Nature Energy最新文献

Climate action and the energy affordability and security crisis caused by the Ukrainian war have accelerated a shift towards variable renewable electricity generation, such as wind and solar power. These energy sources in turn pose new technical challenges for system operators, who must procure new services to support a renewables-based power system. Here we argue that these services have particular economic characteristics that render their optimal procurement a non-trivial exercise. Drawing on the successful collaboration between economic and technical disciplines in wholesale market design, we propose four areas where future collaboration can prove fruitful for designing and procuring the services necessary for secure system operation at high levels of renewable generation.

Green hydrogen is critical for decarbonizing hard-to-electrify sectors, but it faces high costs and investment risks. Here we define and quantify the green hydrogen ambition and implementation gap, showing that meeting hydrogen expectations will remain challenging despite surging announcements of projects and subsidies. Tracking 190 projects over 3 years, we identify a wide 2023 implementation gap with only 7% of global capacity announcements finished on schedule. In contrast, the 2030 ambition gap towards 1.5 °C scenarios has been gradually closing as the announced project pipeline has nearly tripled to 422 GW within 3 years. However, we estimate that, without carbon pricing, realizing all these projects would require global subsidies of US$1.3 trillion (US$0.8–2.6 trillion range), far exceeding announced subsidies. Given past and future implementation gaps, policymakers must prepare for prolonged green hydrogen scarcity. Policy support needs to secure hydrogen investments, but should focus on applications where hydrogen is indispensable.

Wide-bandgap kesterite Cu₂ZnSnS₄ offers an economically viable, sustainably sourced and environmentally friendly material for both single-junction and tandem photovoltaic applications. Nevertheless, since 2018 the record efficiency of such solar cells has stagnated at 11%, largely due to carriers recombining before they are collected. Here we demonstrate enhanced carrier collection in devices annealed in a hydrogen-containing atmosphere. We find that hydrogen is incorporated mainly in n-type layers and on the absorber surface. Furthermore, we show that the hydrogen treatment triggers the out-diffusion of oxygen and sodium from the absorber bulk to the surface, favourably diminishing the acceptor concentration at the surface and increasing the p-type doping in the bulk. Consequently, Fermi-level pinning is relieved and carrier transport in the absorber is facilitated. We achieve a certified efficiency of 11.4% in Cd-free devices. Although hydrogenation already plays a major role in silicon photovoltaics, our findings can further advance its application in emerging photovoltaic technologies.

Sodium-ion batteries have garnered notable attention as a potentially low-cost alternative to lithium-ion batteries, which have experienced supply shortages and price volatility for key minerals. Here we assess their techno-economic competitiveness against incumbent lithium-ion batteries using a modelling framework incorporating componential learning curves constrained by minerals prices and engineering design floors. We compare projected sodium-ion and lithium-ion price trends across over 6,000 scenarios while varying Na-ion technology development roadmaps, supply chain scenarios, market penetration and learning rates. Assuming that substantial progress can be made along technology roadmaps via targeted research and development, we identify several sodium-ion pathways that might reach cost-competitiveness with low-cost lithium-ion variants in the 2030s. In addition, we show that timelines are highly sensitive to movements in critical minerals supply chains—namely that of lithium, graphite and nickel. Our modelled outcomes suggest that being price advantageous against low-cost lithium-ion variants in the near term is challenging and increasing sodium-ion energy densities to decrease materials intensity is among the most impactful ways to improve competitiveness.

Maintaining energy supply is a critical challenge as we strive to transition away from fossil fuels. Energy return on investment (EROI) is a tool widely used by energy analysts to help understand the efficiency with which we extract, deliver and use energy. Initial research in this area focused on the EROI of extracting energy from nature, using direct energy costs where available and deriving indirect energy costs from economic data to infer relatively comprehensive energy cost assessments^1,2. More recent studies have increasingly expanded the boundaries of the denominator by including additional energy required to refine and deliver energy to its final point of use^3,4. Such studies, sometimes called harmonization studies, attempt to ensure consistent comparisons across different energy sources^5,6, and conclude that the EROI of renewables surpasses that of fossil fuels. We find this conclusion surprising, as it is opposite to earlier studies. While we agree on the importance of accounting for all costs associated with energy technologies and applaud the efforts of such studies to “compare apples with apples”⁶, we believe that there are at least five ways in which these assessments could be improved.

First, the most common approach to measuring EROI for renewable technologies is life cycle assessment (LCA). While this approach is usually regarded as accurate within its defined boundary, it is subject to two important types of truncation error⁷. The first is sideways truncation, where many small but collectively significant processes — such as service activities — are excluded because they are individually minor and too numerous to measure. Established LCA cut-off rules often lead to their exclusion, yet they can account for about half of the total energy costs, as demonstrated by more comprehensive environmentally extended input–output analyses (EEIOA) or energy intensities of financial activity^7,8. This truncation could halve the EROI of technologies like solar photovoltaics. The second is downstream truncation, where system-level processes that lie beyond the electrical busbar or inverter — such as storage, firming, and transmission — are typically omitted. These system-level processes are critical for understanding energy transition but are difficult to capture within the scope of an LCA-based EROI study. To address these limitations, studies must expand their boundaries of analysis.

The decarbonization of marine transport is a global challenge due to the range and capacity limitations of renewable ships. Offshore charging stations have emerged as an innovative solution, despite increased investment and extended voyage durations. Here we develop a route-specific model for the optimal placement and sizing of offshore charging stations to assess their economic, environmental and operational impacts. Analysing 34 global and regional shipping routes, we find that offshore charging stations can reduce the cost for electric ships by US$0.3–1.6 (MW km)⁻¹ and greenhouse gas emissions by 1.04–8.91 kg (MW km)⁻¹ by 2050. The economic cruising range for 6,500 20-foot equivalent unit electric ships can increase from 3,000 km to 9,000 km. Voyage time costs for these enhancements vary between a 0% and 30% grace period of the original delivery time frame. We further investigate power-to-ammonia offshore refuelling stations as a proxy for e-fuels, which could potentially replace heavy fuel oil ships for routes over 9,000 km with only a 5% grace period.