From Western Global, manufacturers of Fuel Storage Tanks:
PLASTIC FUEL STORAGE TANKS
Plastic fuel tanks are typically made out of a heavy-duty polyethylene material.
ADVANTAGES OF PLASTIC FUEL STORAGE TANKS
Plastic fuel tanks are more lightweight than steel, making installation and transportation easier and cheaper.
Plastic is an insulator, which slows the transfer of heat from the environment to the contents.
Though off-the-shelf designs will be limited to what the mass-market desires, plastic tanks can come in virtually any shape if you are willing to pay for custom designs.
Plastic is pliable, meaning that its shape may deform under certain stress. Luckily, these deformations can be corrected with little damage to the integrity of the tank.
DISADVANTAGES OF PLASTIC FUEL STORAGE TANKS
There is a limit to how large a plastic fuel tank can be before the integrity of the design becomes compromised. Maximum capacity is generally around 1,700 gallons (6,500 liters).
Exposure to direct sunlight can weaken and degrade plastics, making plastic tanks less suited to outdoor storage.
Because plastic is a softer material than steel, it is easier for plastic tanks to become damaged on the work site. Additionally, it is easier for thieves to drill into a plastic tank to siphon or steal fuel.
Plastic fuel tanks will inevitably absorb some of the fuel or other chemicals stored inside. This can weaken the integrity of the tank and makes it more difficult to recycle the materials, which can be a concern to green outfits.
STEEL FUEL STORAGE TANKS
Steel fuel tanks are typically made in single or double walled designs.
ADVANTAGES OF STEEL FUEL STORAGE TANKS
Because steel is a sturdier material than plastic, they can take more punishment on the worksite than plastic tanks. This also makes fuel theft more difficult.
Unlike plastic, steel is non-porous, meaning that it will not absorb fuel or other chemical contents. This makes recycling the material easier.
Because of the nature of the material and construction, steel tanks can come in much larger capacities than plastic tanks, up to around 30,000 gallons (115,000 liters). This may allow you to take advantage of cheaper fuel prices when they come up in the market.
Steel tanks are not weakened by sunlight, making them ideal for outdoor storage compared to plastic.
DISADVANTAGES OF STEEL FUEL STORAGE TANKS
Steel is heavier than plastic, making it more challenging and expensive to transport and install.
Steel may naturally corrode (rust) over time, if not properly maintained.