# Solar Air-to-Fuel Technologies for a Circular Carbon Economy

## TL;DR

This paper discusses technologies that use solar energy to convert atmospheric CO2 into fuels and chemicals, aiming to create a sustainable circular carbon economy.

## Contribution

The paper introduces emerging solar-powered air-to-fuel technologies and outlines strategies to overcome challenges in CO2 conversion.

## Key findings

- Solar-powered air-to-fuel technologies can help reduce atmospheric CO2 while producing synthetic fuels.
- Key challenges include low CO2 concentration, CO2 stability, and interference from oxygen in air.
- Scalability and future research directions are critical for achieving a net-zero carbon economy.

## Abstract

The CO2 present in our atmosphere is a universally
available
and abundant carbon feedstock, but it exists only in dilute concentrations
(currently around 427 ppm). Clean technologies capable of capturing
atmospheric CO2 using direct air capture and directly converting
it into synthetic fuels and chemicals using solar energy could pave
the way for a circular chemical industry. Challenges in developing
such a solar-powered air-to-fuel technology that mimics photosynthesis
include the use of the low CO2 concentration in air, the
thermodynamic stability of CO2 (and its capture products),
the high O2 content (21%) in air (which often interferes
with catalytic CO2 valorization), and the presence of variable
moisture levels. This perspective explores different concepts and
emerging technologies for the solar-powered conversion of atmospheric
CO2 into fuels and chemicals, examines their scientific
principles, considers their scalability, and offers recommendations
for future research to support the development of a net-zero circular
carbon economy.