Transportation Storage

REL is developing a low-cost, conformable natural gas tank for light-duty vehicles that contains an internal structural cellular core. Traditional natural gas storage tanks are cylindrical and rigid. REL is exploring various materials that could be used to design a gas tank's internal structure that could allow the tank to be any shape. The REL team is exploring various methods of manufacturing the interconnected core structure and the tank skin to identify which combination best meets their target pressure-containment objectives.

Otherlab is developing a natural gas storage tank made of small-radius, high-pressure tubes that allow for maximum conformability to vehicle shape. Current storage options are too rigid, expensive, and inefficient to support adoption of natural gas vehicles. Otherlab's space-filling tube design, modeled after human intestines, provides for maximum storage capacity. This transformational system could be constructed from low-cost materials and well suited to highly automated manufacturing processes.

United Technologies Research Center (UTRC) is developing a conformable modular storage tank that could integrate easily into the tight spaces in the undercarriage of natural gas-powered vehicles. Traditional steel and carbon fiber natural gas storage tanks are rigid, bulky, and expensive, which adds to the overall cost of the vehicle and discourages broad use of natural gas vehicles. UTRC is designing modular natural gas storage units that can be assembled to form a wide range of shapes and fit a wide range of undercarriages.

Eaton is developing an at-home natural gas refueling system that relies on a liquid piston to compress natural gas. A traditional compressor uses an electric motor to rotate a crankshaft, which is tied to several metal pistons that pump to compress gas. Traditional compressor systems can be inefficient and their complex components make them expensive to manufacture, difficult to maintain, and short-lived.

Pacific Northwest National Laboratory (PNNL) is developing a low-cost, conformable natural gas tank for light-duty vehicles utilizing the same metal forming techniques used to fabricate high-strength cruise missile fins. Traditional gas tanks are made using a method known as arc welding, where an electric arc is used to melt and combine metals, which can limit their conformability. PNNL's ultra-light design relies on friction stir welding, where metal is softened—like taffy—instead of melted, which allows the metal to retain its original properties and preserves its conformability.

ARPA-E and Ford Motor Company agreed to mutually conclude this project. Ford is developing an on-board adsorbed natural gas tank system with a high-surface-area framework material that would increase the energy density of compressed natural gas at low pressures. Traditional natural gas tanks attempt to compensate for low-energy-density and limited driving range by storing compressed gas at high pressures, requiring expensive pressure vessels.

Blackpak will use high-strength, high-surface-area carbon to develop a sorbent-based natural gas storage vessel in which the sorbent itself is the container, eliminating the external pressure vessel altogether. This design could store natural gas at comparable or lower weight and smaller size than conventional compressed gas tanks while reducing the pressure of the natural gas in the vehicle tank. By reducing tank pressure, the system will enable home vehicle refueling at greatly reduced complexity and cost, making these systems accessible to the general public.

Texas A&M University is developing a highly adsorbent material for use in on-board natural gas storage tanks that could drastically increase the volumetric energy density of methane, which makes up 95% of natural gas. Today's best tanks do not optimize their natural gas storage capacity and add too much to the sticker price of natural gas vehicles to make them viable options for most consumers. Texas A&M University will synthesize low-cost materials that adsorb high volumes of natural gas and increase the storage capacity of the tanks.

The Center for Electromechanics at the University of Texas at Austin (UT Austin) is developing an at-home natural gas refueling system that compresses natural gas using a single piston. Typically, at-home refueling stations use reciprocating compressor technology, in which an electric motor rotates a crankshaft tied to several pistons in a multi-stage compressor. These compressor systems can be inefficient and their complex components make them expensive to manufacture, difficult to maintain, and short-lived.

Gas Technology Institute (GTI) will partner with Northwestern University, NuMat Technologies, a Northwestern start-up company, and Westport Fuel Systems to identify materials with the best characteristics for low-pressure natural gas storage. The gas-storing materials, known as metal organic framework (MOF) adsorbents, hold natural gas the way a sponge holds liquids. The project team will further develop their computer modeling and screening technique to support the creation of a low-pressure adsorbent material specifically designed for natural gas vehicles.