Across the globe, many pathways are being pursued to reduce greenhouse gas (GHG) emissions. Oil refineries emit a relatively small proportion of GHG emissions directly, but the fuels they produce create substantial emissions when combusted for power generation and transportation.
Our article in the February 2024 edition of Hydrocarbon Engineering, titled “Refinery Greenhouse Gas Reduction Pathways,” discusses strategies to reduce refinery emissions, as well as long-term approaches towards larger reductions across multiple sectors.
Emissions in the refining process
Refineries transform crude oil into useful petrochemicals and fuels through processes, including distillation and cracking, both of which require large amounts of energy and hydrogen.
A refinery starts with crude oil (left) and separates it into a number of fractions. Hydrogen and energy are then applied to ultimately reformulate those components into various marketable fuels, oils, and petrochemicals.
Energy is typically generated by burning natural gas and waste refinery fuel gases, while hydrogen is usually produced by reforming methane into steam, hydrogen, and carbon dioxide. Fuel combustion, methane reforming, and fluid catalytic cracking are collectively responsible for producing the bulk of GHG emissions in the refining process.
Greenhouse gas emissions from a refinery mostly result from energy-producing fuel gas combustion. The hydrogen-producing methane reformer and fluid catalytic cracker also generate significant carbon dioxide.
GHG reduction strategies
While some GHG emission reduction measures can be implemented by individual refineries immediately, others require time and developments beyond the refining process.
In the short term, refineries can make simple equipment and control systems upgrades that reduce fugitive emissions. For example, improving valve and pump seals can reduce product losses and emissions, and implementing advanced device-monitoring can reduce unnecessary flaring.
On an intermediate timeframe, refineries can begin to capture CO2 emissions from fluid catalytic cracking and methane reforming, an efficient process as these emissions are concentrated and reasonably pure. However, carbon capture is expensive and dependent on external transportation and storage systems, so widespread adoption will require government incentives and serviceable infrastructure.
Capturing fuel combustion emissions is less practical because burners are typically scattered throughout the facility. To reduce these emissions, the use of alternative energy sources such as electricity, hydrogen, or biofuels is an option, provided that these sources are available and produced in an environmentally sound manner.
Thinking further into the future, the use of hydrogen and CO2 as feedstocks to create synthetic fuels is under investigation. In addition, as electric vehicle adoption increases, fuel demand will fall, allowing refineries to cut the use of feedstocks that are especially energy and emission-intensive to process, such as oil sands.
Alternative energy sources
Refineries certainly emit GHG gases as they process crude oil, but the bulk of GHG emissions come from burning those fuels in the transportation and power generation sectors. Therefore, significant GHG reductions can only occur if the energy source for those sectors is less carbon intensive.
In the US, the bulk of GHG emission result from the combustion of fuel in the transportation and power sectors. Industry emits about 24% of the total, and refineries are a relatively small part of that sector
Solar, wind, and hydropower are exceptionally clean sources of energy, but each has limitations that make large-scale production difficult.
Hydrogen is a promising alternative because it burns cleanly, has a very high energy value, and can be stored and transported easily. If carbon capture and storage can be applied to methane reformers at scale, refineries may prove instrumental in supplying large quantities of hydrogen until better processes are developed.
Funding the energy transition
Most GHG reduction methods are quite expensive, so government action will be required to induce these actions. Subsidies and tax credits for GHG reduction projects, as well as emissions taxes, can incentivize companies and keep them on a level playing field. In the short term, energy prices are likely to rise, but this is a less important concern compared to the potential costs of unchecked climate change.
