bishop Process™ allowing LNG to be quickly unloaded from ships and directly into salt storage caverns. The project also has the advantage of being located offshore.

Performer: Conversion Gas Imports, L.L.C.

Houston, Texas 77042

Project Impact:
All of the tests of the critical components have been successfully completed. The design, cost and construction analysis have shown that an offshore facility is comparable in cost with onshore conventional tank-based LNG storage and that optimizations could lead to further reductions. The offshore facility would remove all port congestion, remove most if not all not-in-my-back-yard (NIMBY) opposition, and offer many security features. The use of salt caverns offers much greater storage capacity and gas delivery capability than conventional technology. The technology is ready to be demonstrated at a commercial-size, offshore facility in its entirety.

In April, 2003, Conversion Gas completed the conceptual design studies and presented the results to DOE. The results highlighted the feasibility of the Bishop Process™ to offer greater capacity, throughput flexibility, increased security, and reduced costs compared to conventional cryogenic LNG receiving and storage facilities. The successful results of this initial feasibility effort led to a decision to proceed with design, construction, and testing of a full-scale heat exchanger and associated components.

By September, 2003, the project team had tested the largest LNG production pump ever made at discharge pressures exceeding 2,000 psi. These successful tests at Ebara International's Cryogenics Division manufacturing facility in Sparks, Nevada, laid the foundation for the manufacture and testing of a larger pump design that could operate at pressures exceeding 2,400 psi. Following the test by Ebara, Nikkiso field tested a similar-sized pump. Ebara's and Nikkiso's field tests indicate that the two largest LNG pump manufacturers in the world can manufacture pumps suitable for direct salt cavern injection from LNG receiving facilities.

Heat exchangers during testing

On April 12, 2004 a full-scale test of the energy-efficient heat exchanger critical to the Bishop Process was initiated at the AGL Resources LNG peak shaving facility located near Canton, Georgia. Over several days, the heat exchanger flawlessly processed LNG at a design flow rate approaching 4 billion cubic feet-per-day.

Bluewater Offshore successfully conducted wave tank model testing on its “Big Sweep” mooring system at the Canadian Marine Research Center in St. Johns, Newfoundland in April and May of 2004. The model basin tests verified the system under operational conditions with an LNG carrier and extreme (hurricane) conditions without a carrier. The model was scaled at 1:40. Additional designs from FMC, SBM and Remora were also conducted.

An integrated facility design and cost and construction time estimates were developed and presented for an LNG import terminal located in Block Vermilion 179, about 45 miles offshore central Louisiana, in about 100 feet water depths. Facility characteristics include:

  • Weathervaning mooring available 99% in Gulf conditions (except hurricanes)
  • Ship unloads in 12-15 hours at 10,000 cubic meters per hour
  • Cavern gas storage of 6-12 billion cubic feet (Bcf) (two to four ship loads)
  • Send out deliverability of 1.5Bcf/D with a peak of 2.5Bcf/D
The design and cost analysis showed a construction time of under 30 months, costs of $600-$700 million (comparable to onshore tank based terminals) although optimizations could lower this by $100 million.

HNG Storage Company, an experienced developer, owner, and operator of salt-cavern storage facilities, has announced the Freedom LNG Terminal project, an offshore salt-cavern-based LNG receiving terminal. The location of the terminal will be offshore Louisiana. The terminal is planned for operation in late 2008. This project is the first announced application of the Bishop Process™.

Current Status and Remaining Tasks:
The project has been completed. The final report is expected to be completed by May 31, 2005.

Start Date: September 30, 2002
End Date: December 31, 2004

DOE Contribution: $1,854,654
Performer Contribution: $525,700

Contact Information:
CGI - Michael McCall (713-781-4949)
NETL – James Ammer (304-285-4383 or

Additional Information:
GasTips Summer 2004  [PDF 389 KB] - "Critical Components of Salt Cavern-Based Liquefied Natural Gas Receiving Terminal Undergo Field Tests"

OMAE paper - "Salt Domes and the Bishop Process", James F. Davis and Lance J. Van Anglen