Torrefaction is a mild pyrolysis, which has been explored for the pretreatment of biomass to increase the heating value and hydrophobicity. Due to its potential applications for making torrefied ...pellets, which can be used as a high quality feedstock in gasification for high quality syngas production and as a substitute for coal in thermal power plants and metallurgical processes, torrefaction and densification have attracted great interest in recent years from both academia and bioenergy industry. This paper provides a comprehensive review of research progresses in this area, drawing on major contributions from two major research groups of the authors on torrefaction and densification at Canada and Taiwan as well as literatures. It is revealed that torrefaction of various biomass species and their major components, lignin, cellulose and hemicelluloses have been extensively studied in thermogravimetric apparatus (TGA) under both inert (N2) and oxidative (O2, H2O) environments to elucidate the weight loss as a function of temperature, particle size and time. It was found that the higher heating value and saturated water uptake of torrefied biomass were a strong function of weight loss, which represents the degree of torrefaction. When torrefied sawdust is compressed into torrefied pellets, more mechanical energy is consumed and higher die temperature is required to make torrefied pellets of similar density and hardness as regular pellets. Simple economics analyses based on laboratory scale experimental data showed that because of the potential savings from pellets transport, handling and storage logistics, the overall cost for torrefied pellets can be lower than regular pellets in European market for both European and Canadian pellets. The gasification could be improved in terms of both energy efficiency and syngas quality because of the removal of oxygenated volatile compounds from torrefied biomass.
To investigate the nexus among clean energy consumption, economic growth and CO2 emissions, a newly developed bootstrap ARDL bounds test with structural breaks is employed to survey the cointegration ...and causality for G7 countries. We find no cointegration among real GDP per capita, clean energy consumption and CO2 emissions in Canada, France, Italy, the US and the UK. However, cointegration exists in Germany when real GDP per capita and CO2 emissions serve as dependent variables and in Japan when CO2 emissions is the dependent variable. Regarding the results of causality test that we find clean energy consumption causes real GDP per capita for Canada, Germany and the US and CO2 emissions causes clean energy consumption for Germany. Besides, we find feedbacks between clean energy consumption and CO2 emissions for Germany, and unidirectional causality running from clean energy consumption to CO2 emissions for the US. Our study has important policy implications for G7 countries conducting efficient energy-use strategy to reduce CO2 emissions.
•Developed an oil sands with Steam Assisted Gravity Drainage evaluation model.•Conduct a feasibility study of a typical oil sands development with new model.•Quantify the effects of critical ...parameters on the economics of a development.
Oil sands resource is the third largest oil reserve, and 70% of the oil sands are in Canada. The emerging of Steam Assisted Gravity Drainage technology has made the commercial development of oil sands economically feasible. However, with the recent oil price crash, the development of oil sands has faced an uphill battle. A realistic and integrated evaluation model is highly needed to overcome difficulties from the low oil price and provide meaningful and valuable information for operators as well as investors to make the right decision. The existing evaluation models have considerable limitations (i.e., the incapability of evaluating integrated oil sands development with Steam Assisted Gravity Drainage technology, the lack of investigation into the input parameters with historical data, and ignoring the effect of the subsurface reservoir, etc.). This study developed an integrated evaluation model through the analyses of a significant amount of actual historical data. This integrated model includes six subcomponent models, ranging from the subsurface reservoir to infield flowline. Data from 35 Canadian oil sands development with 15 internal and external parameters were collected and investigated. The oil price effect was analyzed and quantified through simulations. The breakeven Western Canada Select oil price of $39/bbl. (equal to the West Texas Intermediate oil price of $55/bbl.) and other key price points and distributions were identified. Also, the top seven geological and technical parameters that contribute 86% of the net present value variations were identified and investigated. These quantified effects of external and internal parameters are useful findings for decision making. Considering various price scenarios and uncertainties of the input parameters, this study has concluded that developing oil sands resources with the Steam Assisted Gravity Drainage technology is economically feasible and socially beneficial after we take all stakeholder interests into consideration, which is true even with the sustainable and realistic oil price in the foreseeable future.
Intergenerational income mobility is lower in the United States than in Canada but varies significantly within each country. Our subnational analysis finds that the national border only partially ...distinguishes the approximately 1,000 regions we analyze within these countries. The Canada-US border divides central and eastern Canada from the US Great Lakes and northeastern regions. Simultaneously, some Canadian regions have more in common with the low-mobility southern parts of the United States than with the rest of Canada; that these areas represent a much larger fraction of the US population also explains why mobility is lower in the United States.
•A sustainable approach of using WCO as a rejuvenator is summarized.•WCO improves cracking resistance but reduces high temperature rutting performance.•Chemical modification of WCO exhibits better ...physical and rheological performances.
In Canada, over 90% of the paved roads are asphalt pavements. Most of these pavements were built decades ago, which are currently exhibiting a significant amount of surface distresses. These distresses includes potholes, rutting (deformation in the wheel path), and cracking. To repair these distressed pavements, the road agencies spend millions of dollars every year, of which a significant portion goes to acquiring new natural aggregates and asphalt. To reduce the rehabilitation cost, road agencies use up to 100% reclaimed asphalt pavements (RAP) in new construction. However, the asphalt available in recycled pavements is oxidized and stiffened due to various environmental processes which are susceptible to thermal and fatigue cracking. To soften and to decrease the viscosity of the RAP materials, various rejuvenators are being in practice. The rejuvenators are able to reactivate and restore the original properties of this long-term aged asphalt binder. Using Waste Cooking Oil (WCO) is one of the eco-friendly solutions which contains the similar lighter oil components of asphalt and can be used as an acceptable rejuvenator. Recent studies showed that WCO has an excellent potential to be used as a good rejuvenator in the hot mix asphalt (HMA) industry. This review article summarizes the performance and adverse effects of WCO as a rejuvenator.
Various green rating systems are established globally to evaluate the sustainability of construction projects. Their categories and criteria have been under constant updates to follow the sustainable ...trend of building development. This paper aims to develop a systematic review of the development of green rating systems. The specific objectives are: 1) discover how interest and research in green rating systems have developed; 2) identify the similarity, difference, strength and weakness of green rating systems; 3) examine whether they fully assess the projects in all aspects of sustainability. Specifically, LEED (Leadership in Energy and Environmental Design), BREEAM (Building Research Establishment Assessment Method), CASBEE (Comprehensive Assessment System for Building Environmental Efficiency) and Green Star NZ were analysed in this paper. The results indicate that BREEAM, LEED, and CASBEE have been utilized since late the 2000s while Green Star NZ is still in its earlier stages. 70% of the research papers focusing on BREEAM, LEED, CASBEE are developed geographically in the USA, Canada, the UK, China, and Australia. Although these four rating systems were initiated in different contexts with different standards, Indoor Environment Quality, Energy, and Material are core common categories for all. Environmental concerns are the main focus in New Construction manuals while Society is emphasized in Neighbourhood Development manuals. Currently, BREEAM has been the only tool which could assess all four sustainable factors. Further in-depth research is anticipated to focus more on economic and institutional factors to improve the capability of green rating systems for sustainability assessment purposes.
•Indoor Environment Quality, Energy, and Material are the main focus in green rating systems.•The total categories, points, and mandatory credits of analysed rating schemes tend to increase and more comprehensive.•BREEAM is considered as the strongest rating system at present.•Currently, no rating scheme could assess a project in all aspects of sustainability.
These days, climate change issues and their impacts on the economy, social and natural system of countries have become the main concern of worldwide, even for those countries that are facing major ...economic problems. These issues arise from the combustion of fossil fuels. One of the major contributors to global CO2 emission is the transport sector. Therefore, in order to identify the trends and characteristics of transport carbon emissions this study reviews the relevant literature significantly; and decomposes carbon emission in this sector in 7 top transport CO2 emitter countries by applying the logarithmic mean Divisia index (LMDI). The results indicated that, during 2000–15, transport carbon emissions increased in the United States, China, India, Canada, Russia, and Brazil whereas decreased in Japan. Hence, in the majority of these countries, energy conservation strategies were not successfully implemented during the study period. In the majority of countries, the main contributor to CO2 emission reductions was carbon intensity, whereas the main drivers of CO2 emission increases were electricity structure and economic output effects. Reductions in carbon emissions could be achieved by further optimizing energy structures, limiting the private vehicle population. A set of policies and regulations, from demand-side and supply-side, must be implemented to be effective in reducing GHGs emissions.
•The study analyzes the patterns of CO2 emissions in 7 top transport carbon emitters.•It uses two methodologies, a review of literature and carbon emission decomposition.•Implementing a set of climate change policies can reduce carbon emission.•The United States and China were the main contributors of transport CO2 emissions.•The main contributor to CO2 emission reductions was carbon intensity.
We investigated how professional role identity change can be accomplished in highly institutionalized contexts characterized by resiliency. We show that the collective professional role identity of ...family physicians was changed through a process of reinterpreting multiple logics and their relationships. Through our inductive analyses, we identified four mechanisms that occurred through social interactions and collectively served to rearrange the constellation of logics guiding physician role identity: (1) revealing the influence of a hidden logic; (2) reinforcing the conflict between logics; (3) reframing the meaning of a dominant logic; and (4) re-embedding the new arrangement of logics. We found that the change in physician professional role identity required significant identity work by a group of actors, but particularly by the managers who had been charged with leading the reform initiative. We contribute to the professional role identity and institutional literatures by showing how others can engage in social interactions with professionals to facilitate the reinterpretation and rearranging of institutional logics that guide collective professional role identity.
Ocean tidal currents, water waves and thermal gradients are a great source of renewable energy. Ocean tidal, osmotic, wave and thermal sources have annual potentials of 800, 2,000, 8000–80,000 and ...10,000–87,600TWh, which are more than global 16,000TWh/y electricity demand. Ocean wave generators produce relatively lower output, however, four to eleven meters tidal range stations have large power generation capacities. Abundant ocean heat energy potentially harvested using ocean thermal energy conversion (OTEC) devices and ocean thermo-electric generators (OTEG). Tidal stations may be tidal range or current types, but a wave energy converter (WEC) may be an oscillating water column (OWC), overtopping, heaving, pitching and surging devices. Ocean thermal energy can be harnessed by open, close Rankine cycles, thermo-electric generators and osmotic power plants. Large bays like Turnagain (USA), Annapolis/Minas Passage (Canada), Seven Barrages/Pentland Firth (UK), La Rance (France), Garorim (South Korea) and Mezen/Penzhin (Russia) have huge tidal current power generation capacities. Power Potential from tidal current stations is more than WEC devices which in turn is more than osmotic, OTEC and OTEG technologies. This paper reviews the current state-of-the-art of tidal, wave, OTEC and OTEG ocean energy technologies.
Although green building technologies (GBTs) have been advocated in the construction industry to address sustainability issues, their adoption is still plagued with barriers. The barriers that hinder ...GBTs adoption need detailed investigation. However, few studies have been conducted on the barriers to GBTs adoption in developing countries such as Ghana. This study aims to investigate the critical barriers to GBTs adoption with reference to the Ghanaian construction market. To achieve the objective, 26 barriers were identified from a comprehensive literature review, and a questionnaire survey was performed with 43 professionals with green building experience. The ranking analysis results indicated that 20 barriers were critical. The top three most critical barriers were higher costs of GBTs, lack of government incentives, and lack of financing schemes (e.g., bank loans). A comparative analysis showed that while the most critical barriers to GBTs adoption in the developing country of Ghana mostly vary from those in the developed countries of the US, Canada, and Australia, higher costs of GBTs remains a top barrier in all the countries. Furthermore, factor analysis revealed that the underlying grouped barriers for the 20 critical barriers were government-related, human-related, knowledge and information-related, market-related, and cost and risk-related barriers. This study also showed that the most dominant of the five underlying groups was government-related barriers, which highlights the government's role in promoting GBTs adoption in Ghana. This study adds to the green building literature by analyzing GBTs adoption barriers within the context of a developing country, which could help policy makers and practitioners take suitable measures to mitigate the barriers and thereby promote the GBTs adoption. Future research will investigate the interrelationships between the critical barriers and their impacts on the GBTs adoption activity.
•The most critical GBTs adoption barrier in Ghana is higher costs of GBTs.•Higher costs of GBTs is a top barrier not only in Ghana, but also in the US, Canada, and Australia.•The underlying grouped barriers are government-related, human-related, knowledge and information-related, market-related, and cost and risk-related barriers.
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