[en] In the last 10-15 years clear progress has been made in research for renewable alternative energies. Technical feasibility is proved in many cases. Efficiency has generally improved and the costs were lowered by a factor of 2 to 3. Nevertheless, commercialization on a broad basis has failed to be realized to date, and the question, whether the renewable energy sources will render an important contribution to the electricity supply in Switzerland or not, is still unanswered. So far the fundamental disadvantages of these energy carriers cannot be overcome. Energy yield related to material input remains low, the area requirements are large and the resulting energy output is usually determined by meteorological and physical factors that cannot be influenced. 1 ref., 10 figs., 5 tabs

[en] This paper is focused on the renewable energy targets set by China in its 12th National Development Plan 2011–2015. In particular, the paper examines deployment targets and the means to achieve them, for hydro, wind and solar. These are its priority technologies, in which the country has a level of competitive advantage. For each of these energy sources, four projections have been produced. These projections show whether and when China will meet its deployment targets in terms of the cumulative amount of gigawatts (GW) of installed capacity by 2015. In doing this, historical data from 2005 to 2010 has been analyzed for all three energy sources. Both the average annual growth rate (AAGR), and the compound average growth rate (CAGR) have been computed, in terms of the world averages and China's national performance over this period. AAGR and CAGR have been used for producing four scenarios for each renewable energy, and a logarithmic scale has been applied to them in order to make them more reliable by smoothing out excessive fluctuations. The most likely scenarios for each technology are described. Finally, the gap between these scenarios and the respective national targets set for 2015 and 2020 are calculated. - Highlights: ► The competitive advantages of China for the Renewable Energy Deployment Targets. ► Hydro target met by 2012 with a GW level higher than 31% the target by 2015. ► Wind target met by 2012 with a GW level higher than 35% the target by 2015. ► Solar target met by 2014 with a GW level higher than 23% the target by 2015. ► Best scenarios and gap analysis for 2015 and 2020 targets.

[en] The article reviews the feasibility and the economic aspects of energy production from biomass and biological waste in the Netherlands. Biomass can be converted to secondary fuel by incineration, gasification, pyrolysis, or thermal hydrogenation. Particular attention is paid to the use of poplar and Miscantus sinensus as energy sources. The average yield of biomass of poplar and Miscantus sinensus is estimated at respectively 10 to 13 tons of dry substance per year per hectare for a 6 to 7 year life cycle and 15 to 20 tons of dry substance per year per hectare for a 10 years life-cycle. The economic aspects of energy production from waste wood, roadside grass, and straw are evaluated. Calculations show that relatively small scale power plants (20 to 50 Mw_el) are feasible in The Netherlands. The most promising technique would be gasification in combination with gas- and steam turbines. (A.S.)

[en] The EU Renewable Energy Strategy (RES) Directive requires that each member state obtain 20% of its energy supply from renewable sources by 2020. If fully implemented, this implies major changes in institutions, infrastructure, land use, and natural resource flows. This study applies a political geography perspective to explore the transition to renewable energy use in the heating and cooling segment of the Swedish energy system, 1980–2010. The Nordic welfare model, which developed mainly after the Second World War, required relatively uniform, standardized local and regional authorities functioning as implementation agents for national politics. Since 1980, the welfare orientation has gradually been complemented by competition politics promoting technological change, innovation, and entrepreneurship. This combination of welfare state organization and competition politics provided the dynamics necessary for energy transition, which occurred in a semi-public sphere of actors at various geographical scales. However, our analysis, suggest that this was partly an unintended policy outcome, since it was based on a welfare model with no significant energy aims. Our case study suggests that state organization plays a significant role, and that the EU RES Directive implementation will be uneven across Europe, reflecting various welfare models with different institutional pre-requisites for energy transition. - Highlights: ► We explore the energy transition in the heating/cooling sector in Sweden 1980–2000. ► The role of the state is studied from a political geography perspective. ► The changing welfare model offered the necessary institutional framework. ► Institutional arrangements stand out as central to explain the relative success. ► The use of renewables in EU member states will continue to vary significantly.

[en] This letter reports on the design and pilot installation of GridShares, devices intended to alleviate brownouts caused by peak power use on isolated, village-scale mini-grids. A team consisting of the authors and partner organizations designed, built and field-tested GridShares in the village of Rukubji, Bhutan. The GridShare takes an innovative approach to reducing brownouts by using a low cost device that communicates the state of the grid to its users and regulates usage before severe brownouts occur. This demand-side solution encourages users to distribute the use of large appliances more evenly throughout the day, allowing power-limited systems to provide reliable, long-term renewable electricity to these communities. In the summer of 2011, GridShares were installed in every household and business connected to the Rukubji micro-hydro mini-grid, which serves approximately 90 households with a 40 kW nominal capacity micro-hydro system. The installation was accompanied by an extensive education program. Following the installation of the GridShares, the occurrence and average length of severe brownouts, which had been caused primarily by the use of electric cooking appliances during meal preparation, decreased by over 92%. Additionally, the majority of residents surveyed stated that now they are more certain that their rice will cook well and that they would recommend installing GridShares in other villages facing similar problems. (letter)

[en] Renewable energy sources are generally regarded as the answer to pollution caused by fossil-fuel-based power. Now some renewable energy technologies have come under attack for creating environmental harm of the very same type that they are supposed to prevent. The opposition includes some environmental groups that claim that renewable energy has detrimental effects on the environment. The charges include the many changes to the ecosystem which result from the use of reservoir-based hydroelectric systems, the combustion products of biomass, the avian mortality caused by wind turbines, and the manufacture and installation of solar collecting panels. This article reviews the pros and cons of these claims and while it agrees that there are, indeed, certain environmental drawbacks, it concludes that the weighing of the energy options indicates that these drawbacks are nearly insignificant when weighed against the major environmental problems and issues surrounding conventional energy sources. To make matters worse, fossil fuels are finite and rapidly depleting. It concludes that the concerns about the harmful environmental impacts of renewable energy sources are not such as to deter policymakers and industry leaders from forging ahead with the vigorous development of these alternative sources of reasonably priced and for the most part, environmentally safe sources of power

[en] Highlights: • This paper presents the transient stability mechanism of IIDGs. • The transient stability sensitivity to droop factors is proposed. • The relation between the network parameters and IIDG’s transient stability is analyzed. • A accurate transient stability judgment is designed. - Abstract: The large-scale application of renewable energy is promising to solve the energy crisis over the world. Renewable energy is generally integrated into distribution networks or microgrids through inverters. Inverter-interfaced distributed generators (IIDGs) have the advantage of utilizing renewable energy effectively and flexibly. However, the wide interconnection of IIDGs causes transient stability to the public grid. This paper presents the transient stability mechanism of the grid-connected IIDGs using droop control. The transient stability mechanism is obtained by combining the transient stability condition and the comprehensive dynamic trace. The transient stability condition is proposed by the transient model and IIDGs’ operation features. The comprehensive dynamic trace is formulated by the active and reactive power curves during transient events. The mechanism is able to reflect the relations between transient stability and droop factors and reveal the transient behaviors of IIDGs. The transient stability judgment is correspondingly developed. A series of simulations demonstrate the correctness and effectiveness of the transient stability mechanism. The transient stability mechanism better expands and develops the utilization of renewable energy.

[en] The loss from curtailing generation based on renewable energy sources is generally seen as an unacceptable solution by the public. The main argument is that it is a loss of green energy and an economic loss to curtail generation with near zero marginal costs. However, this view could lead to overinvestment in grid infrastructure and underinvestment in renewable energy sources. This article argues that some curtailment of fluctuating (variable) generation is optimal. We address the possible contributions to total curtailment from involuntary and voluntary curtailment. The costs of curtailment in terms of lost generation are discussed based on market price and support levels including the rationale for compensating generators for losses. The extent of actual curtailment is illustrated by examples from different global markets. In general, both the value of the curtailed energy and the amount of curtailed energy relative to total fluctuating generation is low but rising. Single generators may be affected considerably if insufficient compensation measures are in place. In the future, optimal curtailment will increase along with an increased share of fluctuating renewable generation. Extending renewable generation comparatively cheaply can be achieved by the installation of additional capacity at offshore locations until optimal curtailment levels are reached. - Highlights: ► Curtailment of renewable generation can be optimal. ► Voluntary and involuntary curtailment categories. ► Compensation for involuntary curtailment should be provided. ► Asymmetrical balancing price provides incentive for voluntary curtailment. ► Network enforcement costs can be reduced per renewable generation.

[en] A distillate of the various views and opinions of the Nigerian Energy Industry as reported by some national and international print media

[en] Description of renewable energy sources use as single ecologically clean technology for electric power generation is given. It is marked, that Kazakhstan total wind energy potential consists in 32 trillions k W·h, that is comparable with energy consumption of all countries in 2500