Transcript The Stirling engine as an alternative for energy

The Stirling engine as an alternative
for energy production from biomass
Enernova Stirling Srl
Stirling Engine - 2006
© Enernova Stirling
Index
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Enernova Stirling profile.
The Stirling Cycle.
The Enernova Stirling Project:
Project phase.
Construction phase.
Main Characteristics.
Market.
Conclusions.
The Stirling Engine – 2006
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Enernova Stirling Srl
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Founded in 2003.
Has 2 main shareholders:
– Sanitaria Scaligera Srl, Italy
– Beniamino Benato, physicist.
Mission: highly optimizing the Stirling engine,
to economically produce electric power from
biomasses (predominantly wood).
The Stirling Engine – 2006
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Enernova Stirling Srl
Management Team
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2 full-time employees:
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1 part-time employee
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Dr. Beniamino Benato, physicist
Dr. Francisco Yepes, programmer
Alessandro Zuccato, general manager
External consultants :
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Engineer Gianantonio Cestari (mechanical designer).
Engineer Dr. Carlo Sordelli (agricultural agent).
Engineer Simonetti, (special materials expert).
The Stirling Engine – 2006
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The Stirling Engine
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First patent in 1816 by Robert Stirling.
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Made of two parts, with different temperatures.
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In the hot part the working fluid expands, while it is
compressed in the cold part.
Isothermal expansion and compression (t=constant).
The mechanical work done equals the net difference
between the heat absorbed in the hot part during
expansion and the heat released to the cold part during
compression.
The Stirling Engine – 2006
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Advantages of the
Stirling Cycle
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High efficiency: an ideal Stirling Cycle has a maximum
theoric efficiency.
Low emissions.
No dependency upon particular fuel characteristics or
particular fuel quality.
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Silent.
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Reversible.
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It is one of the few possibilities for the
economically convenient production of electric
power from biomass.
The Stirling Engine - 2006
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Enernova Stirling’s Project
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Use of advanced optimization techniques
(genetic algorithms) for dimensioning.
Configuration study for maximum
thermodynamic efficiency.
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Designed explicitly to use biomass fuel.
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Advanced technical and design solution
(operating conditions, material research).
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Thermodynamically- optimized design.
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Genetic Algorithm
Dimensioning
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Use of Genetic Algorithms to study the
mathematical space of the parameters
governing a Stirling engine.
Steady-State Genetic Algorithm.
Multi-Objective Genetic Algorithm with two
objectives:
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Minimizing the difference between the power
generated by candidate solutions and the desired
solution given as an input;
Maximizing thermodynamic efficiency.
The Stirling Engine - 2006
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Genetic Algorithm (GA)
Target Function
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Target function used by our GA is given by Martini’s
isothermal sizing procedure (Stirling Engine Design
Manual, William R. Martini, University Press of the Pacific,
2004).
Our GA has been applied to the example given by
Martini, obtaining efficiency improvements during sizing
exceeding 6% for the same output power and using the
same working fluid.
The Stirling Engine - 2006
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Maximum Thermodynamic
Efficiency
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Enernova Stirling proposes an Alpha
configuration which ensures, in principle, an
high thermodynamic efficiency.
For this purpose, two cylinders are used, a hot
one and a cold one, to reduce as much as
possible the inefficiencies due to the proximity
of hot and cold parts.
The Stirling Engine - 2006
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Biomass-Fuel optimized
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The Enernova Stirling engine structure has
been expressly designed to use biomass as
fuel.
For this purpose combustion chamber
conditions and heat exchanger configuration
have been expressly designed to work with
biomass combustion exhaust fumes.
The Stirling Engine - 2006
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The Enernova Stirling
Project
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Enernova considers 3 engine
configurations:
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~3-5 kWe: Home use ;
~20 kWe: Residential / Condominial use
(first prototype engine will be a 20 kWe unit)
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~160 kWe: Industrial applications.
The Stirling Engine - 2006
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The Enernova Stirling
Engine
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Working temperatures:
650-800°C
Mean pressure:
19.7 atm @ 800°C
Extreme pressures:
13.8 atm-28.8 atm
Speed:
600 rpm
Electric power:
> 20 kW
Fluid temperature in the hot part:
782 °C
Fluid temperature in the cold part:
85 °C
Carnot’s Limit:
66%
Real Engine Efficiency:
> 32%
The Stirling Engine - 2006
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The Enernova Stirling
Engine Design Phase
Fully CAD designed.
Dimensioning optimized using genetic
algorithms.
Design phase fully completed in
Q2/2006.
Il motore Stirling – luglio 2006
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The Enernova Stirling
Engine construction
20 kWe prototype almost 100% complete
as of Q2/2006.
Full prototype tests will be completed by
Q3/2006
The Province of Mantova has already
ordered a complete 80 kWe plant
Il motore Stirling – luglio 2006
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A Possible Scenario
Module type (power)
Biomass consumption
Fuel to electricity efficiency
161kWe
160 Kg/h
> 22%
Working hours per year
kWhe produced per year
kWhe produced during plant life
Biomass consumption per year
Biomass productivity
Cultivated hectares for biomass production
7500
1,207,967 kWhe/year
6,039,833
1200 tons/year
35 tons dry substance per hectare
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The Stirling Engine - 2006
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Competitive advantages
of our system
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High fuel-to-electricity transformation efficiency
(>22%).
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Unsupervisioned, automated working mode
possible
Transportability ( 2 x 40’ containers).
Low maintenance costs.
Does not require expensive and complex
auxiliary systems.
Limited system costs (< 2000 € per installed kWe )
The Stirling Engine - 2006
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Competitive advantages
of our system
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No significant environmental impact:
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Conforms to low atmopspheric emission laws
Low quantities of inert residues (ashes),
Silent running,
Small size
Can use other combustibles:
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Biogas,
Painting plant residual gases,
Refuse Derived Fuels,
Oils
The Stirling Engine - 2006
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Competitive advantages
of our system
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Possibility to locate the plants near biomass
production sites (small and medium agricultural
industries, wood industry, etc.)
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Long service life thanks to low rpm working
regimes and high quality, high-tech materials.
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Added Social Value
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The system helps transforming food farming in
non-food farming,so farmers can increase their
income.
It favors the development of local resources
and makes territory less dependent on nonrenewable energies.
It can be used in underdeveloped countries
It may allow the development of small and
medium technologically advanced industries
for the production of system parts and
components.
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It creates diffused occupation for production,
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Actual state of the
development process
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Enernova Stirling is now completing and
testing the prototype.
All tests and experimentation are
expected to be completed by Spring 2007
Production is scheduled to begin in
Spring 2008.
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Market dimension
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We expect a market for transformation of
farming from cultures food to energetic
cultures.
As an example, if the 35% of food production in
province of Verona was transformed to
energetic cultures, there would be the
possibility to install about 700 160-Kwe plants
in 10 years.
Said plants would produce about 110 MWe,
corresponding to the power used in residential
district of Verona.
The Stirling Engine - 2006
It is reasonable to believe that the same
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proportion is valid on a national and European
Market targets
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The short-term market is composed of medium
agricultural industries that want to convert part
of their productions to energetic cultures.
The long-term market remains related to the
conversion of biomasses to energy, (e.g.
residues of agro-industrial productions and
wood industry).
An important part of the market will be
composed of other industries (such as painting
plants, and ceramic tile industry) which want to
recycle their high temperature gas residues,
valorizing them.
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Stirling & Research
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Fine-tuning a Stirling engine is a very complex
task, both scientifically and from an engineering
standpoint;
Designing an efficient Stirling engine allowing
an economically-interesting use of biomass is
still an open problem.
Solution requires state-of-the art knowledge of
physics, engineering, material science and
toolworking.
The Stirling Engine - 2006
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Stirling & Research
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From an economic standpoint, a project to
design and build a Stirling engine requires
adequate financing to conclude all prototypal
phases and appropriately resolve all
engineering problems.
This perspective includes the study of different
sizes and assembly configurations.
The Stirling Engine - 2006
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Conclusions
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Stirling technology is greatly interesting from
the technical standpoint.
Upon market liberalization, it could become a
suitable candidate to produce energy from
renewable sources (e.g. biomass)
As of today, there is no definitive “Stirling
solution”. This makes it an interesting
investment, but requires an economical and
technical research effort.
The Stirling Engine - 2006
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