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Over the past several years, energy investors have shifted towards companies ranking higher in ESG measures, leading many oil and gas companies to explore ways in which they can reduce their carbon footprint. One solution currently available to reduce emissions produced by drilling operations is EcoCell, an energy management system that utilizes battery energy storage to optimize the number of generators online and keep them in their most efficient power to emissions ratio range.

EcoCell™ battery energy storage being utilized on-site for Patterson-UTI Rig 292 in Pennsylvania.
EcoCell™ battery energy storage being utilized on-site for Patterson-UTI Rig 292 in Pennsylvania. (Source: Patterson-UTI Energy Inc.)

Currently, six units are operating with many more scheduled to be installed over the next several months. EcoCell can be deployed during a rig walk or move and once on site, the energy storage system is placed next to the third generator where a fourth generator would be located. By design, EcoCell automatically starts and stops generators based on the rig demand and the state of charge of the batteries, enabling fewer generators to operate at higher loads. EcoCell prolongs the amount of time the rig can operate with one or two generators online by providing additional power if the rig demand surpasses the capacity of the online generator(s). For example, during drilling operations, EcoCell discharges power while the mud pumps are running and recharges the batteries when the pumps are turned off for connections. When the batteries drop to a low state of charge, the unit will automatically start up another generator to recharge the batteries. Tripping operations provide an even greater opportunity for reducing emissions due to the transient demand experienced while hoisting, which traditionally requires at least two generators online. EcoCell is capable of instantaneously providing more than 1.5 times the maximum power of a single generator, therefore, only one generator is required to trip out of the hole with EcoCell.

A case study was recently conducted to quantify the impact that EcoCell is currently having on CO₂ emissions produced by four units that have been deployed for over a month. This provided a more accurate assessment of the potential effect it could have if deployed on a much wider scale. The analysis utilized a baseline generator performance model to compare the emissions of the four rigs equipped with EcoCell against the average emissions of the entire rig fleet over the last month. This was done by running the previous month’s generator power data for each of the four rigs with EcoCell through the baseline generator model to determine the amount of CO₂ emissions that would have been produced without the energy storage system.

The study yielded promising results, highlighted by Rig #2 which was previously equipped with four generators before EcoCell replaced its fourth generator. The other three rigs were equipped with only three generators prior to EcoCell being deployed. As shown in Table 1 below, Rig #2 reduced emissions by a significantly higher percentage than the other rigs due to the additional engine previously in use.

Table 1 - CO₂ Emissions Reduction with EcoCell.
Rig # CO₂ Emissions Reduction
1 11.1%
2 24.8%
3 13.1%
4 6.0%

The current active rig fleet consists of 34 rigs operating four generators and 55 rigs operating three generators. Therefore, to estimate the potential overall reduction in emissions across the fleet, the results from these four rigs equipped with EcoCell were projected across the entire fleet based on the number of generators that each rig currently operates. In all, it seems just over 15% of the total mass of CO₂ emissions produced by the entire fleet could likely be eliminated, as seen in Table 2.

Table 2 - Projected CO₂ Emissions Reduction Across Entire Fleet.
Rig Type Projected CO₂ Reduction
3 Generators 10.7%
4 Generators 24.8%
Fleet Average 15.7%

While EcoCell remains in the early stages of deployment, it shows great promise and may eventually reduce the overall total output of carbon emissions produced from all drilling operations significantly. This technology system is a new tool available to enable a more sustainable future as the industry continues to responsibly meet global demand for energy.