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Decarbonizing electricity generation through deployment of renewable technologies such as wind and solar is a key component of many climate change mitigation efforts. With increasing penetrations, the need to manage variability in renewable generation becomes critical. However, renewable variability is often poorly represented in energy planning studies which focus on energy and capacity adequacy. In this study, we used a hybrid capacity expansion and dispatch model with explicit inclusion of ramping and regulation services to examine balancing requirements in a decarbonizing electricity system. We find that ramping and regulation services needed for management of variable renewables alter the optimal mix of generation and transmission capacity relative to simpler planning models. In particular, we find enhanced value in expanding transmission capacity to access flexibility. • Representing short-term constraints in long-term energy models changes the outcome. • Flexibility is a key constraint in systems with high penetrations of renewables. • Interregional transmission can help provide system flexibility. [ABSTRACT FROM AUTHOR]

• Abatement cost of electrification of road vehicle fleet range from 14 to 21 $/tCO 2e. • Electricity cost is up to 9% higher in scenarios with transport electrification. • Eliminating renewable target negates 60% of GHG benefits of transport electrification. • Use of UCC in half of available fleet may decrease generation capacity needs by 7%. To mitigate emissions from the electricity and transportation sectors, large scale deployment of renewable energy generators and battery electric vehicles are expected in the coming decades. However, adoption of these technologies may exacerbate issues related to mismatch of electricity supply and demand. In this study, we utilize a hybrid capacity expansion and dispatch model to quantify grid impacts of the conversion of the entire road vehicle fleet to electric vehicles by 2050. We examine impacts of policies, such as targeting a renewable energy penetration of 93%, using British Columbia as a case study. Scenarios making use of utility controlled charging of vehicles to balance supply and demand are further analyzed. Results show that although electrifying the entire road vehicle fleet will require generation capacity to increase by up to 60%, relative to a scenario without electrification, levelized cost of electricity only increases by 9% in the same scenario due to availability of low cost generation options such as wind and solar. We also find that a 93% renewable energy target leads to carbon abatement costs 30% lower than a scenario where this policy is removed. Further use of utility controlled charging reduces total system capacity up to 7%. [ABSTRACT FROM AUTHOR]

The use of forest residue may mitigate greenhouse gas emissions by displacing the use of coal or other fossil fuels for electricity generation. However, economic viability of bioenergy requires availability of feedstock at appropriate cost. The current work attempts to quantify delivered biomass cost at plant gate and estimate cost and emission benefits to the electricity system associated with the conversion of coal units to bioenergy. This study is carried out with the optimization model OSeMOSYS, analyzing the Alberta electrical system, its mid-term coal phase-out and renewable energy targets. Alternative scenarios were compared to evaluate the effect of a biomass retrofit option on the incentives needed to achieve 30% renewable penetration by 2030. Results show that although bioenergy has a higher levelized cost than wind power, the system requires less backup capacity and less renewable energy credits to meet renewable energy goals when the biomass retrofit is allowed. In addition, the total system cost to 2060 is found to be 5% less than the scenario without the biomass option. The firm capacity provided by biomass compensates for its higher levelized cost of energy. [ABSTRACT FROM AUTHOR]

As potential activators of brown adipose tissue (BAT), mild cold exposure and sympathomimetic drugs have been considered as treatments for obesity and diabetes, but whether they activate the same pathways is unknown. In 10 healthy human volunteers, we found that the sympathomimetic ephedrine raised blood pressure, heart rate, and energy expenditure, and increased multiple circulating metabolites, including glucose, insulin, and thyroid hormones. Cold exposure also increased blood pressure and energy expenditure, but decreased heart rate and had little effect on metabolites. Importantly, cold increased BAT activity as measured by 18F-fluorodeoxyglucose PET-CT in every volunteer, whereas ephedrine failed to stimulate BAT. Thus, at doses leading to broad activation of the sympathetic nervous system, ephedrine does not stimulate BAT in humans. In contrast, mild cold exposure stimulates BAT energy expenditure with fewer other systemic effects, suggesting that cold activates specific sympathetic pathways. Agents that mimic cold activation of BAT could provide a promising approach to treating obesity while minimizing systemic effects. [ABSTRACT FROM AUTHOR]

A novel instrument is described capable of recording gas electron diffraction (GED) patterns of excited molecular states or transient species with pulsed electron beams. The system incorporates (1) a pulsed optical beam for electronic excitation of materials under study, (2) a synchronously pulsed source of 30–50 keV electrons in a space-charge-limited beam, (3) necessary vacuum environment and sample-handling capabilities, and (4) detection and signal processing equipment using an on-line procedure developed at the University of Arkansas. Data obtained for several test gases demonstrate successful operation of the instrument. The 193 nm laser photofragmentation of carbon disulfide, CS2, is described in detail. In agreement with a recent time-of-flight mass spectrometric study of the same process, carbon monosulfide was observed as the reaction product. This study is the first quantitatively successful joint exercise of on-line multichannel GED data recording and a stroboscopic electron source. The method is expected to be generally useful in determining the structures of excited molecular states or reactive species, and it may enable studies of time-dependent phenomena. The current time resolution is ∼20 ns. [ABSTRACT FROM AUTHOR]