Full spectrum SOLar Direct Air Capture & conversion

Project Information

SolDAC

Grant agreement ID: 101069359

DOI

10.3030/101069359

Project closed

EC signature date 12 May 2022

Start date 1 September 2022

End date 31 August 2025

Funded under

• Climate, Energy and Mobility

Total cost

€ 2 073 781,25

EU contribution

€ 2 073 781,25

Coordinated by

COMET GLOBAL INNOVATION, SL
Spain

Periodic Reporting for period 2 - SolDAC (Full spectrum SOLar Direct Air Capture & conversion)

Reporting period: 2024-03-01 to 2025-08-31

Summary of the context and overall objectives of the project

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.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

During the first 18 months, main activities were focused on the design of the three units that make up the SolDAC system applying a life-cycle thinking approach to sustain all project developments and final outputs.
During the last 18 months, activities were focused on the construction and adaptation of the different subsystems designed during the first reporting period of the project.
The Installation plan for all components located in Lleida was successfully implemented, integrating the FSS, the WH, and the PEC. In addition, an experimental campaign was conducted, yielding satisfactory results for the integration of the PEC with the FSS and the WH with the FSS. It is worth mentioning that several delays were faced due to the late fabrication and delivery of the multijunction solar cells, which shortened the experimental campaign of the PEC with the FSS.
Several challenges were identified and reported as future actions towards a commercially viable system

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

Results so far are:

FSS: during the 2nd part of the project, the team was fully committed to the redesign and fabrication of the FSS. Some factors temporarily postponed the dissemination of the optical and thermal design of the FSS, while the concept has been patented. The results confirm efficiencies in agreement with the simulations, demonstrating the robustness of the novel FSS and validating its technical feasibility. Moreover, these outcomes pave the way for clear future actions towards higher TRL levels and ultimately the realisation of a commercially viable device.

PEC stack: Developed materials for the 2 half-cell reactions, including novel cathode configurations and photoelectrodes for the anodic side, have been evaluated in a benchmark cell, reaching values beyond the proposed KPIs: Faradaic efficiency of ethylene of 70% at 250 mA cm-2, in a system of 10 cm2. The electrode and cell upscaling have also been carried out, and the final PEC system has been fabricated and assessed, reaching values relatively lower than the initial KPIs. Despite this, the 25 cm2 system achieves impressive Faradaic efficiency values of combined C2 products (i.e. ethylene and ethanol). Some relevant achievements detailed under those activities were reflected in two scientific publications (open access) available at the project web page.

DAC: Semi-commercial nanoporous materials have been prepared that can be regenerated with low grade heat down to 60 °C still producing a viable CO2 working capacity. Published work embodies most of the scientific impact of this work package. The full list is accessible in deliverable D7.6.

The results from the complete life cycle assessment of the system, carried out in the frane of WP6 determined that it takes 14 months of operation for the system to mitigate its accumulated emissions, producing carbon neutral ethylene from that point onward. The carbon footprint of the ethylene produced by SolDAC was determined to be negative, with a value of - 1.57 kgCO2 per kilogram, accounting both for the direct emissions of the system and the negative emissions of its production process

SolDAC process