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The Institute for Energy Engineering (IIE) of the Universitat Politècnica de València (UPV), lea...
New cooperative doctorate in energy The Universitat Politècnica de Valencia  (UPV) and the Univer...

 RENEWABLE AND ADVANCED SYSTEMS AREA

Activities in this area aim to conduct studies in renewable energy systems and in energy efficiency, as well as their integration in a multidisciplinary activity in advanced energy systems that involves all the research groups at the Institute.

Major problem for this penetration of renewable energies is linked to the feasibility of these sources, especially in stand-alone applications, but also in grid connected systems when the total contribution of renewable reaches the needed value for sustainability of the energy sector. Possible solutions to this feasibility problem include the combination of several renewable sources in a hybrid system or the addition to the system of energy storage, or both together in a complete system. Hybrid Renewable Energy Systems (HRES) are becoming a possible solution due to the advances in renewable energies technology and associated power electronics.

By combining two or more renewable systems it could be possible to obviate the problem of reliability of each of them and get, in addition, improvements in the total energy efficiency of the system when compared with the corresponding values of each of the systems separately. In summary, HRES could allow for the remediation of the limitations of renewable energies in terms of fuel flexibility, reliability and economics.

Given this potential, many studies have been completed to simulate and optimize the design of HRES, but before the construction of such kind of systems an experimental verification of their capabilities at the minimum significant power is advisable. With this goal, a laboratory has been assembled at the Institute for Energy Engineering of the Polytechnic University of Valencia that allows to assembly HRES combining different renewable sources: photovoltaic, wind, biomass, hydrogen fuel cell, all of the interconnected by a controlled microgrid that supplies to a demand curves simulator, to verify the capability of the selected HRES to satisfy this demand with high reliability. Additionally, there is the capability to storage energy, both in batteries and hydrogen, to cover all the possible HRES configurations.  

1. BIOMASS 

IIE has developed a methodology to optimize the energy use of biomass. This methodology is based on the experience accumulated in several national and international projects as BIODER, BIOVAL, BIOENER, PROBIOGAS or EU-DEEP. This methodology allows to determine the size, location, technologies used and best applications for a specific project to use biomass energy, considering the following aspects:

 - Evaluation of biomass resources and logistic optimization of collection and transport, by using Geographic Information Systems (GIS) for analysis of quantification, location, seasonality, transport costs, and potential biofuel consumers in analyzed area.

 - Biofuel characterization laboratory for the analysis of Higher Heating Value (HHV), immediate analysis, granulometry and apparent density. These analyses are complemented by elementary analysis, thermogravimetric-mass spectrometry (TG-MS) analysis and X-Ray Fluorescence Analysis (FRX). 

- LabDER is a pioneer in biomass gasification systems in the Valencian region and Spain. The laboratory has two biomass gasification plants, each with a power of 10 kWe. The first one works by means of the technology called downdraft fixed bed and the other one is bubbling fluidized bed gasification plant. The generated gas is used for power generation through an internal combustion engine. In the lab, the power generation through biomass gasification is investigated, mainly using woody biomass, although other biomass sources can be tested . The plants are designed, built and launched by the our research group. These plants include gas chromatograph, combustion gas analyzers and process instrumentation (flow, temperature, pressure) for monitoring and optimal operation. 

-LabDER also has a biomass boiler with a nominal power of 15 kW, in which it is investigated the optimization techniques of biomass combustion, depending on its characteristics. The quality of the combustion is analyzed throught a gas analyzer, mesuring the concentration in volume of: CO , CO2 , O2 , NOx and SOx. In addition, system losses and efficiency are calculated in the combustion process.

LabDER also includes the necessary equipment for the preparation of biomass to be used in both: a boiler and gasifier. The available devices are: a crusher, a hammer mill and a pelletizer.

- Simulation of conventional and advanced bioenergy applications with ANSYS, MATLAB-SIMULINK, ASPEN HYSYS and CHEMCAD is also one of the main areas. It has been simulated biomass gasification plants with internal combustion engines and fuel cells, hybrid wind-biomass systems and biorefineries. In this activity, IIE collaborates with universities in Italy (DIAM, Genoa) and Cuba (INSTEC, Habana) for hydrodynamic and thermomechanical modelling of biomass gasifiers and high temperature fuel cells (MCFC).

2. WIND ENERGY

Complementary to the studies carried out in the electrical area, theoretical and experimental studies have been addressed regarding the impact of wind generators in the network.  These studies are based on the simulation of  a wind generator by a real motor-generating set to generate hydrogen as a buffer and stabilizethe wind energy. The system is also used for the experimental verification of advanced techniques of predictive maintenance of the generators.

In addition, hybridization and storage studies include simulations on hybrid systems integrating a wind farm with a biomass gasifier and a electrolyzer, together with gas of synthesis and hydrogen storage in order to analyse its reliability and technologic and economic feasibility.

LabDER has a permanent magnet synchronous three-phase wind turbine of 5 kW peak donated by the company Anelion.  This generator produces alternating current which is converted to DC through an active rectifier. The DC current is sent to the grid inverter where it is converted into 230 v AC permanent magnet 50 Hz and it can introduce energy into the grid, or synchronized with the grid. The wind turbine is located 24 meter height to collect high wind speeds and on a hinged support to exchange different wind turbines for testing, aiming to optimize electricity production. Wind power generation, as solar photovoltaic may be served the loads or be stored in batteries or hydrogen.

3. SOLAR ENERGY

LabDER has a photovoltaic solar plant of 2.1 kWp, composed by crystalline silicon panels (monocrystalline and polycrystalline). The panels are located in the roof of the laboratory. A grid inverter is used to connect the system to the power utility grid or a generator. The grid inverter is single phase, although the micro-grid is three-phase. In the future it is planned to extend the photovoltaic solar system and convert it into a three-phase network. The generation can be monitored by the energy management system, allowing the study of hybrid systems including the photovoltaic. Experimental activities in this research group also include the assessment of different solar panels brands and technologies, operating independently or within a hybrid system. 

4. HYDROGEN GENERATION

IIE is investigating in the novel hydrogen-based energy systems technologies. Collaborations are under negotiation with  companies interested in this topic, such as gas companies, looking for new hydrogen production techniques, and wind generators constructors and operators, that consider hydrogen as a possible buffer to solve some present and future problems of the wind parks. Based on “Life Cycle Analysis” technique, quantitative comparison of different methods of hydrogen production are been carrying out, looking for the optimal match between the environmental and economic aspects of the process. Generating methods under consideration go from the conventional one, based on methane reforming, to advanced systems based on renewable energies (fundamentally wind or hybrid systems), implementing low temperature electrolysis. A second option is the use of nuclear energy in a graphite-gas configuration at very high temperature with cycles of gas turbine. 

In this last approach, it has been linked hydrogen production with the treatment of high-activity nuclear waste by transmutation.

The LabDER hydrogen system works as an energy storage system which consumes the excess of renewable energy production from the hybrid system. This hydrogen can be used as back-up energy source when the other energy systems may not respond to the energy loads in the micro-grid

The hydrogen system is composed by a 7 kW electrolyser which produce 1 Nm3 of hydrogen at 4 bar pressure and purity of 99.8%. This impurity rate is not acceptable to be used in Proton Exchange Membrane (PEM) fuel cells. Thus, it is necessary to increase purity until 99.99%. To do that, a DPSH6 purifier is used.

5. DISTRIBUTED ENERGY RESOURCES 

UE has assumed the compromise of increasing the percentage of renewable energy sources in its energy consumption scenario, substantially reducing the energy intensity factor. These objectives demand the development of innovative technologies for the production, storage, integration and use of energy, with special emphasis in distributed energy systems (DER). To facilitate a significant activity in the development and integration of DER systems and their participation in energy markets, especially the electrical one, LabDER integrates and enlarges all the activities carried out by IIE research groups. 

The main objective of this laboratory is the design, experimentation and technological development of distributed energy systems generation and storage, together with their control and maintenance.

6. ENERGY PLANNING 

This research area is focused in energy modelling. IIE is working on the energy scenarios method to forecast the demand and the energy distribution of a geographic area. These simulations allow evaluating the impact of different energy policies in a region or country, and identify the most suitable technology or energy strategy to satisfy energy demand in a sustainable manner. IIE Energy Planning area has developed during the lasts years SIMUSEN, a tool to define and analyse energy scenarios, which has been used to conduct studies for the regional government, Conselleria de Medioambiente of the Generalitat Valenciana, and Agencia Valenciana de Prospectiva (AVAP).