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Tuesday, July 26, 2011

Sample thesis/ research proposal on renewable enery engineering

Modeling and analysis of Wind Hydrogen energy system

Abstract

Wind-hydrogen energy system is one of the promising energy alternatives for the future which enhances wind energy utilization. Wind energy is the most attractive source of electricity for distributed hydrogen production because the cost of wind-generated electricity is becoming competitive. Hydrogen can be produced from solar and wind energy by using electrolysis and by directly splitting water using photo electrochemistry, photo biological organisms (and other pathways), and heat-driven chemical reaction cycles.

In this study different hydrogen production path ways are studied. A survey of the state-of-the-art of these methods is presented. An integrated wind fuel cell hybrid system is modeled in HOMER to study the potential for application under different wind speed conditions in Ethiopia. The model is also used to show how reliability and competitiveness of wind generated electricity can be enhanced and to determine the key technical parameters influencing the operation of a wind energy system with hydrogen storage.

Introduction

Hydrogen used as an energy carrier potentially offers the nation tremendous long-term energy, environmental, and economic security. Deriving hydrogen from domestic, carbon-neutral resources addresses foreign oil dependence and greenhouse gas emissions. Hydrogen can be produced from various resources: renewable (including solar, wind, biomass, hydropower, and geothermal), nuclear energy, and domestic coal (with sequestration of greenhouse gases). High efficiency and low emissions can be achieved through use of fuel cells in both transportation and distributed electric power generation.

Solar and wind energy are two technologies that are commercially available to provide electricity for electrolysis. The cost of electricity is a significant portion of the cost of making hydrogen with electrolysis. Solar photovoltaic (PV) technology will be attractive as a potential source of electricity if the target price of electricity (5-7 ¢/kWh) for utility applications is achieved. [1]But currently electricity form PV is not competitive. Wind energy is becoming attractive as a potential source of electricity for hydrogen production because of its cost, 3-5 ¢/kWh at sites with good wind speeds (15 mph at 10 meters). [2] Ethiopia is also endowed with good wind resource and it has started some of the largest wind projects in Africa.

The operation of a wind or solar based system highly depends on weather conditions and thus electricity generation is variable in time, and often the pattern does not actually follow the load demand. In order to fulfill the energy requirements during a period of low available resources, energy needs to be stored. The most popular way to store energy is batteries, but they lose their energy content rapidly and therefore they can be only used over a short time period. Batteries also have a limited life cycle and problems with depth of discharge, often requiring replacement of service. A better option might be storage in the form of hydrogen.

The efficiency of utilization of hydrogen in the fuel cell to create electricity is a function of cell voltage. With the increase of voltage, efficiency increases, but when more power (current) is drawn, the efficiency decreases. That is the reason fuel cells are typically operated in a range between 0.6 and 0.8V, with the efficiency level reaching 50%. [3] Renewable energy source efficiencies are as follows: wind turbine 33-38%, PV array 13- 16 %. Additional power drop is caused by voltage regulation devices (DC/DC and AC/DC converters), with which, for the typical commercial inverter, efficiency ranges between 80- 95%. [4]

Objectives

Efficient operation of energy systems under intermittent sources in irregular conditions brings a lot of problems. The objective of this work is to create a system-level model that defines the relationship between elements of wind energy-Fuel Cell system given at intermittent supply conditions and changing energy demand. The scope of this work is to create a conceptual energy storage architecture incorporating renewable, hydrogen generation, hydrogen storage and fuel cell power generation. The objectives will be achieved by analysis and construction of a model for each element of the system. Then the input and output data will be defined and energy fluxes between elements will be calculated. Additionally, the efficiencies of each element and a system will be defined. The conceptual model will be created in HOMER. Finally, the simulation of an operation of the system model for variable input data and calculation of performance of the system and individual devices will be executed and the final results discussed.

Expected outcomes

At the end of the study the expected outcomes of the project are a model of hybrid wind hydrogen energy system that can simulate the performance under various wind resources in Ethiopia and rural electrification (typically day time grinding and night time electricity). Current status of research on hybrid wind fuel cell energy systems and state of the art technologies are identified. Key parameters influencing the operation of such systems are well identified and their effects are well illustrated. An increase in energy efficiency, enhanced reliability of wind energy systems and its competitiveness as a result of fuel cell integration is also quantified.


Tasks

Time

Literature survey


Wind energy

Biweekly report

Fuel cells

Electrolysers

Hydrogen storage

Solar and wind hydrogen systems

Research review on wind hydrogen energy systems

Progress report (1/3rd)


Modeling of wind hydrogen energy system in Homer


Wind resources data collection


Hybrid system components and input data

Wind turbines

Fuel cells

Hydrogen tank

Electrolyzer

Load input

Primary load

Deferrable load

Progress report (2/3)


Simulation and sensitivity analysis


Analysis and presentation of simulation results

Biweekly report

Sensitivity on Wind resources and loads

Results and discussion


Interpretation of simulation results


Conclusions and recommendation

Final reports write up

Progress Report (3/3)


Financial Breakdown

Activities

Unit cost

Amount in birr

Trip to —round trip



Per diem



Subtotal



Contingency (10% of sub total)



Total amount




References

1. Solar Energy Technologies Program Multi-Year Technical Plan 2003-2007 and beyond, DOE Office of Energy Efficiency and Renewable Energy, January 2004.

2. “Island wind-hydrogen energy: A significant potential US resource” – Benjamin K. Sovacool, Richard D. Hirsh, Renewable Energy 33 (2008) 1928-1935

3. EG&G Technical Services, 2004, Fuel cell Hand Book, 7th ed. U.S. Department of Energy Office of Fossil Energy National Energy Technology Laboratory West Virginia

4. “Environmental and economic aspects of hydrogen production and utilization in fuel cell vehicles” – Mikhail Granovskii, Ibrahim Dincer, Marc A. Rosen, Journal of Power Sources 157 (2006) 411-421

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