MIT engineers make converting CO2 into useful products more practical
MIT’s work on converting captured CO₂ into useful chemicals like ethylene prompts debate over whether such technologies can realistically help address climate change. Commenters highlight hard thermodynamic and scaling limits: turning CO₂ back into fuels or feedstocks always requires large amounts of low‑carbon energy, competes with simpler options like cutting fossil use, and can only absorb a small fraction of today’s gigaton‑scale emissions. Many see potential niche roles—using surplus renewable power, replacing fossil‑derived petrochemicals, or providing energy storage—while warning that carbon capture and utilization must not become an excuse to delay emissions reductions.
Scale and practicality of CO₂-to-products
- Several comments stress that global ethylene demand (~300 Mt/yr) would consume only ~1 Gt CO₂, tiny relative to tens of gigatons of annual emissions; synthetically made ethylene would “pile up” if treated as a primary sink.
- Many see this tech as potentially useful for the “last 10%” of emissions or as a non-fossil chemical feedstock, not a primary climate solution.
- Some note the article doesn’t quantify energy per ton of CO₂ or total cost, making overall practicality unclear.
Biological vs engineered sequestration
- Comparisons are made to trees, grasslands, and bamboo; grasslands in some climates sequester carbon more reliably than forests, especially via soil.
- Suggested “natural” strategies: timber for long-lived construction, burying biomass, using wood/fibers instead of concrete/steel.
- Others point out the scale problem: you’d need to grow and bury vast amounts of biomass for many years to offset current emissions.
Thermodynamics and energy needs
- Repeated point: “unburning” CO₂ into energy-rich molecules must require at least as much energy as was gained from burning the fuel, often more due to inefficiencies.
- Some distinguish between low-energy CO₂ capture vs high-energy conversion into fuels/chemicals.
- There’s disagreement on how binding this limit is in practice, but consensus that any large-scale removal must be powered by low-carbon energy.
Economic and policy considerations
- Discussion of chicken-and-egg economics: new processes can’t beat fossil incumbents without scale, but scale requires customers or policy support.
- Suggestions include government intervention, targeted subsidies, or marketing “premium” low-carbon products.
- Concerns raised that fossil-fuel-linked funding may serve more as greenwashing than real decarbonization.
Use of CO₂ and synthetic fuels
- CO₂ is already traded at scale, especially for enhanced oil recovery (EOR); critics say this often just enables more fossil extraction.
- Others argue that, with cheap renewables, synthesizing hydrocarbons (e-fuels) from CO₂ and water could eventually compete with drilled fuels and provide long-term, carbon-neutral energy storage.
- Efficiency of such storage is low compared to batteries/pumped hydro but might still be acceptable for niche or long-duration uses.
Materials and technical details
- The PTFE (a PFAS/Teflon) component raises environmental and regulatory concerns if scaled.
- Copper cost is questioned; replies suggest electricity and plant CAPEX, not copper, dominate costs.
- Some note similar gas-diffusion and PTFE-based electrodes are not new; this work is seen as incremental rather than revolutionary.
Carbon capture as climate strategy
- One camp calls large-scale removal via such tech fundamentally impractical and a distraction from simply not burning fossil fuels.
- Another camp sees parallel tracks: aggressively cut emissions while also developing removal/sequestration for legacy CO₂ and hard-to-abate uses.