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Status of Marine Energy Technologies – Commercialisation Readiness?
Professor AbuBakr S Bahaj, University of Southampton

Globally, the utilisation of oceans resources, such as wind, waves and marine currents (or tides) is gathering pace and their exploitation offer one of the appropriate routes for the production of sustainable electrical power. There are now tangible plans for multi converter deployment in farms or array of what is termed as marine energy, covering the exploitation of the kinetic energy in ocean waves and that found in tidal streams or currents. In 2010 the UK's Crown Estate announce concessions to deploy over 1.6GW of multi-megawatt mix wave and tidal technology farms and arrays in the Pentland Firth by 2020, Recently, it also announced further concessions of sites to exploit the marine resource spanning both north and south of the UK. Globally, there were announcements for technology and energy yield support for the deployment of multiple devices in arrays, especially those announced for the Bay of Fundy in Canada, and other announcements such as those in South Korea and China. This paper will focus on marine energy, aiming to convey the current status of wave and tidal current energy conversion technologies, addressing issues related to their infancy as compared to others renewable technologies such offshore wind, and provide a discourse to current technology readiness at commercial scale deployment.

 

 

 

 

Energy and Cities: Energy Efficiency and Solar Power Potential from Cities
Professor AbuBakr S Bahaj, University of Southampton

Currently more than 50% of the world's population lives in cities and this is projected to rise to 60% by 2030, adding ~1.4 billion more people than today. An increasing number of the world's population is migrating to cities to take advantage of concentrated economic activities and perceived prosperity. In high-income countries today over 78% of the population live in cities and these urban residents are generally the wealthiest and longest-lived citizens. This is in stark contrast to low-income countries where wealth in much lower and the urbanisation rate is projected to rise from 46% to 64% of the population by 2050. Meeting the needs of this changing demographic situation will be challenging for cities. As indicated above studying cities is important as they also impose closer living and working conditions and provide inhabitants optimised infrastructure that supports productivity and drive long term economic growth. It is this infrastructure that is identified here to provide opportunities for city-wide energy analysis and considerations which are geared to assess what contribution can be made to city energy requirement. The assessment was conducted at city scale through (a) analysis of demand reductions based on refurbishment options and (b) electricity generation from building surfaces. This research will report on this aspect of our work on energy and cities. It will describes the development of an efficient and accurate methodology that estimates energy demand reduction through city-wide building interventions such as insulation, windows upgrade etc to determine impact on energy demand and hence city emission targets. In addition, and knowing the buildings details and characteristics, the methodology was extended to estimate the solar radiation to the nearest square metre within a city and apply this to appropriate surfaces for solar photovoltaic (PV) installations. The analysis provides more realistic estimates in the context of spatially dense building areas such as those encountered in cities, automatically identifying building details including required interventions and individual roof areas that are practical for standard PV installation and for aggregating such areas on a city scale. The modelling has been applied to the case of the city of Southampton, UK (>30000 buildings) and demonstrated a high level of accuracy. The results indicate that the city has the potential of reducing energy consumption by around 11% through refurbishment options and can annually produce over 25% of its electricity from solar photovoltaic deployments. Implications to other cities and regions will also be discussed.

 

 

 

 

Paradigm Shift in Energy Science and Technology from Energy Cascading to Exergy Recuperation
Professor Atsushi Tsutsumi , University of Tokyo

The climate change, especially global warming due to CO2 emission from the combustion of fossil fuels, has been a major concern in the last few decades. In order to mitigate the global warming the reduction of energy consumption is essential in terms of energy saving and efficient utilization. So far, heat recovery technology for energy saving and efficient utilization based of the heat cascading utilization principle has been adopted to reduce energy consumption in the industrial processes. However, energy saving by heat recovery in industrial processes has its limitations. Heat can be recycled only as lower-temperature heat, not as heat at same temperature, because heat can transfer only from higher-temperature site to lower-temperature site. Therefore, a hundred percent heat can not be recycled. Recently, we have advanced self-heat recuperation technology based on the exergy recuperative heat utilization principle, which can perfectly recirculate process heat by providing compression work without addition of heat generated by fuel combustion. The self-heat recuperation can recover not only latent heat but also sensible heat in the thermal process, leading to a considerable reduction in the energy consumption for almost all industrial thermal processes such as distillation, PSA gas separation, chemical absorption gas separation, air separation, drying, condensation, desalination, etc. The exergy recuperation causes a paradigm shift in energy science and technology which leads to revolutionary energy saving. In the present paper, a state-of-the-art self-heat recuperation technology based on the concept of exergy recuperation is surveyed and some examples are discussed.

Keywords: exergy, self-heat recuperation, energy efficiency, exergy recuperation, energy saving

 

 

 

Biochar as Enabling Material for Sustainability
Professor Charles Q. Jia , University of Toronto

Biochar is carbon created from photosynthetic biomass using a carbonization or pyrolysis process. Traditionally, it is used as a solid fuel which is renewable and carbon neutral. As carbon in biochar is originated from atmospheric carbon dioxide (CO2), the production and utilization of biochar in non-fuel applications represent a net removal of CO2 from the global carbon cycle – a carbon-negative process. A wide range of biomass has been used as raw material for biochar production, from agriculture wastes to various woody materials. While highly carbonized with carbon contents over 90 wt%, biochar can become chemically stable under ambient conditions. Biochar derived from biomass can also have a porous structure that mimics that of its precursor. Its porous nature, associated internal surface area and chemical stability make biochar desirable in many environmental and energy applications, from air and water purification to soil amendment. In this study, we explore the potential of biochar as material in other areas. We suggest that large-scale utilizations of biochar in diverse, non-fuel applications can be a viable mechanism of offsetting CO2 emissions from human activities and enhancing sustainability. As an example, we demonstrate the potential of biochar as an active electrode material for supercapacitor - a physical energy storage device that can be rapidly charged and discharged for over half million times. Some synthetic porous carbons, such as carbon nanotubes (CNTs) and graphene sheets, have been studied as electrode material and shown promising performance due to their superior capacity of conducting electrons and ions in electrolyte. Our work demonstrates that the structure of monolithic biochar can facilitate both electron conduction and ion transport in electrolyte, but with the added benefits of having a continuous macrostructure that can be scaled more readily and economically than CNTs and other synthetic carbon nanomaterials. Hence, biochar can be a viable choice for electrode material in large-scale, high-performance supercapacitors.

 

 

 

 

 

Study on indirect evaporative cooler (IEC) for air-conditioning in hot and humid region like Hong Kong
Professor Hongxing Yang , Hong Kong Polytechnic University

Latent cooling load of commercial buildings is very high in a hot and humid region like Hong Kong. This study has focused on application of the indirect evaporative cooler (IEC), regarded as a low-carbon cooling device, for fresh air pre-cooling and energy recovery in central air-conditioning systems to break the region limitation of application in hot and humid areas. Exhausted air from air-conditioned space with low temperature and humidity is used as secondary air to cool inlet fresh air. Simulations and experiments have been performed so that the energy and economic performance of this application can be analyzed.  As the dew point temperature of the fresh air is high, condensation may occur in the dry channels.  The project has also taken the condensation from primary air into consideration. A simulation model has been developed and validated. Nine parameters were analyzed in detail under three operation states (non-condensation, partial condensation and total condensation) using four evaluation indexes: condensation ratio, wet-bulb efficiency, enlargement coefficient and total heat transfer rate. The results show that the condensation lowers the wet-bulb efficiency of IEC but improves the total heat transfer rate due to dehumidification. The models were validated experiments. The validated model was then incorporated with TRNSYS for predicting the performance of an IEC hybrid cooling system in a wet market in Hong Kong and the annual simulation results are reported in this presentation.  The study has revealed that this technology can be used in this hot and humid region economically.

 

 

 

 

 

Engineering a Sustainable Future
Mr. Joe Eades , Founder and Managing Director – Ispahan Group

After COP 21 in Paris, we engineers finally have been given the green light to make a significant step change towards engineering a sustainable future.  Much of the technology is already available to begin that journey, the challenge is to bring it together more sustainably, to integrate applications to maximise the use of limited resources available. In the developed world much of the infrastructure already exists, so engineers will need to work with the constraints that this existing infrastructure imposes.  The real opportunity to demonstrate how we can build zero energy, water, climate change resilient communities at scale will be in the developing world where engineers can start with a clean sheet.  This talk will discuss emerging technologies that could be part of this journey and will ask questions on how we as a community can also plan for emerging technology such that we can easily integrate it into the infrastructure plan of tomorrow. 

 

 

 

 

 

Energy, Water and Environment Nexus for Future Sustainable Desalination
Professor Kim Choon Ng , King Abdullah University of Science & technology

From 1965 to 2015, the World’s desalination market has been increasing steadily with a CAGR of 9.3% annually, reaching a capacity of 85.2 mm3/d, as shown in Figure 1. Owing to the challenging seawater conditions in Gulf Cooperation Council (GCC) countries, the thermally-driven desalination methods are still the dominant method of desalination and the share of Multi-stage flashing(MSF)/multi-effect distillation(MED) in these countries is about 30.5 mm3/d or 38% of the total capacity. However, all desalination methods employed hitherto are energy intensive, ranging from 7.5 to 30 kWh-pe per m3. Thus, the consumption of primary energy (expressed in tonne of oil equivalent) in GCC alone amounts to 76,000 toe/d or equivalent to about 0.5 million barrel/d. Given the increasing demand trend for potable water, arising from both from population and economic growth increases, the existing methods of desalination are obviously unsustainable in the future.

Fig.1. Global cumulative desalination capacity, 1965-2015.

The thermodynamic limit for seawater desalination is about 0.8 kWh/m3 at ambient temperature. For an evaporative energy of 2400 kJ/kg of water, the thermodynamic limit of desalting seawater would have an ideal performance ratio (PR) of 417, defined as the equivalent latent energy of product water obtained to the primary energy input to the process. However, today’s practical PRs of thermally-driven and membrane-based desalination methods have attained nominally at levels of 20 and 35+, respectively. A chronological trend of historical improvement in PRs as well as the desired levels of PR for future sustainability is depicted in below figure. The inferior energy efficiencies of desalination are due to the obstinately high losses incurred in processes where the available methods are at best 8.5% (i.e., 35/417) from the ideal limit. This level of water production is energy intensive and is deemed unsustainable in the future. For sustainability, we aim to achieve an energy efficiency target up to 15% of the thermodynamic limit. We highlight the current development of thermally-driven desalination processes that has the capability to attain a high PR and yet meeting the goal of sustainable desalination in the short to medium term.

In this presentation, we present a reliable and low energy method of seawater desalination by integrating the multi-effect distillation (MED) and an adsorption (AD) cycles and the experiments were conducted using a MED+AD pilot plant at KAUST University. The purpose of hybridizing these cycles is to achieve thermodynamic synergy between the cycles, extending the number of evaporative-condensing stages from the conventional 12-15 stages up to 25 or more stages and thereby increasing the production ratio (PR) up to three folds. Recent progress in the pre-treatment of seawater, namely; (i) the partial removal of scale-forming ions of Ca2+, SO42- and Mg2+ in seawater feed, enabling the increase of the top-brine temperature of MED from 70 ℃ up to 120 ℃, (ii) the use of suitable anti-scalant for mitigating scaling and control of biofouling at high temperature for the seawater feed, and (iii) the hybridizing with an AD Cycle to the last stage of MED plant for attaining a bottom brine temperature stage to as low as 10 ℃, have enabled an innovative thermally-driven processes to achieve PRs up to 35 or more. The hybrid cycles are now able to operate with a significantly larger temperature differential in between stages, and the hybrid plant can now approach a PR value that approaches the future sustainability.

 

 

 

 

Advanced Study on Solid State Fermentation from Nanometer to Meter Levels and a Case Analysis
Professor Shizhong Li , Tsinghjua University

Solid state fermentation has attracted more and more attention with advantages of higher volumetric productivity, lower energy requirements, and simplified process over submerged liquid state fermentation, especially for biofuels (e.g. Bioethanol) production from sugar feedstocks. However, there are some shortcomings with relation to solid-state fermentation. For instance, it is out of date for conventional technology and equipment, no way to monitor the course of fermentation on line, hard to realize the automatic control. In this presentation, we will report an advanced study on solid state fermentation at nm, μm, mm, and m levels for improving the above shortcomings, and a proprietary advanced solid state fermentation (ASSF) process derived from  this study which will improve fermentation industry, and can be used to cost-effectively produce ethanol from sugar feedstocks such as sweet sorghum, sugar cane, sugar beet and Helianthus tuberous L as well. A case analysis of cost-effective production of ethanol from sweet sorghum stalks by using ASSF technology is also demonstrated. The demonstration of sweet sorghum ethanol plant with two fermentors of 555m3 using ASSF technology is successfully operated in Dongying, China. The total sugar conversion rate is 94.86% and ethanol yield is 90.5% of theoretical yield., 16 ton of sweet sorghum stalks are used to produce 1 ton of ethanol (99.5%, v/v) and 7 tons vinasse which can feed 1 cattle.

 

 

 

 

Use of solar assisted vapour compression heat pump for heating, cooling in buildings
Professor Yanjun Dai , Shanghai Jiao Tong University

A novel solar thermal assisted vapor compression air conditioning cycle is proposed, aiming at improving the conversion efficiency from solar energy to heating and cooling and offset the unstability of solar energy utilization. Compared with the traditional solar heating and cooling measures, the novel cycle may increase the specific cooling output for unit solar collector area and realize the steady cooling output despite of the big variation of solar radiation. It is expected that the mechanisms how the solar thermal can assist the vapor compression refrigeration cycle under dynamic operation mode will be investigated. Also studied is the efficient integration of solar absorption cooling section with vapor compression process under steady operation mode. The solar combined absorption and vapor compression air conditioning cycle will be intensively studied and optimized .A theoretical model derived from the thermal efficiency factor of solar collectors will be developed in consideration of the demand for effecting solar cooling process. The thermodynamic process operated under three temperature levels, namely, the solar collector temperature, the ambient temperature and the refrigeration temperature, will be evaluated and thermodynamically optimized. Moreover, the transient performance of the novel solar air conditioning system will be the core work for energy saving, the matching of configuration and operation parameters for the components, such as solar collectors, compressor, heat exchanger and expansion valves, et al., as well as the impacts of the different parameters on the system performance, will be studied. The activities are helpful for developing a novel solar energy technology for building energy application.

 

 

 

 

 

 

SMART biochar technology - A shifting paradigm towards advanced materials and healthcare research
Professor Yong Sik Ok , Kangwon National University (KNU)

Biochar, produced through pyrolysis of biomass under low or no oxygen conditions, has found a wide range of applications from soil fertility improvement to removal of contaminants. Initial interest in biochar is to use it as a means to capture carbon dioxide from the atmosphere; however, recent developments are seeing biochar being applied in engineering, and health care and life sciences, some of those applications have large potentials for rapid commercialization. We expect a paradigm shift towards the development of the next generation of biochar with applications in a range of new fields. (This work was supported by the National Research Foundation of Korea (NRF) (NRF-2015R1A2A2A11001432)).

 

 



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