Advances in Hydrogen Energy Technologies:
Oportunities and Challenges in a Hydrogen Economy
4th International Seminar - November 10-11, 2011, Viana do Castelo - Portugal
“Technical-Economic Study Wind Farm with a Hydrogen Storage System
in the Range of MWs”
I. Aso1, José L. Bernal-Agustín 2 and Rodolfo Dufo-López2
1
Centro Nacional de Experimentación en Tecnologías del Hidrógeno y Pilas de Combustible
email: [email protected] URL: www.cnehtpc.es
2
Departamento de Ingeniería Eléctrica Universidad de Zaragoza
email: [email protected]: [email protected] URL http://ie.unizar.es/
Abstract
The intrinsic property of renewable energies is that they are available only at the time in which there is recourse.
In the wind sector, the selling price of power generated is influenced by the demand curve, for this reason, there
is a strategy to store energy generated during the night sell at a higher price than the market brand the instant that
the wind resource available[1][2]. This strategy is based on the integration of wind energy with new technologies
hydrogen on a commercial scale (MWs) to enable increased presence of wind energy in the mix generation
This paper will present a technical and economic study of a virtual pilot plant, comprising the following basic
elements: 6 MW wind farm, hydrogen production system based on a 500 kW electrolyser, hydrogen storage
system for medium pressure gas (20 -30 bar), and energy conversion system using an internal hydrogen
combustion engine 120 kW. For optimizing the operating strategy of the virtual plant GRHYSO (“Gridconnected Renewable HYbrid Systems Optimization”) software is used [3], considering how the optimization
goal to minimize the minimum selling price of electricity to the grid for return on investment in as many years
the wind farm without considering energy storage system.
Keywords: GRHYSO, Wind, Electrolyzer, Hydrogen, Engine.
1
Introduction
Today, wind energy technologies and water
electrolysis are considered mature, although R&D
efforts are still undertaken to enhance performance
and cost savings in both technology fields. In
principle, however, water electrolysis technologies
were not conceived for variable input conditions as
those inherent to the nature of wind resources.
Therefore, system integration improvements are
expected to increase efficiency and reduce capital
and O&M costs [4].
The variable nature of wind energy presents
integration problems for market and grid operators.
These conditions may retard their development in
countries, where market penetration has already
occurred (e.g., in Denmark, Germany or Spain).
Storage systems can provide a solution to this
problem by increasing wind energy’s capability to
follow demand, guarantee a desired amount of
energy, offer a flat curve or a more smoothened
curve.With the help of wind-hydrogen systems,
wind farms would become multi-purpose,
decentralized producers of either electricity or
hydrogen fuel when hydrogen-fuelled vehicles will
enter mass production. In the short term, marginal
but significant benefits can be obtained by
improving dispatch ability and offering reserve
power and grid services.
As of January 2011, installed wind capacity in
Spain amounted to 20,676 MW [4], with which it
covered over 2010, 16.4% of total electricity
demand of the country. However, due to the
characteristics of "electrical island" in the iberian
electricity grid, throughout 2010, there were several
restrictions evacuation of wind farms in periods of
low electricity demand and high wind resource, in
which is estimated to have left the network to dump
44,000 MWh [5], an amount that is growing
exponentially throughout the years, if we consider
that in 2008 were 4,000 MWh in 2009 was 6,000 in
MWh.
2
Simulation Tools
Simulation tools are computer programs that
implement a series of mathematical models which
represent the behavior of different equipment
existing in reality. These applications are useful to
study and understand the behavior (energetic and
economic) of a particular system, as well as to help
the engineering, consulting and scientific
communities in designing and sizing components,
before the physical implementation of system itself.
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1
Advances in Hydrogen Energy Technologies:
Oportunities and Challenges in a Hydrogen Economy
4th International Seminar - November 10-11, 2011, Viana do Castelo - Portugal
Currently, there are several software applications
used to simulate systems based on renewable
energy . In the table below are shown only tools
that implement mathematical models to study windhydrogen facilities
Table 1. Summary of tool characteristics
This paper will present a technical and economic
study of a virtual pilot plant. For optimizing the
operating strategy of the virtual plant GRHYSO
(“Grid-connected Renewable HYbrid Systems
Optimization”) software is used [6], considering
how the optimization goal to minimize the
minimum selling price of electricity to the grid for
return on investment in as many years the wind
farm without considering energy storage system.
3 Installation and Optimization
To sum up, simulation tools for sizing and
designing integrated systems can conclude that
most of tools are based on simplified mathematical
models of main equipment for hydrogen production
from wind: wind turbine and electrolyzer. In all,
wind turbine is modeled by its characteristic curve
(wind speed versus generated electric power)
supplied by the manufacturer, and electrolyzer is
modeled in different ways:
•
Using an efficiency coefficient defined as
the ratio of the chemical energy of
hydrogen
produced
versus
energy
consumed by the electrolyzer (HOMER,
H2RES and THESIS).
•
Using a linear line (with a minimum
efficiency, greater than cero) which relates
hydrogen production with electric power
consumed (HOGA, GRHYSO and
WindHyGen).
•
Using
the
cell
current-voltage
characteristic curve of electrolyzer and
Faraday's Law to calculate the hydrogen
production (TRNSYS-HYDROGEMS and
ESSFER).
In all tools, except Hydrogems, electrolyzer model
is static in which the efficiency is constant and
independent of the operating conditions of the
electrolyzer. In order to perform simulations closer
to reality, it is necessary to consider dynamic
models with more emphasys when electrolyzer is
connected to renewable energy sources, like wind
energy. Also, improvements in auxiliary equipment
modeling (electrolyzers converters, compresors,
etc.) has to be realized.
The facility is situated in Puertollano (Spain),
comprising of the following basic elements: 6 MW
wind farm (3 wind turbine 2 MW each , hydrogen
production system based on a 500 kW electrolyze
(with out purifying) , hydrogen storage system for
medium pressure gas (20 -30 bar), and energy
conversion system using an internal hydrogen
combustion engine 120 kW, in figures below are
showed wind resource , and investment cost
Fig. 1. Wind resource
Table 2.Basic Equipment cost
k€
Wind Turbines
6.750
Electrolyser
750
Hydrogen Storage
250
Power Electronics
65
Hydrogen Engine
120
Engineering
300
Installation
215
8.450 €
As can be seen, the hydrogen system
(electrolyze+storage+reconversion), increase the
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Advances in Hydrogen Energy Technologies:
Oportunities and Challenges in a Hydrogen Economy
4th International Seminar - November 10-11, 2011, Viana do Castelo - Portugal
installation about 20% compared to the initial
investment made by wind turbines only.
Once you know the individual costs and technical
characteristics of each system components, they
must be introduced in the program to proceed
further to optimize, in the figure below shows the
screen to enter data on both electrolyze technical
and economic
4- The sale price of the kWh generated by the
internal combustion engine hydrogen, so
that the installation is amortized over its
lifetime would be 10 c € / kWh.
5- The sale price of the kWh generated by the
internal combustion engine hydrogen, so
that the installation will be amortized over
10 years would be 25 c € / kWh.
Fig. 2. Case 2
Fig. 2. Electrolyze screen
When all the technical parameters and economic
values have been introduced, must be decided the
strategy optimization. The program features various
options such as:
1. Maximize net present value (NPV).
2.
Minimizing the minimum selling price of
hydrogen to NPV = 0.
3.
Minimizing the minimum selling price of
hydrogen to be amortized over N years.
4.
Minimizing the minimum selling price of
electricity for the NPV = 0.
5.
Minimizing the minimum selling price of
electricity to be amortized over N years
Results
Below are the different results that were obtained
for each of the five choices offered by the program
optimization:
1- This gives a negative value of the
investment of 2.5 M €, it mean, at current
date, if the remuneration of the electricity
generated by a hydrogen system is the
same as that of a wind farm is not
profitable to put such facilities.
2- The selling price of hydrogen generated
kgr should be of 13.7 € / kgr, in order to
be amortized hydrogen installation
throughout its life.
3- If the intention is to amortize the
installation of hydrogen in 10 years, the
selling price of hydrogen would have to be
of 31 € / kgr
As can be seen, we are currently far from hydrogen
facilities associated with wind farms are profitable,
whether you think the strategy of selling the
produced hydrogen as a fuel, which is at least one
fact 4 above equivalent to the cost of fossil fuels,
and more than double, compared to cost half the
price of electricity.
Despite these results, it is not considered distant
time horizon, which on the one hand significantly
reduce investment costs associated with equipment
for hydrogen, due to advances being made today, as
well as increasing their efficiency, and secondly,
every day will increase managment needs
renewable energy sources, especially wind power.
Referencies
[1] Rodolfo Dufo-López, José L. Bernal-Agustín,
José
A.
Domínguez-Navarro.
“Generation
management using batteries in wind farms:
Economical and technical analysis for Spain.
Energy Policy, Volume 37, Issue 1, January 2009,
Pages 126-139
[2] José L. Bernal-Agustín, Rodolfo Dufo-López.
“Hourly energy management for grid-connected
wind–hydrogen systems” International Journal of
Hydrogen Energy, Volume 33, Issue 22, November
2008, Pages 6401-641
[3] www.unizar.es/rdufo
[4] www.ree.es
[5]Luis
Manuel
Santos
Moro,
www.energystorageforum.com/ HC Energía
[6] http://task24.hidrogenoaragon.org/
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