The University of Melbourne has completed initial testing of a direct air capture system that extracts carbon dioxide from ambient air. The pilot facility, operating on campus since March 2025, has captured approximately 50 tonnes of CO2 while researchers assess technical performance and economic viability. The work contributes to global efforts evaluating whether direct air capture can meaningfully contribute to climate change mitigation.

Direct air capture differs from conventional carbon capture by extracting CO2 from ambient air rather than concentrated sources like power plant exhaust. This allows carbon removal from anywhere regardless of emission sources nearby. However, atmospheric CO2 concentration is much lower than industrial exhausts, making the capture process more energy-intensive and expensive.

Technical Approach

The Melbourne system uses solid sorbent materials that chemically bind CO2 from air passing through them. Large fans blow ambient air through beds of sorbent material. When the sorbent becomes saturated with CO2, heating releases the captured gas as a concentrated stream. The regenerated sorbent then captures more CO2 in continuous cycles.

The facility contains 12 sorbent beds operating on staggered cycles. While some beds capture CO2, others regenerate. This continuous operation maintains steady CO2 output rather than batch processing. The system captures roughly 200 kilograms of CO2 daily, equivalent to removing emissions from about 40 cars.

Energy Requirements

Energy consumption represents direct air capture’s fundamental challenge. The system requires electricity for fans and heat for sorbent regeneration. The Melbourne pilot uses natural gas for heating and grid electricity for fans, consuming approximately 2 megawatt-hours per tonne of CO2 captured. This energy intensity makes the process expensive and, if fossil fuels provide energy, potentially counterproductive.

Using renewable energy is essential for direct air capture to provide net climate benefits. The University is planning to add rooftop solar panels and battery storage to power the facility from renewables. Even with renewable energy, the substantial energy requirement means direct air capture competes with other uses for that clean energy.

Cost Analysis

Current capture costs total approximately $800-1,000 per tonne of CO2 based on pilot operations. This substantially exceeds costs for industrial carbon capture, which range from $50-150 per tonne. The cost differential reflects the energy intensity of capturing CO2 from dilute atmospheric concentrations versus concentrated industrial streams.

Cost reductions seem possible through larger scale, optimised sorbent materials, and renewable energy integration. Industry proponents suggest costs could drop to $200-300 per tonne at commercial scale. However, these projections remain speculative, and some analysts argue fundamental thermodynamic limits prevent direct air capture from ever competing economically with emission reduction.

Sorbent Performance

The sorbent material determines system performance and costs. The Melbourne system uses a proprietary material developed through collaboration with CSIRO. The sorbent shows good CO2 selectivity and survives thousands of capture-release cycles without significant degradation. However, humidity affects performance, with moisture competing for sorbent binding sites.

Melbourne’s variable humidity complicates operations. Summer days with low humidity allow maximum capture rates, while humid winter days reduce capacity by 20-30%. Compensating through additional sorbent material or air pre-drying both add costs. This climate sensitivity means performance and economics vary substantially between locations.

CO2 Utilisation

The captured CO2 is being used for several test applications. Some supplies greenhouses where elevated CO2 promotes plant growth. Some is converted to calcium carbonate for construction materials. A small amount is being tested for synthetic fuel production, though this requires substantial additional hydrogen input.

None of these utilisation pathways permanently store the CO2 unless buried underground. Greenhouse CO2 returns to atmosphere when plants decompose. Fuels release CO2 when burned. Permanent storage requires geological sequestration, which Australia has limited infrastructure for currently. Developing CO2 storage capacity is crucial for direct air capture to provide actual climate benefits.

Comparison with Natural Solutions

Critics argue that investing in forests and soil carbon provides more cost-effective carbon removal than direct air capture. Natural climate solutions typically cost $20-50 per tonne of CO2 removed. They also provide biodiversity and watershed benefits that direct air capture doesn’t.

Proponents counter that natural solutions have limited ultimate capacity and face permanence concerns. Forests can burn or be cleared, releasing stored carbon back to atmosphere. Direct air capture with geological storage offers more permanent removal. Additionally, direct air capture could eventually remove CO2 faster than natural processes, potentially enabling active drawdown of atmospheric concentrations.

Policy Support

The Australian government hasn’t established specific support mechanisms for direct air capture. Carbon credit schemes don’t yet recognise direct air capture, though this may change as the technology matures. Without policy support, commercial deployment seems unlikely given current costs.

Internationally, the United States offers tax credits up to $180 per tonne for captured and stored CO2. This support has encouraged several commercial projects. European programmes provide research funding but limited operational support. Australia might adopt similar policies if direct air capture proves viable, though current climate policy focuses on emission reduction rather than removal.

Industry Interest

Several Australian companies have expressed interest in direct air capture for carbon offset programmes. Oil and gas companies facing emissions targets see potential for capturing their emissions from ambient air, though the economics don’t yet work without substantial carbon prices. Aviation companies also show interest since their emissions are difficult to eliminate through other means.

Technology companies have approached the University about licensing the sorbent materials for commercial development. However, the path from pilot demonstration to commercial operation spans years and requires substantial capital investment. Finding investors willing to back unproven technology with uncertain policy support remains challenging.

Research Collaborations

The Melbourne group collaborates with international direct air capture researchers including teams at ETH Zurich and Arizona State University. These collaborations share sorbent development knowledge and compare performance across different climate conditions. Australian conditions differ significantly from Swiss or American test sites, providing valuable diversity in performance data.

The collaborations also pool resources for fundamental research on sorbent chemistry and system optimisation. No single research group can explore all possible approaches, so coordinated international efforts accelerate progress. Whether this research yields commercially viable technology remains uncertain, but the scientific foundations are strengthening.

Lifecycle Assessment

Comprehensive lifecycle assessment is examining the system’s full environmental footprint including sorbent material production, equipment manufacturing, and operations. Preliminary results show that renewable energy integration is essential for favourable climate benefits. Natural gas-powered operations barely achieve net carbon removal after accounting for fossil fuel emissions.

The assessment also considers water consumption, land use, and other environmental impacts. While less intensive than many industrial processes, direct air capture at scale could require substantial resources. Understanding these trade-offs informs decisions about whether and where to deploy the technology.

Future Directions

The research team plans to continue operating the pilot for another 18 months, accumulating operational data across different seasons and conditions. They’re also testing second-generation sorbent materials that should improve performance and durability. Additionally, system modifications aim to reduce energy consumption by 15-20%.

If results remain promising, the University might pursue a larger demonstration facility processing 1,000-5,000 tonnes annually. This intermediate scale would bridge the gap between small pilots and commercial facilities while requiring manageable investment. However, funding for this expansion hasn’t been secured and depends partly on government policy signals about long-term carbon removal support.

The direct air capture pilot represents Australia’s contribution to exploring potentially important but uncertain climate technology. Whether direct air capture becomes a significant climate mitigation tool or remains a niche application won’t be clear for another 5-10 years. The Melbourne work ensures Australia has expertise in the field regardless of how the technology evolves globally.