With the push towards net zero by 2050 accelerating, renewable fuels are being explored and developed to phase out petrochemical fuels. Biofuels are gaining more and more attention as a viable type of fuel for heavy industry and transportation sectors, and research has focused on the manufacture of these types of fuels. A study published online in Frontiers of energy research explored their production from a technical and economic point of view.
To study: Technical-economic analysis of a flexible process concept for the production of transport and heat fuels from biomass and renewable electricity. Image Credit: JH Bispo / Shutterstock.com
The push for renewable energies and fuels to reach net zero
The world is warming due to human activities, which facilitates the need to drastically reduce carbon emissions. Various alternative fuels and energy sources have been explored to meet society’s energy needs, including hydrogen, solid state batteries and biofuels. Biofuels have proven to be particularly attractive as an alternative to petrol and diesel derived from petrochemicals.
Operating modes for the hybrid process concept. Image credit: Habermeyer, F et al., Frontiers in Energy Research
In accordance with the European Union’s Green Deal, significant work is underway to increase the share of renewable energies in the total energy mix to 65% by 2030. Currently, the share of renewable energies stands at 32% , which means that this figure will have to double during this decade.
This presents significant technical and economic challenges for the energy sector in the European Union. Short-term mismatches between supply and demand must be corrected. Studies have shown that an approach that uses a combination of energy storage and flexible demand strategies will be necessary to achieve an efficient energy transition from fossil fuels to renewables.
The transport sector is a major emitter of greenhouse gases. Electrification is only part of the transport sector decarbonization plan, as the energy needs of aviation and heavy transport such as shipping, trains and transportation still require high density liquid fuels. energetic. Therefore, low carbon and renewable alternative fuels and associated technologies require increased attention and deployment by 2030.
In addition, biomass-fueled heating and electricity plants must be developed to fill the energy gap left by the phasing out of fossil fuels. While renewables like wind and solar will provide a significant part of renewable energy production solutions, there is still a place for energy production from biomass.
Process diagram – blue means the equipment has only operated in BA mode, orange in EA mode. Image credit: Habermeyer, F et al., Frontiers in Energy Research
Biomass fuel production processes: BtL and PBtL
Two production processes for renewable fuels have been the subject of in-depth studies in recent years. These are known as the process of converting biomass to liquid fuel (BtL) and producing electricity and biomass to fuel (PBtL). BtL converts biomass into hydrocarbon chains that can be used to make renewable fuel via the Fischer-Trope route. PBtL differs from this process by incorporating electrolytic hydrogen into the BtL process. PBtL has higher carbon efficiency levels than BtL.
The processes for transforming biomass into liquid fuel have been explored from a technical and economic point of view in several studies which have demonstrated its economic potential. The realistic production cost of this process varies from 1 to 4 euros per liter for a four hundred MW power plant.e plant, the process showing increasing maturity. Currently, demonstration plants wait to enter service until the promotion of sustainable fuels reaches a point where they can be implemented commercially.
Energy and biomass in liquid fuel have an economic advantage over BtL when cheap renewable energy is available. Adding renewable energy to the biomass conversion process increases fuel efficiency, lowering the cost of production.
Technical-economic analysis of a hybrid model
The study published in Frontiers of energy research took previously published literature on renewable fuels research and development and techno-economic analyzes in the field and presented a hybrid model. A techno-economic analysis was carried out on the commercial viability of the hybrid model.
The hybrid model can switch between processes using only biomass and operational modes of conversion enhanced by electrolysis according to demand. Previous studies have demonstrated the feasibility of a hybrid process, with Müller et al. demonstrating the use of hydrogen generated by a wind farm integrated in an FT-BtL process.
Hybrid systems have a higher initial investment cost, but the advantage of these systems is their lower operating costs. They can produce fuel at lower cost and biomass consumption levels than a stand-alone BtL process. An additional economic benefit is the possibility of temporarily shutting down the electrolyser to avoid high electricity prices in a fluctuating market.
Sankey carbon flow diagram for case 1.1 BA mode (A), EA mode (B). Image credit: Habermeyer, F et al., Frontiers in Energy Research
The hybrid process showed an overall carbon efficiency rate of 53.3% against 61.1% for the PBtL models and 35.4% for the BtL models. The production costs of the hybrid model amounted to 1.08 € 2019 / L. The net production costs could be lowered by 0.07 €.
Although the study found that the most economically viable process due to current renewable electricity prices was BtL, changing market forces like the cost of electricity and biomass, technological advancements and trends towards cheaper electrolysers could make the hybrid model economically feasible in the future. Further studies will be needed in the future on the processes to realize their full potential and move the world towards net zero by 2050.
Habermeyer, F et al. (2021) Technical-economic analysis of a flexible process concept for the production of transport and heat fuels from biomass and renewable electricity [online] Before. Energy Res. | bordersin.org. Available at: https://www.frontiersin.org/articles/10.3389/fenrg.2021.723774/full