Ineffective carbon offset
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Biodiversity offsets, their effectiveness and their role in a nature positive future
Biodiversity offsetting is a mechanism for addressing the impacts of development projects on biodiversity, but the practice remains controversial and its effectiveness generally poor. In the context of the Global Biodiversity Framework and the emergence of new approaches for mitigating damage, we need to learn from the past. In this Review, we explore biodiversity offsetting, its effectiveness and its future prospects, especially in relation to ‘nature positive’ goals. Offsets often fall short of their stated goal: to achieve at least no net loss of affected biodiversity. However, such failures are prominent because offsets have more explicit quantitative objectives than most other conservation approaches, whose effectiveness is also variable. These clear objectives provide the potential for the transparency that alternative approaches to addressing negative human impacts on biodiversity lack. Unfortunately, promising alternatives are scarce, so offsetting and offset-like mechanisms remain a necessary component of strategies to halt and reverse nature loss. However, improving their performance is essential. No quick and easy solution exists; instead, upholding best practice principles and rigorous implementation — including in the face of challenges from opposing narratives and interest groups — remains key.
Diversity of biomass usage pathways to achieve emissions targets in the European energy system
Biomass is a versatile renewable energy source with applications across the energy system, but it is a limited resource and its usage needs prioritization. We use a sector-coupled European energy system model to explore near-optimal solutions for achieving emissions targets. We find that provision of biogenic carbon has higher value than bioenergy provision. Energy system costs increase by 20% if biomass is excluded at a net-negative (−110%) emissions target and by 14% at a net-zero target. Dispatchable bioelectricity covering ~1% of total electricity generation strengthens supply reliability. Otherwise, it is not crucial in which sector biomass is used, if combined with carbon capture to enable negative emissions and feedstock for e-fuel production. A shortage of renewable electricity or hydrogen supply primarily increases the value of using biomass for fuel production. Results are sensitive to upstream emissions of biomass, carbon sequestration capacity and costs of direct air capture.
Carbon-coating effect on the performance of photolithographically-structured Si nanowires for lithium-ion microbattery anodes
The applications of three-dimensional Si nanowire anodes in lithium-ion microbatteries have attracted great interest in the realization of high-capacity and integrated energy storage devices for microelectronics. Combining Si nanowires with carbon can improve the anode performance by aiding its mechanical stability during cycling. Here, we incorporate photolithography, cryogenic dry etching, and thermal evaporation as the commonly used methods in semiconductor technologies to fabricate carbon-coated Si nanowire anodes. The addition of amorphous carbon to Si nanowire anodes has an impact on increasing the initial areal capacity. However, a gradual decrease to 0.3 mAh cm−2 at the 100th cycle can be observed. The post-mortem analyses reveal different morphologies of Si nanowire anodes after cycling. It is indicated that carbon coating can help Si nanowires to suppress their volume expansion and reduce the excessively produced amorphous Si granules found in pristine Si nanowire anodes.
Rising greenhouse gas emissions embodied in the global bioeconomy supply chain
The bioeconomy is key to meeting climate targets. Here, we examine greenhouse gas emissions in the global bioeconomy supply chain (1995–2022) using advanced multi-regional input-output analysis and a global land-use change model. Considering agriculture, forestry, land use, and energy, we assess the carbon footprint of biomass production and examine its end-use by provisioning systems. The footprint increased by 3.3 Gt CO2-eq, with 80% driven by international trade, mainly beef and biochemicals (biofuels, bioplastics, rubber). Biochemicals showed the largest relative increase, doubling due to tropical land-use change (feedstock cultivation) and China’s energy-intensive processing. Food from retail contributes most to the total biomass carbon footprint, while food from restaurants and canteens account for >50% of carbon-footprint growth, with three times higher carbon intensity than retail. Our findings emphasize the need for sustainable sourcing strategies and that adopting renewables and halting land-use change could reduce the bioeconomy carbon footprint by almost 60%.
Flash Joule heating for synthesis, upcycling and remediation
Electric heating methods are being developed and used to electrify industrial applications and lower their carbon emissions. Direct Joule resistive heating is an energy-efficient electric heating technique that has been widely tested at the bench scale and could replace some energy-intensive and carbon-intensive processes. In this Review, we discuss the use of flash Joule heating (FJH) in processes that are traditionally energy-intensive or carbon-intensive. FJH uses pulse current discharge to rapidly heat materials directly to a desired temperature; it has high-temperature capabilities (>3,000 °C), fast heating and cooling rates (>102 °C s−1), short duration (milliseconds to seconds) and high energy efficiency (~100%). Carbon materials and metastable inorganic materials can be synthesized using FJH from virgin materials and waste feedstocks. FJH is also applied in resource recovery (such as from e-waste) and waste upcycling. An emerging application is in environmental remediation, where FJH can be used to rapidly degrade perfluoroalkyl and polyfluoroalkyl substances and to remove or immobilize heavy metals in soil and solid wastes. Life-cycle and technoeconomic analyses suggest that FJH can reduce energy consumption and carbon emissions and be cost-efficient compared with existing methods. Bringing FJH to industrially relevant scales requires further equipment and engineering development.
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