Ethanol is an essential component in gasoline blends. As a renewable fuel produced from corn or other biomass, ethanol reduces emissions during combustion and helps refiners meet federal emissions regulations as well as important sustainability goals.
However, the multistage ethanol production process — everything from milling corn to liquefaction, cooking and fermentation — can emit significant volumes of carbon dioxide (CO2). Though current production techniques for corn-based ethanol blends can reduce life cycle emissions by more than 40% over unblended gasoline, reducing the CO2 emitted by the ethanol process represents an opportunity to enhance environmental benefits.
As fuel producers look for ways to reduce carbon intensity of fuel production and improve overall process design, more and more ethanol producers are evaluating carbon capture and sequestration opportunities.
Carbon capture projects may also be eligible for certain tax credits for clean energy projects under the 2022 federal Inflation Reduction Act. In Canada, the 2021 Net Zero Emissions Accountability Act establishes a carbon pricing regime that is creating further momentum for carbon capture technologies.
Carbon Capture Clones
Within the heavy industrial sector, repeatable design and standardization of equipment and components is the order of the day. Applying these principles to a carbon capture system can help ethanol producers — along with some other industries — to achieve savings and operations efficiencies.
Though carbon capture is a complex process, multiple proven pre- and post-combustion process technologies make it entirely feasible to capture CO2 emissions. Applying this process technology in a consistent manner results in a standardized inside battery limits (ISBL) design, which can be replicated or cloned, while the outside battery limits (OSBL) design can be customized for each location.
Plug and Play at Multiple Sites
For one large ethanol producer, we began with the concept of developing a carbon capture unit that standardizes design specifications for compressors, dehydration skids, auxiliary equipment and pipe spools. These cloned designs are repeated as blocks to be dropped in as carbon capture units at multiple ethanol processing facilities. The carbon capture units include multi-stage compressors that drive the gas stream to a triethylene glycol (TEG) dehydration skid. After the water is separated from the gas stream, the water is then returned to the ethanol or waste treatment facility, while the CO2 is pumped into a pipeline.
The CO2 capture equipment is housed in a building. The layout of the equipment is cloned, and the building can be rotated to any angle needed to fit within the multiple site plots. The equipment is engineered to uniform specifications within each building, regardless of the site layout. Some custom, site-specific design will be required for outside battery limits (OSBL) aspects of the project and may include geotech surveys, civil engineering and certain other activities to meet varying requirements of individual sites.
By modularizing as many components as possible, constructability in the field becomes much easier and improves with each unit installed as skilled trades and craft become much more familiar with work packages. Additionally, project quality is improved as components such as pipe racks are fabricated in controlled shop environments.
The cloning project planning and development process moves through these five stages.
- Stakeholder alignment. The standardization process begins with early input from stakeholders. This step is essential as stakeholders are asked to review all possible variations before the site design phase begins. This feedback and buy-in helps mitigate late changes, which could increase project costs and push out schedules.
- Block identification. Based on feedback on which equipment and piping layouts can be standardized, engineering proceeds to an evaluation of where blocks should start and stop within the clone unit. Numbering and other identification methods for blocks and components also are developed at this stage.
- Block design and review. Based on feedback and input from project stakeholders, a locked-in block design is executed. The design plan is considered final at this stage.
- Site-specific design. All custom design is executed under this phase and may include arrangement of blocks based on topography, geography, tie-in locations, proximity to other equipment and maintenance access. It is anticipated that each project will require some site-specific OSBL design.
- Lessons learned and process improvement. Following startup and commissioning a review of all design, procurement and construction is done to identify how block design processes can be improved to increase efficiencies, reduce costs and tighten schedules for later installations.
The clone units allow different types of process facilities to minimize costs for engineering, procurement, fabrication and construction. By replicating one design many times, efficiencies ranging from sourcing of long-lead equipment and components to fabrication in controlled shop environments can drive down costs and improve lead times. Construction schedules may also be compressed as more units are installed and crews gain familiarity with installation procedures.
These design concepts can be applied to a wide range of assets, from liquid natural gas plants to compressor stations to hydrogen production facilities. Though designing and building these types of carbon capture units will not achieve assembly line efficiencies, cloning of significant portions of the plant can greatly simplify a complex process.
Sustainable and low-carbon initiatives are underway throughout the oil, gas and chemical industry, while simultaneously enabling many players to enhance their services through profitable and lasting portfolios.