Energy Storage System Enables Operations with Zero Generators Online

Battery energy storage systems (ESS) have been proven to significantly reduce emissions and fuel consumption on drilling rigs since the industry's first system was deployed in 2018. These systems leverage their stored energy to reduce the number of generators online and operate the remaining generators at high load where they are most efficient. Control methodology has traditionally required at least one generator to be online to follow the grid formed by the generator(s) and bias the load higher or lower. However, during operations where power demand is lower than the capacity of a single generator, the battery becomes fully charged leaving the system with no mechanism to artificially increase generator load. This results in a single generator running at low load for extended periods of time. A new automated energy-saving feature, characterized by the absence of ambient noise typically associated with generators, was developed to address this issue and create opportunities for additional fuel and emissions reductions. When the system determines that the operation will not require significant power consumption for an extended period, it will automatically initiate a shutdown of the last online generator and switch to the automated energy-saving mode, using only the batteries to form the electrical grid and supply power to all rig equipment. The rig will continue to operate in this mode until the battery state of charge drops to a certain threshold, at which point it will automatically launch a generator. When the additional generator comes online, it will run at a high load for a brief period to quickly recharge the battery. This accomplishes both goals of reducing generator runtime and increasing average generator load. A calculated approach was necessary to maximize the time in the energy-saving mode while avoiding any impact to operations. Additionally, the control scheme was designed to minimize the number of generator starts while taking precautions to stay within the discharge limitations of the batteries. This feature was deployed to the fleet of ESS, resulting in additional fuel and emissions savings not possible with the traditional systems. Factors including ambient temperature and the operator-specific drilling program produced a wide range of efficiency improvement across the fleet.