Composite structures, composite storage tanks, vehicles including such composite storage tanks, and related systems and methods

A vehicle comprising:

• a frame;
• and
• a composite storage tank configured to store at least one fluid, a wall of the composite storage tank comprising:
• an inner region comprising a first composite material;
• an outer region comprising a second composite material configured in part to secure the composite storage tank to the frame;
• at least one permeation barrier positioned between the inner region and the outer region and supported by at least one of the inner region and the outer region;
• a stem integrally formed into one or more of the inner region, the outer region, and the permeation barrier, wherein the stem extends to a port and the port provides a fluid pathway for filling and/or usage of the fluid in the vehicle operation;
• and
• a conduit connected to the stem at the port, wherein the conduit is configured to transport a fluid between the composite storage tank and another component of the vehicle.

A method of forming a composite fluid storage tank comprising:

• forming an inner composite region by applying at least one ply of a first composite material on a forming surface of a tool configured in a shape of at least part of the composite fluid storage tank;
• applying at least one permeation barrier to an outer surface of the inner composite region, the at least one permeation barrier configured to substantially inhibit permeation of a fluid to be stored in the composite storage tank;
• applying a venting layer over the at least one permeation barrier, the venting layer comprising a material configured to enable gasses to pass through the venting layer and substantially prevent liquids from passing through the venting layer;
• forming an outer composite region by applying at least one ply of a second composite material on an outer surface of the venting layer;
• and
• curing the inner composite region and the outer composite region with the at least one permeation barrier to form the composite fluid storage tank.

A composite storage tank comprising:

• a wall structure including at least three regions comprising:
• an inner region comprising a supporting composite layer;
• an outer region comprising a structural composite layer;
• at least one permeation barrier positioned between the inner region and the outer region and supported by the inner region and the outer region, the at least one permeation barrier configured to substantially inhibit permeation of a fluid through the wall structure of the composite storage tank;
• and
• at least one venting layer comprising a material positioned between the at least one permeation barrier and the outer region, the material configured to enable gasses to pass through the at least one venting layer.