Does biomass energy consumption reduce total energy CO2 emissions in the US?

This study investigates the causal relationship between total biomass energy consumption, total energy CO₂ emissions, and GDP in the United States for the period January 1973–December 2016 by employing a directed acyclic graph (DAG) techniques and the Autoregressive Distributed Lag (ARDL) model. Additionally, this paper examines the existence of the environmental Kuznets curve (EKC) hypothesis. The result of the DAG reveals that total biomass energy consumption and GDP have a unidirectional contemporaneous causal relationship with total energy CO₂ emissions. Based on the results of the ARDL, we find that a 1% increase in per capita total biomass energy consumption causes a 0.65% reduction in per capita total energy CO₂ emissions in the long-run. This finding implies that expanding the usage of biomass is one way to reduce and control greenhouse gases in the US. Moreover, we find that the inverted U-shaped EKC hypothesis is satisfied for the US case. Findings from this study suggest that energy policies should stimulate an increase of biomass production for reducing total energy CO₂.     

基于完全竞争的生物质制氢产业市场结构分析

相对化石能源,生物质氢能源是一种理想的可再生能源,由于尚未形成有效的产业化市场价格机制,其产业化应用进展缓慢,对此,本文从完全竞争市场模型出发分析其产业化的理论机理。首先,建立了完全竞争的生物质制氢厂商的社会福利优化模型,然后,讨论了优化模型解的两个条件,进一步得出了生物质制氢厂商利润最大化的条件。在此基础上,从增加生物质制氢供给,降低厂商研发成本角度提出了初步的政策建议。     

Urban forest biomass estimates: is it important to use allometric relationships developed specifically for urban trees?

Many studies have analyzed the benefits, costs, and carbon storage capacity associated with urban trees. These studies have been limited by a lack of research on urban tree biomass, such that estimates of carbon storage in urban systems have relied upon allometric relationships developed in traditional forests. As urbanization increases globally, it is becoming important to more accurately evaluate carbon dynamics in these systems. Our goal was to understand the variability and range of potential error associated with using allometric relationships developed outside of urban environments. We compared biomass predictions from allometric relationships developed for urban trees in Fort Collins, Colorado to predictions from allometric equations from traditional forests, at both the individual species level and entire communities. A few of the equations from the literature predicted similar biomass to the urban-based predictions, but the range in variability for individual trees was over 300%. This variability declined at increasingly coarse scales, reaching as low as 60% for a street tree community containing 11 tree species and 10, 551 trees. When comparing biomass estimates between cities that implement various allometric relationships, we found that differences could be a function of variability rather than urban forest structure and function. Standardizing the methodology and implementing averaged equations across cities could be one potential solution to reducing variability; however, more accurate quantification of biomass and carbon storage in urban forests may depend on development of allometric relationships specifically for urban trees.     

Influence of grass suppression and sowing rate on the establishment and persistence of forb dominated urban meadows

In practice in the UK, grasses and ruderal forbs recruited from the urban soil seed bank often have a detrimental impact on establishment and development of sown meadows. This study investigated the effect of graminicide, and sowing rate on establishment, survival and longer term development of sown meadow forbs. A seed mix containing 19 forb species was sown at two sowing rates in a randomized block experiment in Sheffield, UK. The two most abundant grasses recruited, Arrhenatherum elatius, and Holcus lanatus, were highly damaging to survival and development of sown forbs. Cutting the meadow to 50 mm during the first year did not alleviate grass competition. Weedy ruderal forbs had a lesser effect on sown forbs than the perennial grasses. Where a graminicide was used, sown forb density and biomass were significantly higher in the second and third year of the study, and forb richness significantly greater in all 3 years. Sown forb density was higher at the high sowing rate in all three years, and forb richness in years 1 and 2. Sowing rate did not significantly increase forb biomass in any year. In general, suppressing grass growth had a more beneficial effect on sown forb establishment and development than increasing sowing rate.