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Electrification of the transportation industry is necessary; however, range anxiety has proven to be a major hindrance to individuals adopting electric vehicles (EVs). Agrivoltaic systems (AVS) can facilitate the transition to EVs by powering EV charging stations along major rural roadways, increasing their density and mitigating range anxiety. Here we conduct case study analyses of future EV power needs for Oregon, USA, and identify 174 kha of AVS viable agricultural land outside urban boundaries that is south facing and does not have prohibitive attributes (designated wetland, forested land, or otherwise protected lands). 86% highway access points have sufficient available land to supply EV charging stations with AVS. These AVS installations would occupy less than 3% (5 kha) of the identified available land area. Installing EV charging stations at these 86% highway access points would yield 231 EV charging stations with a median range of 5.9 km (3.6 mi), a distance comparable to driver expectations, suggesting that this approach would serve to mitigate range anxiety. AVS powered rural charging stations in Oregon could support the equivalent of 673,915 electric vehicles yr⁻¹, reducing carbon emissions due to vehicle use in OR by 3.1 mil MTCO₂yr⁻¹, or 21%.

 

The coverage of center pivot irrigation systems used around the world has increased. One potential factor driving their adoption is improved water application efficiency relative to some other sprinkler or surface irrigation approaches. Center pivot irrigation systems may be further improved by dynamic elevation spray application (DESA). DESA systems adjust the nozzle height in response to plant growth and canopy heterogeneities. The DESA approach is relatively new and there is uncertainty in its economic viability and worthiness of further investigation. Thus, an economic scenario analysis was performed to explore the potential economic benefits of DESA based on permutations of irrigation pivot efficiency without DESA, water-saving potential of DESA, and water cost. The weighted costs and benefits of the height-adjusted approach for a set of water cost savings scenarios showed the net return price with the water cost savings per season. We show that DESA could have economic viability at current component costs and is worthy of further investigation and refinement. 

To examine spatial and temporal scales of katabatic flow, a distributed temperature sensing (DTS) optical fiber was deployed 2 km down a mild slope irregularly interrupted by small-scale drainage features as part of the Mountain Terrain Atmospheric Modeling and Observation (MATERHORN) experiment conducted at the U.S. Army Dugway Proving Ground, Utah. The fiber was suspended at two heights near the surface, enabling measurement of variations in lapse rate near the surface at meter-scale spatial resolution with 1-min temporal resolution. Experimental results derived from the DTS and tower-mounted instrumentation indicate that airflow through small-scale drainage features regulated the local cooling rate whereas topographic slope and distance along the drainage strongly influenced the larger-scale cooling rate. Empirical results indicate that local cooling rate decays exponentially after local sunset and basin-wide cooling rate decreases linearly with time. The difference in the functional form for cooling rate between local and basin-wide scales suggests that small-scale features have faster timescales that manifests most strongly shortly after local sunset. More generally, partitioning drainage flow by scale provides insight and a methodology for improved understanding of drainage flow in complex terrain. 

A new Variable Rate Drip Irrigation (VRDI) emitter that monitors individual water drops was designed, built, and tested. This new emitter controllers water application directly by monitoring the volume applied in contrast to uniform drip irrigation systems that control water application indirectly by pressure compensation and operational times. Prior approaches assumed irrigation volumes based on flow rates and time and typically did not verify the applied amount of water applied at each water outlet. The new VRDI emitter self-monitors the total volume of water applied and halts the flow once the desired total water application has been achieved. This study performed a test for a new VRDI emitter design with two inner diameters of 0.11 cm and 0.12 cm and two outer diameters 0.3 cm and 0.35 cm compared to a commercial drip emitter. Laboratory tests verify that the integrated volume measurements of the VRDI system are independent of pressure. Conversely, the flow rates of the commercial pressure-compensated drip lines were not independent of pressure. These results demonstrate that this form of VRDI is technically feasible and is shown to be energy efficient, requiring lower system operating pressures than pressure-compensated lines. The VRDI system can reduce water consumption and related water costs. 

Expanding populations, the impacts of climate change, availability of arable land, and availability of water for irrigation collectively strain the agricultural system. To keep pace and adapt to these challenges, food producers may adopt unsustainable practices that may ultimately intensify the strain. What is a course of technological evolution and adoption that can break this cycle? In this paper we explore a set of technologies and food production scenarios with a new, reduced-order model. First the model is developed. The model combines limitations in the sustainable water supply, agricultural productivity as a function of intensification, and rising food demands. Model inputs are derived from the literature and historical records. Monte Carlo simulation runs of the model are used to explore the potential of existing and future technologies to bring us ever closer to a more sustainable future instead of ever farther. This is the concept of a moving sustainability horizon (the year in the future where sustainability can be achieved with current technological progress if demand remains constant). The sustainability gap is the number of years between the present and the sustainability horizon. As demand increases, the sustainability horizon moves farther into the future. As technology improves and productivity increases, the sustainability horizon is closer to the present. Sustainability, therefore, is achieved when the sustainability horizon collides with the present, closing the sustainability gap to zero. We find one pathway for water management technology adoption and innovation that closes the sustainability gap within the reduced-order model’s outputs. In this scenario, micro-irrigation adoption, minimal climate change impacts, reduced food waste, and additional transformative innovations such as smart greenhouses and agrivoltaic systems are collectively needed. The model shows that, in the absence of these changes, and continuing along our current course, the productivity of the agricultural system would become insufficient in the decade following 2050. 

This research presents a new variable rate drip irrigation (VRDI) emitter design that can monitor individual water drops. Conventional drip systems cannot monitor the individual water flow rate per emitter. Application uniformity for conventional drip emitters can be decreased by clogged emitters, irregular emitter orifices, and decreases in pressure. A VRDI emitter can overcome the irrigation challenges in the field by increasing water application uniformity for each plant and reducing water losses. Flow rate is affected by the diameter of the delivery pipe and the pressure of the irrigation delivery system. This study compares the volumetric water flow rate for conventional drip emitters and new VRDI emitters with variable diameters inner (1 mm, 1.2 mm, 1.4 mm, and 1.6 mm) and outside (3 mm, 3.5 mm, 4 mm, and 4.5 mm) with three pressures (34 kPa, 69 kPa, and 103 kPa). The tests revealed that the new VRDI emitter had flow rates that increased as the operating pressure increased similar to a conventional drip tube. The flow rate was slightly increased in the VRDI with pressure, but even this increase did not show large changes in the flow rate. The flow rate of the conventional drip tube was 88% larger than the VRDI emitter for all pressures (p < 0.05). However, operating pressure did not affect the drop sizes at the VRDI emitter, but the generalized linear mixed models (GLM) results show that volume per drop was impacted by the outside diameter of the VRDI outlet (p < 0.05). The interaction between the inner and outside diameter was also significant at p < 0.01, and the interaction between outside diameter and pressure was statistically significant at p < 0.01. The electronic components used to control our VRDI emitter are readily compatible with off-the-shelf data telemetry solutions; thus, each emitter could be controlled remotely and relay data to a centralized data repository or decision-maker, and a plurality of these emitters could be used to enable full-field scale VRDI. 

Agrivoltaic systems are designed to mutually benefit solar energy and agricultural production in the same location for dual-use of land. This study was conducted to compare lamb growth and pasture production from solar pastures in agrivoltaic systems and traditional open pastures over 2 years in Oregon. Weaned Polypay lambs grew at 120 and 119 g head −1 d −1 in solar and open pastures, respectively in spring 2019 ( P = 0.90). The liveweight production between solar (1.5 kg ha −1 d −1 ) and open pastures (1.3 kg ha −1 d −1 ) were comparable ( P = 0.67). Similarly, lamb liveweight gains and liveweight productions were comparable in both solar (89 g head −1 d −1 ; 4.6 kg ha −1 d −1 ) and open (92 g head −1 d −1 ; 5.0 kg ha −1 d −1 ) pastures (all P > 0.05) in 2020. The daily water consumption of the lambs in spring 2019 were similar during early spring, but lambs in open pastures consumed 0.72 L head −1 d −1 more water than those grazed under solar panels in the late spring period ( P < 0.01). No difference was observed in water intake of the lambs in spring 2020 ( P = 0.42). Over the entire period, solar pastures produced 38% lower herbage than open pastures due to low pasture density in fully shaded areas under solar panels. The results from our grazing study indicated that lower herbage mass available in solar pastures was offset by higher forage quality, resulting in similar spring lamb production to open pastures. Our findings also suggest that the land productivity could be greatly increased through combining sheep grazing and solar energy production on the same land in agrivoltaics systems.