ERTC 2023 Conference Newspaper

ERTC 2023

Conversion to a green refinery configuration: Assessing options, risks, and viability

Scott Sayles and Robert Ohmes Becht

Introduction In order to meet the mandates of the Paris Agreement, as well as carbon intensity and greenhouse gas emission reductions, fos- sil fuel-based transportation fuels will be substituted by a combination of electric vehicles, bio-derived and renewable fuels. Existing refining and petrochemical assets are key elements in this equation, and there is a need to examine processing and con- figuration options to align to the new feed- stock and product profiles as well as energy input options. Those entities that are able to meet the changes in this dynamic market while remaining profitable will continue as viable enterprises. Framing Renewable Fuels Challenge The regulatory environment provides the economic structure for the viable conver- sion of fossil fuel refineries into biorefin- eries (see Figure 1 ). The first step in the conversion is removing carbon from fired sources, while the reduction of fossil feed- stocks and replacement with bio-feeds and renewable sources will occur over a longer duration. The power requirements of the refin- ery will be satisfied from green sources or highly integrated systems. Electricity will increasingly be generated from low-carbon sources such as wind turbines, solar pan- els, and nuclear energy. The co-processed steam from gasification or steam meth- ane reforming (SMR) and/or auto thermal reforming (ATR) operations will supplant the steam from on-demand boilers, thereby reducing fired duty. At the same time, hydrogen will replace fossil fuel combustion in higher-temperature furnaces. Reducing pre-combustion emissions entails the removal of carbon from the fuel gas system. Pre-combustion configu- rations are summarised in Figure 2 . Post- combustion removal uses either chemical or physical separation technologies to remove the CO₂ from the flue gases. Refining Schemes Biorefinery schemes start with the avail- able technologies and are feed-depend- ent, as shown in Figure 3 . The renewable challenge is to get feedstock to the pro- cessing facilities on a scalable basis, along with associated costs and a sustainabil- ity basis. Seed oils are the easiest of the potential feeds but are in competition with the food supply and are not a long-term viable option. The third-generation feeds, such as wood waste or municipal waste, require further upgrading, and the current challenge is to create a sufficient supply of those feedstocks. Feed and Product Possibilities A refinery effectively takes low H/C fos- sil crudes or biomass and converts them into high H/C ratio products using hydro- gen addition and/or carbon rejection processes:

100%

• Fast pyrolysis : The use of fast pyrolysis converts biomass into a liquid that is high in water content and oxygen compounds. The pyrolysis oil and fossil fuel are not compatible and, when mixed, produce a sediment that fouls equipment. As such, this is not a recommended option. • Gasification : Gasification converts all carbon-containing molecules into hydrogen, CO (syngas), and CO₂. The products are further converted to additional hydrogen or, via Fischer-Tropsch reactions, into many different molecular combinations. • Hydrothermal liquefaction : Hydro- processing thermal liquefaction (HTL) is an upgrading option to convert biomass at moderate temperatures and high pressure via depolymerisation and deoxygenation to simpler molecules. • Refinery feeds : In general, fossil feeds and renewable feeds are not compatible, thereby requiring separate processing until the renewable oxygen content is reduced to nearly zero. Options The conceptual configuration for the biore- finery depends on the viewpoint and risk profile of the operator. Table 1 gives exam- ples of biorefineries and the progression to the scale required to meet the current transportation fuel demand. u Renewable process train : The renewa- ble feeds from triglycerides are processed in a pretreatment unit (PTU) and then directly into the hydroprocessing units. v Hydrogen demand increase and hydro- gen supply options : Hydrogen demand and generation are anticipated to increase from the current capacity of 2.5 mtpa to 9 mtpa, with a drive to shift to lower emission tech- The renewable challenge is to get feedstock to the processing facilities on a scalable basis, along with associated costs and a sustainability basis

Scope 1, 2 & 3

Conversion to bio refinery

Scope 2

Zero carbon emissions

Scope 1

The nal biofuel renery conguration is dependent on the feeds and transportation fuel state. Biomass pre - processing is critical. Siting of the pre - processing system : eld or renery? Types of feeds : seed oil, celluloses, pyrolysis?

2022

2030

2050

Approach to zero carbon emissions

Figure 1 Roadmap to a biofuel refinery

• Cashew nut oil • High oleic sunflower oil extract • Animal fat • Brown grease • Tall oil pitch • Wastewater oil collections (fats, oil, and grease, or FOG). w Lignocelluloses : Lignocellulosic mate- rials like woody biomass and waste are the most difficult to convert and require pre- treating to remove contaminants prior to entering the refinery.

u Triglycerides: A reasonable scale bio- feed facility would be in the 250 tkpa to 3 mtpa range. The best possible economic outcome is to leverage existing fossil fuel refineries and supply chains. The feed- stocks are different enough in composition that the feedstock storage considerations need modification. v Advanced renewables : Feeds not read- ily processed using current technology are considered advanced renewable feeds, such as:

Post - combustion carbon capture

Cryogenic Membranes

Absorption

Adsorption Pressure or temperature s wing d esign

Physical

Chemical

Gas absorption

Gas separation

Alumina

Zeolite Activated carbon

Dimethyl ethers

Amines

Chilled ammonia

Caustic

Others

Post - combustion removes the carbon after burned FG2 FG3 FG4 FG5

Flue gas or vent

FG1

FG5+n

Total FG

Total ue gas + air

Pre - combustion removes the carbon prior to burning 2 3 4

Unit No

5+n

Fired heaters

Boilers

Other sources

R3 R5 Pre - combustion fuel or combustion gas R4

CO pph

R5+n

Oxygen

H production

Cryogenic pure oxygen

Membranes enriched air

SMR with CO capture

Gasication

Figure 2 Pre- and post-combustion carbon removal

Name

Status

Size,

Notional capital cost,

Comments

TPA

$/kT PA

Cellulosic biorefinery

Demonstration

<250,000

3,600-13,200

US DOE

Corn ethanol

Commercial Commercial

250,000-500,000 370,000-7,500,000

750-1,600

Many sites

Fischer-Tropsch (FT), gas to liquid (GTL)

3,250-19,000

China, SASOL South Africa, GTL proposed in Louisiana 96,000 BPD, Shell Qatar

Hydroprocessing Hydrocracking

Suggested processing options

Catalytic cracking (FCC) processes

Renewable feed refinery

Commercial

500,000-2,800,000

560-2,100

TotalEnergies Provence, ENI Venice, Chevron, Rodeo,CA Refinery & Marathon Dickinson, ND & Martinez, CA

Pyrolysis/thermal cracking

Fossil refinery conversion

Feasibility study

All

Unknown

Part of the 2050 zero

to biorefinery

initiative

Expected liquid (Vol % recovery)

Figure 3 Hypothetical renewable diesel liquid vs carbon efficiency

Table 1 Examples of biorefineries and progression required for the scale to meet current transportation fuel demand