Transporting grain by pipelines

by Stormy Wylie
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U.S. university researcher believes grain pipelines could be the answer to future transportation problems.

   Asystem of pipelines used to transport grain across the United States may be the answer to several challenges facing agriculture in the 21st century, according to a researcher at the University of Missouri, Columbia.

   Grain pipelines could be used to preserve the identity of biotechnology-produced grain products, to expand the capacity of the current U.S. transportation infrastructure and introduce more competition in grain shipments, and to alleviate some of the congestion on the upper Mississippi and Illinois waterways, according to Henry Liu, director of the Capsule Pipeline Research Center. Dr. Liu spoke recently at the 1999 technical conference of the Grain Elevator and Processing Society in Tampa, Florida, U.S.

   He said grain pipelines could address several agriculture transportation challenges raised in a 1998 report by the U.S. Department of Agriculture. These challenges included new products produced by biotechnology, structural shifts in U.S. agriculture caused by larger farms, long-term constraints and intermodal competition in the U.S. rail industry, capacity of the nation's waterways, the adequacy of rural roads, and infrastructure improvements.

   Dr. Liu also envisions a grain pipeline linking Mexico to the United States, enhancing the North American Free Trade Agreement.

   “Grain pipelines are by no means the solution to all of these challenges or threats,” Dr. Liu said. “However, in situations where volume is sufficient and transportation distances are not too short or too long, grain pipelines will be most cost-effective and will become an asset for agricultural producers.”

   The grain pipeline is based on capsule pipeline technology, which can be used to transport not only grain but also chemicals, fertilizers, solid waste and even packages and mail, Dr. Liu said.

   The capsule pipeline is the third generation of pipelines, he said. The first and second generations were liquid and slurry pipelines.

   There are two types of capsule pipelines: hydraulic and pneumatic. The hydraulic capsule pipeline (HPC) uses liquid — usually water — to suspend and propel capsules while pneumatic capsule pipelines (PCP) use gas — usually air — to move the capsule.

   Because air is too light to provide sufficient buoyancy and hydrodynamic lift to suspend capsules, large PCP capsules must be wheeled vehicles that roll through the inside of the pipeline. For HPC capsules to become waterborn, the liquid inside the pipeline must travel at velocities in the range of eight to 12 feet per second, he said. The water in the pipe must move at approximately 90% of the lift-off velocity (the rate at which capsules are lifted off the floor of the pipeline) to lessen abrasion of the pipeline and capsules, he said.

   While PCPs move at higher speeds and do not directly come in contact with cargo, HCPs are more energy efficient and economical, Dr. Liu said. “Both HCPs and PCPs have their respective niches,” he said.

   HCPs of one to three feet in diameter are better suited for transporting grain, he said, while PCPs are best suited for intercity freight transportation. However, both will play an important, albeit different, role in the transportation of agricultural products in the 21st century, Dr. Liu said.


   Pneumatic capsule pipeline technology can be traced back to the early 1800s when Danish engineer George Medhurst found that letters and other goods could be transported in small tubes at speeds as high as 100 mph.

   Many PCP systems are already being used on a small scale. Most banks use pneumatic capsule pipelines to send money or documents from the drive-up window to a customer's car. PCPs also are used in large hospitals to transport medicine or blood supplies, and in airports and large factories, Dr. Liu said.

   These pipelines are usually less than 12 inches in diameter and cover only short distances, such as between neighboring buildings.

   Larger and longer PCPs are being used in Japan and the former Soviet Union to transport minerals. An 11-mile, 48-inch diameter pneumatic capsule pipeline is used to move rock in the Republic of Georgia. Since 1983, Sumitomo Metal Industries in Japan has operated a 36-inch diameter PCP to transport limestone from a mine to a cement plant over a distance of two miles.

   In the United States, a New Jersey express mail company has developed a large PCP, but the system has not been used commercially, Dr. Liu said, because of the industry's hesitance to use the new technology and because the cost of the alternative transportation mode (in U.S. dollars per ton per mile) as it is currently designed is no cheaper than existing transportation methods, such as truck, rail or conveyor belt.

   However, the costs of future PCP systems designed to use linear induction motors — the same technology used in high-speed electric trains and roller coasters — could be reduced by as much as 50%, giving them “an overwhelming economic advantage” over current systems, Dr. Liu said.

   Unlike PCPs, HCP technology is still in the research and development stage, he said. Hydraulic capsule pipeline technology has been studied in the U.S., Canada, Japan and other nations since the 1960s.

   Since 1990, the University of Missouri-Columbia has organized an industry/government consortium to fund HCP research. The work so far has focused on transporting coal. A coal log pipeline near Columbia is ready for commercial use pending the test of a large pilot plant still under construction. This pilot plant could also be used to test grain pipelines, Dr. Liu said.

   The same technology used for coal log pipelines — the special pumping mechanism, inlet and outlet system and computer controls — can be modified for grain pipelines, he said.

   “Grain pipelines based on HCP are not only technologically feasible but also economically promising,” Dr. Liu said.

   In many cases, transporting grain by HCPs could be more cost-effective than by train or truck, he said. Future HCP systems, as in the case of newer PCP systems, will likely use high-speed linear induction motors to pump and inject capsules, he said.

   Grain pipelines are also better for the environment, Dr. Liu said. The water used to move grain capsules through the pipeline will be recycled through the return pipe. In the case of a pipeline that transports grain inland from a barge terminal on a river, the water can be used for irrigation or other purposes, he said. Since only clean water is used in the pipeline, there is no safety or pollution potential, he added.

   The pipeline can have bends and slopes as long as the radius is large enough, Dr. Liu said. Also, the pipeline would need to be buried several feet below the frost line in order to prevent the water in the pipe from freezing in winter and to protect the pipe from future construction and plowing, Dr. Liu said.

   Large grain elevators could build branches to hook onto the main pipeline, he said.


   According to a 1988 study by Dr. Liu's colleague at the University of Missouri, J.P. Wu, transporting grain by pipeline is cheaper than by truck or train as long as the throughput is greater than approximately 1 million tons (32 million bus). Grain pipelines are cheaper than barge transportation only in distances shorter than about 150 miles.

   Dr. Wu's study of the economics of using HCP systems to transport grain in the Midwestern grain belt examined the cost of grain pipelines ranging in diameter from 1 to 3 feet and in lengths from 10 to 1,000 miles. The capital cost included not only pipelines, but also buildings, machinery to handle grain at pipeline terminals, right-of-way acquisition and engineering design as well as operation and maintenance costs such as energy, insurance, salaries and maintenance.

   The study showed that greater throughput capacity of grain pipelines can be obtained by increasing the pipe diameter. For example, increasing to a 3-foot diameter pipe from a 1-foot diameter pipe will increase throughput to 8 million tons per year from 900,000 tons per year.

   “This greatly favors economy of scale for grain pipelines,” Dr. Liu said.

   Dr. Wu's study also assumed that the grain pipeline would operate only four months per year, following harvest. If during the off season the pipeline was used to transport some other cargo, the economics of the grain pipeline is “even more promising,” Dr. Liu said.

   More research is needed to select promising grain pipeline routes and to conduct a site-specific economic analysis, Dr. Liu said. He said the major grain pipeline routes that should be considered include one from the Grain Belt to cities along the Great Lakes, one from Kansas City to the West Coast and one from St. Louis to New Orleans.

   Grain pipeline technology in the United States can be developed within five years with an aggressive and well-planned research and development program, Dr. Liu said. He estimated the cost for such research at about U.S.$5 million.

   Technical research focused on capsule design and handling, including loading and unloading at terminals, can be done in three years at a cost of about U.S.$2 million, Dr. Liu said. Updating the 1988 economic analysis and identifying the most economically feasible routes for grain pipelines will take about two years at a cost of about $500,000. A pilot plant, built at a scale large enough to simulate future commercial grain pipeline systems, will cost another $2 million.

   Dr. Liu is currently seeking funding from a consortium of government agencies such as the U.S.D.A. and industry, including large grain companies, major pipeline shippers and agricultural cooperatives.

   “By pooling their resources, each partner in the consortium will get maximum leverage for their research dollars,” Dr. Liu said.

   Two real issues may become obstacles to the use of grain pipelines, Dr. Liu said. These include lack of eminent domain and opposition by railroads, which may not allow grain pipelines to cross their right-of-way. However, these issues have been studied for coal pipelines and various solutions exist, Dr. Liu said.

   Many problems can be solved by introducing new legislation, he said. “With America's farmers backing grain pipelines, passing remedial legislation for grain pipelines should not be a problem in most states and in Congress,” Dr. Liu said.