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Insight

Generator Combines the Best of Two Fuels

Wed, 01/21/2015 - 13:09

Bi-fuel technologies, which run on the simultaneous combustion of two fuels, have been around since the early 1900s. However, early designs lacked the proper controls to make them function effectively. Technological advancements in controls have made bi-fuel engines efficient and economical.

Generac Bi-Fuel generators spare users from the hassle of refueling by operating mainly on utility-supplied natural gas. However, when it fires up, a Bi-Fuel starts entirely on diesel fuel. As soon as the coolant reaches a minimum temperature and the generator starts to accept load, natural gas is supplied into the combustion air stream. As compression takes place, the diesel ignites normally and provides the spark needed to ignite the natural gas. The amount of gas is increased while the amount of diesel is lowered as the load is applied. Generac has conducted thorough testing and fuel ratio mapping to ensure safe and reliable operations under different combinations of load and temperature. Generac’s PowerManager control system continuously monitors coolant temperature, intake manifold temperature and pressure, kilowatt load, and engine speed, so the fuel mixture is instantly adjusted as needed. Under normal conditions, natural gas will make up to 75% of the mixture. The GenLink can display the natural gas flow in graphs and numbers. The software also allows and remotely. This trait allows for reduced onsite diesel storage, which translates into lower diesel, installation, operation, and maintenance costs. Similarly, the low cost of diesel allows this generator to reduce the costs of fuel. Moreover, because of their use of natural gas, Bi-Fuel generators are cleaner and more environmentally friendly than generators that run solely on diesel. Generac’s hybrid generators emit about 30% less nitrogen oxides and 50% less particulate matter than similar diesel-operated units. In addition, natural gas combustion results in less contamination of lubricating oil and reduced engine wear. Peak cylinder pressures and exhaust temperatures are also lower during bi-fuel combustion than during operations that exclusively use diesel. Furthermore, the Bi-Fuel engine’s transient load response is the same as a diesel engine. The PowerManager controller senses the signature vibration signal created just before pre-ignition occurs and immediately reduces the supply of natural gas. If the condition persists, natural gas is shut off and the engine continues running just on diesel with no loss of power during the transition, and an alert is issued. Since the standard diesel system is always active, diesel instantly becomes the primary fuel source when there are sudden load changes. This makes the Generac Bi-Fuel respond like a regular diesel engine while providing the benefits of an engine operated with natural gas.