Public procurement for carbon reduction in infrastructure projects - An international overview

Carbon emissions emanating from infrastructure construction projects are substantial and stem primarily from production of construction materials and use of energy for construction transport and site activities. In recent years, public infrastructure clients world-wide have begun to include carbon reduction goals in their procurement requirements. This is however a new and complex field where practices vary and are still developing. In this paper, we compare models for carbon reduction requirements in infrastructure construction projects based on case studies of large projects in Australia, USA, the Netherlands, Sweden and UK. We found that open, functional carbon reduction requirements were considered innovative but entailed costs for calculating baselines and risks for speculation. Also, high time pressure in projects limits contractors\u27 opportunities to explore reduction opportunities. Thus, specific, prescriptive requirements may play an important role in client-led, long-term innovation processes. Organizational competence and resources on the buyer side are essential, and policies for carbon reduction should aim to increase client capacity. Further, procurement practices are developed in mutual interaction between clients and suppliers over longer periods of time, which limits possibilities to transfer procurement policies and requirements between contexts

Climate impact from peat utilisation in Sweden

The Europeans Union’s (EU’s) climate and energy strategy aims at reducing the emissions of greenhouse gases (GHG) by 20 % (compared to 1990) and to increase the share of renewable energy to 20 % by the year 2020. Increased use of bioenergy is considered key in these efforts. Moreover, the EU regards the Emission Trading System (ETS) to be the main policy instrument for reaching these objectives. This thesis investigates the effectiveness of these instruments for reaching climate policy objectives in the EU. Focus lies on the climate impacts from bioenergy due to how they affect atmospheric carbon dioxide (CO2) over time; the climate impacts of peat; and how allocation rules in the EU ETS should be designed to reduce emissions in a cost effective way. The analysis shows that there is a climate impact from using forest residues for energy which depends on how fast the CO2 emission pulse is compensated by uptake of atmospheric CO2 (or avoided emissions in the reference case). Assuming all other factors equal, biofuels with slow uptake rates have a stronger climate impact than biofuels with fast uptake rates. The time perspective over which the analysis is done is crucial for the assessment. Over a 100 year perspective the use of branches and tops are better for climate mitigation than stumps which in turn are better than coal. Over a 20 year time perspective this conclusion holds, but the relative differences between these fuels are smaller. The climate impacts from using peat for energy can vary considerably depending on the characteristics of the peatland in question, the choice of after-treatment strategy and assumptions regarding after-treatment parameters. Over 300 years, we estimate the climate impacts from peat to range from being lower than the impacts of natural gas to higher than those of coal. In phases I and II of the EU ETS emission allowances have to a large extent been allocated free of charge to firms based on historic emissions, so called grandfathering. As production levels change, old installations are closed and new installations opened, Member States wish to limit the entitlement to allowances and update the allocation. However, the analysis shows that adjusting the initial allocation may affect firms’ behaviour and significantly reduce their incentives to become more CO2 efficient. Benchmarking (allocation based on production and sector common benchmarks or a prescribed cap) may offer a way to move from grandfathering in phase I and II of the EU ETS toward the long term goal of auctioning. Benchmarking preserves firms’ incentives to become more CO2 efficient, but involves a production subsidy. Climate efficient use of bioenergy and peat should be incentivized, taking into consideration effects on carbon stocks, while also considering other ecosystem services. This could for instance be accomplished by establishing a credit system for land-use related CO2 reductions, which could be linked to the EU ETS

Structure of human argininosuccinate synthetase

Argininosuccinate synthetase catalyzes the transformation of citrulline and aspartate into argininosuccinate and pyrophos phate using the hydrolysis of ATP to AMP and pyrophos phate. This enzymatic process constitutes the rate limiting step in both the urea and arginine citrulline cycles. Previous studies have investigated the crystal structures of argininosuccinate synthetase from bacterial species. In this work, the first crystal structure of human argininosuccinate synthetase in complex with the substrates citrulline and aspartate is presented. The human enzyme is compared with structures of argininosuccinate synthetase from bacteria. In addition, the structure also provides new insights into the function of the numerous clinical mutations identified in patients with type I citrullinaemia also known as classic citrullinaemi

An Unprecedented Fe-III(mu-OH)Zn-II Complex that Mimics the Structural and Functional Properties of Purple Acid Phosphatases

This communication reports the synthesis and X-ray structure of the first mixed-valence (FeZnII)-Zn-III complex containing the Fe-III(mu-OH)Zn-II structural unit. Based on the structure, physicochemical solution studies, and the catalytic properties toward the hydrolysis of the diester 2,4-bis(dinitrophenyl)phosphate (BDNPP), it is proposed that complex 1 employs a hydrolytic mechanism similar to that proposed for red kidney bean purple acid phosphatase, including a nucleophilic attack by the terminal, Fe-III-bound hydroxide and the concomitant release of 2,4-dinitrophenolate. Furthermore, it is demonstrated that the mu-hydroxo group in the {Fe-III(mu-OH)(mu-ROPO3)Zn-II} intermediate is unable to hydrolyze the monoester 2,4-dinitrophenylphosphate (DNPP), which suggests that the mu-hydroxo group is a significantly poorer nucleophile than the terminally Fe-III-bound OH- group