The doping effect of Italian feed-in tariffs on the PV market

In less than six years, Italy has become one of the leading markets for PV power plants and one of the countries in the world with the largest number of installations and installed peak power. Such a quick and large growth is due to a series of feed-in tariff schemes that have been uncapped until 2012. As a matter of fact, any size or any number of PV power plants could be installed during a period of three years. Since the feed-in tariffs are not paid by national taxes but are charged on the electricity bills, Italian energy users are now due to pay each year a surcharge of 9 billion euros on their energy bills. This paper aims at discussing this development by highlighting the benefits but also some significant drawbacks that the application of uncontrolled feed-in tariffs has produced

Energy saving in tooling machines: a new unified approach to reduce energy consumption

Tooling machines are included in some EU directives, which set specific targets for the reduction of energy consumption in the near future. This paper aims to introduce a design approach that can be useful both for safety functional decomposition and for energy consumption evaluation of a generic tooling machines. This design approach tries to unify the existing divergent approach to energy efficient and safe tooling machines. A very simple application, already installed in some lathe machines currently produced in the EU, will give us all the necessary data (activity time counter) to perform a quantitative assessment in term of unified energy-efficient and safe machines. Moreover, the main results of an extensive survey made by a lathe manufacturer on real machines utilization and some measurement of wasted energy during standby mode of different machines will be presented. Those measurements show that it is not possible to define a proper LCA design method without considering that the wasted energy is a function of the size and type of processes and the specific operating conditions of the machine. Measurements, performed during stand-by of lathes with regenerative drives, are presented at the end of the paper

Sustainable mini-grid

Abstract Paper summarized the research done in min-grid field. Mini-grid is small, stand-alone power system, which role is to provide constant and affordable electricity in remote places, where the connection with main grid is unprofitable. Mini-grids are important tools in fight with power-poverty in developing countries. The economics of power technologies is widely analyzed in different studies. The paper presents the advantages of application of integrated sustainable assessment for analyzing different power technologies for mini-grids. The paper highlight the importance of environmental and social aspects and its influence on local community

Opportunities of Power-to-Gas technology

This paper presents an overview of power-to-gas technologies by describing the potential, the type of technologies and the challenges that are to be faced in order to introduce them in the energy system of large areas where large shares of renewable energy have been introduced or are planned to be introduced. When large electrical grids have too large a share of intermittent renewables, there is a strong need of energy storage to balance the supply and demand with time and to avoid curtailment of renewable energy power plants. At the same time, energy storage is fundamental in small or remote grids, where the demand may be strongly different form the supply of energy during the day and during the year. In those cases reaching large shares of renewable power plants may be impossible without energy storage systems. Another important aspect that has to be studied in order to introduce energy storage systems on small or large grids, is the flexibility of operation of all power plants connected with the grid

Challenges in load balance due to renewable energy sources penetration: The possible role of energy storage technologies relative to the Italian case

With the rapid growth of the electricity produced by RES (renewable energy sources), especially those highly variable and unprogrammable (e.g. wind and solar power), the need of energy system flexibility increases significantly. Since RES currently represent a significant fraction of the power supply, their variable nature poses challenges to power grid operation, such as RES curtail and loss in global efficiency of thermoelectric plants, since they are often operated at part-load as fluctuating back-up power. In particular, thermoelectric plants recently moved their role from base-load power to fluctuating back-up power. Such a cycling operation represents a less obvious effect of grid flexibility requirement due to RES penetration. Main effect is the increment of both energetic costs, due to reduced efficiency operation, and wear-and-tear costs. This aspect is deeply analysed in reference to the Italian electricity generation mix in the period 2008-2012. Moreover, the possible coupling of energy storage systems with thermoelectric plants is highlighted as an alternative solution respect to retrofitting of existing plants

Humid Air Gas Turbine Cycle: a Possible Optimization

The humid air turbine (HAT), patented by FLuor Daniel, is an innovative cycle which allows to obtain an increase in efficiency and power production. The modification proposed by DEF allows to optimize the plant when natural gas is injected in the combustion chamber. Assuming a TIT (Temperature Inlet Turbine) at 1273°K and the cooling of recirculating water in the refrigerators, we studied the effects of the relative humidity and the compression ration on the cycle's performances. The aim of this paper is to suggest the parameters which allow to obtain high efficiency with high specific power, the possibility to modulate power production without a decrease in efficiency and low water consumption

feasibility analysis of coupling an orc to a mgt in a biogas plant

Abstract An increasing interest is devoted to biogas plants as they might play a key role in the reduction of current fossil fuel consumption for power production. The main component of the plant is the anaerobic digester where the organic fraction of waste products is converted in a gas with high concentration of methane and carbon dioxide. This biogas is converted in power and heat in a cogeneration unit that may consist in a micro gas turbine or an internal combustion engine. Electric power is used to satisfy the plant internal need and the surplus is sold to the grid. A portion of the heat is used to keep the digester at a constant temperature as requested by the anaerobic digestion, the reaming is generally dissipated. This study focuses on the potential of using an Organic Rankine Cycle as a possible additional thermal user to reduce the amount of dissipated heat and increase the power production. The study is based on an existing biogas plant operating in the town of Viareggio (Italy) which will be equipped with a 600kWe micro gas turbine. The integration of the two systems was studied in detail to have high values of thermal energy recovery. A reference and a modified solution were simulated in AMESim by considering a yearlong period with actual ambient conditions. Off-design behavior of all the components was also included in the simulation. The results of the investigation showed that a thermal energy recovery up to 77% could be achieved. From the economic point of view, the plant modification for introducing the ORC system has a payback period lower than 6 years and an interesting profitability index

Feasibility study and design of a low-energy residential unit in Sagarmatha park for environmental impact reduction of high altitude buildings

The project presented in this paper is geographically set within Sagarmatha National Park, a wide area located on the Nepalese mountainside of Everest and declared as World Heritage Site since 1979. In recent years the park was the focus of several studies and initiatives, aimed at improving the management of its many-sided ecosystem, significantly influenced by climate change and increase of human activities and tourism, which occurred from the end of the 1970s, as well as by practices that are harmful both to human health and to our environment (e.g. burn up kerosene or animal excrements in order to obtain heat). Research work has focused on designing a residential unit that meets population needs, in terms of simplicity of realization, replicability, use of local materials, environmental compatibility and exploitation of available renewable energies. For this purpose a thorough analysis was conducted to identify the housing standard characteristic of reference context and Sherpa people, concerning indoor thermal comfort conditions, construction techniques, availability and skills of local workforce. Data necessary for the design phase were obtained through a collaboration with researchers of Ev-K2-CNR center, active at 5,050 meters a.s.l. in Nepal at the base of Mount Everest with a laboratory/observatory (known as the "Pyramid") for highaltitude meteorological studies since 1989. Climate conditions were registered by specific monitoring stations at certain times (2002-2008); during preliminary stage, these values were considered representative of the local context chosen for the project, that is Namche Bazar, a village located within the park, in a central point both from the logistic and altimetric/weather points of view. For the residential unit under investigation, two different constructive approaches were selected and compared: earthbags and straw bales. Both techniques have several advantages, in particular availability of raw material (jute bags, soil, straw), simplicity (e.g. earthbag constructions are realized using the ancient technique of pisé, combined with flexible bags or tubes), durability, insulation performance, costeffectiveness. Through a specific software for calculation of winter/summer thermal loads, different combinations of selections of structure and insulation were examined for both solutions, in order to achieve the optimum for the case study. Furthermore on the base of data monitored on site, a specific assessment was carried out to evaluate the potential of solar and wind resources. Aiming at entirely covering the heat and electric energy needs by exploiting renewable energy sources, various plant configurations were finally assumed. Every single choice was made to reduce human influence on land resources, such as timber, and to improve internal and external environmental quality

Solid-oxide electrolyzer coupled biomass-to-methanol systems

Abstract Biomass-derived fuels are attractive due to the reduced greenhouse gas emissions and the potential contribution to the development of the agricultural industry. Particularly, 2nd generation biofuels, e.g., synthetic biodiesel as a high-performance and alternative mobility fuel, can be produced via biomass-gasification based processes. There are mainly three types of biomass gasification processes: (1) moving- or fixed-bed gasifier for coal gasification with oxidizing blast gas (air + hot syngas) (2) fluidized-bed gasifier that uses air (oxidant agent) to fluidize the bed and the added carbon-containing particle, and (3) entrained flow gasifier that uses pure oxygen to reach high operating temperature. The entrained flow gasifier seems to be a promising choice with high scale-up potential, due to the high-pressure operation and none N2 diluted syngas production, which can lead to the compact design of down-stream equipment. Particularly, the syngas produced contains no tar, and low methane and CO2. The disadvantage of this gasification technology is the need of high-purity O2 supply of, usually from an air separation unit (ASU). Therefore, solid-oxide electrolysis offers very good opportunity of integrating with entrained-flow gasifier, due to that (1) possible pure oxygen production to avoid the ASU, (2) high operating temperature for better heat integration with the original gasification process, and (3) hydrogen production via steam electrolysis for adjusting the syngas composition. In this paper, the integration of the SOE in the EFG-based biomass to methanol systems (SOEC case) is investigated and technically compared with the traditional biomass-to-liquid system (base case), whose syngas composition is adjusted by water-gas-shift reactors. The results show that, the mass yield of the methanol is set as around 69.4 t/hr, SOEC case can achieve higher energy efficiency, the energetic efficiencies of the base case and SOEC case were 47.95% and 59.1%, respectively

Dynamic modelling of a low-concentration solar power plant: A control strategy to improve flexibility

This paper deals with a dynamic analysis on a low concentration solar power plants coupled with Organic Rankine Cycles (ORC), which can be an alternative to PV systems because of their capability of providing a smoother electricity production due to their thermal inertia. At least within certain restraints, moreover they are able to exploit diffused solar radiation. The dynamic model of a plant with static Compound Parabolic Collectors and an ORC system, using a rotary volumetric expander, was developed using the simulation tool AMESim. All the main components of the plant are modelled: solar collectors field, heat transfer fluid circuit, heat exchangers and the ORC system. The plant response to the radiation of different days was analyzed to quantify the daily production and the trend of various plant parameters. Real ambient conditions were employed for the simulations by using data obtained by historical series. The results showed that the employment of a volumetric expansion device with variable rotating speed allows the plant to operate at different radiations and ambient temperatures without the need of any storage system or external heat sources. Results can be extended to other applications, such as low temperature waste heat recovery or geothermal systems