group 4 – marine energy marine current modelling for energy production james glynn kirsten...
Post on 16-Dec-2015
216 Views
Preview:
TRANSCRIPT
Group 4 – Marine EnergyGroup 4 – Marine EnergyGroup 4 – Marine EnergyGroup 4 – Marine Energy
Marine Current Modelling For Energy Production Marine Current Modelling For Energy Production
James Glynn Kirsten HamiltonTom McCombes
Malcolm MacDonald
James Glynn Kirsten HamiltonTom McCombes
Malcolm MacDonald
Project DefinitionProject Definition
• Investigate the characteristics of the tidal resources in Scotland and demonstrate how to match those resources with the appropriate Marine current technology
• Investigate the characteristics of the tidal resources in Scotland and demonstrate how to match those resources with the appropriate Marine current technology
Project FlowchartProject FlowchartSTAGE 1
A. Resource Investigation B. Technology Investigation
ii) Vertical axis turbine
iii) Oscillating Hydrofoil
i) Horizontal
axis turbine TOMS software
A. Matching Methodology
STAGE 2
Environmental Impact & Planning
Assessment
B. Case study
Mapping Tidal Data
STAGE 3
Expert system
A. Conclusion of Resource AnalysisA. Conclusion of Resource Analysis
• Tidal Flow Model Resultant Phase & Tidal Flow
• UKHO EasyTide port & Chart surface flow data Cyclic Bulk Flow Velocity Corrected Flow, Meander, Surface Friction,
Venturi effects Energy Loss. Manning Vs Bernoulli
• Velocity Shear Model - TOM’s Detail Bathymetry Vs Approx Geometry Shear Effects Boundary Layer Thickness Manning No. Cf & Drag Correlation
• Vertical & Horizontal Vel Distribution
• Tidal Flow Model Resultant Phase & Tidal Flow
• UKHO EasyTide port & Chart surface flow data Cyclic Bulk Flow Velocity Corrected Flow, Meander, Surface Friction,
Venturi effects Energy Loss. Manning Vs Bernoulli
• Velocity Shear Model - TOM’s Detail Bathymetry Vs Approx Geometry Shear Effects Boundary Layer Thickness Manning No. Cf & Drag Correlation
• Vertical & Horizontal Vel Distribution
Model ValidationModel Validation
The Strait of MessinaThe Strait of Messina
The Strait of MessinaThe Strait of MessinaModel ValidationModel Validation
• Map Strait of Messina Bathymetry•
• Seabed Geology Surface roughness Cf wall
• Map Strait of Messina Bathymetry•
• Seabed Geology Surface roughness Cf wall
Model ValidationModel Validation
Model ValidationModel Validation
• Map Strait of Messina Bathymetry
Seabed Geology Surface roughness Cf wall
• Map Strait of Messina Bathymetry
Seabed Geology Surface roughness Cf wall
Model ValidationModel Validation
Seabed equivalent diameter
10km 100m 10m 1m 10cm 1cm 1mm
Seabed equivalent diameter
10km 100m 10m 1m 10cm 1cm 1mm
Seabed equivalent diameter
10km 100m 10m 1m 10cm 1cm 1mm
Seabed equivalent diameter
10km 100m 10m 1m 10cm 1cm 1mm
100 200 300 400 500 600 700 800 900 1000 1100
10
20
30
40
50
60
70
80
0.5
1
1.5
2
100 200 300 400 500 600 700 800 900 1000 11001.5
2
2.5Velocity at non-dimensional depth 1
Cross-streamw ise ordinate
Vel
ocity
[m/s
]
Model ValidationModel Validation
Model ValidationModel Validation
100 200 300 400 500 600 700 800 900 1000 11001.5
2
2.5Velocity at non-dimensional depth 1
Cross-streamw ise ordinate
Vel
ocity
[m/s
]
Model ValidationModel Validation
• Velocity profile from Coles law assumes turbulent BL & similitude. May not be the case
• Algorithm computationally expensive: savings if power law is adopted
• Need other profiles to compare with: USGS use 7th power law
• Is just a curve fit
• Velocity profile from Coles law assumes turbulent BL & similitude. May not be the case
• Algorithm computationally expensive: savings if power law is adopted
• Need other profiles to compare with: USGS use 7th power law
• Is just a curve fit
B. Conclusion of Technology Investigation
B. Conclusion of Technology Investigation
• 3 Main Generic Technology Types Horizontal Axis Turbine,
Oscillating Hydrofoil. Quasi-Dynamic Modelling,
BEM, Yaw Correction, Time Step
Flow conditions & Model Geometry
System Loads Torque Power
• 3 Main Generic Technology Types Horizontal Axis Turbine,
Oscillating Hydrofoil. Quasi-Dynamic Modelling,
BEM, Yaw Correction, Time Step
Flow conditions & Model Geometry
System Loads Torque Power
Vertical Turbine ModelVertical Turbine Model
• Multi-Streamtube BEMS model for Darrieus type turbine is in production. Nothing really to show for it. Yet. Except:
• Multi-Streamtube BEMS model for Darrieus type turbine is in production. Nothing really to show for it. Yet. Except:
SIF & Blockage effectsSIF & Blockage effects• Significant Impact Factor> what exactly is it?
The recognition and quantification of the fact that placing energy extraction devices in a tidal stream must vary the characteristics of that resource
If the average flow in a stream is 2.0 m/s, and one was to place 5 turbines in that stream, the average flow rate will experience a net decrease, with localised increases, causing turbulence and potentially affecting the actual topography of the site through sediment transport, scouring and so forth
Chow and Manning have to agree, that placing obstructions in a tidal stream reduces the net flow rate, due to blockage and energy losses.
If the kinetic energy flux in a stream is a function of velocity cubed and c.s.a, this energy comes from the gravitational effects of the sun and moon. If one extracts a portion of this energy from the stream, which has had work done on it by gravity, mass continuity tells us therefore that the velocity must decrease, inversely with energy extraction.
It would be very handy to be able to model this, as some kind of optimal deployment ratio must be achievable
Since work is being done, on the body of water, it will continue to be done after exiting the turbine, thus we may expect the flow to rejuvenate at some point.
The ability of flow recovery (turbulent, slow) is an approximation of free stream
• Significant Impact Factor> what exactly is it? The recognition and quantification of the fact that placing energy extraction
devices in a tidal stream must vary the characteristics of that resource If the average flow in a stream is 2.0 m/s, and one was to place 5 turbines in that
stream, the average flow rate will experience a net decrease, with localised increases, causing turbulence and potentially affecting the actual topography of the site through sediment transport, scouring and so forth
Chow and Manning have to agree, that placing obstructions in a tidal stream reduces the net flow rate, due to blockage and energy losses.
If the kinetic energy flux in a stream is a function of velocity cubed and c.s.a, this energy comes from the gravitational effects of the sun and moon. If one extracts a portion of this energy from the stream, which has had work done on it by gravity, mass continuity tells us therefore that the velocity must decrease, inversely with energy extraction.
It would be very handy to be able to model this, as some kind of optimal deployment ratio must be achievable
Since work is being done, on the body of water, it will continue to be done after exiting the turbine, thus we may expect the flow to rejuvenate at some point.
The ability of flow recovery (turbulent, slow) is an approximation of free stream
SIFSIF• ..investigators have also noted that for any site, only a finite proportion of the
total energy can be extracted without significantly altering the site’s general flow speed, which could have economic and environmental consequences..
• The SIF is unique to particular sites and may vary between 10% and 50% of the energy in the flow Carbon Trust 2005
• RGU’s envir impact suggest 10% max flow reduction ~ could be more• Packing densities suggested at 60m lateral and 250m longitudinal • Based on Chow’s Open Channel Hydraulics obstruction correction factors
can be applied to a case study, with sensitivity analysis, to see effects• Flow velocity is not constant, but varies with the sine of the period, at the
specified instant, as does time-step acceleration, work done and force, if desired
• Further, flow passes through the swept area in a quantity depending on efficiency and pitch angle (axial predominantly).
• Using these parameters, Chow’s correction factors and sensitivity SIF can be calculated, and related back to previous work, Couch, Bryden.
• ..investigators have also noted that for any site, only a finite proportion of the total energy can be extracted without significantly altering the site’s general flow speed, which could have economic and environmental consequences..
• The SIF is unique to particular sites and may vary between 10% and 50% of the energy in the flow Carbon Trust 2005
• RGU’s envir impact suggest 10% max flow reduction ~ could be more• Packing densities suggested at 60m lateral and 250m longitudinal • Based on Chow’s Open Channel Hydraulics obstruction correction factors
can be applied to a case study, with sensitivity analysis, to see effects• Flow velocity is not constant, but varies with the sine of the period, at the
specified instant, as does time-step acceleration, work done and force, if desired
• Further, flow passes through the swept area in a quantity depending on efficiency and pitch angle (axial predominantly).
• Using these parameters, Chow’s correction factors and sensitivity SIF can be calculated, and related back to previous work, Couch, Bryden.
Results analysisResults analysis
• Study undertaken on two distinct sites• Some interesting relationships…
Further model input information perhaps Suggested: “..analysis suggests a non-linear
relationship between energy extracted and velocity deficit.” C&B
10% extraction = 5 k rejuvenation/recovery distance
• Results: Channel used displays venturi effects, RGU have square cross-section, and uniform length, but general accord with findings
• Study undertaken on two distinct sites• Some interesting relationships…
Further model input information perhaps Suggested: “..analysis suggests a non-linear
relationship between energy extracted and velocity deficit.” C&B
10% extraction = 5 k rejuvenation/recovery distance
• Results: Channel used displays venturi effects, RGU have square cross-section, and uniform length, but general accord with findings
AnalysisAnalysis
Energy capture vs deployment
0
1E+13
2E+13
3E+13
4E+13
5E+13
6E+13
7E+13
8E+13
9E+13
1E+14
3.64297707 7.28595414 10.92893121
Number of turbines
kW
h p
er year
.
Energy capture
Suggested optimum
Technology ComparisonsTechnology Comparisons
• Efficiency-Velocity-Area 3D Curve Optimal site specific device characteristics Extractable energy
• For each technology compare: Size of inflow AREA Flow VELOCITY POWER output or EFFICIENCY
• Allow tidal developer to immediately identify how the different technologies perform in respect to their size and the relationship to velocity and efficiency
• Efficiency-Velocity-Area 3D Curve Optimal site specific device characteristics Extractable energy
• For each technology compare: Size of inflow AREA Flow VELOCITY POWER output or EFFICIENCY
• Allow tidal developer to immediately identify how the different technologies perform in respect to their size and the relationship to velocity and efficiency
Proposed MethodologyProposed Methodology
• Objective : To define rules to match the most appropriate technology to a particular resource site
• A number of tools have been developed throughout the project for this purpose: Surface Tidal Current Spreadsheet The influence of shear on the Velocity distribution for
a profile 3 generic technology models
• Performing analysis between different technologies and their power output and efficiency for varying flow
• Objective : To define rules to match the most appropriate technology to a particular resource site
• A number of tools have been developed throughout the project for this purpose: Surface Tidal Current Spreadsheet The influence of shear on the Velocity distribution for
a profile 3 generic technology models
• Performing analysis between different technologies and their power output and efficiency for varying flow
Proposed Methodology Proposed Methodology
• 2 parts Analysing resource Matching the resource with a particular technology for
the most suitable power output
• Resource Methodology: Manual, step by step process Essentially complete
• Technology Methodology Preliminary stages and defining logic for the process Hopefully automated process with a series of inputs
and programmed outputs
• 2 parts Analysing resource Matching the resource with a particular technology for
the most suitable power output
• Resource Methodology: Manual, step by step process Essentially complete
• Technology Methodology Preliminary stages and defining logic for the process Hopefully automated process with a series of inputs
and programmed outputs
Reso
urce M
etho
do
log
yR
esou
rce Meth
od
olo
gy
Technology MethodologyTechnology Methodology
• Use the velocity distribution of the profile to answer the following questions: What type of technology to use? What size of the machine? How many machines? Where to locate the machines? What is the combined power output of the machines? What is the efficiency of the machines? What is the appropriate distance that the next set of
machines should be spaced along the length the channel?
• Use the velocity distribution of the profile to answer the following questions: What type of technology to use? What size of the machine? How many machines? Where to locate the machines? What is the combined power output of the machines? What is the efficiency of the machines? What is the appropriate distance that the next set of
machines should be spaced along the length the channel?
Technology MethodologyTechnology Methodology
• Calculate the most appropriate range of velocity for various modular sizes of each technology type
• e.g. for arbitrary values …
• Calculate the most appropriate range of velocity for various modular sizes of each technology type
• e.g. for arbitrary values …
Type of Technology and most Appropriate Size for Velocity Range
Flow velocity Velocity RangeHorizontal
TurbineVertical Turbine
Oscillating Hydrofoil
v1 2.0 - 2.2
size 1
size 1
size 1v2 2.3 - 2.5
v3 2.6 - 2.9
size 2
v4 3.0 - 3.2
size 2
v5 3.3 - 3.5
v6 3.6 - 3.9
size 2v7 4.0 - 4.2
v8 4.3 - 4.5
size 3
v9 4.6 - 4.9
size 3v10 5.0 - 5.2
size 3v11 5.3 - 5.5
v12 5.6 - 5.9
Tech
no
log
y Meth
od
olo
gy
Tech
no
log
y Meth
od
olo
gy
WIP: WebsiteWIP: Website
Next Steps:Next Steps:
• Finish programming and calculations for the resource methodology & (quasi-rigorous) validation of all models
• Complete case study on the Sound of Jura to prove robustness of work and further quantify methodology
• Examine economic and cost issues for different technology types and resource characteristics
• Complete website
• Finish programming and calculations for the resource methodology & (quasi-rigorous) validation of all models
• Complete case study on the Sound of Jura to prove robustness of work and further quantify methodology
• Examine economic and cost issues for different technology types and resource characteristics
• Complete website
top related