Ikenna J. Okeke

Energy scarcity and subsequent global fuel market shocks have become a significant concern for the United States. Process heating in industry accounts for over half of all industrial energy usage and is almost entirely (>95%) supplied by natural gas, coal, and byproduct fuels. Many existing alternatives, technologies, and strategies can reduce dependency on this fossil fuel usage to promote energy security and competitiveness. It is expected that adoption of alternatives is limited by capital investment. A working group exploratory exercise was performed to evaluate the current barriers to alternative process heat technology adoption for the manufacturing sector. Although the working group’s findings emphasize electro-technologies due to their emergence as the central topic of discussion, we have contextualized these results by providing a fair and consistent comparison against several alternative thermal technology options. The most reported issue was the lack of financial incentives, with the second key issue for engineers and manufacturing sector decision-makers being the lack of awareness or understanding of available alternatives. This paper aims to provide an analysis of the levelized cost of heating for a variety of alternatives as part of addressing concerns from the emergent patterns reported in the exploratory exercise, as well as provide guidance on barriers to further adoption. Levelized cost of heating analysis considered the capital investment, operations and maintenance, lifespan, and fuel stream costs of various systems delivering heat to the product or process as a generalized cost per megawatt-hour delivered. The analysis indicates that biomass burners, industrial open-loop heat pumps, and central-receiver heliostat fields are at cost parity under average 2024 United States natural gas and electricity prices against well-optimized natural gas burners, though further cost reductions are necessary for consistent adoption.

Low-carbon fuels, feedstocks, and energy sources can play a vital role in the decarbonization of clinker production in cement manufacturing. Fuel switching with renewable natural gas, green hydrogen, and biomass can provide a low-carbon energy source for the high-temperature process heat during the pyroprocessing steps of clinker production. However, up to 60% of CO₂ emissions from clinker production are attributable to process-related CO₂ emissions, which will need the simultaneous implementation of other decarbonization technologies, such as carbon capture. To evaluate the potential of fuel switching and carbon capture technologies in decarbonizing the cement industry, a study of the facility-level CO₂ emissions is necessary. This study evaluates the potential for using a single low-carbon fuel as an energy source in clinker production for cement manufacturing compared to conventional clinker production (which uses a range of fuel mixes). In addition, conventional carbon capture (operated with natural gas-based steam for solvent regeneration) and electrified carbon capture configurations were designed and assessed for net-zero emission targets. Carbon emissions reductions with and without biogenic emissions credits were analyzed to ascertain their impact on the overall carbon accounting. Results show that carbon emissions intensity of cement can vary from 571 to 784 kgCO₂eq/metric ton of cement without carbon capture and from 166.33 to 438.66 kgCO₂eq/metric ton of cement with carbon capture. We find that when biogenic carbon credits are considered, cement production with a sustainably grown biomass as fuel source coupled with conventional carbon capture can lead to a net-negative emission cement (−271 kgCO₂eq/metric ton of cement), outperforming an electrified capture design (35 kgCO₂eq/metric ton of cement). The carbon accounting for the Scope 1, 2, and biogenic emissions conducted in this study is aimed at helping researchers and industry partners in the cement and concrete sector make an informed decision on the choice of fuel and decarbonization strategy to adopt.

As a low-carbon fuel, feedstock, and energy source, hydrogen is expected to play a vital role in the decarbonization of high-temperature process heat during the pyroprocessing steps of clinker production in cement manufacturing. However, to accurately assess its potential for reducing CO2 emissions and the associated costs in clinker production applications, a techno-economic analysis and a study of facility-level CO2 emissions are necessary. Assuming that up to 20% hydrogen can be blended in clinker fuel mix without significant changes in equipment configuration, this study evaluates the potential reduction in CO2 emissions (scopes 1 and 2) and cost implications when replacing current carbon-intensive fuels with hydrogen. Using the direct energy substitution method, we developed an Excel-based model of clinker production, considering different hydrogen-blend scenarios. Hydrogen from steam methane reformer (gray) and renewable-based electrolysis (green) are considered as sources of hydrogen fuel for blend scenarios of 5%-20%. Metrics such as the cost of cement production, facility-level CO2 emissions, and cost of CO2 avoided were computed. Results show that for hydrogen blends (gray or green) between 5% and 20%, the cost of cement increases by 0.6% to 16%, with only a 0.4% to 6% reduction in CO2 emissions. When the cost of CO2 avoided was computed, the extra cost required to reduce CO2 emissions is $229 to $358/ metric ton CO2. In summary, although green hydrogen shows promise as a low-carbon fuel, its adoption for decarbonizing clinker production is currently impeded by costs.