A power plant for integrated waste energy recovery from liquid air energy storage and liquefied natural gas

Liquefied natural gas(LNG)is regarded as one of the cleanest fossil fuel and has experienced significant developments in recent years.The liquefaction process of natural gas is energy-intensive,while the regasification of LNG gives out a huge amount of waste energy since plenty of high grade cold energy(-160℃)from LNG is released to sea water directly in most cases,and also sometimes LNG is burned for regasification.On the other hand,liquid air energy storage(LAES)is an emerging energy storage technology for applications such as peak load shifting of power grids,which generates 30%-40%of compression heat(-200℃).Such heat could lead to energy waste if not recovered and used.The recovery of the compression heat is technically feasible but requires additional capital investment,which may not always be economically attractive.Therefore,we propose a power plant for recovering the waste cryogenic energy from LNG regasification and compression heat from the LAES.The challenge for such a power plant is the wide working temperature range between the low-temperature exergy source(-160℃)and heat source(-200℃).Nitrogen and argon are proposed as the working fluids to address the challenge.Thermodynamic analyses are carried out and the results show that the power plant could achieve a thermal efficiency of 27%and 19%and an exergy efficiency of 40%and 28%for nitrogen and argon,respectively.Here,with the nitrogen as working fluid undergoes a complete Brayton Cycle,while the argon based power plant goes through a combined Brayton and Rankine Cycle.Besides,the economic analysis shows that the payback period of this proposed system is only 2.2 years,utilizing the excess heat from a 5 MW/40 MWh LAES system.The findings suggest that the waste energy based power plant could be co-located with the LNG terminal and LAES plant,providing additional power output and reducing energy waste.

Exploration and Application Practice of Energy Conservation Theory and Method in Steel Manufacturing Process System

This article briefly discusses the theoretical basis and overall goals of energy conservation in the steel manufacturing process system.It is proposed that in the process of implementing system energy conservation,it is necessary to fully recognize and utilize the characteristics and functional advantages of the steel manufacturing process,pay more attention to energy quality,firmly grasp the overall goal of system optimization,focus on the integrated optimization of gas,steam,and waste heat systems,and propose the idea of constructing a"steel chemi-cal gas electricity heating cooling multi generation system".Based on practice,the main principles,models,and effects of implementing systematic energy conservation in steel enterprises have been proposed.

Techno-Economic Analysis of a Grid-Connected Waste to Energy Gasification Plant:A Case Study

With population growth around the world,municipal waste disposal and continued energy demand becomes some of the major challenges to deal with.In order to address these,an approach is required for an optimal waste management system that offers the population benefit with a lower environmental impact.This study evaluates the technical-economic and environmental impact analysis of a grid-connected waste to energy(WtE)plant to power a Univerisiti Teknologi Malaysia(UTM)community.The energy recovery potential of the waste stream was assessed using the life cycle assessment(LCA)method with GaBi^(TM) software(version 4).A technical,economic and environmental analysis was then carried out for the grid-connected WtE system using HOMERPro software with gasification conversion technology.The cash flow analysis was based on levelized costs of energy(LCOE)and total net present value(NPV).The results gave an NPV for the system at USD 1.11×10^(7),with most of the effects resulting from the grid operating costs and the LCOE of USD 0.43/kWh compared to the grid unit price of USD 0.7/kWh which corresponds to a saving of$0.27/kWh in energy purchase.From an environmental point of view,the results showed a significant reduction in carbon dioxide emissions from around 2,000 tons per year to around 400 tons per year.With regard to the amount of waste sent to landfills,the results show a significant improvement from 142,605.5 kg/year to 0.13 kg/year.

Comparative Study on Distributed Waste Pyrolysis Cold Emission Energy Station and Incineration Power Generation

The proper terminal disposal of organic solid waste such as domestic waste is a worldwide issue.Landfill covers a large area,with limited capacity,and a single landfill will be filled one day;incineration is costly to build and operate.These methods all need to transfer and centralized treatment,and secondary pollution is difficult to control,against the purification law of the nature."NIMBY effect"is very serious,and the social cost of treatment is increasing,becoming a heavy financial burden."The Distributed Waste Pyrolysis Cold Emission Energy Station"developed by Hunan Zhongzhou Energy-Saving Technology Co.,Ltd.overcomes these disadvantages and constructs a more appropriate environmental economic industrial chain for the treatment of organic solid waste such as urban and rural household waste.Based on its technical characteristics,this paper compares it with waste incineration power generation project in the aspects of secondary pollution control,treatment effect,energy utilization,investment and operation economy,etc.

China Should Adopt Integration Policies to Reduce Energy Waste

China should pilot renewable energy integration policies similar to those adopted in Germany and Texas in the Beijing-Tianjin-Hebei region to transmit excess energy and reduce wasted wind power.Renewable energy integration will be fundamental to China?s transition to a low-carbon economy.Although China now leads the world in terms

Novel Technology and Products: Fluidized Bed Incineration and Energy Recovery for Waste Disposal——Developed by the Institute for Thermal Power Engineering, Zhejiang University

The waste referred to includes solid waste and sludge. Solid waste is mainly from urban garbage and industrial waste. Sludge is from water treatment factories, paper mills, chemical factories, pharmaceutical factories, rivers and lakes. The waste and sludge are very harmful to water organisms, human health and drinking water, and directly affect the environment. Sludge and waste also occupy large areas of land. There are several methods to treat waste and sludge, such as burial, chemical treatment and incineration. Incineration is more effective than the

2D Materials as Protective Coating against Low and Middle Temperature (100°C - 300°C) Corrosion-Erosion in Waste to Energy Plant: Case of Graphene

The combustion of MSW contains several species which if liberated into the flue gas will participate in erosion-corrosion reactions with the alloy surface and with the oxide layers. Actually with the evolution of material science and the discovery of 2D materials, we can handle that situation as well as possible. The graphene as 2D material presents a lot of advantage due to it physical properties such: melting point, boiling point and thermal conductivity, which can help to manage the problem of low and middle temperature (100°C - 300°C) erosion-corrosion into the boiler wall of waste to energy. The aim of the study was focused on analyzing the resistance at low and middle temperature (100°C - 300°C) in the enclosed environment and the corrosion-erosion resistance abilities of the graphene sheet as the 2D protective coating material. This paper analyzed the possibility of using the graphene in the aggressive environment which is waste to energy boiler. The results obtained from this study after simulation using ANSYS software which is one of the best software for simulations showed that Graphene protects the furnace walls against corrosion-erosion for temperatures lower than 400°C and that in the presence of certain impurities such as: sodium (Na), sulfur (S), chloride (Cl) and Phos- phorous (P), Sodium Chloride (NaCl), Hydrogen Chloride (HCl), Dioxide of Carbone (CO2) and Dioxide of Sulfur (SO2).

Techno-Economic Analysis of Power Production by Using Waste Biomass Gasification

Energy recovery from waste biomass can have significant impacts on the most pressing development challenges of rural poverty and environmental damages. In this paper, a techno-economic analysis is carried out for electricity generation by using timber and wood waste (T & WW) gasification in Iceland. Different expenses were considered, like capital, installation, engineering, operation and maintenance costs and the interest rate of the investment. Regarding to revenues, they come from of the electricity sale and the fee paid by the Icelandic municipalities for waste collection and disposal. The economic feasibility was conducted based on the economic indicators of net present value (NPV) and discounted payback period (DPP), bringing together three different subgroups based on gasifier capacities, subgroup a: 50 kW, subgroup b: 100 kW and subgroup c: 200 kW. The results show that total cost increases as the implemented power is increased. This indicator varies from 1228.6 k€ for subgroups a to 1334.7 k€ for subgroups b and 1479.5 k€ for subgroups c. It is worth mentioning that NPV is positive for three subgroups and it grows as gasifier scale is extended. NPV is about 122 k€ (111,020 $), 1824 k€ (1,659,840 $) and 4392 k€ (3,996,720 $) for subgroups a, b and c, respectively. Moreover, DPP has an inversely proportional to the installed capacity. It is around 5.5 years (subgroups a), 9.5 months (subgroups b) and 6 months (subgroups c). The obtained results confirm that using small scale waste biomass gasification integrated with power generation could be techno-economically feasible for remote area in Iceland.

Solid Waste Management and Incineration Practice: A Study of Bangladesh

Considering the geographical location and one of the very densely populated countries in the world, Bangladesh is very vulnerable to climate change and its adaptability. This paper has been designed with an attempt to inform the policy maker of Bangladesh regarding the potentiality of MSW as a renewable source of energy in Bangladesh. It deals with modern waste collection, management and incineration practices based on densely populated cities or towns like Bogura Municipality and Chattogram City Corporation. Waste to Energy (WtE) conversions not only reduce the land pressure problem in urban areas, but also generate electricity and heat to supply to the surrounding urban areas. The increase in generation of methane (CH4) from municipal solid wastes (MSW) alarms the world to take suitable initiative for the sustainable management of MSW, as it is stronger than carbon dioxide (CO2). By burning one mole of CH4, 890 kJ·mol-1 heat is produced which is a major source of energy. This treatment technology is used in destruction of solid waste by controlled burning at high temperatures. With the release of heat, it can be accompanied and this heat from combustion can be converted into energy. This type of incineration is a high-quality treatment for Municipal or City Corporation solid waste like Bangladesh where were over crowded cities, towns and it can reduce the quantity and volume of a large amount of waste to landfill, which can recover energy and dispose in the compact zone. The results also examined that the total amount of solid waste produced in Bogura municipality is lower than that of Chattogram City Corporation. The percentage compositions of waste patterns are shown in both the Cities. The paper discusses these problems, analyses and finally, a recommendation has been proposed in order to understand the industrial situation enhanced.

Environmental and economic vision of plasma treatment of waste in Makkah

An environmental and economic assessment of the development of a plasma-chemical reactor equipped with plasma torches for the environmentally friendly treatment of waste streams by plasma is outlined with a view to the chemical and energetic valorization of the sustainability in the Kingdom of Saudi Arabia（KSA）. This is especially applicable in the pilgrimage season in the city of Makkah, which is a major challenge since the amount of waste was estimated at about 750 thousand tons through Arabic Year 1435 H（2015）, and is growing at a rate of 3%–5% annually. According to statistics, the value of waste in Saudi Arabia ranges between 8 and 9 billion EUR. The Plasma-Treatment Project（PTP） encompasses the direct plasma treatment of all types of waste（from source and landfill）, as well as an environmental vision and economic evaluation of the use of the gas produced for fuel and electricity production in KSA, especially in the pilgrimage season in the holy city Makkah. The electrical power required for the plasmatreatment process is estimated at 5000 kW（2000 kW used for the operation of the system and 3000 kW sold）, taking into account the fact that：（1） the processing capacity of solid waste is 100 tons per day（2） and the sale of electricity amounts to 23.8 MW at 0.18 EUR per kWh.（3） The profit from the sale of electricity per year is estimated at 3.27 million EUR and the estimated profit of solid-waste treatment amounts to 6 million EUR per year and（4） the gross profit per ton of solid waste totals 8 million EUR per year. The present article introduces the first stage of the PTP, in Makkah in the pilgrimage season, which consists of five stages：（1） study and treatment of waste streams,（2） slaughterhouse waste treatment,（3） treatment of refuse-derived fuel,（4）treatment of car tires and（5） treatment of slag（the fifth stage associated with each stage from the four previous stages）.

A Survey of the Gasification of Residual Household Waste

Solid waste is a promising renewable fuel that can substitute conventional fuel. According to the researchers, thermoconversion of solid waste such as municipal solid waste or residual household waste (RHW) is beneficial to society. However, due to its heterogeneity, the gasification of RHW is more complex. This review article discusses the steps that RHW must undergo before its thermoconversion and the state of the art of solid waste gasification. First, characterisation methods of RHW are surveyed. Second, the properties of RHW, the production lines of refuse derived fuel (RDF) from RHW, the influence of RDF composition and operating parameters such as equivalence ratio and temperature are reviewed. Moreover, RDF gasification products, scientific barriers and proposed solutions are evaluated. In conclusion, concerning emissions, costs and technical aspects related to each thermochemical process, it can be said that gasification is a promising technique for the recovery of RHW. However, studies on cogasification of waste and biomass on a pilot-industrial scale are still scarce and synergistic effects of this cogasification need to be clarified.

Energy recovery from solid wastes in China and a Green-BRI mechanism for advancing sustainable waste management of the global South

The only proven alternative for the recovery of value from materials that cannot be recycled is waste to energy(WTE).The first part of the paper provides evidence as to the advantages of WTE over landfilling and examines the role of WTE in the urban environment.The second part of the paper is a holistic analysis of the legislative instruments used in China,that have led to the construction of nearly 400 plants from 2005 to 2019.The Chinese government was instrumental in the development of Public and Private Partnerships(PPPs),in form of Build-Operate-Transfer(BOT),or Build-Own-Operate(BOO)models with a lifetime of 20 years to 30 years.The government accepts most of the investment risk by participating in the equity structure,providing strong tax and policy incentives,and becoming fully engaged in public education and acceptance of new WTE projects.The construction and operation of these plants by the private sector had to comply with the governmental performance standards in order to receive incentives,such as an appreciable credit over the price of electricity received by coal-fired plants.The last part of this paper examines how the elements of the Chinese renewable energy and waste management laws,may be transposed to federal and state legislation for potential application in countries of the Belt and Road Initiative(BRI)region.

Energy and materials recovery from post-recycling wastes:WTE

One of the most misunderstood technologies in some parts of the world and widely adopted technologies in others is the recovery of energy and materials by the controlled combustion of post-recycling wastes.This technology is commonly called waste-to-energy,or simply WTE.After all possible efforts for recycling or composting wastes,there remains a large post-recycling fraction that is either landfilled or used as fuel in WTE power plants that also recover metals and minerals.Several nations,e.g.,Switzerland,Japan,Sweden,Belgium,Denmark,and Germany,have succeeded in phasing out landfilling by processing all theãir post-recycling municipal solid wastes(MSW)in WTE power plants.This paper reviews the evolution and importance of WTE in the twenty-first century,with special focus on the world’s largest economies:the EU,US,and China.

Waste to energy(WTE)in China:from latecomer to front runner

This paper discusses the 2000-2018 evolution of energy and metals recovery from urban wastes in the European Union and China.As a result of the zero-landfilling directive,in twenty years the European Union tripled its recycling rate(11%-30%)and its composting rate(6%-17%),doubled its WTE rate(14%-28%)and more than halved its landfilling(64%-25%).At the beginning of this century,the rapidly growing cities of China were literally surrounded by landfills.Therefore,the national government instituted policies,such as a credit of US$30 per MWh of WTE(waste to energy)electricity that resulted in the construction,by 2020,of 510 WTE plants with an annual WTE capacity of 193 million tons.In comparison,the European Union(EU)WTE capacity is 96 million tons and the USA has remained static at about 27 million tons,i.e.,10%of its post-recycling MSW(municipal solid waste),with the other 90%being landfilled.In the first decade of this century,two WTE technologies,moving grate and circulating fluid bed were developed in China at about the same rate.However,since 2010,the moving grate technology has become dominant and the WTE plants are built functionally and esthetically comparable to and U.S.plants.

Techno-economic assessment of energy generation through municipal solid waste:a case study for small/medium size districts in Pakistan

There is an increase in annual waste generation due to urbanization,industrialization,and population growth.The waste management crisis in developing countries and its complexity from region to region has inspired extensive research work in this area.Poor management not only results in environmental hazards,but it also causes significant socio-economic losses.Due to the absence of comprehensive studies on waste to energy(WTE)assessment,this study assesses and reports the merits of alternative technologies for converting WTE in small and medium-size districts.Quantitative analysis for waste collection data in this study uses a pilot study approach to provide useful insights and waste classification.A cantonment district of Pakistan(Wah Cantt)has been used as a case study for performing a technological and economic assessment of energy generation through the use of thermal and biological treatment processes.A mathematical modeling approach has been adopted for generating an economic value of each technology through which this waste can be processed.Further,the levelized cost of energy(LCOE)based assessment has been performed to provide a methodological framework for selecting the most feasible WTE technology in a small or medium-size district.Based on the model results,anaerobic digestion appears to be the most sustainable technology due to the organic nature of waste in Wah Cantt,land legislation,and availability of area to install a waste plant.Considering all the waste collected,the district can generate approximately 14.4 MW of energy through thermal treatment,19,110 m^(3) of daily biogas through anaerobic digestion,and 5 million tons of fertilizer through composting.Hence,if a proper supply chain is established for converting a portion of Pakistan’s annual waste generation,a significant amount of waste energy potential can be restored.

A new process to improve short-chain fatty acids and bio-methane generation from waste activated sludge

As an important intermediate product, short-chain fatty acids（SCFAs） can be generated after hydrolysis and acidification from waste activated sludge, and then can be transformed to methane during anaerobic digestion process. In order to obtain more SCFA and methane,most studies in literatures were centered on enhancing the hydrolysis of sludge anaerobic digestion which was proved as un-efficient. Though the alkaline pretreatment in our previous study increased both the hydrolysis and acidification processes, it had a vast chemical cost which was considered uneconomical. In this paper, a low energy consumption pretreatment method, i.e. enhanced the whole three stages of the anaerobic fermentation processes at the same time, was reported, by which hydrolysis and acidification were both enhanced, and the SCFA and methane generation can be significantly improved with a small quantity of chemical input. Firstly, the effect of different pretreated temperatures and pretreatment time on sludge hydrolyzation was compared. It was found that sludge pretreated at 100°C for 60 min can achieve the maximal hydrolyzation. Further, effects of different initial p Hs on acidification of the thermal pretreated sludge were investigated and the highest SCFA was observed at initial p H 9.0with fermentation time of 6 d, the production of which was 348.63 mg COD/g VSS（6.8 times higher than the blank test） and the acetic acid was dominant acid. Then, the mechanisms for this new pretreatment significantly improving SCFA production were discussed. Finally,the effect of this low energy consumption pretreatment on methane generation was investigated.

Optimization of listening time of S-MAC for wireless sensor networks

In wireless sensor networks, sensor nodes are usually battery-operated computing and sensing devices, hence operations are limited by the initially equipped batteries, which are hard to be recharged or replaced. ：In this sense, saving energy consumption becomes significant. As most energy waste is from the always-on wireless interface, S-MAC is suggested to reduce energy consumption by introducing periodic listen/sleep scheme. However, when designing the listening time, S-MAC fails to consider the traffic distribution factor. In this article, an optimization for this scheme is proposed based on the distribution model. Evaluations show that the optimized S-MAC achieves considerable improvement in energy and latency.