Comment on "How green is blue hydrogen?"

This paper is written in response to the paper “How green is blue hydrogen?” by R. W. Howarth and M. Z. Jacobson. It aims at highlighting and discussing the method and assumptions of that paper, and thereby providing a more balanced perspective on blue hydrogen, which is in line with current best available practices and future plant specifications aiming at low CO2 emissions. More specifically, in this paper, we show that: (i) the simplified method that Howarth and Jacobson used to compute the energy balance of blue hydrogen plants leads to significant overestimation of CO2 emissions and natural gas (NG) consumption and (ii) the assumed methane leakage rate is at the high end of the estimated emissions from current NG production in the United States and cannot be considered representative of all-NG and blue hydrogen value chains globally. By starting from the detailed and rigorously calculated mass and energy balances of two blue hydrogen plants in the literature, we show the impact that methane leakage rate has on the equivalent CO2 emissions of blue hydrogen. On the basis of our analysis, we show that it is possible for blue hydrogen to have significantly lower equivalent CO2 emissions than the direct use of NG, provided that hydrogen production processes and CO2 capture technologies are implemented that ensure a high CO2 capture rate, preferably above 90%, and a low-emission NG supply chain

Comment on “How green is blue hydrogen?”

This paper is written in response to the paper “How green is blue hydrogen?” by R. W. Howarth and M. Z. Jacobson. It aims at highlighting and discussing the method and assumptions of that paper, and thereby providing a more balanced perspective on blue hydrogen, which is in line with current best available practices and future plant specifications aiming at low CO2 emissions. More specifically, in this paper, we show that: (i) the simplified method that Howarth and Jacobson used to compute the energy balance of blue hydrogen plants leads to significant overestimation of CO2 emissions and natural gas (NG) consumption and (ii) the assumed methane leakage rate is at the high end of the estimated emissions from current NG production in the United States and cannot be considered representative of all-NG and blue hydrogen value chains globally. By starting from the detailed and rigorously calculated mass and energy balances of two blue hydrogen plants in the literature, we show the impact that methane leakage rate has on the equivalent CO2 emissions of blue hydrogen. On the basis of our analysis, we show that it is possible for blue hydrogen to have significantly lower equivalent CO2 emissions than the direct use of NG, provided that hydrogen production processes and CO2 capture technologies are implemented that ensure a high CO2 capture rate, preferably above 90%, and a low-emission NG supply chain

Overall Process Analysis and Optimisaton for CO2 Capture from Coal Fired Power Plants basen on Phase Change Solvents Forming Two Liquid Phases

In this work the potential of a novel post-combustion CO2 capture process is analysed with respect to the integrated overall process. As solvent a blend of two amines (DEEA/MAPA) which forms two liquid phases under CO2 loading is used. The two phases have distinct physical characteristics. Only the heavy phase, rich in CO2 loading, is led to the desorber. The novel solvent combination promises very low energy consumption compared to a 30 wt.-% MEA solution. The efficiency penalty, taking into account the integrated overall process, is very low too. Furthermore, different integration configurations in the overall process are investigated to show the effect in greenfield and retrofit power plant cases

Psychological factors and their impact for the implementation of information techology in education and training - experiences of the ELECTRA-Project

In this work the potential of a novel post-combustion CO2 capture process is analysed with respect to the integrated overall process. As solvent a blend of two amines (DEEA/MAPA) which forms two liquid phases under CO2 loading is used. The two phases have distinct physical characteristics. Only the heavy phase, rich in CO2 loading, is led to the desorber. The novel solvent combination promises very low energy consumption compared to a 30 wt.-% MEA solution. The efficiency penalty, taking into account the integrated overall process, is very low too. Furthermore, different integration configurations in the overall process are investigated to show the effect in greenfield and retrofit power plant cases.<p>Attribution-NonCommercial-NoDerivs 3.0 Unported (CC BY-NC-ND 3.0)</p

Density measurements and modelling of loaded and unloaded aqueous solutions of MDEA (N-methyldiethanolamine), DMEA (N,N-dimethylethanolamine), DEEA (diethylethanolamine) and MAPA (N-methyl-1,3-diaminopropane)

<p>NOTICE: this is the author’s version of a work that was accepted for publication in International Journal of Greenhouse Gas Control. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in International Journal of Greenhouse Gas Control, VOL 25 , June 2014 DOI:10.1016/j.ijggc.2014.04.017</p

eNRTL Parameter Fitting Procedure for Blended Amine Systems: MDEA-PZ Case Study

<p>Attribution-NonCommercial-NoDerivs 3.0 Unported    (CC BY-NC-ND 3.0) </p

VLE data and modelling of aqueous N,N-diethylethanolamine (DEEA) solutions

This work focuses on N,N-diethylethanolamine (DEEA), a tertiary amine relevant in the phase-change solvents context. Vapour liquid equilibrium data for CO2 loaded aqueous solutions of DEEA are presented. These, along with data for pure DEEA and the binary system H2O-DEEA available in literature, are represented by a model correlating the activity coefficients with the electrolyte non-random two-liquid (eNRTL) model. The model is shown to represent the experimental data well. The equilibrium model allows for simulating the regeneration of the solvent, thereby providing a measurement for the energy demand of the process. Experimental heat of absorption data presented by Kim (2009) are used to validate the predictions of the model

Kinetics of CO2 Absorption by Aqueous 3-(methylamino)propylamine Solutions: Experimental Results and Modeling

Experimental data and a model for the initial kinetics of CO2 into 3-(methylamino)propylamine (MAPA) solutions are presented in work. MAPA has been tested as an activator for tertiary amines with encouraging results. The measurements were performed in a string of discs contactor and, as no initial kinetics data are available in literature, additional measurements were carried out and in a wetted wall column. The obtained overall mass-transfer coefficients from both apparatuses are in reasonable agreement. To obtain values for the observed kinetic constant, inline image, the experimental results were interpreted using a two-film mass-transfer model and invoking the pseudo-first order assumption. Needed experimental values for density, viscosity, and Henry's law coefficient for CO2 were measured and are given. The results indicate that MAPA is almost twice as fast as piperazine, eight times faster than 2-(2-aminoethyl-amino)ethanol (AEEA), and 15 times faster than monoethanolamine, when comparing unloaded 1 M solutions at 25°C. The observed kinetic constant was modeled using the direct mechanism. The final expression for inline image can be applied for any concentration and temperature within the experimental data range, and, together with the presented physical data, comprises a complete model for calculating absorption fluxes. © 2014 American Institute of Chemical Engineers AIChE J, 60: 3792–3803, 201