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Article Environmental Sciences

Global temperature goals should determine the time horizons for greenhouse gas emission metrics

Sam Abernethy et al.

Summary: This study proposes a novel framework to calculate time horizons aligning with specific temperature goals and presents emission metrics for methane using these time horizons. The commonly used time horizon of 100 years underestimates the environmental impact of methane compared to the values calculated for the Paris Agreement goals of 1.5 degrees C and 2 degrees C.

ENVIRONMENTAL RESEARCH LETTERS (2022)

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Review Chemistry, Physical

Review and comparison of various hydrogen production methods based on costs and life cycle impact assessment indicators

Mengdi Ji et al.

Summary: Hydrogen is a clean and renewable secondary energy source which many countries are pursuing to combat global warming. This paper provides an overview of various hydrogen production technologies, including fossil fuel or biomass-based production, electrolysis, and thermochemical cycles. While the mainstream approach involves obtaining hydrogen from natural gas and coal, electrolysis and thermochemical cycles coupled with new energy sources show considerable potential for development.

INTERNATIONAL JOURNAL OF HYDROGEN ENERGY (2021)

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Article Engineering, Chemical

Process Integration of an Autothermal Reforming Hydrogen Production System with Cryogenic Air Separation and Carbon Dioxide Capture Using Liquefied Natural Gas Cold Energy

Jeongdong Kim et al.

Summary: This study proposes a novel ATR process that integrates ASU and LNG regasification to utilize cold energy as an operating utility for hydrogen production, resulting in improved overall efficiency. Optimal performance of the system with a feed stream of 827.5 kmol/h LNG produces 2508.0 kmol/h of hydrogen gas with a purity of 99.2%, reducing exergy destruction by 18.6% and achieving an exergy efficiency approximately 25.4% higher than that of the SMR process. An economic evaluation using net present value (NPV) shows the proposed system has a NPV of 338.9 million USD, which is 72.6% higher than hydrogen production with the SMR process from LNG.

INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH (2021)

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Article Energy & Fuels

How green is blue hydrogen?

Robert W. Howarth et al.

Summary: Despite the lower carbon dioxide emissions, the greenhouse gas emissions from the production of blue hydrogen are still quite high due to the release of fugitive methane. The use of blue hydrogen appears challenging to justify on climate grounds, as even with reduced methane emission rates, the emissions are still greater than simply burning natural gas.

ENERGY SCIENCE & ENGINEERING (2021)

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Article Environmental Sciences

2010-2015 North American methane emissions, sectoral contributions, and trends: a high-resolution inversion of GOSAT observations of atmospheric methane

Joannes D. Maasakkers et al.

Summary: This study used GOSAT observations to analyze methane emissions over North America from 2010 to 2015, finding that US anthropogenic methane emissions were slightly higher than EPA estimates, with oil and gas production sectors showing significantly higher emissions. The study also indicated a decreasing trend in wetland emissions, highlighting the need for better understanding of these emissions. Despite discrepancies in emission estimates, the study found an overall increasing trend in US anthropogenic emissions driven by unconventional oil and gas production in the eastern US from 2010 to 2015.

ATMOSPHERIC CHEMISTRY AND PHYSICS (2021)

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Article Environmental Sciences