The scientists from the Central University of Ecuador in Quito have found a solution to one of the oil industry most pressing problems: flaring of associated petroleum gas (APG). They have created a modular, container-type power plant operating on oxy-fuel combustion with carbon dioxide capture. This system not only eliminates toxic flaring but also converts associated gas into a source of electricity but also simultaneously stores virtually all the resulting CO₂. As a result, remote oil fields can generate their own energy and significantly reduce the greenhouse gas and soot emissions.
The development was created taking into account the real-world conditions of the Ecuadorian Amazon where most wells are located far from pipelines, and gas itself often contains impurities – primarily hydrogen sulfide and carbon dioxide. As under these conditions, ordinary transportation of APG for processing is difficult and expensive, it is typically flared on-site.
The researchers selected three of the most suitable oil fields with sufficient gas volumes and a high proportion of methane. This is crucial, as the gas composition makes a direct impact on the entire plant efficiency: the more methane, the more energy can be recovered.
After they selected the suitable fields, the researchers constructed a gas processing chain.
It is as follows. First, gas is purified from hydrogen sulfide using a diethanolamine solution, which is necessary to protect the equipment and improve the fuel quality. Then, gas is burned not in the air but in nearly pure oxygen (96.7%) produced on-site in a cryogenic air separation unit. This eliminates nitrogen from the process and produces an output stream consisting primarily of CO₂ and water vapor. This is a key advantage of the technology as carbon dioxide is easily captured in this form. Some of the CO₂ is recycled back into the process to stabilize the temperature, and the remaining volume is compressed and prepared for injection into the reservoir. Moreover, the entire plant is designed as container modules that can be delivered and quickly deployed directly at the field.
Simulations have confirmed the design feasibility.
The 272-megawatt plant demonstrated a thermal efficiency of 33.1%, with an overall energy efficiency of approximately 40%. Oxygen production requires 0.385 kWh per kilogram, while CO₂ capture reaches 99.99% with energy consumption of 0.41 kWh per kilogram. Calculations also confirmed direct dependence of efficiency on gas composition. The higher the methane content, the better the result: at 70%, it is approximately 28%, and at 95%, it reaches 38%. On the other hand, heavy hydrocarbons reduce efficiency because they require greater oxygen consumption.
The importance of this technology is particularly noticeable on a global scale.
Today, approximately 148 billion cubic meters of APG are flared annually worldwide. This represents a huge wasted energy resource. The systems developed by the Ecuadorian researchers allow this volume to be converted into 520 terawatt-hours of electricity per year, comparable to the energy consumption of Spain.
Such systems are capable of simultaneous capturing up to 381 million tons of CO₂. Scientists estimate that this would require approximately 220 modules, each with a capacity of 272 megawatts.
The main energy consumption in the system is associated with operation of the cryogenic air separation unit and CO₂ compression – they are the ones which consume a significant portion of the generated energy, reducing overall efficiency to 33%. However, optimization of CO₂ recirculation and the steam cycle can raise the efficiency by approximately 2%. Furthermore, if the hydrogen sulfide content in the feed gas is minimal, it is possible to eliminate the purification step, which will simplify the design and reduce the system cost.
