Electrolysis assisted biomassgasification for biofuels production- a technoeconomic perspective

Sennai Mesfun (RISE)Klas Engvall, Carina Lagergren (KTH)Andrea Toffolo (LTU)

Background

2

Biomass gasification-based biofuels

• Scalability of gasifier

• Multiple process steps

GasifierPrimary gas

cleaningReformer WGS

Final gas cleaning

SynthesisBiomass Transport fuel

steamO2/steam steam

CO2

Background

3

Electrolysis assisted biomass gasification

• reduce process steps?

• increase productivity for the same carbon source

GasifierPrimary gas

cleaningMCEC

Final gas cleaning

SynthesisBiomass Transport fuel

steam

CO2

O2+CO2CO2

O2CO2/O2

separation

electricity

Objectives

4

investigate Molten Carbonate

Electrolysis Cell (MCEC) for syngas

conditioning

“To produce knowledge specific to the

operating range, scale and feasibility of

MCEC as an alternative pathway to a

multiple-stage downstream conditioning of

raw-syngas (from biomass gasification) prior

to its synthesis to transport grade biofuel”

extent of linking electricity to liquid fuels

Technology track and scope of work

5

• Host facility – sawmill (generic)

• Molten Carbonate Electrolysis Cell (MCEC)

• Sustainable Aviation Fuel (SAF)Sawmill

Biomass dryingSize reduction

GasificationPrimary gas cleaning

MCECAGR

FTS & upgrading

Biomass Boiler Steam

system

Biofuels

stea

m

thQelW

SAF facility

ByproductsLu

mb

er

thQ

Timber

thQ

+

net,elW

MCEC — operational parameters

• polarization curve

• stack temperature

• methane behavior

• CO2 recycle (anode)

6

CO32- Elektrolyt CO3

2-

Positive electrode (Anode)

Negative electrode (Cathode)H2OCO2

O2: CO2 (1:2)

H2: CO (2:1)

2CO32- " O2 + 2CO2 + 4e- (R3)

H2O + CO2 + 2e- " H2 + CO32- (R1)

H2O + CO D H2 + CO2 (R2)

POWER

MCEC — operational parameters

7

polarization curves stack temperature

stack size

El. use

MCEC — operational parameters

8

methane vs current density methane vs stack temperature

Cases evaluated

9

➢ MCEC integrated with 3 gasification technologies (20 MW LHV

syngas)

▪ WoodRoll (WR, Cortus Energy AB)

▪ Dual Fluidized Bed (DFB, e.g. GoBiGas)

▪ Bubbling Fluidized Bed direct heated (BFB, Andritz Carbona)

➢ 2 process configuration

▪ side-fired steam reformer (SMR)

▪ electric heated steam reformer (eSMR)

➢ Economic indicators: investment and production cost estimates for

the studied cases

BPST

SMR AGR

FTR

Decanter

H

Dryer

Sawn wood

Timber

CO2+O2

steam

Gasifier

flue gas

air

process heat

Cryogenic

O2-rich

CO2

Comp.

MCEC

FTL

FT tailgas

acid gas

el.

steamsteam

process steam

condensate

Biomass boiler

sawdustwoodchips

bark

condensate

𝐎𝟐:𝐂𝐎𝟐(𝟏:𝟐)

Anode

𝟐𝐂𝐎𝟑𝟐− → 𝐎𝟐 + 𝟐𝐂𝐎𝟐 + 𝟒𝒆−

Cathode 𝐇𝟐𝐎 + 𝐂𝐎𝟐 + 𝟐𝐞− → 𝐇𝟐 + 𝐂𝐎𝟑

𝟐−

𝐇𝟐𝐎 + 𝐂𝐎 ↔ 𝐇𝟐 + 𝐂𝐎𝟐

𝐇𝟐𝐎 𝐂𝐎𝟐 𝐇𝟐 𝐂𝐎 𝐂𝐇𝟒

𝐇𝟐:𝐂𝐎(𝟐:𝟏)

𝐂𝐎𝟑𝟐− 𝐄𝐥𝐞𝐜𝐭𝐫𝐨𝐥𝐲𝐭𝐞 𝐂𝐎𝟑

𝟐−

el. CO2_cap.

el.

syngas

water

Process configuration (20 MW LHV syngas)

20 MW14-18 MW

SMR to eSMR

9-13% increase

Carbon balance (Dual fluidized bed)

11

Normalized to carbon in syngas

Carbon balance (Bubbling fluidized bed)

12

Normalized to carbon in syngas

Economic performance

Parameter Unit Value Remark

Biomass SEK/MWh 172.5 mixed bark, sawdust, woodchips

Electricity SEK/MWh 400

Oxygen SEK/ton 600

Scrubber oil SEK/MWh 1060 DFB configuration

Annuity - 0.1 ~20 years, 8% interest

O&M % 3 of Total Fixed Capital Inv. (TFCI)

Production cost

Production cost

Production cost

Concluding remarks

• MCEC activity varies depending on syngas composition & requirements for downstream upgrading, WR<DFB<<BFB

• Syngas yield increase by 15-31% compared to WGS conditioning

• For a given MCEC size, lower current densities pronounce methane content of the syngas, e.g. suitable for SNG process

• Electrification of other process sections can boost carbon efficiency, worth checking electrical heating for the gasification process (DFB & WR)

• Process capital intensive (TFCI ~55% production cost), about 35% TFCI derives from gas conditioning section that include MCEC

17

Thank you for your attention!

Questions?

This project is carried out within the collaborative research program Renewable transportation fuels and systems, financed by the Swedish Energy Agency and f3 Swedish Knowledge Centre for Renewable Transportation Fuels.

www.f3centre.se/en/renewable-transportation-fuels-and-systems/