Robert Gresser is Director of the Sustainable Energy Innovation Platform of Solvay Corporate Research & Innovation, where he is in charge of all corporate programs related to energy. He is a Chemical Engineer with a PhD in Physical Chemistry and joined Rhône-Poulenc (now Solvay) in 1981 as a research engineer. Since 1995, he has focused on marketing and innovation, reinforcing the alignment of innovation, marketing and strategy and piloting innovation programmes.
Currently, 130 million tonnes per year of CO2 are used in industrial processes, including enhanced oil recovery (EOR) - 60 million tonnes; urea / fertiliser production - 36 million tonnes; and in other applications such as the food and beverage industry. This quantity could be multiplied by a factor of five in 2030 as new uses emerge.
The main CCU technologies are:
- Direct use, allowed by cheap access to CO2: more than 60 million tonnes of CO2 are extracted from natural domes for economic reasons. Here a cheap capture technology could make it possible to re-use CO2 from flue gas emissions.
- Specialty chemicals made from CO2: mainly niche applications (e.g. polycarbonate), with a low impact on CO2 levels. It’s generally easier and cheaper to make these products from fossil CO2.
- Mineralisation with initial developments in alkaline waste carbonation. Large-scale development requires natural ores (wollastonite, olivine…) which are limited by a slow conversion rate.
- Power to Liquid: this is already industrial and could be the largest pathway for CCU in fuels, due to the replacement of fossil carbon by recycled carbon (circular economy approach).
Focusing on Power to Liquid, this involves the conversion of CO2 into methanol (MeOH) using H2 produced by electrolysis. Here the challenge is to identify an adequate industrial ecosystem and the appropriate economic conditions to allow a financially acceptable scheme for this conversion. A complete simulation of a 125MW Power to Liquid process, producing 100 kT of MeOH from 150 kT/y of CO2, leads to a cost for MeOH of 600-700 EUR/T for an electricity price of 45 EUR/MWh. The cost of electricity is the major variable here, since a 10 EUR/MWh increase in the cost of electricity leads to a 100 EUR/T increase in the cost of MeOH.
Although the cost of the Power to Liquid MeOH is higher than for fossil MeOH, it is in the same order of magnitude as biofuels if we compare the cost of their energy content (20-30 EUR/GJ). The development of Power to Liquid can be accelerated by:
- Its use in transportation fuel by direct blending, transformation into methyl tert-butyl ether (MTBE), transesterification for the biodiesel process or transformation into gasoline via the methanol to gasoline (MTG) process.
- A regulatory scheme that will allow it to be competitive with biofuels (EU transport directive).
- Development of new fuels (e.g. dimethyl ether (DME)) requiring adaptations for the transport industry.
Power to Liquid could find its place within the context of energy transition, by offering flexible capacities to store energy excesses arising from an increase in renewables. The electricity is transformed into MeOH and fuels that can be transported and stored. By allowing better financial management of baseload assets, the transformation into fuel of the excess energy that cannot be absorbed by the grid makes it possible to keep an acceptable production capacity.
The CCU industry already exists mainly in current applications of CO2 and can be boosted by cheap CO2 capture technologies. Power to Liquid could be the largest pathway for CCU, contributing to energy transition. It should be considered in a circular economy context: each tonne of CO2 recycled to make transportation fuel can avoid one tonne of fossil CO2 to make the same fuels. It could be competitive versus biofuels if we can resolve the challenges of its incorporation and compatibility with fuels (from drop in to new fuels). The long-term horizon for CCU is the transformation of CO2 using energy from the sun, and micro-algae could probably be the earliest pathway.