Landfills all around the world are one of the major sources that contribute towards global warming and climate change. Although landfilling should be prioritized last in the waste management hierarchy due to highest greenhouse gas emissions as compared to other waste management systems it is still very common around the world. In this study, methane emissions are estimated by applying First Order Decay model to landfills in Pakistan over the latest data available by Pakistan Environmental Protection Agency. Results demonstrate that nearly 14.18 Gg of methane is emitted from the landfills in Pakistan each year. By combusting this methane in the form of biogas collected from the landfills as a waste management scheme we can reduce greenhouse effect up to ~88%. Same percentage is observed when we apply the similar analysis over the potentially improved practice. Also, Pakistan is facing severe economic crises due to continuous increasing gap between energy demand and supply. Demand is increasing exponentially while supply is observed to remain constant over the last few years due to frozen capacity in spite of having significant renewable/alternate energy resources. Current electricity shortfall has reached up to 6000 MW. Present operational landfills in Pakistan can only contribute up to ~0.1% to cater the total deficit which does not make any significant difference but if 75% of the total waste generated today is collected and 50% of it landfilled then Pakistan has the potential to produce ~83.17 MW of power that can contribute up to 1.4% to overcome the current power shortage. The outcomes of this paper may also be applicable to other developing countries having similar resources

By 2050, UK plans to create 'low carbon society'. To meet this ambitious target, UK's heating sector must be completely decarbonized. The identification and deployment of low carbon heating sources is thus an urgent policy and research priority. Recovering heat from sewage wastewater is relatively new and attractive option as it can help UK move towards its climate change targets while decarbonising the heating sector & reducing the reliance on fossil fuels. In the domestic context, wastewater is normally discharged at higher temperature than ambient (a carrier of heat/ thermal energy) losses its energy to (ground) environment before it reaches to WWTP. Recovering this heat from wastewater could be a considerable source of energy, revenue and is environmental friendly as it results in the reduction of GHG emissions, resource conservation and in increase share of renewable energy. In last decade, many cities around the world have successfully implemented wastewater thermal energy recovery but UK is lagging behind. Pilot project such as in Scotland is leading the way, but further research is needed to build the evidence base and replicate the concept elsewhere in UK. The Home Energy 4 Tomorrow (HE4T) project at London South Bank University (LSBU) was created to address this evidence gap. The project objectives include sizing the heat potential recoverable from wastewater at designated sites. The current paper forms part of the HE4T project and the second in series of output on wastewater heat recovery in UK. In this paper we present some initially measured data, variations in wastewater temperature and flow, steady state and dynamic model results wastewater temperature and the potential heat recovery of the designated site. Early results, their limitations and possible routes to address these limitations are discussed along with policy implications for UK heat strategy.

As oil and gas field development moves further into deep seas, maximizing hydrocarbon extraction at an acceptable cost is one of the greatest challenges facing the industry today. In this regard, considerable attention has been given to understanding the flow behavior in long and deep flow line risers of different topologies through transient multiphase simulation. However, the application of the large diameter to the above scenario is still an unresolved issue creating a great deal of uncertainty. This is mainly due to the limitation of the available experimental and field data being confined to much smaller diameters.In view of the aforementioned, an experimental campaign to investigate the flow behavior in a 254-mm nominal-diameter horizontal flow line vertical riser has been performed. A numerical model to study the dynamic behavior of the large-diameter horizontal flow line vertical riser system is also developed using OLGA software with the intention of identifying the capability of this software. This article presents the comparison of the simulation and experimental data in terms of near riser base and flow line pressure variations along with flow regime predictions. The existence of the multiple roots in the OLGA code is also reported for the first time. Additionally, a review on the state-of-the-art application of the code and analysis of the numerical experiment performance of the code are included.

An experimental investigation of adiabatic upward co‐current air–water two‐phase flow has been carried out to determine the flow patterns in a 12.2=m‐high and 250=mm nominal diameter vertical pipe. The visual observations of flow patterns were supplemented by statistical analysis of the time‐averaged void fraction determined by pressure drop method. Four flow patterns were identified in the vertical test section, namely dispersed bubbly, bubbly, agitated bubblyand churn/forth flow within the experimental superficial velocity range ( ja = 0.18–2.2 m/s and jw = 0.18–1.2 m/s). Conventional slug flow consisting of smooth bullet‐shaped bubbles (Taylor bubble) and liquid slugs was never observed; instead, agitated bubbly flow was the most dominant flow pattern in relevant superficial velocity range. On the basis of the visual and statistically extracted information, a flow pattern map was developed and compared with the existing flow pattern maps. Available flow regime transition models compared against the present experimental data yielded poor agreement with none of the existing models predicting the transitions as a whole. A satisfactory agreement was obtained with other large diameter studies with inconsistencies mainly attributable to confusion in the identification of the flow patterns. © 2013 Curtin University of Technology and John Wiley & Sons, Ltd.

By 2050, the UK government plans to create ‘Net zero society’. 1 To meet this ambitious target, the deployment of low carbon technologies is an urgent priority. The low carbon heat recovery technologies such as heat recovery from sewage via heat pump can play an important role. It is based on recovering heat from the sewage that is added by the consumer, used and flushed in the sewer. This technology is currently successfully operating in many cities around the world. In the UK, there is also a rising interest to explore this technology after successful sewage heat recovery demonstration project at Borders College, Galashiels, Scotland. 2 However, further experimental research is needed to build the evidence base, replicate, and de-risk the concept elsewhere in the UK. The Home Energy 4 Tomorrow (HE4T) project at London South Bank University was created to address this evidence gap. This is the fourth article in the series of outputs on sewage heat recovery and presents some results using sewage data from the UK’s capital London. These data are scarce and provide useful information on the variation of flows and temperatures encountered in the sewers of the UK’s capital. Lastly, we discuss the recoverable heat potential along with policy implications for the UK heat strategy. Practical application This work focuses and accentuate that in order to meet climate change targets, substantial improvements can come by heat recovery from the raw (influent) and treated wastewater (effluent from wastewater treatment plant) that is still unexploited in the UK. The estimation presented indicates that there is much theoretical potential in the UK with significant opportunity for future energy and revenue retrieval along with GHGs emission reduction in the longer term to fulfil the ‘net zero’ objective. This work aims to raise awareness and seek support to promote pilot scale studies to help demonstrate technical and economic feasibility in the building industry.

The demand for natural resources has increased exponentially due to the consistent growth of the global population and urbanization. This has resulted to considerable environmental challenges that are potentially affecting the global sustainable development goals. Therefore, it is important to develop sustainable strategies to manage urban wastes as well as produce and utilize energy. Flammable gases being generated from the sewage systems can be a prospective renewable resource of energy. However, existing studies suggest that the potential of sewage gas utilization for energy production has not been explored effectively. This paper focuses on identifying key design elements of sewage systems in an Anaerobic Digester (AD) to optimize the process of conversion of human waste into energy source. The paper uses a kinetic model to describe the fermentation process and thus evaluating the effect of key parameters on biogas (specifically methane) gases production in an anaerobic digester environment.