SunCHem: an integrated process for the hydrothermal production of methane from microalgae and CO2 mitigation

Abstract

We describe a potential novel process (SunCHem) for the production of bio-methane via hydrothermal gasification of microalgae, envisioned as a closed-loop system, where the nutrients, water, and CO 2 produced are recycled. The influence on the growth of microalgae of nickel, a trace contaminant that might accumulate upon effluent recycling, was investigated. For all microalgae tested, the growth was adversely affected by the nickel present (1, 5, and 10 ppm). At 25 ppm Ni, complete inhibition of cell division occurred. Successful hydrothermal gasification of the microalgae Phaeodactylum tricornutum to a methane-rich gas with high carbon gasification efficiency (68-74%) and C1-C3 hydrocarbon yields of 0.2 g C1-C3 /g DM (DM, dry matter) was demonstrated. The biomass-released sulfur was shown to adversely affect Ru/C catalyst performance. Liquefaction of P. tricornutum at short residence times around 360°C was possible without coke formation.

Microalgal Biotechnology: Prospects and Applications

“…Microalgae have attracted a great deal of attention for CO2 fixation and biofuel production because they can convert CO2 (and supplementary nutrients) into biomass via photosynthesis at much higher rates than conventional biofuel crops can. This biomass may then be transformed into methane or hydrogen, using processes mediated by anaerobic bacteria; an integrated process for hydrothermal production of methane via microalgae has been discussed recently [111][112]. Of particular interest is the production of oils by microalgae because of the ease of their synthesis (a lack of a nitrogen source usually suffices to trigger this form of secondary metabolism).…”

Optimal process design for the polygeneration of SNG, power and heat by hydrothermal gasification of waste biomass: Process optimisation for selected substrates

“…A decomposition-based modelling approach is then [19] for a mixture of wet primary and secondary sludges. Ash content is based on digested sludge from ECN [20, ID 2810], from which the one for undigested sludge is determined via a digester mass balance [19] c ID 2190 from ECN [20] d residue of ethanol production from lignocellulosic biomass [21] e Phaeodactylum tricornutum [22] adopted to systematically develop candidate flowsheets. First, the thermochemical conversion and the energy requirements of the process units are computed in energy-flow models that are developed in flowsheeting software [10].…”

“…In the latter case, excess heat from the SNG production might thereby also satisfy the requirement for the process (in particular, biomass pretreatment and ethanol distillation), and very favourable effects might emerge from process integration [21]. Finally, microalgae are considered as a photosynthetically efficient energy crop that are cultivable in photobioreactors on marginal land, from which a reduced environmental impact compared to land-based energy crops can be expected [22,35].…”

Catalytic supercritical water gasification of plastics with supported RuO2: A potential solution to hydrocarbons–water pollution problem

“…Ruthenium-based catalysts have been found to be very effective in the conversion of carbonaceous materials, with high carbon gasification efficiencies in moderate-temperature hydrothermal media [3,[8][9][10][11]. Among the ruthenium-based catalyst, the most reported have been Ru/C [12][13][14], Ru/TiO2 [10,15] and Ru/Al2O3 [16][17]. Sometimes it is not clear from literature if the ruthenium had been used in the reduced form or as the oxide.…”