Mixed-Integer Linear Programming (MILP) Approach for the Synthesis of Efficient Power-to-Syngas Processes

Abstract

Within the context of energy transition scenarios toward renewable resources, superstructure optimization is implemented for the synthesis of sustainable and efficient Power-to-Syngas processes. A large number of reactors (reverse water-gas-shift, steam reforming, dry reforming, tri-reforming, methane partial oxidation reactor, and water electrolyzer) and separators (PSA, TSA, cryogenics, membranes, and gas-liquid scrubbing) are included within a single MILP framework, accounting for typical operating conditions of each process-unit, under the specified simplifying assumptions. Power is minimized in the context of sustainable feedstocks: water and biogas or carbon dioxide from direct air-capture. The objective function adds the thermal to the electrical contribution to the total power, the latter being weighted by a pseudo-price of null (i.e., sustainable, in-house electricity production), or unitary value (i.e., electricity purchased, possibly generated from non-sustainable sources). Simultaneous operations of multiple reactor technologies are allowed to identify possible synergies. With biogas and null value of the pseudo-price, the results identify plant configurations mainly run via electricity, which constitutes up to 97% of the total power for cooperating partial oxidation of methane and water electrolysis. Alternatively, lower total demands are attained at the expenses of thermal duty when electricity is penalized: the endothermic reactors are operated. With carbon dioxide, the total power demand dramatically increases due to the large consumptions of direct-air capture and water electrolysis. The resulting topologies always favor membrane separation, adsorption, and cryogenics over absorption technologies.

Recent advances in direct air capture by adsorption

“…83 Because a DAC facility can provide on-site CO 2 generation anywhere, its application is advantageous in addition to its environmental benefits. Recently, the potential application of adsorption-based DAC in indoor air removal, 115,191,193,208,209 CO 2 fertilization, 178,210 biomass production, [211][212][213][214][215] fuel production (CH 4 , 68,70,75,[216][217][218][219][220][221][222] methanol, 71,[223][224][225][226] aviation fuel, 73,[227][228][229][230][231][232] hydrocarbons 233 ), chemicals (Fischer-Tropsch process, 234,235 carbon nanotubes, 236 dimethyl carbonate, 237 syngas 238,239 ), mineralization, [240][241][242][243][244] storage, 245,246 enhanced oil recovery (EOR), …”

Remote Renewable Hubs for Carbon-Neutral Synthetic Fuel Production

“…Mass and energy balances are also enforced between interconnected plants in order to guarantee consistency of flows at system level. Such approaches, which usually rely on LP or MILP models, have for instance been applied to the design of integrated biorefineries (Kokossis et al, 2015), the design of power-to-syngas processes (Maggi et al, 2020) and power-tochemicals networks (Schack et al, 2016;Liesche et al, 2019). Such an approach is adopted in this paper, as discussed next.…”

Remote Renewable Hubs For Carbon-Neutral Synthetic Fuel Production

“…Mass and energy balances are also enforced between interconnected plants in order to guarantee consistency of flows at system level. Such approaches, which usually rely on LP or MILP models, have for instance been applied to the design of integrated biorefineries [32], the design of power-to-syngas processes [33] and power-to-chemicals networks [34,35]. Such an approach is adopted in this paper, as discussed next.…”