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Renewable energy policies contribute to solving some of the current environmental challenges, such as climate change mitigation and decarbonization, and people around the world are usually willing to pay for a greater presence of renewable energies. That willingness to pay (WTP) can be translated into a gain in social well-being. But not all renewables are equally valued, nor do all people experience the same gain in terms of well-being. Over the last 25 years, many choice experiments have focused on analyzing social preferences for different external effects associated with renewables. This article presents a meta-analysis of choice experiments to examine the evidence on WTP for renewable energies. We examined 63 articles across 28 countries, with a total sample of 52,948 participants and 84,821 observations. We used three econometric approaches (Generalized Least Squares, Weighted Least Squares, and a Panel Data Model) to estimate the willingness to pay of households for renewables around the world. Results show that the promotion of renewable energies is socially demanded, with an average minimum WTP of between €113 and €124 per household per year. The results also show that onshore wind farms are the preferred renewable energy source for electricity generation, whereas people are more reluctant about offshore wind in comparison with other renewable technologies. Finally, some geographic patterns are found, with people from Asia and southern Europe showing, respectively, a lower and higher willingness to pay for renewable energies

Global warming represents a serious challenge, which requires the adoption of renewable energy technologies worldwide. However, it can negatively affect the availability of renewable energy resources, such as wind, which are needed for electricity generation. In this context, there is an increasing need for more accurate evaluations of wind turbine power curves. A novel methodology to model the power curves of wind turbines, which combines the use of artificial neural networks (ANN) and Fuzzy logic rules, is proposed in this paper. This methodology assesses the role of environmental temperature in the power curve and the impact of temperature increases on wind energy production. The application of this methodology is illustrated with the simulation of the impact of global warming on the electricity generation of a wind farm. Due to the non-linear relationship between the power output of a turbine and its primary and derived parameters, it is shown that ANN combined with an expert system formed by a Fuzzy logic module fit power curve modeling processes well. The application of the methodology shows that an increase in temperatures would trigger a small reduction in the performance of wind turbines.

Photovoltaic demand-side generation (PV-DSG), defined as the production of electricity by means of panels or arrays which are installed on the customer's side of the meter, has received much attention lately by academics and policy-makers all over the world. Some countries have promoted this form of generation, whereas others have lagged behind. This is the case of Spain, where PV-DSG has not taken-off. The aim of this paper is to provide a critical overview of the Spanish regulation for PV-DSG, approved in 2015, and its impact on demand-side generation in this country. The impacts of the new regulation on PV-DSG are calculated with real data from a household PV installation. It is found out that the current regulation is highly unfavourable for the adoption of PV-DSG, given the small savings for investors (consumers) for the adoption of PV-DSG compared to buying the electricity from the grid.

A complex regulatory package implementing a new support scheme for renewable electricity was adopted in Spain in 2013 as a response to escalating support costs, which have mostly been related to solar PV promotion. A lot has been written about the retroactivity of the new Spanish regulation and its negative impact on investors’ confidence and future deployment. The aim of this paper is to analyze the implications of this regulation on the profitability of those plants in Spain. Using real data from a very common PV plant, the results show that the new support scheme has a considerable impact on the cash-flows of those plants. However, our simulations also show that the degree of reduction in the internal rates of return critically depends on different factors. Under some restrictive assumptions, the savings in support costs due to the new regulation are only around 7.6% if remuneration for investment is maintained after 2019, and around 57% if such support is removed after 2019.

Aim of study: This paper objective focuses on the contribution of multifunctional natural forest silviculture, incorporating both private and public product managements, to forest and woodland economics.Area of study: Spain and California (USA).Material and methods: This conceptual article has developed a critical revision of the existing literature on the main economic issues for multifunctional natural forest silviculture in the last decades.Main results: Multifunctional natural silviculture has secular roots as a local practice, but as a science of the natural environment applied to the economic management of forest lands it is still in the process of maturation. Timber silviculture remains the central concern of forest economics investment in scientific publications. By contrast, silvicultural modeling of the natural growth of firewood, browse and other non-timber forest products from trees and shrubs receives scant attention in scientific journals. Even rarer are publications on multifunctional natural silviculture for forest and woodland managements, including environmental services geared to people’s active and passive consumption. Under this umbrella, private environmental self-consumption is represented by the amenities enjoyed by private non-industrial landowners. As for environmental public products, the most relevant are carbon, water, mushrooms, recreation, landscape and threatened biodiversity.Research highlights: This paper is a good example for the conceptual research on forestry techniques and economic concepts applied to multifunctional silviculture in Mediterranean areas of Spain and California. The combination of technical knowledge and private and public economic behaviors definitively contributes to the multifunctional management of natural forest systems.

Aim of study: This paper objective focuses on the contribution of multifunctional natural forest silviculture, incorporating both private and public product managements, to forest and woodland economics., Area of study: Spain and California (USA), Material and methods: This conceptual article has developed a critical revision of the existing literature on the main economic issues for multifunctional natural forest silviculture in the last decades., Main results: Multifunctional natural silviculture has secular roots as a local practice, but as a science of the natural environment applied to the economic management of forest lands it is still in the process of maturation. Timber silviculture remains the central concern of forest economics investment in scientific publications. By contrast, silvicultural modeling of the natural growth of firewood, browse and other non-timber forest products from trees and shrubs receives scant attention in scientific journals. Even rarer are publications on multifunctional natural silviculture for forest and woodland managements, including environmental services geared to people’s active and passive consumption. Under this umbrella, private environmental self-consumption is represented by the amenities enjoyed by private non-industrial landowners. As for environmental public products, the most relevant are carbon, water, mushrooms, recreation, landscape and threatened biodiversity., Research highlights: This paper is a good example for the conceptual research on forestry techniques and economic concepts applied to multifunctional silviculture in Mediterranean areas of Spain and California. The combination of technical knowledge and private and public economic behaviors definitively contributes to the multifunctional management of natural forest systems.

Los exámenes y pruebas de evaluación tienen un papel destacado dentro de los materiales docentes. Ello es así debido al doble papel que juegan: por una parte, son cruciales para evaluar el nivel de conocimientos adquiridos por los estudiantes; pero también orientan al estudiante sobre cómo preparar las asignaturas. Por tanto los exámenes son una herramienta fundamental en la docencia. Teniendo en mente esta consideración, el objetivo de este proyecto era doble: (a) obtener un análisis objetivo y cualificado de los exámenes y métodos de evaluación utilizados, así como (b) recoger sugerencias que permitan mejorar los procesos de evaluación de las asignaturas consideradas.

[EN] We evaluate the added value of a forecast service that can provide probabilistic predictions for adverse weather events for two differentiated seasons, corresponding to the same productive cycle. The paper builds on a cost-loss dynamic model, by considering the role of forecasting systems in the decision making process. We present the analytical solution for this problem which is consistent with the numerical results in the literature. However, we prove that there is a range of regions for the opti-mal policy depending on the cost of crop protection, the avoided loss and the quality of the information available. Finally, we illustrate the results with a numerical example., [ES] Evaluamos el valor añadido de los servicios meteorológicos que proporcionan predicciones probabilísticas para eventos climáticos adversos considerando dos estaciones diferentes, correspondi-entes a un mismo ciclo productivo. Este artículo se apoya en un modelo coste-pérdida dinámico para considerar el papel de los sistemas de predicción y alerta temprana en los procesos de toma de decisión. Se presenta la solución analítica para este problema, que es consistente con los resultados numéricos en la literatura. Sin embargo, probamos que la política óptima presenta numerosas regiones distintas depen-diendo del coste de proteger, la pérdida evitada y la calidad de la información disponible. Finalmente, ilustramos los resultados con un ejemplo numérico.

One of the main criteria to assess the success of instruments to support electricity from renewable energy sources (RES-E) is cost-effectiveness. However, a consensus on the definition of cost-effectiveness does not yet exist in the literature. For some authors, cost-effectiveness refers to the minimisation of RES-E generation costs, but others define it as the minimisation of the costs of RES-E support. This paper compares the two main interpretations of this concept using a mathematical model. The optimisation problems of both approaches are formally stated, the corresponding optimality conditions are obtained, the optimal solutions of both approaches are compared and some rent transfer mechanisms from consumers to producers are proposed. It is shown that the minimisation of generation costs does not imply that consumer costs are minimised, and that the minimisation of consumer costs does not imply that generation costs are minimised. In addition, two types of mechanisms of transfer of rents from consumers to producers which lead to the same optimal solution for both approaches are proposed.

From mid-2007 to September 2008, the Spanish PV sector experienced an investment boom, which led to a ten-fold increase in solar PV deployment. The concern of the government about the large increase in the associated support costs through a feed-in tariff led to the implementation of several cost-containment regulations. These included a cap on the electricity generation being eligible for support, a grid access charge, a generation charge, a shortening of the support period and the updating of tariffs below the consumer price index. The aim of this paper is to analyze the impact of those cost-containment mechanisms on the profitability of solar PV plants in Spain. The results show that these measures have had a moderate impact on the profitability of those plants, which is still relatively high, with internal rates of return which are always above 7% in all the simulated cases. However, their impact is mediated by different features of the plant, including the levels of the initial investment (upfront costs), borrowing and operation and maintenance (O&M) costs. It is also mediated by policy variables (such as changes in the tariff-updating method and the level of the grid-connection charges) and by other variables, e.g., the interest rates of loans. The specific impact of each of the cost-containment measures has also been analyzed. Our findings show that the generation charge has the greatest impact, followed by the change in the tariff-updating mechanism, the generation cap, the shortening of the support period and the grid access charge.

The cost-effectiveness of support for renewable electricity is a main criterion to assess the success of policy instruments, together with effectiveness. The costs of support are also a source of significant concern for governments all over the world. However, significant confusion exists in the literature on the cost-effectiveness of public support for renewable electricity. While some authors define the concept of cost-effectiveness as that which complies with the equimarginality principle, many others, including documents from relevant organisations (European Commission, International Energy Agency, Intergovernmental Panel on Climate Change) define it as >the lowest costs of support>, generally equating it with the minimisation of consumer costs. The aim of this paper is to clarify the differences between both approaches and their policy implications regarding the choice of instruments and design elements. It is shown that they partly overlap and that their policy implications clearly differ, leading to very different policy prescriptions. While the former favours technology neutral instruments and design elements, the >minimisation of consumer costs> approach favours instruments and design elements which adjust support levels to the costs of the technologies.

This paper presents an optimal control model to analyze reforestations with two different species, including commercial values, carbon sequestration and biodiversity or scenic values. We discuss the implications of partial or total internalization of environmental values, showing that internalizing only carbon sequestration may have negative impacts on biodiversity-scenic values. To evaluate the practical relevance, we compare reforestations in the South-west of Spain with cork-oaks (a slow-growing native species) and with eucalyptus (a fast-growing alien species). We do the analysis with two different carbon crediting methods: the Carbon Flow Method and the Ton Year Accounting Method. With the first method, the forest surface increases more, but using mainly eucalyptus. With the second, additional reforestations are done mainly using cork-oaks. We value the impact on visitors of these reforestations using stated preferences methods showing that, when these values are internalized, cork-oaks are favored.