• Energy Research

Abstract Cold storage is a valid solution for the energy peak reduction in the air conditioning field, which strongly affects the energy consumption in the civil sector. An innovative storage device, called ColdPeak , has been already tested in a recently published work, demonstrating unparalleled properties in terms of charging/discharging storage power. Now, the unit is analyzed from the environmental point of view by means of a LCA (Life Cycle Assessment) methodology: the air conditioning system integrating the ColdPeak unit has been compared with a conventional system from the environmental point of view, assuming the same potentiality of cold energy and including a sensitive analysis on the energy saving potential of the innovative device (5–25% of the energy required by the conventional system). In the sensitivity analysis, the energy saving is counter-balanced by the energy load required for the manufacturing and installation of an additional component in the air conditioning system (the ColdPeak device itself). The environmental footprint that considers the material and the energy to fabricate the ColdPeak is very low if compared with the amount of energy saved thanks to its application. As a matter of fact, the LCA study reports that the integration of the cold storage unit allows a significant reduction of environmental footprint in terms of Global Warming Potential (−17%), Acidification Potential (−15.5%), Eutrophication Potential (−18%), Eco-toxicity (−16%), Human Health (−18%) and Fossil Depletion (−18%). The paper also reports the temporal trend of the environmental footprint that shows a pay-back period for the construction of the innovative integrated system of less than one year for all the investigated categories.

In this paper, a comparison is provided between liquid-liquid and liquid-solid partitioning systems applied to the removal of high concentrations of 4-nitrophenol. The target compound is a typical representative of substituted phenols found in many industrial effluents while the biomass was a mixed culture operating as a conventional Sequencing Batch Reactor and acclimatized to 4-nitrophenol as the sole carbon source. Both two-phase systems showed enhanced performance relative to the conventional single phase bioreactor and may be suitable for industrial application. The best results were obtained with the polymer Hytrel™ which is characterized by higher partition capability in comparison to the immiscible liquid solvent (2-undecanone) and to the polymer Tone™. A model of the two systems was formulated and applied to evaluate the relative magnitudes of the reaction, mass transfer and diffusion characteristic times. Kinetic parameters for the Haldane equation, diffusivity and mass transfer coefficients have been evaluated by data fitting of batch tests for liquid-liquid and liquid-solid two phase systems. Finally, preliminary results showed the feasibility of polymer regeneration to facilitate polymer reuse by an extended contact time with the biomass.

The well-known world energetic matter, mainly due to the worldwide growing energy consumption gone with a reduction of oil and gas availability, and to the environmental effects of the indiscriminate use of fossil fuels in our economy, is leading to the development of clean innovative technologies for the reduction of GHG emissions and the creation of a more sustainable economic structure worldwide. But, realizing and installing renewable energy plants have an environmental “footprint” that has to be evaluated to quantify the real impact of renewable technologies on the environment. Nowadays, the most important tool to evaluate this impact of a product is the Life Cycle Assessment (LCA). To this aim, several impact categories are defined; among these the most important are the Global Warming, the Abiotic Depletion, the Eutrophication, the Acidification, the Land Use and the Human toxicity. The aim of this work is to present a Life Cycle Assessment of an innovative solar technology, the Molten Salt Concentrating Solar Power (CSP) plant, developed by Italian Research Centre ENEA and able to produce clean electricity by using solar energy. The Life Cycle Assessment was carried out by means of the SimaPro7 software, one of the most used LCA software in the world. It is worth assess that these types of software are an indispensable tools for leading LCA studies. In the second part of the study the environmental performance of the CSP plant was compared with th ese of conventional oil and gas power plants.

Current hydrogen production processes, which depend upon the use of fossil fuels, are discussed. The means which can be used to increase efficiency, and to enable both up-and down-scaling, are considered, in particular the use of catalysts and inorganic membranes. Biomass as an alternative energy source for the production of biohydrogen through both aerobic and anaerobic fermentation has the potential to make hydrogen a truly environmentally friendly fuel.

Geothermal brines can be a resource of energy, freshwater and minerals. Even when rejected after their exploitation to produce energy in a power plant, the brines can be a source of freshwater and minerals, and can have a residual enthalpy that can be recovered to produce additional power. The different reuse scenarios of these wasted brines depend on the composition and temperature at which they must be reinjected into the wells. On this basis, geothermal energy production is a perfect case study to investigate the water–energy nexus and to optimize the integrated energy- and water-production processes. In this paper, two case studies of brine reuse for both energy and water production are presented with the related process analysis, basic design and technical–economic analysis. A methodology to evaluate the exergy efficiency of the processes is presented by analyzing minimum work of separation, the maximum achievable work and the additional primary energy required for integrated production. The novel approach to estimate the process efficiency for integrated geothermal energy and desalination plants is applied to the case studies and discussed in light of literature results.

This paper presents the modeling theory and results of an innovative thermal energy storage (TES) facility, ideated, realized, and tested by ENEA (Italy). This prototype enabled the thermocline storage with molten salts in a novel geometry ideated for small-medium scale decentralized solutions, which includes two vertical channels to force the circulation through two heat exchangers, respectively, and realized for charging and discharging phases (in a single tank). A thermophysical model was built and tested properly for this particular geometry in order to analyze the temperature distribution along the radius. The numerical results well reproduced the experimental values. Furthermore, the analytical solution provided a short-cut methodology able to evaluate the thermocline distribution (along the vertical axis) depending on both the time and the radius values. Hence, the influence of the radial position (r) on the thermocline degradation was studied finding that, at the edges (r → 1), the thermocline remains unchanged for longer (around ten times more) than at the center of the tank (r → 0). The obtained numerical modeling and the analytical correlation can be useful for the process analysis to scale-up the thermal storage system and to evaluate the system reliability for industrial plants.

AbstractThe biodegradable plastics were introduced in the 1980s to detect possible renewable feedstock to produce nonpetroleum‐based plastics as well as to reduce the environmental problems due to the increase of landfill volume. Furthermore, the biodegradable plastics have been used to reduce the environmental impact (in terms of energy requirement from nonrenewable resources and CO2 gas emissions) derived from production, utilization, and disposal of petroleum‐based plastics, like polyethylene terephthalate (PET). To this end, in the last years, different typologies of bioplastics were introduced (both biodegradable plastics and plastics made from renewable resources) like Mater‐Bi (made from starch), poly‐3‐hydroxybuyrate, polycaprolactone, and polylactic acid (PLA).Nowadays, the most important tool to evaluate the environmental impact of a bioplastic and/or of a petroleum‐based plastic (conventional plastic) is the life cycle assessment (LCA) that determines the overall impact of a plastic on the environment by defining and analyzing several impact indices directly related to production, utilization, and disposal of the considered plastics.In this work, the LCA (cradle to grave) of PLA bottles for drinking water was developed and compared to the LCA of PET bottles for the same use.The obtained results highlighted that the true advantage of the PLA bottles with respect to the PET bottles arises from the use of renewable resources, but this benefit is paid in environmental terms due to the higher impact on human health and ecosystem quality (due to the use of pesticides, consumption of land, and consumption of water for the production of raw materials). © 2010 American Institute of Chemical Engineers Environ Prog, 2011

AbstractThe production of biogas requires the development of cheap and effective inline monitoring of 11 systems; specifically, pure biogas for specialized applications (solid oxide fuel cells) needs 12 very low concentrations of volatile organic compounds' contaminants. In this work, we report an application of a system, Bionote, already tested at very low concentrations (ppb) for biomedical applications. In details, we applied a gas sensors array of functionalized transducers to the detection of three target analytes (methanol, acetone, and isoprene) to high concentrations of analytes (up to 10,000 ppm). The results were widely satisfactory, because they demonstrate in this range the applicability of the system, which is largely reversible as well. The low cost and very low response times of these sensors stimulate in the direction of their full development and application for online monitoring of biogas in production processes.