Karin Andersson

Chemical composition of cement pore solutions

Abstract The chemical compositions of the pore solutions extracted from seven different cement pastes (one Swedish and one French standard Portland cement, sulfate resistant, blast-furnace slag, fly ash, silica, and high alumina cement) have been determined. Analyses covered Na, K, Ca, Mg, Al, Fe, and Si as well as pH and Eh (redox potential). Ionic strengths in the range 0.03–0.29 M and pH-values in the range 12.4–13.5 were obtained. Only the pore solutions from the slag cement and the French Portland cement were reducing (negative Eh). The dominating cations of standard Portland, sulfate resistant, slag, silica and fly ash cement pore solutions were Na and K, and in sulfate resistant cement also Ca. The main components in the pore solutions of aluminate cement were Na and Al. The Si and Fe concentrations were low in all pore solutions.

Sorption of strontium and cesium on rocks and minerals

Sorption, rock mineral, The sorption of strontium and cesium on some common Swedish igneous rocks (granite, gneiss and diabase) and eleven rock-forming and accessory minerals (quartz, orthoclase, biotite, muscovite, hornblende, magnetite, hematite, fluorite, calcite, apatite and serpentine) has been studied using batch techniques. The solid sorbents were characterized with respect to mineralogy and cation-exchange capacity. The water phase used in the experiments was a synthetic groundwater with a composition representative of a groundwater from granitic rock. The influence on the sorption of parameters such as pH of, and presence of anions in the water, contact time, nuclide concentration, particle size and liquid/solid ratio was studied. The most important parameters influencing the sorption were the nuclide concentration, the groundwater composition and the mineral composition (e.g., presence of minerals with high cation-exchange capacity and/or high surface/mass ratio).

A comparative life cycle assessment of marine fuels liquefied natural gas and three other fossil fuels

Air emissions from shipping have received attention in recent years and the shipping industry is striving for solutions to reduce their emissions and to comply with stricter regulations. Strategies to reduce emissions can consist of a fuel switch, engine changes, or end-of-pipe technologies, but they do not necessarily imply reduced life cycle emissions. The present paper assesses the environmental performance of marine fuels from well-to-propeller using life cycle assessment (LCA). Four fossil fuels are compared: heavy fuel oil (HFO), marine gas oil, gas-to-liquid (GTL) fuel, and liquefied natural gas (LNG), combined with two exhaust abatement techniques: open-loop scrubber and selective catalytic reduction. LNG and other alternatives that comply with the SECA 2015 and Tier III NO x requirements give decreased acidification and eutrophication potentials with 78–90 per cent in a life cycle perspective compared with HFO. In contrast, the use of LNG does not decrease the global warming potential by more than 8–20 per cent, the amount depending mainly on the magnitude of the methane slip from the gas engine. None of the fossil fuels scrutinized here would decrease the greenhouse gas emissions significantly from a life cycle perspective. The study supports the need for LCA when evaluating the environmental impact of a fuel change, e.g. it is found that the highest global warming potential during the whole life cycle is connected to the alternatives with GTL fuel.

Will the ship energy efficiency management plan reduce CO2 emissions? A comparison with ISO 50001 and the ISM code

The Ship Energy Efficiency Management Plan (SEEMP) is the sole international regulatory instrument expected to affect rising CO2 emissions from shipping in the short-term. In this article, we discuss present gaps in the SEEMP guidelines through a comparison with the international standard for energy management systems (EMS), ISO 50001, and with the International Safety Management (ISM) code, which sets requirements for safety management systems in shipping companies. We show that the SEEMP lacks crucial features found in typical management system standards, such as requirements on policy and management reviews. Moreover, best-practice in the form of the ISO 50001 addresses important aspects, such as monitoring, energy auditing, design, and procurement processes in much more detail. In the context of previous research on these instruments and on energy efficiency in general, we argue that these gaps may be detrimental to the success of the SEEMP, both from the societal perspective of CO2 abatement and from the perspective of companies’ success in energy management. This requires further attention by academia, policy-makers and industry.

Possible Retention of Iodine in the Ground

At the eventual release of radionuclides from a deep underground repository for high level waste, the only anionic fission product would be iodine, assuming reducing conditions (1–3). The major species would be I− although leaching experiments on tuff from the Nevada Test Site have indicated that other species may be present (4). The retention of these anionic species would be low in most bedrocks (5–7). In this paper, the sorption of iodide on various minerals and compounds is discussed as well as the prospect of using common geologic media as iodide retarding backfill materials in an underground waste repository.

Fuels for short sea shipping: A comparative assessment with focus on environmental impact

Short sea shipping is facing harder requirements on exhaust emissions in the coming years as stricter regulations are enforced in some regions of the world. In addition, shortage of conventional fuels as well as restrictions on greenhouse gas emissions makes the search for new fuels of interest. The objective of this article is to assess important characteristics to evaluate when selecting fuels for short sea shipping. The following four criteria are considered: (1) local and regional environmental impacts, (2) overall environmental impact, (3) infrastructure and (4) fuel cost and competition with other transport modes. Special focus is put on environmental impact, and life cycle assessment is used for the environmental assessment. The fuels compared in this study are heavy fuel oil, marine gas oil, biomass-to-liquid fuel, rapeseed methyl ester, liquefied natural gas and liquefied biogas. This study shows that liquefied natural gas will reduce the local and regional environmental impacts more relative to the other fuels investigated here. Furthermore, liquefied biogas is found to be the most preferable if all environmental impact categories are considered. This study also highlights the importance to consider other impact categories for short sea shipping compared to deep sea shipping and shows that NOX emission is the dominant contributor to all assessed environmental impact categories with local and regional impacts.

Sorption of Actinides in Well-Defined Oxidation States on Geologic Media

The long-lived actinides and their daughter products largely dominate the biological hazards from spent nuclear fuel already from some 300 years after the discharge from the reactor and onwards . Therefore it is essential to make reliable assessments of the geochemistry of these elements in any concept for long-term storage of spent fuel or reprocessing waste, etc.

Sorption of Some Fission Products and Actinides in Concrete Systems

The sorption of some actinides (Th, U, Np, Pu and Am) and fission products (I, Cs) was measured on two types of Standard Portland cements as well as on samples from old (70 years) hydro power dam constructions using a batch technique. Pore water compositions were analysed, and artificial pore water solutions were used as aqueous phases in the experiments. Measurements were also performed on five other concrete types (not reported in detail in this paper) to illustrate the effects of the cement matrix composition on the sorption behaviour of the radionuclides. The sorption of actinides in the trivalent (americium), tetravalent (thorium) pentavalent (neptunium) and hexavalent (uranium) states was high in all the studied concrete systems. Generally, the sorption of cesium was low due to the low exchange capacity of the cement and the high concentration of competing cations in the pore waters. The sorption of iodine was much higher than in most silicate minerals of geologic origin. The differences between the various concrete systems were generally minor in terms of their sorbing capacities.

Diffusion of radionuclides in concrete and concrete/bentonite systems

Various construction materials are under consideration for nuclear waste repositories. Two important materials are concrete and bentonite clay, which will act as mechanical barriers and prevent convective water flow. These barriers will also retard transport (diffusion controlled) of dissolved radionuclides by a combination of mechanical constraints and chemical interactions with the solid. An important issue is the possible change of the initial sodium bentonite into the calcium form due to interaction with calcium from the concrete. The initial leaching of concrete was studied using radioactive spiked concrete in contact with compacted bentonite. Measurement were made of the diffusion of Cs, Am and Pu into 5 different types of concrete in contact with pore water. The diffusivity measured for Cs agrees reasonably well with data found in the literature. No movement could be measured for Am and Pu (< 0.2 mm), even though the contact times were extremely long (2.5 and 5 yr, respectively). The diffusion of Na, Ca and Cs from concrete into bentonite was also measured.

Cost-effective choices of marine fuels in a carbon-constrained world: results from a global energy model.

The regionalized Global Energy Transition model has been modified to include a more detailed shipping sector in order to assess what marine fuels and propulsion technologies might be cost-effective by 2050 when achieving an atmospheric CO2 concentration of 400 or 500 ppm by the year 2100. The robustness of the results was examined in a Monte Carlo analysis, varying uncertain parameters and technology options, including the amount of primary energy resources, the availability of carbon capture and storage (CCS) technologies, and costs of different technologies and fuels. The four main findings are (i) it is cost-effective to start the phase out of fuel oil from the shipping sector in the next decade; (ii) natural gas-based fuels (liquefied natural gas and methanol) are the most probable substitutes during the study period; (iii) availability of CCS, the CO2 target, the liquefied natural gas tank cost and potential oil resources affect marine fuel choices significantly; and (iv) biofuels rarely play a major role in the shipping sector, due to limited supply and competition for bioenergy from other energy sectors.