Journal of the American Chemical Society最新文献

The high penetration of weather-dependent renewable energy sources (WD-RESs) such as wind and solar has raised concerns about the security of electric power systems during abnormal weather conditions. The role of RESs has been discussed in worldwide blackout events, yet remains controversial. In this study, we find that although WD-RESs are non-dispatchable and weather sensitive, blackout intensities and extreme weather vulnerability are mitigated in high-penetration WD-RES grids. The causal effects of WD-RESs on blackouts generally decrease in high-penetration WD-RES power systems, and WD-RESs are not mainly responsible for the occurrence of blackouts in extreme weather conditions. The results of our research contribute to the debate on RES integration and power system security, offer a guide for the study of power system resilience and provide a reference for the ambitious high-penetration RES goals of the future.

Flexible photovoltaic (PV) devices are a promising research field with potential for wearable, portable, indoor and internet-of-things applications. Substantial progress has been made in recent years, with flexible emerging PVs reporting power conversion efficiencies (PCEs) of over 24%. Yet, there is a need for a unifying protocol to assess PV performance, compare research results, and evaluate state-of-the-art achievements in flexible PVs. Here we present a protocol for measuring PCE over 1,000 bending cycles under 1% strain. Moreover, several good practice guidelines are proposed, including those related to bending procedures, flexibility testing with and without encapsulation, and ambient conditions during testing (for example, temperature, humidity and illumination). Notably, the importance of the uniform application of the bending radius and the testing of parallel and perpendicular orientations of the bending axis with respect to the direction of the electric current are emphasized. These recommendations aim to promote consistency in device comparison and allow for better reproducibility.

The United States’ greenhouse gas (GHG) emissions reduction goals, along with targets set by the International Maritime Organization, create an opportunity for battery electric shipping. In this study, we model life-cycle costs and GHG emissions from shipping electrification, leveraging ship activity datasets from across the United States in 2021. We estimate that retrofitting 6,323 domestic ships under 1,000 gross tonnage to battery electric vessels would reduce US domestic shipping GHG emissions by up to 73% by 2035 from 2022 levels. By 2035, electrifying up to 85% of these ships could become cost effective versus internal combustion engine ships if they cover 99% of annual trips and charge from a deeply decarbonized grid. We find that charging demands from electrifying these ships could be concentrated at just 20 of 150 major ports nationwide. This study demonstrates that retrofitting to battery electric vessels has economic potential and could significantly accelerate GHG emission reductions.

Low-carbon hydrogen is considered a key component of global energy system decarbonization strategy. The US Inflation Reduction Act incentivizes low-carbon hydrogen production through tax credits that vary based on life-cycle greenhouse gas emissions intensity of hydrogen. Blue hydrogen or hydrogen produced from natural gas coupled with carbon capture and sequestration is one such pathway. Here we develop a geospatial, measurement-informed model to estimate supply-chain specific life-cycle greenhouse gas emissions intensity of blue hydrogen produced with natural gas sourced from the Marcellus and Permian shale basins. We find that blue hydrogen production using Permian gas has a life-cycle emissions intensity of 7.4‚Äâkg‚Äâcarbon dioxide equivalent per kg hydrogen (kgCO₂e‚Äâkg^‚àí1‚ÄâH₂), more than twice that of hydrogen produced using Marcellus gas of 3.3‚ÄâkgCO₂e‚Äâkg^‚àí1‚ÄâH₂. Eligibility for tax credits should therefore be based on life-cycle assessments that are supply-chain specific and measurement informed to ensure blue hydrogen projects are truly low carbon.

Carbon dioxide (CO₂) and absorbent regeneration are the most energy-intensive processes in carbon capture loops. Conventional carbon capture technologies typically consume substantial amounts of heat and involve multiple steps for regeneration. Here we demonstrated one-step electrochemical regeneration of CO₂ and alkaline absorbent from carbon-containing solutions in a modular porous solid electrolyte (PSE) reactor. By performing hydrogen evolution and oxidation redox reactions, our PSE reactor selectively split NaHCO₃/Na₂CO₃ solutions, which typically come from air contactors after CO₂ absorption, into NaOH absorbent in the catholyte and high-purity CO₂ gas in the PSE layer. No chemicals were consumed and no by-products were generated. High Na⁺-ion transport number (~90%), high capture capacity retention (~90%), low energy consumptions (50 kJ mol_CO2⁻¹ and 118 kJ mol_CO2⁻¹ at 1 mA cm⁻² and 100 mA cm⁻² for bicarbonate, respectively) and long-term stability (>100 hours) were demonstrated. We achieved industrially relevant carbon regeneration rates of up to 1 A cm⁻² (~18 mmol cm⁻² h⁻¹), highlighting the promising application potential.