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Conformable Core Gas Tank

ARPA-E Award: 
Calumet, MI
Project Term: 
09/01/2012 to 09/30/2016
Project Status: 
Technical Categories: 
Image of REL's technology
Critical Need: 

Today's natural gas vehicles are fitted with on-board fuel tanks that are too large, cumbersome, and expensive to properly facilitate the widespread adoption of natural gas vehicles in the U.S. and globally. Additionally, the low volumetric density of natural gas--roughly 30% less energy by volume than gasoline--limits the driving range of natural gas vehicles and makes cost-effective storage solutions a significant challenge. Dramatic improvements must be made to the capacity, conformability, and cost of on-board storage to accelerate natural gas vehicle adoption.

Project Innovation + Advantages: 

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. REL's conformable internal core would enable higher storage capacity than current carbon fiber-based tanks at 70% less cost. REL is developing small-scale prototypes that meet their durability, safety, and cost goals before scaling up to a full-sized prototype.

Potential Impact: 

If successful, REL's foam core gas tank would provide improved storage capacity and fit easily into any natural gas vehicle, enabling their widespread use.


Improving the convenience of natural gas vehicle ownership could reduce our dependence on foreign oil and make consumers less vulnerable to sudden oil price shocks.


Natural gas vehicles produce approximately 10% less greenhouse gas emissions than gasoline-powered vehicles throughout the fuel life cycle.


Compressed natural gas currently costs half as much per gallon of gasoline equivalent. With the average American spending over $2000 per year on gas, enabling the use of natural gas vehicles could save drivers $1000 per year.

Innovation Update: 
(As of May 2016) 
The REL team has designed an internally structured gas tank to overcome challenges of using natural gas as a transportation fuel. The team’s tank improves capacity, conformability, and cost of an on-board storage tank, all of which are key obstacles for natural gas vehicle adoption. REL has also become an active member of multiple natural gas groups and associations to address technical concerns and draft proposed standards for industry review. REL’s initial target application is natural gas pickup trucks. By replacing the standard cylindrical tanks that exist today, owners can utilize more of their cargo space. REL has developed small-scale prototypes and intends to scale up to a full-sized prototype operating within a vehicle. In December 2014, REL and Michigan Technology Institute jointly announced $2.1M in funding from Southwestern Energy to integrate their full-scale tank design into a 1500 Chevy demonstration truck by mid-2016. 
During its ARPA-E award, REL developed new casting methods to create an internally structured gas tank that enables tanks to be manufactured in various shapes. The internal structure adds strength and durability to the tank walls. REL has designed their tank in Schwarz P-surface shape, resembling the skeletal structure of a sea urchin. This shape allows for internal stresses to be distributed throughout the structure of the tank. REL’s casting innovations include a sacrificial core structure, thermal isolation dye coating, and distinct, yet complementary, field-assisted casting techniques. The tank technology utilizes an efficient internal tank structure, has separate internal volumes, and has a substantial conformability advantage over current cylindrical high pressure tanks.
For a detailed assessment of the REL team's project and impact, please click here.

ARPA-E Program Director: 
Dr. Jason Rugolo
Project Contact: 
Dr. Adam Loukus
Endres Machining Innovations, LLC
Release Date: