Critique of Direct Air Carbon Capture Technology (DACCS)

This document is a white paper by Joseph Romm, a senior research fellow at the University of Pennsylvania Center for Science, Sustainability, and the Media. The paper argues that direct air carbon capture and storage (DACCS), a technology that removes CO2 from the atmosphere and stores it underground, is not scalable and that the concept of net zero emissions is a dangerous myth. The paper makes the following main points:

- DACCS is expensive and inefficient: DACCS requires a lot of energy, water, and materials to capture CO2 from the air, which is very diluted. The cost of DACCS ranges from several hundreds to thousands of dollars per ton of CO2, much higher than other carbon capture and removal methods. The efficiency of DACCS is very low, around 5% to 10%, meaning that most of the energy used is wasted.
- DACCS faces technological and social barriers: DACCS is still at an early stage of development and has not been proven to be commercially viable or scalable. DACCS also faces challenges in siting, as it needs to be located near sources of low-carbon electricity and geological storage, which may not be available or acceptable in many regions. DACCS also competes with other uses of land, water, and energy, and may raise equity and justice concerns.
- DACCS has high opportunity costs: DACCS is not a good use of carbon-free power, as it could be used more effectively to directly replace fossil fuels in various sectors. DACCS also diverts attention and resources from the urgent need to reduce emissions at the source. DACCS should not be relied on as a solution to climate change, as it may not be available or affordable at the scale and speed needed.
- Net zero is a misleading concept: Net zero emissions implies that any emissions that cannot be avoided can be offset by carbon removals, such as DACCS. However, this concept is based on unrealistic assumptions and models that rely heavily on unproven and unscalable technologies. Net zero also creates a false sense of security and complacency, as it suggests that we can overshoot the temperature targets and then cool down later. Net zero also ignores the cumulative and irreversible nature of CO2 in the atmosphere, and the risks of tipping points and feedbacks.
- The only safe and feasible way to limit warming is to cut emissions rapidly: The paper concludes that the world has the technological capability and investment dollars to decarbonize the economy and meet the Paris climate targets, but the policies and actions of most countries are insufficient. The paper urges policymakers and the public to focus on the deployment of carbon-free energy in every sector, and not to gamble on uncertain and costly carbon removal technologies.