Lignocellulosic waste (LW) is abundant in availability and is one of the suitable substrates for anaerobic digestion (AD). However, it is a complex solid substrate matrix that hinders the hydrolysis stage of anaerobic digestion. This study assessed various pre-treatment and post-treatments of lignocellulosic waste for anaerobic digestion benefiting from advanced P-graph and GaBi software (Thinkstep, Germany) from the perspective of cost and environmental performances (global warming potential, human toxicity, ozone depletion potential, particulate matter, photochemical oxidant creation, acidification and eutrophication potential). CaO pre-treatment (P4), H2S removal with membrane separation post-treatment (HSR MS) and without the composting of digestate is identified as the cost-optimal pathway. The biological (P7- Enzyme, P8- Microbial Consortium) and physical (P1- Grinding, P2- Steam Explosion, P3- Water Vapour) pre-treatments alternatives have lower environmental impacts than chemical pre-treatments (P4- CaO, P5- NaOH, P6- H2SO4) however they are not part of the near cost optimal solutions. For post-treatment, the near cost optimal alternatives are H2S removal with organic physical scrubbing (HSR OPS) and H2S removal with amine scrubbing (HSR AS). HSR AS has a better performance in the overall environmental impacts followed by HSR MS and HSR OPS. In general, the suggested cost-optimal solution is still having relatively lower environmental impacts and feasible for implementation (cost effective). There is very complicated to find a universal AD solution. Different scenarios (the type of substrate, the scale, product demand, policies) have different constraints and consequently solutions. The trade-offs between cost and environment performances should be a future extension of this work.

This study introduces a new graphical decision-making tool to facilitate the rapid selection of transportation modes with minimum energy consumption or emissions, indicating the most sustainable transportation mode. Greenhouse gas (GHG) and air pollutants (NOx, PM and SO2), together with a composite price-weighted total environmental burden (TEB), are considered in the analysis. The graphical tool, which has a similar appearance to a phase diagram, presents a map of energy use (or emission) of different transportation modes based on the values of the ratio of the transportation distances (R) and the absolute load (L). A freight transportation case study (Rotterdam to Antwerp and Genova) demonstrates the construction and application of the graphical tool. For this case study, the electric train is the transport mode that offers the lowest energy consumption and minimum TEB. The graphical decision tool can also indicate the next-best solutions when one or more options (e.g. electric train) are not available. In this scenario, general cargo shipping achieves the lowest GHG emission, but heavy lorry imposes the lowest TEB. The developed tool further demonstrates the impacts of possible future fuels and technology developments on transportation selection, including renewable biodiesel and transport electrification under different grid mixes (e.g. Latvia, Sweden and EU-28). Further criteria, including economics, can be included for future study using the proposed tool as a foundation. The graphical approach transforms the transport selection problem into an easily understandable format from which arises sound solutions.

Waste to energy (WtE) is one of the suitable alternatives in handling municipal solid waste (MSW). This study assesses the GHG emissions (CO2eq) of incineration and anaerobic digestion (AD) under different electricity production mix. The electricity production mix of China, Malaysia, Japan, Russia, UK, US (East), Czech Republic, Germany, France and Finland were considered. Incineration has a lower net CO2eq emission in China and Malaysia. However, the AD is environmentally preferable than incineration in Russia, Japan, Czech Republic, Germany, US (East), UK, Finland and France. The net CO2eq emission of incineration in China (9.41 kg CO2eq/t MSW) is lower than a country with greener electricity mix e.g. France (401.76 kg CO2eq/t MSW) where the main electricity source is nuclear. This is due to the higher avoided CO2eq emission compare to generate electricity from fossil fuel. Electricity produces from the WtE process is identified as the major factors in affecting the net CO2eq emission than the other two assessed factors (waste collection and transportation (distance), the efficiency of the WtE process). This suggests energy efficiency plays a significant role in enhancing the net CO2eq emissions and to reduce the carbon intensity of WtE.

Anaerobic digestion (AD) serves as a promising alternative for waste treatment and a potential solution to improve the energy supply security. The feasibility of AD has been proven in some of the technologically and agriculturally advanced countries. However, development is still needed for worldwide implementation, especially for AD process dealing with municipal solid waste (MSW). This paper reviews various approaches and stages in the AD of MSW, which used to optimise the biogas production and quality. The assessed stages include pre-treatment, digestion process, post-treatment as well as the waste collection and transportation. The latest approaches and integrated system to improve the AD process are also presented. The stages were assessed in a relatively quantitative manner. The range of energy requirement, carbon emission footprint and the percentage of enhancement are summarised. Thermal hydrolysis pre-treatment is identified to be less suitable for MSW (-5% to +15.4% enhancement), unless conducted in the two-phase AD system. Microwave pre-treatment shows consistent performance in elevating the biogas production of MSW, but the energy consumption (114.24-8,040 kWeh t-1) and carbon emission footprint (59.93-4,217.78 kg CO2 t-1 waste) are relatively high. Chemical (∼0.43 kWeh m-3) and membrane-based (∼0.45 kWeh m-3) post-treatments are suggested to be a lower energy consumption approach for upgrading the biogas. The feasibility in terms of cost (scale up) and other environmental impacts (non-CO2 footprint) needs to be further assessed. This study provides an overview to facilitate further development and extended implementation of AD.

Waste-to-energy supply chains are important potential contributors to minimising the environmental impacts of municipal solid waste by reducing the amounts of waste sent to landfill, as well as the fossil fuel consumption and environmental footprints. Accounting for the spatial and transport properties of the waste-to-energy supply chains is crucial for understanding the problem and improving the supply chain designs. The most significant challenge is the distributed nature of the waste generation and the household energy demands. The current work proposes concepts and a procedure for targeting the size of the municipal solid waste collection zone as the first step in the waste-to-energy supply chains synthesis. The formulated concepts and the provided case study reveal trends of reducing the net greenhouse gas savings and energy recovery by increasing the collection zone size. Population density has a positive correlation with the greenhouse gas saving and energy recovery performance. For smaller zone size the energy recovery from waste approaches and in some cases may surpass the energy spent on waste transportation. The energy recovery and greenhouse gas savings remain significant even for collection zones as large as 200 km 2 . The obtained trends are discussed and key directions for future work are proposed.

The greenhouse gas emissions footprint and global warming potential are widely-used for environmental sustainability studies. However, environmental sustainability is far wider than carbon emissions and climate change. This review aims to highlight the importance of considering air pollutants in optimisation studies and evaluate the limitation of the current assessments for air emissions, particularly in relation to transportation. The source of air pollutants is firstly overviewed with special attention on non-stationary sources, freight and sea transportation. The type of measurement to obtain the emission data and the available optimisation models on transport mode choice selection were then summarised. The strengths and Weaknesses' have been indicated. The identified gap includes greenhouse gas and air pollutants not being evaluated simultaneously and the interaction between the different pollutants are not being adequately considered. A better assessment framework and impact categories classification are consequently required. The summarised assessment model of transportation mode choice shows that the current viewpoint on low emissions, green or environmental sustainability options refers to carbon dioxide as a part of greenhouse gas. Attention towards a better emission assessment and management has been supported in this study through critical discussion. The next step of this work is to develop a methodology to measure greenhouse gas and air pollutants simultaneously by considering the synergistic effect and the discussed limitation. It is important for minimising the potential of footprint shifting and poor decision-making.

Transportation is one of the largest air pollutants as well as the Greenhouse Gas (GHGs) contributors. The inclusion of air pollutants in optimisation studies is less established than the use of CO2 and/or GHGs which are often used as an indicator of environmental sustainability. This study aims to assess environmentally sustainable alternatives for freight transportation by considering both GHG and air pollutants. A case study identifying air emissions of different freight transport modes for moving goods from Rotterdam is presented. The assessed freight transports include articulated lorry, container ship, bulk carrier, and rail operated by diesel. The environmentally sustainable freight transport of the studied route based on the common practice (GHGs only) and the inclusion of air pollutants are discussed. Evaluation of the results shows that transport with lower GHG emissions does not result on PM and SOx as well. A possibility of inappropriate decision making has been consequently highlighted. The impact of loaded capacity in moving the goods on the emission is assessed from the perspective of logistics service provider. A further comprehensive study which includes the entire life cycle is needed as this study only considers the tank to wheel emissions.

Around 21% of the world's power production is based on natural gas. Energy production is considered to be the significant sources of carbon dioxide (CO2) emissions. This has a significant effect on the global warming. Improving power plant efficiency and adding a CO2 capture unit into power plants, have been suggested to be a promising countermeasure against global warming. This paper presents a new insight to the application of energy efficient technologies in retrofitting natural gas combined cycle (NGCC) power plants with CO2 capture. High fidelity models of a 420 MW NGCC power plant and a CO2 capture plant with CO2 compression train have been built and integrated for 90% capture level. These models have been then validated by comparisons with practical operating data and literature results. The novelty of the paper is to propose optimal retrofitting strategies to minimize the efficiency penalty caused by integrating carbon capture units into the power plant, including (1) implementing heat transfer intensification techniques to increase energy saving in the heat recovery steam generator (HRSG) of the power plant; (2) extracting suitable steam from the HRSG to supply the heat required by the capture process, thus on external heat is purchased; (3) employing exhaust gas recirculation (EGR) to increase the overall energy efficiency of the integrated process, which can benefit both power plant (e.g. increasing power plant efficiency) and capture process (e.g. reducing heat demands). Compared with the base case without using any integrating and retrofitting strategies, the optimal solution based on the proposed approaches can provide sufficient heat to CO2 capture process, and keep the same power generation. The optimal solution shows that, the flue gas flow-rate is reduced 33% in the inlet of CO2 capture process, heat demand in CO2 capture decreases 43%, heat output from the power plant increases from 0 MW to 133 MW, and more than 22% of profit is obtained in the integrated system. This demonstrates the validity and efficiency of the proposed approaches in retrofitting existing NGCC power plants with CO2 capture. (C) 2015 Elsevier Ltd. All rights reserved.

•Analysis considers the temperature and duties of the available waste heat.•Models for organic Rankine cycles, absorption heat pumps and chillers proposed.•Exploitation of waste heat from site processes and utility systems.•Concept of a site energy efficiency introduced.•Case study presented to illustrate application of the proposed methodology.

In this paper, the integration of Gas Engines with the Rankine cycle and Organic Rankine cycle for use as a combined cooling, heating and power (CCHP) system was investigated. The gas engine model, Organic Rankine Cycle model, Rankine Cycle model and single effect absorption chiller model were developed in Aspen HYSYS V7.3®. The system performance of the combination of the Rankine Cycle and Organic Rankine Cycle was investigated with two different configurations. The series and parallel combination of Rankine and Organic Rankine Cycle integration with the gas engine showed an increase of 7% and 15% respectively both in the overall system efficiency and power generated. The trigeneration system provided a cooling duty of 18.6 kW, a heating duty of 704 kW to a district heating system with 3.9 MW of power generated and an overall trigeneration efficiency of 70%. The system also gave a 9% increase in the power generated when compared to the gas engine without waste heat recovery whilst bottoming with Rankine cycle, Organic Rankine cycle and Absorption refrigeration system.Keywords: Modelling, Trigeneration, Gas Engines, Waste Heat Recovery, Rankine Cycle, Organic Rankine Cycle.

This paper presents a novel design method for optimal integration of Combined Cycle Gas Turbine (CCGT) power plant with CO2 capture. Different design strategies have been investigated to improve the efficiency of the CCGT power plant, including supplementary firing, steam cycle regeneration, gas cycle regeneration and gas cycle intercooling. Finally, an amine-based post-combustion carbon capture process has been built to capture CO2 at the exit of the HRSG of the CCGT power plant. The case study shows that, improving the efficiency of CCGT power plant before the integration of carbon capture process will significantly reduce the efficiency penalty caused by integrating carbon capture units into the power plant.

Nearly one-third of the world's energy consumption and 36% of its carbon dioxide (CO2) emissions are attributable to manufacturing industries. The adoption of advanced technologies could provide technical energy savings in industry of 27-41 EJ (Extra J), along with a reduction in CO2 emissions of 2.2-3.2 GT/y, about 7-12% of today's global CO2 emissions. The paper describes the activities within European EFENIS project (which stands for Efficient Energy Integrated Solutions for Manufacturing Industries) aimed at demonstrating the benefits of novel site-level energy saving technologies and their contribution to EU policies in the area of energy efficiency. It also covers scientific and technological as well as non-scientific barriers which the project targets, the methodology and structure of the project, its intermediate and expected final outcomes and impacts as the contribution to European strategy towards low carbon and energy efficient economy.

In this work, waste heat is defined and a methodology is developed to identify the potential for waste heat recovery in a process site, considering the temperature and quantity of waste heat sources from the site processes and the site utility system (including fired heaters and, the cogeneration, cooling and refrigeration systems). To support the methodology, the concept of the energy efficiency of a site is introduced - the fraction of the energy inputs that is converted into useful energy (heat or power or cooling). Mathematical models of waste heat recovery technologies using heat as primary energy source, such as organic Rankine cycles (using both pure and mixed organics as working fluids), absorption chillers and absorption heat pumps are provided and applied to assess the potential for recovery of waste heat. The methodology is illustrated using a case study of a petroleum refinery. The energy efficiency of the site increases by 12 % as a result of the energy recovered from waste heat.

In this paper the integration of gas engines with combined cooling, heating and power (CCHP) systems was presented. The gas engine model was integrated of Rankine cycle and organic Rankine cycle in Aspen HYSYS V7.3 for potential waste heat recovery and utilization. The effect of exhaust gas temperature at different operating conditions on the efficiency and output power of the system were investigated and compared. The system integration resulted in an increase of 7% and 5% in the overall system efficiency and output power respectively. The system integration offered potential recovery of the waste heat for additional power generation whilst providing cooling and heating demands.

This paper addresses a conceptual study investigating the techno-economic feasibility for the thermal Integration of LNG cold vaporisation energy in power generation applications. In conventional regasification systems, this valuable LNG cold energy is often being wasted to ambient heat sources, representing a thermodynamic inefficient process with a significant thermal impact on the local environment. A combined facility consisting of a non-integrated Combined Cycle Power Plant (CCPP) and an LNG receiving terminal employing traditional Open Rack Vaporisers (ORV) technology, has been modelled, as a base case. Retrofit strategies for the integration of LNG cold energy have been investigated, and their impacts on power production and system efficiency are systematically compared. Retrofit design options considered in this work include the use of a propane Rankine cycle coupled with the direct expansion of natural gas, the integration of a closed-loop water cycle or open-loop water circuit with a steam Rankine cycle, and the facilitation of integrated air cooling for a gas turbine. (C) 2013 Elsevier Ltd. All rights reserved.

In this paper gas engine model was developed in Aspen HYSYS V7.3 and validated with Waukesha 16V275GL+ gas engine.Fuel flexibility, fuel types and part load performance of the gas engine were investigated.The design variability revealed that the gas engine can operate on poor fuel with low lower heating value (LHV) such as landfill gas, sewage gas and biogas with biogas offering potential integration with bottoming cycles when compared to natural gas.The result of the gas engine simulation gave an efficiency 40.7% and power output of 3592kW.

The optimal design of large scale utility systems is complex, as these systems are required to provide the heat and power requirements for individual processes contained within the total processing site. Targeting methods have been proposed which enable engineers to fully scope options prior to more detailed design. Targeting for Total Sites is an extension of the established Pinch Technology Targeting methodologies and has been used extensively in industry. The Total Site Targeting methodology includes data extraction methods, the formation of Total Site Profiles, Total Site Composite Curves and the Site Utility Grand Composite Curve.

The development of Information and Communication Technology (ICT) appears to be increasing in pace on a yearly basis. The development of new hardware, new communication methods, and software availability to exploit these new technologies, offers new opportunities in the education sector. The existing generation of learners quickly become conversant with the new technologies available, and are able to exploit them to their advantage. However, new technologies are far more slowly adopted by academic institutions, and it is usually not even clear how older technologies can be integrated into the curricula for the benefit of both learners and teachers. In addition, future employers also have a vested interest in graduating chemical engineers possessing a range of skills related to the use of commercially available software and technologies.This paper examines some of the technologies that are being exploited for teaching and learning in Chemical Engineering at The University of Manchester, and in addition how the learning of required software and technology skills can be acquired. These include internet based technologies which are being used to host virtual learning environments, which are now able to support many learning based activities such as discussion boards, teaching and learning materials, student work submission, feedback, and grading. Skills in commercially available general software, such as word processing, presentations, and spreadsheets, are also required to be acquired by learners. Skills in mathematical modelling software packages and chemical engineering simulation packages also need to be integrated into the curriculum. In addition the paper will look at technologies not yet exploited specifically in chemical engineering at Manchester, but which are making impacts in engineering disciplines elsewhere.