Environmental and health impact assessment of Liquid Organic Hydrogen Carrier (LOHC) systems – challenges and preliminary results

Abstract

Liquid Organic Hydrogen Carrier (LOHC) systems offer a very attractive way to store and transport hydrogen, a technical feature that is highly desirable to link unsteady energy production from renewables with the vision of a sustainable, CO 2 -free, hydrogen-based energy system. LOHCs can be charged and discharged with considerable amounts of hydrogen in cyclic, catalytic hydrogenation and dehydrogenation processes. As their physico-chemical properties are very similar to diesel, today's infrastructure for liquid fuels can be used for their handling thus greatly facilitating the step-wise transition from today's fossil system to a CO 2 emission free energy supply for both, stationary and mobile applications. However, for a broader application of these liquids it is mandatory to study in addition to their technical performance also their potential impact on the environment and human health. This paper presents the first account on the toxicological profile of some potential LOHC structures. Moreover, it documents the importance of an early integration of hazard assessment in technology development and reveals for the specific case of LOHC structures the need for additional research in order to overcome some challenges in the hazard assessment for these liquids. Broader contextDue to increasing environmental awareness, many countries try to optimize their economies for a low-carbon growth turning towards renewable energy sources. Nevertheless, to fully exploit these sources fundamental change in our energy supplies is needed. Hydrogen is considered a main player in future energy systems, especially for mobile applications but its storage poses a technological challenge. Liquid Organic Hydrogen Carrier (LOHC) systems offer a very attractive way to store and transport hydrogen that links unsteady energy production from renewables with the vision of a sustainable, CO 2 -free, hydrogen-based energy system. LOHCs can be charged and discharged with considerable amounts of hydrogen in cyclic, catalytic hydrogenation and dehydrogenation processes. As their physico-chemical properties are very similar to those of diesel, today's infrastructure for liquid fuels can be used for their handling thus greatly facilitating the step-wise transition from today's fossil system to a CO 2 emission free energy supply for both, stationary and mobile applications. However, for a broader application of these liquids it is mandatory to study in addition to their technical performance also their potential impact on the environment and human health.

Hydrogenation of the liquid organic hydrogen carrier compound dibenzyltoluene – reaction pathway determination by 1H NMR spectroscopy

“…According to eqn (5), the sum of all fractions for the different types of hydrogen atoms is 1. Thus, if three fractions are known, the fourth can be calculated according to eqn (5). For this study, the fractions of %CS [7. The fractions of the chosen chemical shift integrals were calculated for all Hx-DBT species and are shown in Table 2.…”

“…Other important selection criteria for suitable LOHC systems are derived from economic, safety, environmental and health impact assessments. 5 During the hydrogen storage process, the hydrogen-lean LOHC compound is transformed into the hydrogen-rich compound by a catalytic hydrogenation reaction. The hydrogenated compound of the LOHC system can be stored 6 and transported 7 in large quantities with no energy losses over time for a later release of hydrogen and energy on demand, i.e.…”

Adsorption Isotherm of Dibenzyl Toluene and its Partially Hydrogenated Forms Over Phenyl Hexyl Silica

“…Due to the chemical bonding of the hydrogen in the hydrogenated LOHC compound, the latter can store H 2 at ambient conditions over longer periods. Recent studies shows the potential of dibenzyltoluene (H0-DBT) as a competitive LOHC system due to its reasonable hydrogen storage capacity and thermal stability [5,6]. Each H0-DBT molecule can store 9 molecules of hydrogen in the form of octadecahydrodibenzyltoluene (H18-DBT).…”

“…This concept is based on the reversible cycle of hydrogenation and dehydrogenation for uptake and release of hydrogen [1][2][3][4][5]. The LOHC system consists of a pair of dehydrogenated and hydrogenated compounds representing the hydrogen lean and rich forms, respectively.…”

Immobilization and Characterization of SiO₂-supported Ir-complex Catalyst for Practical Hydrogen Generation from Formic Acid

“…However, H2 gas is difficult to handle and store because of the high risk of explosion. Consequently, H2 conversion into some other chemical substance has been proposed in recent years 1), 2) . Chemical H2 storage materials, called hydrogen carriers, have high density and volume storage capacities, together with safe and easy handling characteristics.…”