Halophyte Plants and Their Residues as Feedstock for Biogas Production—Chances and Challenges

Abstract

The importance of green technologies is steadily growing. Salt-tolerant plants have been proposed as energy crops for cultivation on saline lands. Halophytes such as Salicornia europaea, Tripolium pannonicum, Crithmum maritimum and Chenopodium quinoa, among many other species, can be cultivated in saline lands, in coastal areas or for treating saline wastewater, and the biomass might be used for biogas production as an integrated process of biorefining. However, halophytes have different salt tolerance mechanisms, including compartmentalization of salt in the vacuole, leading to an increase of sodium in the plant tissues. The sodium content of halophytes may have an adverse effect on the anaerobic digestion process, which needs adjustments to achieve stable and efficient conversion of the halophytes into biogas. This review gives an overview of the specificities of halophytes that needs to be accounted for using their biomass as feedstocks for biogas plants in order to expand renewable energy production. First, the different physiological mechanisms of halophytes to grow under saline conditions are described, which lead to the characteristic composition of the halophyte biomass, which may influence the biogas production. Next, possible mechanisms to avoid negative effects on the anaerobic digestion process are described, with an overview of full-scale applications. Taking all these aspects into account, halophyte plants have a great potential for biogas and methane production with yields similar to those produced by other energy crops and the simultaneous benefit of utilization of saline soils.

Biochemical Profile and In Vitro Therapeutic Properties of Two Euhalophytes, Halocnemum strobilaceum Pall. and Suaeda fruticosa (L.) Forske., Grown in the Sabkha Ecosystem in the Algerian Sahara

“…The ash content reflects mineral and inorganic compounds such as mineral salts, which are essential for the plant. The ash content of traditional grass is about 5 to 10% [20], but halophytes in general have a higher ash content than other plants [21]. This is consistent with the findings of this study, where the ash content ranged from 20 to 30%.…”

Pentacyclic triterpenoids saponins pannosides A-E from Tripolium pannonicum

“…Typically, the plant thrives on saline soils, including salt marshes, salt meadows, and other regions with high salt concentrations (Cacador et al, 2016). It has been studied primarily from an ecological or nutritional perspective (Szymańska et al, 2015;Turcios et al, 2021; ) but rarely has research been undertaken on a single chemical compound; nevertheless, compounds such as quercetin, luteolin, apigenin, and caffeoylquinic acid have been reported (Wubshet et al, 2013). In our ongoing halophyte metabolite screening study, previously unknown saponins, pannoside A-E (1-5), were isolated from the whole plant of T. pannonicum, which are the first saponin compounds isolated from the plant.…”

Rock Samphire, a Candidate Crop for Saline Agriculture: Cropping Practices, Chemical Composition and Health Effects

“…Therefore, sea fennel is a plant with multiple uses since it can be grown as a vegetable or ornamental species, while its essential oil can be used in various industry sectors, e.g., the production of bio-pesticides that can be applied for insect control in organic cropping systems or the production of biogas [31]. Thus, the aim of this review is to compile the recent information about the chemical composition and the active constituents of the various plant parts of C. maritimum.…”