Solar fuels from supercritical water gasification of algae: Impacts of low-cost hydrogen on reformer configurations

Alireza Rahbari, Alec Shirazi, Mahesh B. Venkataraman and John Pye

Applied Energy, 2021, vol. 288, issue C, No S0306261921001550

Abstract: Liquid transport fuels produced from biomass are of growing importance, due to increasingly ambitious targets for CO2 emissions reduction. However, a mismatching hydrogen-to-carbon ratio in biomass feedstocks, versus that required for conventional fuels, requires that supplementary hydrogen be added or surplus carbon be removed in the production process, with many possible process configurations. Here, we consider these alternative configurations for a process incorporating a supercritical water gasification reactor, syngas reformer and downstream Fischer–Tropsch liquid fuel synthesis unit. The feedstock is microalgae, process heat is supplied using a concentrating solar-thermal collector, and additional hydrogen is supplied from photovoltaics-powered electrolysers. Using a dynamic techno-economic process model to capture solar resource dynamics, configurations are optimised for lowest produced fuel cost. Three syngas reformer types are considered: steam methane reforming (SMR), with solar heat driving the conversion of CH4 into syngas; partial oxidation/dry reforming (PO/DR), with added hydrogen instead serving that same purpose; and autothermal reforming (ATR), combining both H2 and heat. Furthermore, for SMR, both CO2 dumping and H2 addition cases are considered. At present-day 9.72 AUD/kg hydrogen costs, SMR with CO2 dumping is cheapest, yielding gasoline equivalent at 3.76 AUD/L. With cheaper hydrogen, the optimal configuration shifts to SMR with H2 addition, then ATR, then PO/DR, reaching a fuel cost of 2.99 AUD/L at H2 cost of 2.1 AUD/kg. The design of future biofuels processes will depend greatly on the cost of hydrogen.

Keywords: Concentrated solar power; Supercritical water gasification; Reforming; Fischer–Tropsch synthesis; Techno-economic optimisation (search for similar items in EconPapers)
Date: 2021
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (4)

Downloads: (external link)
http://www.sciencedirect.com/science/article/pii/S0306261921001550
Full text for ScienceDirect subscribers only

Related works:
This item may be available elsewhere in EconPapers: Search for items with the same title.

Export reference: BibTeX RIS (EndNote, ProCite, RefMan) HTML/Text

Persistent link: https://EconPapers.repec.org/RePEc:eee:appene:v:288:y:2021:i:c:s0306261921001550

Ordering information: This journal article can be ordered from
http://www.elsevier.com/wps/find/journaldescription.cws_home/405891/bibliographic
http://www.elsevier. ... 405891/bibliographic

DOI: 10.1016/j.apenergy.2021.116620

Access Statistics for this article

Applied Energy is currently edited by J. Yan

More articles in Applied Energy from Elsevier
Bibliographic data for series maintained by Catherine Liu ().