Introduction
With the aim of promoting the circular economy and generating solutions to mitigate current environmental problems, the National Hydrogen Centre is working on a project that focuses on the recovery of CO2 to obtain fuels and high-added-value products.
The main innovation of this project lies in the integration of different technologies. The Fischer–Tropsch processes for fuel production, methanol production, anaerobic digestion, oxy-gasification, and electrolysis are included. The gas obtained from oxy-gasification (CO and H2) and AD (CO2) facilities, together with a supply of renewable H2 from an electrolyzer, could be used to feed the Fischer–Tropsch and MeOH plants. On the other hand, the biogas (CH4 and CO2) from AD could feed the upgrading pilot plant for biomethane production. This idea therefore supports a technological system that constitutes a new concept of advanced biomass biorefinery.
Methods
The system consists of different pilot plants that host the following processes:
- Oxy-gasification: This allows synthesis gas to be obtained from lignocellulosic biomass waste. The use of oxygen as a gasifying agent allows a gas with a higher calorific value to be produced. This gas can supply the Fischer–Tropsch and methanol production processes, promoting the production of renewable fuels and methanol (e-fuels).
- Fischer–Tropsch: This is a widely studied process. It is based on the catalytic synthesis of hydrocarbons of industrial interest (gasoline, diesel, kerosene, etc.). Waxes are also obtained, which can be transformed into products with added value.
- Methanol production: This pilot plant produces methanol from the hydrogenation of CO2. Its use as an alternative fuel and H2 carrier is being promoted.
- Anaerobic digestion + biogas upgrading: The Anaerobic Digestion Plant, together with a biogas treatment stage, will enable biogas and biomethane to be obtained from abundant waste in the region, such as agricultural and livestock by-products. This pilot plant could become a source of energy for other facilities, as they will be able to use this sustainable fuel, thereby promoting the concept of the circular economy and reducing the use of fossil fuels. Additionally, CO₂ from biogas could be used in the other plants to produce various renewable fuels.
Furthermore, this project includes the installation of an electrolyzer to meet the H2 requirements of the Fischer–Tropsch, methanol, and biogas upgrading plants, as well as the oxygen required for the oxy-gasification process.
Results
The fundamental objective is to optimize processes for subsequent scaling up to demonstrate that this integrated “biorefinery” concept is a sustainable and technically and economically viable alternative for the production of renewable fuels and energy generation from the available waste or by-products in the surrounding area. CO2 emissions from this technological complex are also significantly reduced by using the synthesis gas obtained in oxy-gasification as a feedstock in Fischer–Tropsch processes and methanol production, as well as using the biogas produced as an energy source in the facilities.
According to the research lines established and in agreement with the different capacities of the pilot plants, the goal is to generate 1.5 kg/h of gasoline and up to 1.5 kg/h of methanol. This will be the result of the valorisation of 50 kg/h of forest biomass in the entrained flow reactor of the oxy-gasification pilot plant. On the other hand, the Anaerobic Digestion Plant will process 100 kg/day of different types of organic waste (agri-food industry waste, municipal solid waste fractions, sewage sludge, etc.), and the upgrading unit will produce 0.13 Nm3/h of biomethane (96%).
It should also be noted that by-products such as digestates, wastewater, waxes, char, and ash will be characterized and processed for their reuse in a way that directly impacts on the population, such as the development of fertilizers that can be applied to the surrounding land.
Conclusions
This technological platform enables the analysis of synergies and process compatibility on an industrial scale, representing a new concept in advanced biomass biorefining. It facilitates the recovery of waste and by-products, providing economic and social benefits to the local area. Furthermore, the portable design of these pilot plants enables companies and research centres requiring these capabilities to find solutions.
