Search

High levels of observed city involvement in energy and climate initiatives indicate that free-riding has been much less of a barrier to local climate protection efforts than suggested by theories of collective action. This study investigates why local governments have adopted various energy and climate change policy instruments despite the non-excludability of climate benefits. This paper advances theories of institutional collective action (ICA) and policy diffusion by testing ICA based hypotheses that local officials are able to overcome collective action problems to the extent that the costs of these initiatives are minimized through policy network interactions, the extent to which climate action produces localized benefits or compliments local environmental, development or growth management efforts, and the extent to which energy and climate protection efforts generate selective benefits to elected and appointed local government officials who advance their career interests depending on the existing configurations of political system institutions. Analysis of adoptions of the Climate Protection Agreements by Florida Cities indicates larger cities are more likely to adopt climate agreement, while district elections decrease the likelihood of climate policy adoption. Moreover, economic development rather than growth management or environmental problem situation is linked to climate initiatives. [ABSTRACT FROM AUTHOR]

With the rising demand for renewable energy and environmental protection, anaerobic digestion of biogas technology has attracted considerable attention within the scientific community. This paper presents a comprehensive review of research achievements on anaerobic digestion developments for biogas production. The review includes a discussion of factors affecting efficiency (temperature, pH, C/N ratio, OLR and retention time), accelerants (greenery biomass, biological pure culture and inorganic additives), reactors (conventional anaerobic reactors, sludge retention reactors and anaerobic membrane reactors) and biogas AD processes (lignocellulose waste, municipal solid waste, food waste, livestock manure and waste activated sludge) based on substrate characteristics and discusses the application of each forementioned aspect. The factors affecting efficiency are crucial to anaerobic digestion, because they play a major role in biogas production and determine the metabolic conditions for microorganism growth. As an additive, an accelerant is not only regarded as a nutrient resource, but can also improve biodegradability. The focus of reactor design is the sufficient utilization of a substrate by changing the feeding method and enhancing the attachment to biomass. The optimal digestion process balances the optimal digest conditions with the cost-optimal input/output ratio. Additionally, establishment of theoretical and technological studies should emphasize practicality based on laboratory-scale experiments because further development of biogas plants would allow for a transition from household to medium- and large-scale projects; therefore, improving stability and efficiency are recommended for advancing AD research. [ABSTRACT FROM AUTHOR]

Fast depleting fossil fuels and the growing awareness for environmental protection have led us to the energy crisis. Hence, efforts are being made by researchers to investigate new ways to extract energy from renewable sources. ‘Microgrids’ with Distributed Generators (DG) are being implemented with renewable energy systems. Optimization methods justify the cost of investment of a microgrid by enabling economic and reliable utilization of the resources. This paper strives to bring to light the concept of Hybrid Renewable Energy Systems (HRES) and state of art application of optimization tools and techniques to microgrids, integrating renewable energies. With an extensive literature survey on HRES, a framework of diverse objectives has been outlined for which optimization approaches were applied to empower the microgrid. A review of modelling and applications of renewable energy generation and storage sources is also presented. [ABSTRACT FROM AUTHOR]