Inquiries: Insights into CO2 remediation based on the principles of physics revealed
Carbon dioxide (CO2) emissions, pumped into the atmosphere by human activities, are taking a heavy toll on Earth's climate. As the fight against climate change gets more intense, efforts to remove CO2 directly from the atmosphere have gained traction.
A recently published report, led by an MIT physicist, delves into the various experimental methods to capture CO2 on a grand scale, along with their fundamental physical limitations. The report focuses on approaches that show the most potential for capturing CO2 at gigatons per year - the scale we need to make a significant impact on climate stabilization.
Commissioned by the American Physical Society's Panel on Public Affairs, the report appeared in the journal PRX. Professor Washington Taylor of MIT, who chaired the report, spoke to MIT News about the physical constraints of carbon dioxide removal (CDR) and why it's worth pursuing alongside global efforts to cut carbon emissions.
What motivated you to examine CDR through a physical science lens?
The burning of ancient carbon deposits is the root cause of climate change, causing an increase in global temperatures. In recent years, there's been significant interest in finding technologies to directly extract CO2 from the atmosphere. Properly managing atmospheric carbon is crucial in dealing with our impact on the Earth's climate.
Physics offers valuable insights into this issue, as the possibilities are highly constrained by thermodynamics, mass issues, and other factors. This report aimed to shed light on whether we can affect carbon levels not just by changing our emissions profile but also through direct CO2 removal from the atmosphere.
What carbon dioxide removal methods did you consider?
The experimental CDR methods we examined can be broadly classified into two categories: cyclic and once-through processes.
Imagine we're in a sinking boat with a hole, desperate to keep from drowning. In the boat analogy, a cyclic process would be using a repeatable sponge-like mechanism to absorb water and eject it. An example of cyclic CDR is chemical direct air capture (DAC), in which fans blow air across a material that captures CO2. When the material becomes saturated, energy is used to release the CO2, and the material can be reused.
An alternative approach is the once-through class, similar to using cartons of paper towels to help the boat stay afloat. Once-through CDR methods aim to accelerate natural processes, such as enhanced rock weathering, by which certain rocks absorb CO2 from the atmosphere. The key difference is that once-through approaches may avoid energy constraints but encounter limitations due to chemical central laws and the need for enormous quantities of material.
Does the report have any concluding remarks on the feasibility and desirability of CDR methods?
Initially, we thought that CDR would require energy beyond our reach due to the second law of thermodynamics. However, after careful deliberation, we struck a balance between two opposing perspectives. On one hand, CDR may not serve as a silver bullet; large-scale removal will demand extensive resources and energy. On the other hand, completely ignoring CDR could compromise our drive toward emissions reductions.
Our conclusion was that research and development on CDR methods should be selectively and prudently pursued, despite the expected cost, energy, and material requirements. At a policy level, an economic and policy framework is needed that incentivizes emissions reductions and CDR within the same framework, so the market can optimize climate solutions.
Ultimately, if humanity is serious about managing climate change, substantial CDR, in addition to aggressive emissions reductions, may be necessary. We have the scientific knowledge to reduce emissions and bring CO2 levels down to more manageable levels, but now it's up to our societal and economic acumen to implement solutions for the greater good of humanity and our planet's ecosystems before we encounter even greater challenges.
- The report, led by an MIT physicist, investigates various ways to capture CO2 on a massive scale, as a means to combat climate change.
- The ways to remove carbon dioxide (CDR) from the atmosphere have gained attention due to the effects of CO2 emissions on Earth's climate.
- The burning of ancient carbon deposits, a primary cause of climate change, has sparked interest in finding energy-efficient technologies for direct CO2 extraction.
- The report, published in the PRX journal, discusses both cyclic and once-through experimental CDR methods, with their advantages and limitations.
- In the cyclic CDR methods, the CO2 is absorbed and released repeatedly, much like a sponge, an example being chemical direct air capture (DAC).
- Once-through CDR methods focus on accelerating natural processes, such as enhanced rock weathering, aiming to remove CO2 from the atmosphere without depleting energy resources.
- The report suggests that while large-scale CDR will require significant resources and energy, ignoring it could hinder our worldwide efforts to cut carbon emissions.
- The authors advocate for research and development in CDR methods, even with the anticipated cost, energy, and material requirements, while emphasizing the need for an economic and policy framework that incentivizes both emissions reductions and CDR.
- The report underscores the importance of implementing CDR methods, alongside aggressive emissions reductions, as a crucial step in managing climate change and preventing further challenges to our planet's ecosystems and society.
