5 Search Results

This study investigates methane pyrolysis (MP) to produce hydrogen and carbon black while eliminating process CO2 emissions via a high technology readiness level (TRL) arc plasma pyrolysis technology. The process was modeled using Aspen Plus, which revealed that the specific energy consumption is approximately 39 kWh/kg H-2 without on-site power generation and 32 kWh/kg H-2 with on-site power generation. The process was evaluated using technoeconomic analysis (TEA) via a discounted cash flow analysis, using 2023 dollars. For the annual capacity of about 52 kMT H-2 (based on Monolith's commercial plant scale), the total capital cost of the plant is estimatedmore » to be nearly $1 billion, while electricity and feedstock costs are identified as the primary contributors to the overall levelized hydrogen production cost. The revenue generated from the sale of black carbon significantly offsets the high electricity costs. The minimum selling price (MSP) of hydrogen produced via this method ranges from $1.10-1.36/kg H-2, demonstrating its economic competitiveness with incumbent steam methane reforming (SMR) technology (similar to$1/kg H-2) and water electrolysis ($4-5/kg H-2). Sensitivity analysis revealed that the carbon black price, electricity costs, and natural gas (NG) feedstock cost are the most impactful factors affecting the MSP of hydrogen. Given the recent high market value of carbon black (>$1.8/kg since 2024) and forecasted increase in market demand and price in the near future, the MP process has high potential to produce H-2,H- with very small process emissions and a competitive cost relative to incumbent technology. The life cycle greenhouse gas emission (GHG) is analyzed considering various allocation methods and are summarized in a separate manuscript.« less

Steam methane reforming of natural gas is the primary method of producing hydrogen in the United States, accounting for 95% of all hydrogen produced there. Methane pyrolysis, an alternative production pathway that decomposes natural gas into solid carbon and hydrogen, both eliminates CO 2 emissions associated with methane reforming and allows for additional income from carbon black. A life-cycle inventory of this process has been developed using ASPEN Plus to model the methane pyrolysis (plasma arc) process. From well to gate, hydrogen production via methane pyrolysis produces 2.78 kg CO 2 e/kg H 2 of greenhouse gas emissions using massmore » allocation of emissions between hydrogen and carbon black coproducts. The well-to-gate emissions are mainly driven by electricity consumption (∼38 kW h/kg H 2 ), which accounts for 81% of the emissions; if renewable electricity is used, well-to-gate emissions can be reduced to −0.448 kg CO 2 e/kg H 2 . • Methane pyrolysis is a viable alternative method of hydrogen production. • Mass allocation of emissions between hydrogen, carbon black, and coke. • Electricity is the main contributing factor to WTG emissions of hydrogen produced. • H 2 WTG emissions decrease from 2.72 to −0.437 kgCO 2 e/kgH 2 using renewable energy.« less

Ethanol is a promising feedstock for sustainable aviation fuel production; however, conventional routes face significant energy and cost challenges, particularly due to the ethanol dehydration step to ethylene. Here, this study leverages breakthrough experimental data to perform comprehensive techno-economic and life-cycle assessments of an innovative ethanol-to-jet process. The process employs a single-step catalytic conversion, enabled by multifunctional Cu-ZrO₂/SBA-16 catalyst, to directly upgrade ethanol into a mixed olefin stream rich in n-butene. The single-step conversion eliminates the costly ethanol dehydration step in the conventional process. High selectivity toward n-butene offers key advantages: it simplifies downstream oligomerization into jet-range hydrocarbons and enablesmore » the co-production of renewable n-butene alongside sustainable aviation fuel. The analysis estimates a minimum fuel selling price as low as $$\$$$$2.50 per gallon, whether using corn ethanol or cellulosic ethanol from corn stover. Life cycle CO₂ equivalent emissions are projected to be as low as 10.6 g CO₂eq/MJ sustainable aviation fuel, representing over 70% reduction compared to conventional petroleum-based jet fuel. This one-step ethanol upgrading approach not only facilitates SAF and n-butene co-production but also provides operational flexibility. The ability to tailor product outputs allows the ethanol-to-jet process to adapt to varying feedstocks, incentive programs, and market dynamics, ultimately enhancing the economic viability of sustainable aviation fuel production.« less

The development of microalgal biorefineries, utilizing high-value coproducts, offers a strategy to lower biofuel production costs, while the use of saline-tolerant microalgal species contributes to reducing freshwater consumption. This study evaluates the life cycle performance of saline microalgae cultivation and conversion at a national scale by analyzing economics, greenhouse gas (GHG) emissions, marginal GHG avoidance cost (MAC), water scarcity footprints, land-use change emissions, and resource availability. The Algal Biomass Assessment Tool (BAT) is applied for site selection, while algae farm and conversion models are used for techno-economic analysis (TEA). The Greenhouse Gases, Regulated Emissions, and Energy use in Technologies (GREET)more » model is employed for life cycle assessment (LCA) by integrating the outputs from BAT and TEA. Our findings demonstrate that electricity and nutrient consumption are the primary drivers of base case GHG emissions, while biomass yield is the key factor determining both GHG emissions and economic performance. Saline microalgal biorefineries can achieve a MAC limit of $$\$$$$80–200/tonne when high-value bio-coproducts, such as whey protein concentrate, are benchmarked, contingent on supply-demand conditions and other market drivers. However, this reduction may not be compatible with current carbon prices. Further increase in biomass yield, reductions in energy and nutrient usage, and the careful selection of high-value protein coproduct targets with high conventional GHG emissions during the design stage are recommended. Additionally, saline microalgal biorefineries show great potential in addressing water stress, as the electricity requirements for desalinating brackish and saline water are relatively low compared to the overall system electricity demand.« less

With the extensive application of IoT techniques, IoT devices have become ubiquitous in daily lives. Meanwhile, attacks against IoT devices have emerged to compromise IoT devices by tampering with system pre-installed programs or injecting new malware. To mitigate these attacks, integrity enforcement of IoT systems has been proposed. The integrity of an IoT device system includes load-time integrity and runtime integrity. In this paper, we design an IoT system based on ARM TrustZone to enforce the system integrity. First, we establish the root of trust and propose a hybrid booting approach consisting of both secure boot and trusted boot tomore » enforce the system load-time integrity. Second, we investigate a paging-based process integrity measurement method to measure the NW processes and conduct remote attestation based on the measurement results ensuring the NW runtime process integrity. We implement an IoT prototype system on a NXP i.MX6Q SABRE SD development board to assess its feasibility. Finally, real-world experiment results demonstrate that our prototype introduces negligible performance overhead to the original system.« less