[en] Highlights: • The PSC-ASU can save up to 19% on capital costs compared with the double-column ASU. • The PSC-ASU can reduce energy cost by 14.5% compared with Linde’s single-column ASU. • The pressure ratio of the main air compressor is 21% lower than that of the double-column ASU. • The PSC-ASU is more cost-effective when applied in a low-carbon, fossil-fuel power plant. The rapid integration of intermittent renewable sources into the electricity grid is driving the need for more flexible, low-carbon fossil-fuel plants with lower capital costs. This then drives the need to improve the cryogenic air separation unit (ASU). To address this changing landscape, we explore a Praxair single-column ASU (PSC-ASU) design with the goal of reducing costs and improving flexibility, compared to a conventional double-column ASU. The PSC-ASU incorporates partial air condensation and air pre-separation in the bottom reboiler with a phase separator as well as N₂-enriched vapor condensation in the upper reboiler to decrease energy consumption, as compared to Linde’s single-column ASU. All three of the above-mentioned ASU designs are simulated in Aspen Plus and analyzed. An economic analysis is applied to evaluate the relative cost savings of the PSC-ASU compared to the double-column ASU. Results suggest that the specific energy consumption of the PSC-ASU is significantly lower than that of Linde’s single-column ASU due to a drastically improved oxygen recovery rate. Although this improved oxygen recovery rate is still lower than that of the double-column ASU, the required pressure ratio of the main air compressor is 21% lower than that of the double-column ASU. As a result, the specific energy consumption of the PSC-ASU is only 1.9% greater than that of the double-column ASU for producing 95.1 mol% O₂. However, the PSC-ASU reduces the hourly capital cost by 19% due to the elimination of a high-pressure column. This would effectively decrease the total hourly cost of the ASU, and thus the total hourly cost of low-carbon, fossil-fuel power plants that require oxygen.

[en] Highlights: • Level of interest towards EE varies greatly with countries’ renewable energy mix. • Energy efficiency is important even for renewable-rich countries. • Iceland, Norway and New Zealand are top-three renewable-rich OECD countries. • Policies need to be synchronized with technological advancements. - Abstract: The relevance of energy efficiency policy measures for renewable-rich countries could be different from those countries that have a limited share of renewables in their electricity generation mix, and are therefore likely to focus on low-carbon energy generation policies. This paper presents a comparative analysis of the energy efficiency initiatives of the three highest renewable-rich OECD countries, namely: Iceland, Norway and New Zealand. The paper then focuses on a comprehensive review of New Zealand's energy efficiency policies since a formal “Energy Efficiency and Conservation Act” came into force. This paper then highlights the future challenges for New Zealand and offers some policy recommendations, which may also be applicable for other renewable-rich countries.

[en] Highlights: • Dry feed, pressurized oxy-coal combustion was demonstrated at 15 bar and ~100 kW. • A novel burner and furnace design featuring co-axial, low-mixing flow was tested. • Excellent flame stability and high turn-down ratio were observed. • Complete combustion was achieved with less than 1% (v/v) oxygen in the flue gas. • Char burnout enhanced by gasification reactions in pressurized oxy-fuel environment. Pressurized oxy-combustion is a promising technology for low-carbon, fossil fuel utilization. It has the potential of improved efficiency and economics compared with conventional atmospheric pressure oxy-combustion. Washington University in St. Louis has proposed a new pressurized oxy-combustion process, namely Staged Pressurized Oxy-Combustion, which has the potential to improve further the plant efficiency, operational flexibility, and economics. This process burns pulverized coal in a pressurized, oxy-combustion environment, which has not been demonstrated in a pilot-scale system before. To address this gap, a 100 kW_th pressurized oxy-combustion facility was designed and constructed. This facility has a unique burner and furnace design featuring a co-axial, low-mixing flow field, which is drastically different from conventional coal-fired boiler designs where strong mixing is sought by introducing swirl or recirculating flows. This work aims to present the first pilot-scale experimental results of a dry-feed, pressurized oxy-combustion system. The tests focused on exploring flame stability and shape, char burnout, and fine particulate matter formation. Testing results suggest that the burner has excellent flame stability. The flame shape is consistent with the design philosophy and agrees with large eddy simulations. Importantly, complete char combustion can be achieved with an oxygen mole fraction in the flue gas of only 0.8%, as opposed to a required value of ~3% for conventional atmospheric pressure air-fired or oxyfuel combustion, which reduces the costs of both oxygen generation upstream and oxygen removal downstream. The testing results show promise for dry-feed, pressurized oxy-combustion, and the new burner and furnace design.

[en] As the global electricity systems are shaped by decentralisation, digitalisation and decarbonization, the World Energy Council's Innovation Insights Briefs explore the new frontiers in energy transitions and the challenges of keeping pace with fast moving developments. We use leadership interviews to map the state of play and case studies across the whole energy landscape and build a broader and deeper picture of new developments within and beyond the new energy technology value chain and business ecosystem. The topic of this briefing is energy storage. We interviewed energy leaders from 17 countries, exploring recent progress in terms of technology, business models and enabling policies. We showcase these in 10 case studies. While the brief addresses energy storage as a whole, most insights are focused on electrical storage. Our research highlighted that today's mainstream storage technologies are unlikely to be sufficient to meet future flexibility requirements resulting from further decentralisation and decarbonization efforts. Furthermore, a restricted focus on lithium-ion batteries is putting the development of more cost-effective alternative technologies at risk. A detailed list of the interviews with innovators, energy users and producers can be found at the end of this brief. Annex 4 provides a list of acronyms and abreviations. With major decarbonizing efforts to remove thermal electric power generation and scale up renewable energies, the widespread adoption of energy storage continues to be described as the key game changer for electricity systems. Affordable storage systems are a critical missing link between intermittent renewable power and 24/7 reliability net-zero carbon scenario. Beyond solving this salient challenge, energy storage is being increasingly considered to meet other needs such as relieving congestion or smoothing out the variations in power that occur independently of renewable-energy generation. However, whilst there is plenty of visionary thinking, recent progress has focused on short-duration and battery-based energy storage for efficiency gains and ancillary services; there is limited progress in developing daily, weekly and even seasonal cost-effective solutions which are indispensable for a global reliance on intermittent renewable energy sources. The synthesis of thought leadership interviews and case studies with 37 companies and organizations from 17 countries helped derive the following key takeaways and also provide the impetus to the solution steps that we discuss in detail later in this brief: 1 - Shared road-maps: Energy storage is a well-researched flexibility solution. However, while the benefits of energy storage are clear to the energy community, there has been limited bridge-building with policy-makers and regulators to explore the behavioural and policy changes necessary to encourage implementation. 2 - Market design - Access and stacking: Market access and the ability to stack different services simultaneously will enable cost-effective deployment of energy storage, regardless of the technology. 3 - More than batteries: Energy storage is too often reduced to battery technologies. Future-proofing our energy systems means considering alternative solutions and ensuring technologies have equal market opportunities. Demonstration projects of such technologies are necessary to disprove bias towards specific technologies. 4 - Sector coupling: Energy storage presents a sector coupling opportunity between hard-to-abate sectors, such as mobility and industry and clean electricity. Different vectors of energy can be used, including heat, electricity and hydrogen. 5 - Investment: Relying on investments by adjacent sectors such as the automotive sector is not enough. The energy sector must adopt more aggressively technologies aligned with the end-goal: affordable clean energy for all.

[en] Highlights: • Process design and optimization of MPAC power plant. • Modular design for low cost, flexibility, and load-following capability. • 1.7% higher efficiency than a state-of-the-art power plant. • Low-cost approach for pollutants removal at high pressure. • Readily modifiable to staged pressurized oxy-combustion system for carbon-capture. The rapid retirement of dispatchable, fossil-based electricity sources and the influx of intermittent energy sources, both driven by the impetus towards a low-carbon future, have led to concerns about the reliability of the grid. The future need for on-demand, rotating, inertial-based assets that can be low carbon and flexibly meet changing demand to balance against intermittency will be essential. Hence, future fossil-based power generation will need to be highly efficient and flexible, and have the ability to add carbon capture when required. This study describes the process design of a modular pressurized air combustion power plant, which involves burning coal in air under pressure in parallel, modular boilers. After treatment, the high-pressure flue gas is passed through a series of turbines and inter-heaters to recover most of the compression work. The high-pressure operation allows for thermal recovery of the latent heat of moisture of the flue gas by integration into the steam cycle, which results in a plant efficiency that is 1.7% higher than that of the conventional atmospheric air-fired power plant. Moreover, the modularity enhances the flexibility of the power plant, with an improved ability for load following. This work also discusses the path to convert the modular, pressurized-air combustion process to a staged, pressurized oxy-combustion process, which is one of the most promising carbon capture processes. This can be accomplished by adding a frontend air separation unit and a backend CO₂ compression and purification unit.

[en] The World Energy Council's definition of energy sustainability is based on three core dimensions: Energy Security, Energy Equity, and Environmental Sustainability of Energy Systems. Balancing these three goals constitutes a 'Trilemma' and balanced systems enable prosperity and competitiveness of individual countries. The World Energy Trilemma Index presents a comparative ranking of 128 countries' energy systems. It provides an assessment of a country's energy system performance, reflecting balance and robustness in the three Trilemma dimensions. To provide greater insight, we have evolved the methodology for the 2019 Trilemma and, for the first time, introduced visualisation of historical trends to enable the Trilemma performance of individual countries to be tracked back two decades to 2000. The new time-series analysis provides insights into a country's historical trends, challenges and opportunities for improvements in meeting energy goals now and in the future. The Index demonstrates the impact of varying policy pathways countries have taken in each of the dimensions over the past 20 years. Looking at these trends can inform a dialogue on national energy policy to promote coherence and integration to enable better calibrated energy systems in the context of the global energy transition challenge. Ten countries achieve the top AAA balance grade in the 2019 World Energy Trilemma Index, representing top quartile performance in every dimension. Since 2000, no countries have consistently improved in each dimension every year; instead most show historical trends with a variety of peaks and troughs in a general upward direction. Overall Trilemma performance for 119 countries over the 20-year period has improved, with only 9 countries seeing their overall performance declining. The rate of improvement in overall Trilemma performance also increases as the transition progresses and encourages countries to improve their energy policies. The overall top three countries across all three Trilemma dimensions are Switzerland, Sweden and Denmark. For the Energy Security dimension, the top performing countries in 2019 are Sweden, Denmark, and Finland. The top of the Energy Equity dimension traditionally ranks well-endowed or well-connected countries and geographically concentrated populations with access to abundant and affordable energy: Luxembourg, Bahrain and Qatar are the top performers in 2019. The leaders of the 2019 ranking for the Environmental Sustainability of Energy Systems are countries making steady gains on the pathway to decarbonization and pollution control, in the context of sustainable economic growth. The top performers in this dimension are also the overall Trilemma leaders - Switzerland, Denmark and Sweden. Across the different regions of the world, pathways through the transition are different, and leading countries in each region represent this diversity. The top 10 2019 Trilemma ranking is dominated by European countries, with Switzerland as the top performer in Europe both due to robust baseline systems and coherent policies improving upon these. Uruguay ranks highest of all Latin American and Caribbean countries, with high scores in the Security and Sustainability dimensions. In the Middle East and Gulf region, Israel ranks highest due to its performance in Sustainability compared to the regional average. New Zealand, with a placing in the global top 10, heads up the Asia-Pacific region with an AAA grade. Mauritius is ahead of other countries in Africa, balancing both Equity and Sustainability performance. Canada represents the best overall performance in the North American region due to strong Energy Security and a commitment to balanced and integrated energy policy