Thermal Gasification

Mature technology needing more support to scale-up

High-maturity technology retains potential for further optimization
Thermal gasification is a versatile gas production technology that can utilize dry biomass or Municipal Solid Waste (MSW). These feedstocks are heated to 1000°C with a controlled amount of oxygen to break down organic molecules to produce syngas (consisting of hydrogen, carbon dioxide, and carbon monoxide). The syngas then undergoes methanation and purification steps to produce biomethane (or Bio-SNG).

Figure 1 – Thermal gasification with biomethane synthesis process flow

The technology is at Technology Readiness Level 8, since all steps of the process have demonstrated commercially in other industrial and energy production processes. The major challenge behind scaling-up the technology is centered around the optimization of the process that would increase the efficiency, which is today around 60%-65%. However, an increase in efficiency of 20% could potentially be achieved if pyrolysis stage heat is recovered and reinjected into the process.³

Thermal gasification is not considered yet as a priority by public authorities
Several demonstration-scale projects were announced in recent years in Europe, of which some are already in operation, including the flagship project “Gaya”, which has undergone extensive testing to assess the performance and feasibility of the technology in the French energy context. Such projects have recently been benefiting from a regulatory sandbox, which allows developers to perform broader experiments to match the closest possible market conditions. This regulatory push is being acknowledged by public authorities who recognize the potential of the technology and the role it might play in decarbonizing the gas mix.

However, the sector is still in the process of early development, implementing several pilot projects whose objective is the production of low-carbon gas for injection into the gas network. Although the recent progress that has been made over the past months, low-carbon gas from thermal gasification is still not considered as one of the main technologies that will help to reach net-zero by 2050. Public authorities are not granting it a key role within the national decarbonization strategies, whether in Programmation Pluriannuelle de l’Énergie (PPE) or in Stratégie Nationale Bas-Carbone (SNBC). Consequently, the sector does not benefit from subsidies or financial aid in the same way as low-carbon gas produced from anaerobic digestion or direct combustion of biomass, which reduces its competitiveness today.

Figure 2 - Thermal gasification projects and status.⁴

Large production capabilities: Up to 2.5 bcm in 2030 and 11.8 bcm potential by 2050

Considering all the energy and non-energy usages of dry biomass and MSW, where a considerable portion is currently allocated to direct combustion of biomass (around 90% of the energy use), analysis performed by Guidehouse has shown a potential ranging from 17 million tons (Mt) to 30 Mt of feedstock by 2050 that could be mobilized to produce green gas from thermal gasification. This potential will ultimately depend on the demand level, Levelized Cost of Energy (LCOE) reduction, as well as regulatory and incentive framework development that would play a significant role in increasing the competitiveness of the technology. 

This potential corresponds to a production level up to 2.5 bcm in 2030 and up to 11.8 bcm in 2050, as shown in Figure 3. 

Figure 3 - Thermal gasification potential projection in France to 2050

Despite today’s low volumes...low-carbon gas from thermal gasification offers numerous economic, technical, and environmental advantages for end consumers 

Available volumes to be scaled up
Demand players, primarily industrials, have expressed strong interest in deploying low-carbon gases in their processes, provided sufficient volumes are available and that the technology is economically competitive. However, besides the fact that thermal gasification projects have recently been given some space to undergo broader experimentations on real-time market situations, there were no viable signs showing that the market is expected to rapidly grow in the short term. As a result, industrials have no warranties to engage an energy transition strategy primarily based on network-based low-carbon gas and rather focus on other competitive technologies that are highly subsidized.

Given today’s limited volumes, industrials are currently not considering network-based low-carbon gas in their short-term transition strategies (up to 2030). However, they are intending to include it in their mix, either as a permanent solution, in case techno-economic viability is optimal, or at least as a transition solution, primarily within processes where green hydrogen and electric solutions are expected and preferred but not yet available.

Indeed, there is a significant need to scale-up to achieve a higher part in the gas mix (see our recommendations at the end). In the short term, this means that projects under development need to be supported, primarily projects under preliminary assessment that would need technical and financial support from different stakeholders to move to the development phase.

LCOE is still not competitive, even though a significant reduction is already expected

Figure 4 – Projected LCOE for thermal gasification and alternative technologies

For industrial heat production, direct biomass combustion has the lowest LCOE when compared with alternative technologies, as represented in Figure 4. Being mature, the expected cost decrease of direct biomass combustion is only based on a slight improvement in the efficiency of the boilers, as well as on the change in the price of feedstock, which is very uncertain but likely to increase due to the increase in demand, and likely more stringent sustainability criteria that will be applied over time.

As for anaerobic digestion and thermal gasification, production cost is expected to decrease due to scale effect and an easier network injection process, while the uncertainty remains around feedstock (woody biomass + MSW) cost that we expect to increase due to increased demand and competition (e.g., Sustainable Aviation Fuels production). The cost reduction of thermal gasification is, however, expected to be higher, since the gap to optimal maturity is bigger than that facing anaerobic digestion, which will only see some modest increases in process efficiency. In addition, this technology has also benefited from different incentives and is particularly promoted by a few EU governments that several years ago decided to scale-up anaerobic digestion gas capacities.

Consequently, the investment capacity growth and scale economies are expected to benefit more for thermal gasification, as it has a bigger development potential in the short and medium terms, resulting in a higher cost reduction compared with anaerobic digestion.

Figure 5 – Operating temperatures vs. technologies

The flexibility of thermal gasification for network injection purposes represents a considerable advantage over direct biomass combustion, which typically provides heat production over a relatively limited temperature range (up to 800°C). Biomethane from thermal gasification offers diverse usages: fuel for combustion in energy and manufacturing industries, a reagent within chemical reactions, as well as usage as a fuel in alternative mobility.

Heat generated by biomass combustion is not adapted to high-temperature and energy-intensive processes such as steel, cement, and glass, as seen in Figure 5. It is rather favored in other sectors that require thermal energy at relatively lower temperatures (paper, food, etc.).

Other solutions may be preferred in energy-intensive processes such as electric furnaces/boilers or through green hydrogen usage. However, optimal techno-economic maturity of these solutions will likely not be achieved in the short and medium run.

Therefore, substitution of natural gas with green gas in several sectors that are relying on gas boilers appears to be one of the most attractive solutions, particularly in high-temperature processes, such as for iron reduction within the steel sector, where temperatures are reaching up to 1000°C or glass production where temperatures can reach 1500°C.

Using low-carbon gas from the network offers better resiliency and energy access
The gas infrastructure allows an almost uninterrupted supply for its customers with an unplanned outage time of 0.07 minutes per year/customer (as opposed to 4 minutes per year/customer for electricity network). Thermal gasification-injected gas thus offers much better resiliency compared with biomass boilers that need to be supplied by trucks, which may be more susceptible to being impacted by logistics problems (e.g., resulting from bad weather).

In addition to the adaptation needs that are necessary to move from a fuel/gas boiler to a biomass one, several risks regarding the continuity of biomass-sourced heat production should be considered, primarily around scheduled maintenance periods for which manufacturers must have backup solutions to supply their process or even unplanned interruptions due to technical problems (quality of inputs for MSW installations, etc.).

Significant environmental benefits of using thermal gasification gas

Figure 6 – GHG emissions of thermal gasification and alternative solutions⁵

Thermal gasification and direct biomass combustion have a favorable environmental balance compared to natural gas, considering the entire value chain (e.g., production/supply, conversion, transport, and combustion), and able to meet and in some cases far exceed the minimum GHG thresholds set under the European Renewable Energy Directive II for heat production: 70% less emissions compared to fossil fuel reference⁶ in 2021 and 75% in 2026.

The GHG balance of biomass direct combustion varies significantly by feedstock type, as represented in Figure 6, primarily due to the difference in the production/supply phase of some inputs that go through more energy-intensive processes to covert the biomass into a densified wood pellet. It is also important to note that thermal gasification goes through a conversion process to transform biomass into gas prior to injection, which accounts for the biggest part of the process emissions, in contrast with biomass combustion, which is directly burned to produce heat.

The transport phase balance is considered as advantageous for thermal gasification since the injected gas takes advantage of the gas network flexibility, which allows gas transport over large distances. This allows thermal gasification plants to be geographically centralized and close to biomass supply zones, allowing relatively short distances for road transport to supply biomass resources. As for direct biomass combustion, plants need to be closer to consumption areas, since heat networks only allow short distances heat transport. As a result, it is requiring more geographic distribution of combustion units and therefore significant road transport capabilities for feedstock supply.

As for combustion, CO2 combustion emissions are considered zero, both for biomass-sourced thermal gasification and for biomass direct combustion, as the CO2 that is released is assumed to be sequestered during the growth of the biomass. However, non-CO2 greenhouse gas emissions (CH4 and N2O) are accounted in CO2 emissions for both production processes.

Our recommendations to scale

1. Gain consumer confidence
   Develop a strategy to increase industrial consumers’ confidence. Work with consumers AND industry associations (ex: France Chimie, Union des Industries Utilisatrices d’Énergie). 
   A- Define the needs and propose a production structure to guarantee the production levels needed countrywide.
   B- Promote the benefits of thermal gasification and work together to build Sector Transition Plans or decarbonization pathways.
   
   
2. Quantify benefit
   Quantify the benefits from energy system and social perspectives (investment optimization, better use of public support actions, economic development).
   
   
3. Collaboration with public authorities
   Set up a joint plan with the governmental bodies and agencies that elaborate and execute low-carbon energy roadmaps (Direction Générale des Entreprises, Direction Générale de l’Énergie et du Climat, ADEME) as well as with other local authorities (e.g., regions) to present the benefits and to give thermal gasification a bigger role in French energy transition strategy.
   
   
4. Create scale effect
   Propose a plan to create scale effects on the production side. Plan for private and public R&D to increase the maturity, size, and number of facilities, and quantify and define the necessary skills.
   
   
5. Create subsidies to build demand
   Generate demand with targeted, supported local projects (e.g., purchase obligation), and at least reduce the competitiveness gap with subsidized biomass.
   
   
6. Propose specific targets and actions
   Propose targets and actions to be implemented within national strategies: SNBC (pre- and post-2030) and PPE.

This article was co-authored by Guidehouse’s Al Abbas Lamrini and Romain Capaldi.

Sources:

¹European Biogas Association

²18.4 bcm if both biogas and biomethane capacities are considered. Some of the biogas capacities could be upgraded to produce biomethane as well.

³Association Technique Energie Environnement.

⁴GRTgaz.

⁵Guidehouse, Biomass Thermal Energy Council, Gaya Project, Agence de la Transition Ecologique (ADEME).

⁶Fossil Fuel Reference for heat production in RED II is 288 gCO2eq/KWh (80 gCO2eq/MJ).