• Energy Research

The use of renewable energy, including solar process heating, and of efficient energy conversion technologies, have been considered in the literature to improve the energy performance of cheese production. However, most of the studies considered one energy source at a time and hardly accounted for the carbon emission impact. In this paper, a mixed integer linear programming model is developed and applied to a reference cheese factory in Italy to identify the least cost mix of solar thermal energy, natural gas-based trigeneration and symbiotic waste heat recovery from nearby industries via district heating that allows to achieve assigned carbon emission reduction goals. The study reveals that fossil fuel based trigeneration is economically attractive, leading to savings in annual equivalent systems costs of approximately 18–20% over the baseline configuration, but does not contribute to decarbonization, generally causing a percentage increase of carbon emissions of approximately 30% from the baseline configuration. In addition, the combination of cogeneration and waste heat recovery from a remote source (300 m up to 1000 m far away from the user) may be more cost-efficient than solar heating to meet a 30% carbon emission reduction constraint for most combinations of electricity and natural gas prices.

Co-firing of solid biomass in existing large scale coal power plants has been supported in many countries as a short-term means to decrease CO2 emissions and rapidly increase renewable energy shares. However, many countries face challenges guaranteeing sufficient amounts of biomass through reliable domestic biomass supply chains and resort to international supply chains. Within this frame, novel pre-treatment technologies, particularly pelletization and torrefaction, emerged in recent years to facilitate logistics by improving the durability and the energy density of solid biomass. This paper aims to evaluate these pre-treatment technologies from a techno-economic and environmental point of view for two reference coal power plants located in Great Britain and in Italy. Logistics costs and carbon emissions are modelled for both international and domestic biomass supply chains. The impact of pre-treatment technologies on carbon emission avoidance costs is evaluated. It is demonstrated that, for both cases, pre-treatment technologies are hardly viable for domestic supply. However, pre-treatment technologies are found to render most international bioenergy supply chains competitive with domestic ones, especially if sourcing areas are located in low labour cost countries. In many cases, pre-treatment technologies are found to guarantee similar CO2 equivalent emissions performance for international compared to domestic supply chains

In the last few years, the water-energy nexus concept has emerged as a global issue. However, studies on European countries are relatively few, and often focused on agriculture. Cooling purposes represent the main part of industrial water demand, and waste-heat recovery is a main strategy to improve resource efficiency. This paper presents a real case study of low-temperature waste-heat recovery in an electric steelmaking industry and evaluates the impact of feasible interventions on primary energy and water consumption, as well as on CO2 equivalent emissions. Based on a Europe wide review of energy and water prices, of energy sources and corresponding resource efficiency indicators, a Monte Carlo model was developed to undertake a generalization of the case study to the EU-15. It was found that solutions with the lowest primary energy demand and the lowest CO2 equivalent emissions demonstrate the greatest water footprint. This is the case of some southern European countries, where heat recovery projects with the highest water intensity are feasible due to high electricity and low water prices. As increasing carbon prices may exacerbate this phenomenon, inducing a switch to water intensive technologies, incentives to carbon emission reduction should be carefully designed.

Abstract Italy is a large producer of biogas from anaerobic digestion, which is mainly used for power generation with limited use of cogenerated heat. Other utilization pathways, such as biomethane injection into the natural gas grid or biomethane used as a vehicle fuel, remain unexplored. Given the dense grid of natural gas pipelines and existing Compressed Natural Gas (CNG) refueling stations in northern Italy, significant market opportunities for biogas could also arise in the heating and transport sectors. The main objectives of this paper are to explore the potential role of agricultural biogas in different utilization pathways. Biogas combustion for simultaneous production of heat and power in small Combined Heat and Power (CHP) facilities is also assessed, as is upgrading to biomethane for transport or natural gas grid injection in the specific context of northern Italy. The spatially explicit optimization model BeWhere is used to identify optimal locations where greenfield biogas plants could be installed and to determine the most economic and environmentally beneficial mix of conversion technologies and plant capacities. Carbon price, for instance in the form of tradable emission permits, is assessed as a policy instrument and compared with other options such as price premiums on biomethane or electricity costs. Results show that starting from a carbon price of 15 EUR/tCO 2 , the cogeneration option is preferable if plants are located in the proximity of existing district heating infrastructure. CNG plants are only competitive starting at a carbon price of 70 EUR/tCO 2 in areas with high feedstock availability. The sensitivity analysis for energy prices reveals that a larger number of CNG facilities are included in the optimal mix at higher gas wholesale prices. This further indicates that specific premiums are needed to expand the biomethane market share, while greenhouse gas emission reductions would primarily be achieved by fostering cogeneration of electricity and heat supported by carbon price-based policy instruments.

Decisions on space heating of industrial buildings involve several conflicting objectives and solutions prospected by economic optimization (e.g. life cycle cost minimization) models may be far from the real preferences of decision makers. To overcome this limit, multi-criteria decision analysis which has hardly been used at single building level, especially in industrial contexts, could be a helpful methodology. This paper presents the application of a well-known multi-criteria approach, the Analytic Hierarchy Process (AHP), to the selection of space heating systems for an industrial building. We discuss the technologies available for industrial heating, criteria elicited from the decision maker and the ranking of alternatives identified with our AHP model. As very little is reported in literature about industrial energy system choices, our study, although focused on an individual case, may shed some light on decision making in this sector. To this end, we also compare our results with evidence on residential heating systems choices derived from literature. Investment costs are the most important criterion for industry, whereas qualitative attributes and operational costs are most important for homes. Qualitative attributes also significantly affect industrial heating system choices and, as the AHP is particularly effective in handling these aspects, we suggest it could be used for tactical energy planning models.

In Italy biogas support schemes are being revised to include subsidies for the production of biomethane. Energy policies should foster environmentally optimal solutions, especially because social acceptance issues often arise in the case of biogas. In this paper we use the external cost methodology to quantify the environmental impact of airborne emissions associated with biogas-based energy vectors and their corresponding fossil substitutes These are evaluated at supply chain level and incorporated in a spatially explicit optimization model. The method is applied to northern Italy to compare the potential impact of alternative policy options. It is found that, while the external costs of biogas-based pathways are always lower than corresponding fossil fuel based pathways, the differences are generally so small that policies based on internalization of external costs alone would not lead to further development of biogas-based technologies. For all utilization pathways, consideration of local externalities leads to a less favourable evaluation of biogas-based technologies, which results in external costs even higher than the substituted fossil fuel if biogas is allocated to local heating.

Italy has witnessed an extraordinary growth in biogas generation from livestock effluents and agricultural activities in the last few years as well as a severe isomorphic process, leading to a market dominance of 999 kW power plants owned by “entrepreneurial farms”. Under the pressure of the economic crisis in the country, the Italian government has restructured renewable energy support schemes, introducing a new program in 2013. In this paper, the effects of the previous and current support schemes on the optimal plant size, feedstock mix and profitability were investigated by introducing a spatially explicit biogas supply chain optimization model, which accounts for different incentive structures. By applying the model to a regional case study, homogenization observed to date is recognized as a result of former incentive structures. Considerable reductions in local economic potentials for agricultural biogas power plants without external heat use, are estimated. New plants are likely to be manure-based and due to the lower energy density of such feedstock, wider supply chains are expected although optimal plant size will be smaller. The new support scheme will therefore most likely eliminate past distortions but also slow down investments in agricultural biogas plants.

Specific Organic Rankine Cycle (ORC) units dedicated to biomass-based power production have recently been developed through the introduction of novel organic working media and technology innovation. For small systems, ORC technology appears as an efficient alternative to conventional generation if also process waste heat can be exploited, as resulted in the last few years from the successful operation of several demonstration plants in Austria and Switzerland. The present study aims to investigate the impact of the introduction of ORC units in an industrial context from a system perspective, with particular reference to industrial districts, which are characterized by the concentration in small areas of a large number of medium- and small-sized firms. The paper focuses on the opportunity of combining ORCs, traditional Rankine cycles and multi-source district heating to meet energy requirements in an industrial district in North Eastern Italy. To this end, a mixed-integer linear programming model oriented to economical optimization of the system is developed and sensitivity analysis is carried out in order to determine the conditions for the expansion of biomass-based power generation in the analyzed industrial district and to evaluate potential for CO2 emission reduction. Copyright © 2004 John Wiley & Sons, Ltd.