The Midwestern U.S. landscape is one of the most highly altered and intensively managed ecosystems in the country. The predominant crops grown are maize (Zea mays L.) and soybean [Glycine max (L.) Merr]. They are typically grown as monocrops in a simple yearly rotation or with multiple years of maize (2 to 3) followed by a single year of soybean. This system is highly productive because the crops and management systems have been well adapted to the regional growing conditions through substantial public and private investment. Furthermore, markets and supporting infrastructure are highly developed for both crops. As maize and soybean production have intensified, a number of concerns have arisen due to the unintended environmental impacts on the ecosystem. Many areas across the Midwest are experiencing negative impacts on water quality, soil degradation, and increased flood risk due to changes in regional hydrology. The water quality impacts extend even further downstream. We propose the development of an innovative system for growing maize and soybean with perennial groundcover to recover ecosystem services historically provided naturally by predominantly perennial native plant communities. Reincorporating perennial plants into annual cropping systems has the potential of restoring ecosystem services without negatively impacting grain crop production and offers the prospect of increasing grain crop productivity through improving the biological functioning of the system.

Technoeconomic analyses using established tools such as SuperPro Designer^® require a level of detail that is typically unavailable at the early stage of process evaluation. To facilitate this, members of our group previously created a spreadsheet-based process modeling and technoeconomic platform explicitly aimed at joint fermentative‒catalytic biorefinery processes. In this work, we detail the reorganization and expansion of this model—ESTEA2 (Early State Technoeconomic Analysis, version 2), including detailed design and cost calculations for new unit operations. Furthermore, we describe ESTEA2 validation using ethanol and sorbic acid process. The results were compared with estimates from the literature, SuperPro Designer^® (Version 8.5, Intelligen Inc., Scotch Plains, NJ, 2013), and other third-party process models. ESTEA2 can perform a technoeconomic analysis for a joint fermentative‒catalytic process with just 12 user-supplied inputs, which, when modeled in SuperPro Designer^®, required approximately eight additional inputs such as equipment design configurations. With a reduced amount of user information, ESTEA2 provides results similar to those in the literature, and more sophisticated models (ca. 7%–11% different).

Styrene is an important commodity chemical used in polymers and resins, and is typically produced from the petrochemical feedstocks benzene and ethylene. Styrene has recently been produced biosynthetically for the first time using engineered Escherichia coli, and this bio-based route may represent a lower energy and renewable alternative to petroleum-derived styrene. However, the economics of such an approach has not yet been investigated. Using an early-stage technoeconomic evaluation tool, a preliminary economic analysis of bio-based styrene from C₆-sugar feedstock has been conducted. Owing to styrene’s limited water solubility, it was assumed that the resulting fermentation broth would spontaneously form two immiscible liquid phases that could subsequently be decanted. Assuming current C₆ sugar prices and industrially achievable biokinetic parameter values (e.g., product yield, specific growth rate), commercial-scale bio-based styrene has a minimum estimated selling price (MESP) of 1.90 USD kg⁻¹ which is in the range of current styrene prices. A Monte Carlo analysis revealed a potentially large (0.45 USD kg⁻¹) standard deviation in the MESP, while a sensitivity analysis showed feedstock price and overall yield as primary drivers of MESP.

: Maize is an important crop for many smallholder farmers in the world. Maize weevils () cause a significant loss in quality and quantity during maize storage, especially in tropical regions. Hermetic storage of maize has been shown to be effective in controlling maize weevils in laboratory and field settings. The objective of this research was to test the effectiveness of steel barrels that could be used by smallholder farmers for hermetic storage. Six 208 L (55 gal) steel barrels were each loaded with 170 kg (375 lb) of maize at an average moisture of 13.4% w.b., with initial weevil population densities of 25 live weevils kg^-1 (11 live weevils lb^-1) of maize. All six barrels were stored at 27°C (81°F) under non-hermetic conditions for 120 d, corresponding to approximately three weevil lifecycles. After 120 d, weevil population densities had increased to an average of 99 live weevils kg^-1 (45 live weevils lb^-1) in all six barrels. Three of the six barrels were subsequently hermetically sealed. After an additional 30 days (150 days since experiment start), the weevil population densities were zero in every hermetically sealed barrel (100% mortality) and averaged 141 live weevils kg^-1 (64 live weevils lb^-1) in the non-hermetic barrels. All barrels where then exposed to non-hermetic conditions for an additional 40 days (approximately one weevil lifecycle). The barrels previously under hermetic conditions had zero live weevils, while the other barrels averaged 214 live weevils kg^-1 (98 live weevils lb^-1), demonstrating that all stages of weevils (eggs, larvae, and pupae) were killed. Means of barrel oxygen content, test weight (TW), moisture content (MC), temperature, and humidity were significantly different between the hermetically sealed and control treatments. In contrast, broken corn and foreign material (BCFM) and mechanical damage (MD) were not significantly different. Hermetically sealed steel barrels may be an effective maize storage option for smallholder farmers. Keywords: BCFM, Maize weevil, Mechanical damage, Moisture content, Mortality, Mycotoxins, Test weight.

Livestock in the state of Iowa, United States (US) produce over 50 × 10⁶ Mg of wet-basis manure yearly. Biogas production from manure’s anaerobic digestion (AD) can reduce greenhouse gas emissions, control odors, and provide renewable energy. Despite these benefits, AD is rarely deployed at swine farms in Iowa. In this work, we explore the economics of AD systems in Iowa to evaluate reasons for low deployment and explore the production cost impacts of biogas cleaning and injection into the natural gas grid, amending manure with biomass, and centralizing digesters across multiple farms. This work presents a static, spreadsheet-based technoeconomic model that embodies literature-based estimates of key system technical parameters, costs, and transportation fuel incentives and permits the examination of various scenarios. Key findings include that under the model assumptions, distributed, farm-scale digesters are not competitive with average natural gas prices in Iowa. A centralized production scenario can be competitive, provided that programs such as the low-carbon fuel standard (LCFS) and the renewable fuel standard (RFS) have sufficiently high credit values.

Bioenergy cropping systems afford the prospect to provide a more socially and ecologically sustainable bioeconomy. By creating opportunities to diversify agroecosystems, bioenergy crops can be used to fulfill multiple functions in addition to providing more environmentally benign fuels. Bioenergy crops can be assembled into cropping systems that provide both food and energy and which also provide cleaner water, improved soil quality, increased carbon sequestration, and increased biological diversity. In so doing, they improve the resilience of agroecosystems and reduce risks associated with climate change. Beyond the farmgate, bioenergy crops can improve the economic prospects of rural communities by creating new jobs and providing opportunities for local investment.