Risks in the design of regional hydrogen hub systems: A review and commentary.

Early investments in regional hydrogen systems carry two distinct types of risk: (1) economic risk that projects will not be financially viable, resulting in stranded capital, and (2) environmental risk that projects will not deliver deep reductions in greenhouse gas emissions and through leaks, perhaps even contribute to climate change. This article systematically reviews the literature and performs analysis to describe both types of risk in the context of recent efforts in the United States and worldwide to support the development of "hydrogen hubs" or regional systems of hydrogen production and use. We review estimates of hydrogen production costs and projections of how future costs are likely to change over time for different production routes, environmental impacts related to hydrogen and methane leaks, and the availability and effectiveness of carbon capture and sequestration. Finally, we consider system-wide risks associated with evolving regional industrial structures, including job displacement and underinvestment in shared components, such as refueling. We conclude by suggesting a set of design principles that should be applied in developing early hydrogen hubs if they are to be a successful step toward creating a decarbonized energy system.

Electric vehicle battery chemistry affects supply chain disruption vulnerabilities.

We examine the relationship between electric vehicle battery chemistry and supply chain disruption vulnerability for four critical minerals: lithium, cobalt, nickel, and manganese. We compare the nickel manganese cobalt (NMC) and lithium iron phosphate (LFP) cathode chemistries by (1) mapping the supply chains for these four materials, (2) calculating a vulnerability index for each cathode chemistry for various focal countries and (3) using network flow optimization to bound uncertainties. World supply is currently vulnerable to disruptions in China for both chemistries: 80% [71% to 100%] of NMC cathodes and 92% [90% to 93%] of LFP cathodes include minerals that pass through China. NMC has additional risks due to concentrations of nickel, cobalt, and manganese in other countries. The combined vulnerability of multiple supply chain stages is substantially larger than at individual steps alone. Our results suggest that reducing risk requires addressing vulnerabilities across the entire battery supply chain.

Expert elicitation of the timing and uncertainty to establish a geologic sequestration well for CO2 in the United States.

Many studies anticipate that carbon capture and sequestration (CCS) will be essential to decarbonizing the U.S. economy. However, prior work has not estimated the time required to develop, approve, and implement a geologic sequestration site in the United States. We generate such an estimate by identifying six clearance points that must be passed before a sequestration site can become operational. For each clearance point (CP), we elicit expert judgments of the time required in the form of probability distributions and then use stochastic simulation to combine and sum the results. We find that, on average, there is a 90% chance that the time required lies between 5.5 and 9.6 y, with an upper bound of 12 y. Even using the most optimistic expert judgements, the lower bound on time is 2.7 y, and the upper bound is 8.3 y. Using the most pessimistic judgements, the lower bound is 3.5 y and the upper bound is 19.2 y. These estimates suggest that strategies must be found to safely accelerate the process. We conclude the paper by discussing seven potential strategies.

Dynamic responses of SO2 pollution to China's environmental inspections.

We evaluate the effect of rotating inspections carried out by China's central government in 2016 to 2017 in response to the country's air pollution crisis on the environmental performance of targeted cities and coal power plants. Using a staggered difference-in-differences (DID) design, we find that during one-month inspections concentrations of sulfur dioxide (SO2) at coal power plants in targeted cities are on average lower by 25 to 52% compared to not-yet-inspected cities but revert by 54 to 62% on average once scrutiny ends. Following inspections, SO2 pollution increases more quickly at state-owned plants accountable to the central government, compared to state-owned plants accountable to the local (city or below) government. Our results suggest that for most plants SO2 concentration changes during inspections may have been due primarily to the operation of end-of-pipe SO2 removal devices, while following inspections local state-owned plants may have reduced output.

Risks of decoupling from China on low-carbon technologies.

For most technologies, the cure is likely worse than the disease.

Improving Evaluation of Energy Policies with Multiple Goals: Comparing Ex Ante and Ex Post Approaches.

Sustainability policies are often motivated by the potential to achieve multiple goals, such as simultaneously mitigating the climate change and air quality impacts of energy use. Ex ante analysis is used prospectively to inform policy decisions by estimating a policy's impact on multiple objectives. In contrast, ex post analysis of impacts that may have multiple causes can retrospectively evaluate the effectiveness of policies. Ex ante analyses are rarely compared with ex post evaluations of the same policy. These comparisons can assess the realism of assumptions in ex ante methods and reveal opportunities for improving prospective analyses. We illustrate the benefits of such a comparison by examining a case of two energy policies in China. Using ex post analysis, we estimate the impacts of two policies, one that targets energy intensity and another that imposes quantitative targets on SO2 emissions, on energy use and pollution outcomes in two major energy-intensive industrial sectors (cement, iron and steel) in China. We find that the ex post effects of the energy intensity policy on both energy and pollution outcomes are very limited on average, while the effects of the SO2 emissions policy are large. Compared with ex ante analysis, ex post estimates of benefits of the energy intensity policy are on average smaller, and differ by location in both sign and magnitude. Accounting for firm-level heterogeneity in production processes and policy responses, as well as the use of empirically grounded counterfactual baselines, can improve the realism of ex ante analysis and thus provide a more reliable basis for policy design.

Mercury Benefits of Climate Policy in China: Addressing the Paris Agreement and the Minamata Convention Simultaneously.

National commitments under the Paris Agreement on climate change interact with other global environmental objectives, such as those of the Minamata Convention on Mercury. We assess how mercury emissions and deposition reductions from national climate policy in China under the Paris Agreement could contribute to the country's commitments under the Minamata Convention. We examine emissions under climate policy scenarios developed using a computable general equilibrium model of China's economy, end-of-pipe control scenarios that meet China's commitments under the Minamata Convention, and these policies in combination, and evaluate deposition using a global atmospheric transport model. We find climate policy in China can provide mercury benefits when implemented with Minamata policy, achieving in the year 2030 approximately 5% additional reduction in mercury emissions and deposition in China when climate policy achieves a 5% reduction per year in carbon intensity (CO2 emissions 9.7 Gt in 2030). This corresponds to 63 Mg additional mercury emissions reductions in 2030 when implemented with Minamata Convention policy, compared to Minamata policy implemented alone. Climate policy provides emissions reductions in sectors not considered under the Minamata Convention, such as residential combustion. This changes the combination of sectors that contribute to emissions reductions.

Quantifying coal power plant responses to tighter SO2 emissions standards in China.

We evaluate the impact of China's new air pollution standards on sulfur dioxide (SO2) emissions by comparing newly available data from Continuous Emissions Monitoring Systems (CEMS) at coal power plants with satellite measures. First, we show that following the July 2014 deadline for implementing tighter emissions standards, stack concentrations of SO2 reported by CEMS declined by 13.9%. Second, on average the ratios of the declines of SO2 measures in the satellite data and the CEMS data are about 0.5. However, the degree of correspondence between the two data sources varies by policy stringency, with weak correspondence found in key regions facing the toughest new limits. Third, large plants achieved compliance earlier than small (typically) power and heat cogeneration plants. To achieve continued air quality improvement, our results suggest a need for increased scrutiny of emissions data quality and monitoring practices and clear long-term targets.

A rice glutamate receptor-like gene is critical for the division and survival of individual cells in the root apical meristem.

Glu receptors are known to function as Glu-activated ion channels that mediate mostly excitatory neurotransmission in animals. Glu receptor-like genes have also been reported in higher plants, although their function is largely unknown. We have identified a rice (Oryza sativa) Glu receptor-like gene, designated GLR3.1, in which mutation by T-DNA insertion caused a short-root mutant phenotype. Histology and DNA synthesis analyses revealed that the mutant root meristematic activity is distorted and is accompanied by enhanced programmed cell death. Our results supply genetic evidence that a plant Glu receptor-like gene, rice GLR3.1, is essential for the maintenance of cell division and individual cell survival in the root apical meristem at the early seedling stage.