Global decarbonization potential of CO2 mineralization in concrete materials.

CO2 mineralization products are often heralded as having outstanding potentials to reduce CO2-eq. emissions. However, these claims are generally undermined by incomplete consideration of the life cycle climate change impacts, material properties, supply and demand constraints, and economic viability of CO2 mineralization products. We investigate these factors in detail for ten concrete-related CO2 mineralization products to quantify their individual and global CO2-eq. emissions reduction potentials. Our results show that in 2020, 3.9 Gt of carbonatable solid materials were generated globally, with the dominant material being end-of-life cement paste in concrete and mortar (1.4 Gt y-1). All ten of the CO2 mineralization technologies investigated here reduce life cycle CO2-eq. emissions when used to substitute comparable conventional products. In 2020, the global CO2-eq. emissions reduction potential of economically competitive CO2 mineralization technologies was 0.39 Gt CO2-eq., i.e., 15% of that from cement production. This level of CO2-eq. emissions reduction is limited by the supply of end-of-life cement paste. The results also show that it is 2 to 5 times cheaper to reduce CO2-eq. emissions by producing cement from carbonated end-of-life cement paste than carbon capture and storage (CCS), demonstrating its superior decarbonization potential. On the other hand, it is currently much more expensive to reduce CO2-eq. emissions using some CO2 mineralization technologies, like carbonated normal weight aggregate production, than CCS. Technologies and policies that increase recovery of end-of-life cement paste from aged infrastructure are key to unlocking the potential of CO2 mineralization in reducing the CO2-eq. footprint of concrete materials.

National priorities in the power system transition to net-zero: No one size fits all.

Net-zero emissions targets are increasingly being adopted globally. However, there is a disconnect between policy mechanisms, that primarily focus on incentives to reduce emissions, and technological requirements to achieve this aim. In this context, an absence of CO2 removal incentives effectively precludes complete decarbonization, while potentially increasing the cost. Here, we quantify the effectiveness of carbon tax, negative emissions credit, and technology improvements in delivering net-zero targets cost-effectively in the UK, Poland, Texas, and Wyoming power systems. We show that the combination of a carbon tax and negative emissions credit is critical to reaching net-zero targets. From the techno-economic perspective, while all cost reduction is welcome, a further cost reduction of renewable energy is uniquely valuable in minimizing the transition cost. However, even with the availability of electricity storage, dispatchable and low-carbon thermal plants are key to cost-effectively maintaining system reliability, regardless of the costs of other alternatives.

Hydrogen Production and Its Applications to Mobility.

Hydrogen has been identified as one of the key elements to bolster longer-term climate neutrality and strategic autonomy for several major countries. Multiple road maps emphasize the need to accelerate deployment across its supply chain and utilization. Being one of the major contributors to global CO2 emissions, the transportation sector finds in hydrogen an appealing alternative to reach sustainable development through either its direct use in fuel cells or further transformation to sustainable fuels. This review summarizes the latest developments in hydrogen use across the major energy-consuming transportation sectors. Rooted in a systems engineering perspective, we present an analysis of the entire hydrogen supply chain across its economic, environmental, and social dimensions. Providing an outlook on the sector, we discuss the challenges hydrogen faces in penetrating the different transportation markets.

Inefficient investments as a key to narrowing regional economic imbalances.

Policy led decisions aiming at decarbonizing the economy may well exacerbate existing regional economic imbalances. These effects are seldom recognized in spatially aggregated, top-down, and techno-economic decarbonization strategies. Here, we present a spatial economic framework that quantifies the gross value added associated with low carbon hydrogen investments while accounting for region-specific factors, such as the industrial specialization of regions, their relative size, and their economic interdependencies. In our case study, which uses low carbon hydrogen produced via autothermal reforming combined with carbon capture and storage to decarbonize the energy intensive industries in Europe and in the UK, we demonstrate that interregional economic interdependencies drive the overall economic benefits of the decarbonization. Policies intended to concurrently transition to net zero and address existing regional imbalances, as in the case of the UK Industrial Decarbonization Challenge, should take these local factors into account.

CO2 mitigation or removal: The optimal uses of biomass in energy system decarbonization.

Owing to its versatility, biomass can be used for a range of CO2 mitigation and removal options. The recent adoption of end-of-century temperature targets at the global scale, along with mid-century economy-wide net zero emission targets in Europe, has boosted demand forecasts for this valuable resource. Given the limited nature of sustainable biomass supply, it is important to understand most efficient uses of biomass, both in terms of avoided CO2 emissions (i.e., substituted energy and economic services) and CO2 removal. Here, we quantify the mitigation and removal potential of key bio-based CO2 removal pathways for the transport, power, construction, and iron and steel sectors in Europe. By combining the carbon balance of these pathways with their economics, the optimal use of biomass in terms of CO2 avoidance and removal costs is quantified, and how these evolve with the decarbonization of the European energy system is discussed.