Tenth Year Annual Report:
Carbon Capture: Future Plans
Co-Producing Electricity and High Value Co-Products
In order to facilitate/accelerate the development of commercial-scale co-production of low carbon electricity and liquid transportation fuels, the Williams Group is seeking to identify analogous - but possibly more economically attractive - systems that co-produce electricity and high value chemicals as well as transportation fuels. Although the markets for chemicals are more limited than those for transportation fuels, these systems may nonetheless represent important near-term opportunities for demonstrating complex co-production plants at commercial scales: gaining realistic information about their construction and operation, enabling further development of the component technologies and learning about their interactions/integration, and understanding the economic viability of such plants in multiple markets (electricity, chemicals and CO2). The researchers will use their established technoeconomic modeling capability to construct and compare (against baseline plants that co-produce electricity and FTL transportation fuels already analyzed) the economics of co-production in three separate areas:
- agricultural chemicals: ammonia,
- petrochemicals: olefins via the methanol to olefins (MTO) process,
- transportation fuels: gasoline [via methanol-to-gasoline (MTG) technology].
Novel Plant Configuration and Operation
In order to identify plant configurations that maximize return on investment, the Williams Group will vary a number of key design parameters:
- Biomass to coal input ratio: critical to the economic performance as a function of GHG emissions price.
- Electricity to co-product output ratio: critical to plant economics as a function of the crude oil price.
- Variable co-product output ratio: plants that are designed to vary their output mix based on both diurnal and seasonal variations in the value of the co-products. For example, electricity is not economical to store, and its price varies significantly during the day; in contrast, chemicals such as ammonia, olefins and gasoline can be economically stored and their value is relatively constant. We will investigate plants that take advantage of these features by maximizing power production during the day (when electricity prices are high) and maximizing the production of chemicals or liquid fuels at night (when electricity prices are low).
Advanced Technologies for Co-Production
In addition to the commercial (or near-commercial) technologies focused on thus far, the Williams Group will investigate a series of advanced technologies to understand implications for commercializing these in co-production systems (to understand what might be gained via pursuit of these advanced technology options):
- Biomass torrefaction: a low temperature (~250° C) pretreatment process that facilitates biomass milling, pelletization, transportation, and co-gasification with coal.
- Water slurry co-gasification of torrefied biomass and coal: a variant on a commercial oxygenblown, entrained flow gasification system (GE) that is well suited to co-production and CO2 capture.
- Liquid phase methanol synthesis: a technology that provides high single-pass conversion of syngas to methanol, which makes it especially well suited for MTG and MTO co-production systems. The technology has been demonstrated in commercial operation, but has not yet been widely deployed.
- Oxygen production using ion transport membranes (ITM): a novel oxygen transport ceramic membrane that has the potential for reduced capital cost and power consumption compared with standard cryogenic air separation systems.
- Solid oxide fuel cells: high temperature electrochemical conversion devices (constructed of materials very similar to those used in ITM) that can potentially significantly increase the efficiency of power production, especially when pressurized and combined with gas turbines.
Focus on Near-Term Deployment of Co-Production Systems
While past work has focused on identifying the most promising co-production options for widespread deployment, the Williams Group will make a major shift in emphasis to examine more closely technologies, economics, and policies for early deployment of co-production systems. The technologies emphasized will be those with modest biomass input percentages that involve co-gasification in suitable coal gasifiers rather than having separate gasifiers for coal and biomass (modeled in all research to date).
Hitherto the group's economic analyses have been on Nth of a kind (NOAK) plants to identify the most promising options for widespread deployment. Now the researchers will extend their economic modeling to include 1st of a kind (FOAK) plants, which is essential in order to understand adequately the economic challenges of early deployment - understanding FOAK economics is key to communicating with project developers, policy makers, investors and other key stakeholders information relating to near-term deployment of these technologies.Focused attention will be given to deployment opportunities for co-production systems as repowering units at sites for old coal power plants that are candidates for early retirement under EPA environmental regulations that are already getting underway. Particular emphasis will be given to opportunities for CO2 enhanced oil recovery, especially where CO2 pipeline infrastructure is already in place.
Finally, Williams and colleagues will carry out policy analysis to explore the extent to which politically feasible incentives might be crafted with the expectation that CO2 EOR opportunities will not be sufficient to make FOAK plants economic, nor will federal carbon mitigation policy be in place in the near term to help incentivize FOAK plants. One promising approach they will pursue is to describe how an energy security enhancement + diversity of supply policy (with, for example, production tax credits as the awards), coupled to EPA's prospective carbon mitigation regulations, might be crafted to simultaneously incentivize co-production systems that offer significant carbon-mitigation benefits and discourage carbon-intensive co-production systems (e.g., those that involve no CCS).
Co-Production in China
Analysis of co-production systems will be extended to Chinese conditions, with an emphasis on the economics of such systems in China, in collaboration with our colleagues at both Tsinghua University (Zheng LI and his group) and at North China Electric Power (Guangjian LIU and others). The main rationale is that co-production systems based on coal and coal + biomass may be established in the market first in China, as a logical extension of the extensive use of coal for chemicals in the country. In China, there are hundreds of plants with coal gasifiers and synthesis reactors used to make chemicals and there are coal companies now engaged in chemicals manufacture that are well-positioned to extend this coal chemicals experience to the coproduction of liquid fuels and electricity.
Energy Storage Technologies
In the year ahead, the Arnold Group will be continuing work on assessment and optimization by examining how the regime of optimal storage efficiency differs among various available chemistries and how these can be integrated within hybrid systems. In particular, the team will focus on issues related to extended lifetime analysis for batteries subject to stochastic charge. They will also continue to refine their battery characterization models, and incorporate these models into improved energy allocation control programs.