• Energy Research

Abstract Due to growing interest in biofuels as alternative renewable energy sources, several recent studies have assessed the sustainability of their production. Emergy is a widely used environmental indicator for this purpose, as it counts exploitation of natural resources and direct and indirect solar energy requirements of biofuel production. Depending on whether a biofuel is first, second or third generation, its production system differs in nature and the indications derived from emergy evaluations vary as well. This article aims to provide guidelines on how to interpret and properly use the results of emergy evaluation of first, second and third generation biofuels. These guidelines are useful for correct emergy assessment of biofuels and clarify the actual meaning of emergy evaluation outcomes.

The comparison of the Ecological Footprint and its counterpart (i.e. biocapacity) allow for a classification of the world's countries as ecological creditors (Ecological Footprint lower than biocapacity) or debtors (Ecological Footprint higher than biocapacity). This classification is a national scale assessment on an annual time scale that provides a view of the ecological assets appropriated by the local population versus the natural ecological endowment of a country. We show that GDP per capita over a certain threshold is related with the worsening of the footprint balance in countries classified as ecological debtors. On the other hand, this correlation is lost when ecological creditor nations are considered. There is evidence that governments and investors from high GDP countries are playing a crucial role in impacting the environment at the global scale which is significantly affecting the geography of sustainability and preventing equal opportunities for development. In particular, international market dynamics and the concentration of economic power facilitate the transfer of biocapacity related to “land grabbing”, i.e. large scale acquisition of agricultural land. This transfer mainly occurs from low to high GDP countries, regardless of the actual need of foreign biocapacity, as expressed by the national footprint balance. A first estimation of the amount of biocapacity involved in this phenomenon is provided in this paper in order to better understand its implications on global sustainability and national and international land use policy.

Abstract An evaluation of the investment required to implement a second generation bioethanol production chain is presented in this study. An integrated agro-industrial system can be an appropriate solution to accomplish the European requirement for the partial substitution of bioethanol for gasoline by 2020. A biorefinery system is hypothesized within the Province of Siena (Italy), fed by residual energy and material flows from local productions: straw from agriculture and residual geothermal heat from geothermal electricity generation; the output is calibrated to replace 10% of gasoline consumption within the Provincial area. The physical consistency of the investment required to implement the production process, as well as the benefit of the biofuel–gasoline substitution, have been evaluated by means of the emergy methodology. Emergy is a thermodynamics-based indicator that contributes to identify and measure all the inputs supporting a given system, expressed in a common unit (solar emergy Joules – semj). Results show that the benefit of saving gasoline, in emergy terms, almost doubles the emergy investment to produce biofuel. The case of a biorefinery fed by natural gas instead of local residual geothermal heat is also presented. The Unit Emergy Investment (UEI) of bioethanol produced in a biorefinery that uses residual straw and geothermal heat is 9.16E + 08 semj/g (the case of the Province of Siena); it is 1.84E + 09 semj/g (in case natural gas is used to fuel the process). Finally, the comparison between the UEI of bioethanol evaluated in this study and UEV of bioethanol calculated in other studies is presented.

Abstract This study presents a possible implementation of a second generation bioethanol production chain within the Province of Siena (Tuscany, Italy) by means of a biorefinery, and its consequences for the regional GHG balance in order to meet the European requirements for partial substitution of 10% bioethanol for gasoline by 2020. According to the last GHG balance of the territory of the Province of Siena, the transport sector represents the main contributor to the overall GHG emissions within the Province. A biorefinery project is hypothesized, fed by residual straw (from the local production of wheat, barley and oat) and residual geothermal heat (from local geothermal power plant) in order to produce bioethanol. The target of the production plant was about 8200 tons/year of bioethanol, representing the amount needed to replace 10% of the gasoline consumed in 2008 in the Province of Siena. The results of the Life Cycle Assessment (LCA) of the entire production chain have been included within the GHG balance of the Province of Siena in order to assess the effect of this substitution. The emissions derived from the production chain have been added to the current gross CO2eq emissions, and the CO2eq avoided, thanks to the substitution of bioethanol, has been subtracted. The main results of this paper are: 1) the territory of the Province of Siena produces enough straw to implement the bioethanol production chain (38,000 tons/year of ethanol out of 147,000 tons/year of straw); 2) the emissions deriving from the entire bioethanol production chain are about 601.51 kg CO2eq per ton of bioethanol produced (about 4932 tons of CO2eq are the emissions associated to the production of 8200 tons of bioethanol); 3) the use of the produced bioethanol in Siena's transport sector could bring about a reduction of 15,393 tons of CO2eq in emissions, equal to 6% of the net CO2eq emissions.

Bioethanol is obtained from various raw biomasses and by means of optimized process technologies. It can be a substitute for gasoline, which implies greenhouse gas (GHG) emission reduction. The type of feedstock determines the classification of bioethanol: first generation (starch-based biomass or simple sugar-based feedstock) and second generation (lignocellulosic material as straw and wood). Second generation bioethanol production requires cellulosic biomass, which overcome the problems of first generation like food competition and low efficacy in GHG emission reduction. Sustainability evaluations of (first and second generation) bioethanol production have been proposed in the past by means of systemic indicators like emergy analysis and Life Cycle Assessment (LCA). A joint use of emergy and LCA of a possible implementation of a second generation bioethanol production chain is presented in this study. The emergy methodology has been used to test the physical consistency of the investment required to implement the production process, as well as the benefit of the biofuel-gasoline substitution. The effect of this substitution has been also evaluated by including the LCA of this production chain within the GHG balance of the Province of Siena.

One of the main goals of any (sustainability) indicator should be the communication of a clear, unambiguous, and simplified message about the status of the analyzed system. The selected indicator is expected to declare explicitly how its numerical value depicts a situation, for example, positive or negative, sustainable or unsustainable, especially when a comparison among similar or competitive systems is performed. This aspect should be a primary and discriminating issue when the selection of a set of opportune indicators is operated. The Ecological Footprint (EF) has become one of the most popular and widely used sustainability indicators. It is a resource accounting method with an area based metric in which the units of measure are global hectares or hectares with world average bio-productivity. Its main goal is to underline the link between the (un)sustainability level of a product, a system, an activity or a population life style, with the land demand for providing goods, energy, and ecological services needed to sustain that product, system, activity, or population. Therefore, the traditional rationale behind the message of EF is: the larger EF value, the larger environmental impact in terms of resources use, the lower position in the sustainability rank. The aim of this paper was to investigate if this rationale is everywhere opportune and unambiguous, or if sometimes its use requires paying a special attention. Then, a three-dimensional modification of the classical EF framework for the sustainability evaluation of a product has been proposed following a previous work by Niccolucci and co-authors (2009). Finally, the potentialities of the model have been tested by using a case study from the agricultural context.

An energy transition is needed in order to meet the European pledge of reaching climate neutrality by 2050. This transition cannot ignore the renewable resources available from 70% of the Earth (namely, the oceans and seas). This concept is fundamental for the planet, especially for the Mediterranean area. Marine renewable energies are still under-deployed in the Mediterranean area for many reasons, including legislative constraints, lower energy availability, and technological readiness. An appropriate participatory process including all actors (e.g., policymakers, firms, citizens, and researchers) is necessary for a correct path toward decarbonization. The BLUE DEAL project was conceived and implemented by 12 Mediterranean partners to tackle these issues and set the route for blue energy deployment in the Mediterranean area. Activities already conducted include a survey to probe the perceptions and attitudes of citizens toward blue energy. The survey targeted about 3,000 persons in 12 Mediterranean sites with the aim of bringing citizens into the discussion on future technologies. The results showed that although blue energy is still relatively unknown to the general public (only 42% of respondents were aware of these technologies), there was a general willingness (70%) to host one or more such installations in their areas. Here, we describe our survey method and some empirical results with suggestions for replicability and recommendations on how to use it for policymaking purposes.