SolDAC’s main ambition was to reinvent the ethylene industry, which is the chemical industry’s primary building block, by proving an emerging breakthrough technology for producing technically and economically competitive and climate-neutral sustainable ethylene and co-product ethanol from solar energy and air.
The project features a photoelectrochemical conversion (PEC) unit, allowing the direct conversion of CO2 into ethylene. The PEC exploits bandwidth-selected light from a solar collector (FSS) that splits the solar spectrum for electricity and heat generation at efficiency higher than standalone PV modules and standalone solar thermal collectors. Heat is used in an innovative direct air capture (DAC) unit at ultralow temperature (~60°C), fostering the eventual circular integration with heat networks. The DAC unit removes carbon dioxide from the air, concentrates it to 95+% and compresses it to feed the PEC stack and a pipeline for carbon dioxide storage. This allows the carbon footprint of the whole sun-to-chemicals process to be offset and enables gain in carbon credits, opening an opportunity to exceed climate-neutrality and produce carbon-negative C2 products. The process is energetically self-sufficient, economically viable and carbon-negative on the condition that each unit (DAC, PEC, FSS) reaches new targets in efficiency.
The overall objectives are:
- To produce carbon-neutral ethylene and by-product ethanol from the air in an independent off-grid decentralised and market-competitive process powered by solar energy.
- To guarantee the techno-economic feasibility of the SolDAC process.
- To demonstrate the reduction of the "cradle to grave" carbon-footprint of the SolDAC individual process units.
- To popularise Carbon Capture, Utilisation and Storage (CCUS) technologies in society.
SolDAC responds to most of the strategic directions outlined by the EU 2050 long-term strategy for net-zero GHG emissions as follows:
- The SolDAC process does not add further pressure on the energy system. The FSS system allows the complete use of the whole solar spectrum, reaching efficiency that rivals with the best combined power generation plants. The utilisation of an independent off-grid energy source restraints the energy available on site and sets the implicit requirement of DAC and PEC units with unprecedented efficiency.
- The project relies on solar energy as only source of renewable electricity, heat and light that is combined with the CO2 and water resources available in the air to produce C2 products. SolDAC’s autonomous process is virtually replicable in any setting.
- The successful implementation of the integrated SolDAC process, brings along the benefits from the EU Emissions Trading System (ETS) on carbon credits. The production of carbon-neutral C2 products will allow to close the carbon cycle above the ground, fostering circularity and eliminating the emissions associated with the production from petrochemicals.
- Thanks to the DAC unit, this project shows the promise for a carbon-neutral (and possibility carbon-negative) C2 products production, cancelling the emissions of a sector that is deemed difficult to decarbonise.
