design and testing of a new concrete wind turbine tower...wind power asce iowa section conclusions...

Hexcrete Tower Project (DE-EE0006737)

Design and Testing of a New Concrete Wind

Turbine Tower

Sri Sritharan

Wilkinson Chair Professor, College of Engineering

Iowa State University

ASCE Structural Engineering Conference

ASCE Iowa SectionWind Power

Outline

2

• Global perspectives

• Wind power in Iowa

• Tall towers

• Existing technology and challenges

• Hexcrete technology development

• Design

• Testing


Wind Forecasts vs. Actual

3


Wind Power Global Capacity4


5


Evolution of Size and Power of Wind Turbines

6

400 – 500 homes

10 – 15 homes

500 – 600 homes


Levelized Cost of Enegy

7


Levelized Cost of Energy for Different Technologies (2010$)8


Market Forecast for 2016 - 2020

9


Wind Power in Iowa

10

• A leading U.S. state in wind power generation

• ~100 wind farms and > 3500 utility scale turbines

• > 6000 wind energy related employees

• Annual land lease payment: > $16M Annually

• Total capital investment: ~$12B

• 2016: 35% of electricity by wind

• Installed capacity

• 6,300 MW (current)

• 10,000 MW by the end of 2017

• 20,000 MW by 2030


2015 – Electricity Generation by wind

11

Wind Power ASCE Iowa Section

Installed

Capacity


Tower Height

13


Benefits of Taller Towers• Increased wind speed

• Steadier wind condition

• Higher power output (wind

speed & harvest time)

• Facilitates increase in turbine

capacity and blade length

• Harvest energy where the

demand is high (especially in

the US)

Black line indicates 80-m hub height

Red line indicates 110-m hub height

Blue line indicates 140-m hub height

Gross Capacity Factor (%)

Lan

d A

rea (

km

2) NREL


Rotor

Diameter

15


Wind Potential at 80-m Hub Height

Existing Technology (100m dia, 1.62 MW, 110m HH): 10.2 TW


Wind Potential at a 110 m Hub Height

Including Average Technology (100m dia, 1.62 MW, 110m HH): 10.2 TW



Includes Future Technology


Current

Technology


Limitations• Transportation

• Cost increase

• Maintenance


Concrete Technology

• Curved sections –

increases formwork and

labor costs

• Normal concrete –

increases overall

dimensions, limiting the

rotor diameter

• Large and heavy sections

– increases logistical

challenges and

transportation costs


The Hexcrete Solution (Phase I)


Features of Hexcrete

• Uses High Strength Concrete (HSC) and/or

Ultra-High Performance Concrete (UHPC)

• Facilitates tailorability

• Uses easily transportable lightweight modules

• Relies on post-tensioned connections

• Increases tower life span

• Avoids specialized formwork and high labor

costs during prefabrication


Expected prefabrication…

• Uses existing technology……


Cell Assembly

• Form cells on or

off site and stack

on top of each

them


Different Options (Phase II)


Connection Tests @ ISU• All three connections have been shown to

be viable


Phase III - Developments

• 120 m and 140 m tall tower

and foundation design

• Tower optimization

• FSI investigation

• Testing

• Erection plan

• Commercialization


120 m (394 ft) – 2.3 MW Tower Design (HT1)

31

• Base diameter: 25.7 ft

• Frequency: 0.33 Hz

• Number of strands per column: 74 strands

Tower base Two third tower heightTower top

One third tower height


Fluid-Structure Interaction

Structural coupling between rotor and tower

Mesh moving problem for FSI

Preliminarily FSI results:


Full-scale testing of Hexcrete tower section

33

Crosshead

Actuators

Actuators


Precast Fabrication


Test Unit Construction


Testing and Instrumentation


Load Protocol• Four loading directions were

selected

• Three load cases were chosen

based on largest overturning

moment (1.1), shear (4.2), and

torsion (2.2).

• Each of the three load cases were

applied for operational and extreme

loads

• Example of Operational Loading

shown below

Operational Load Tests

Load

Case Load direction Loading Percentages

Test 1 4.2 3 ±25%, ±50% (3x)*, ±75%, ±100% (3x)

Test 2 4.2 1 ±25%, ±50% (3x), ±75%, ±100% (3x)

Test 3 1.1 2 ±25%, ±50% (3x), ±75%, ±100% (3x)

Test 4 1.1 4 ±25%, ±50% (3x), ±75%, ±100% (3x)

Test 5 2.2 3 ±25%, ±50% (3x), ±75%, ±100% (3x)

Test 6 4.2 3 ±50% (3x), ±100% (3x)


Hexcerte Cell Test Video


Extreme Loads


Ultimate torsion load test


Fatigue Load Testing


Fatigue Test Video


Commercialization Plan

• Establish an erection plan

• Evaluate LCOE

• Develop prototype options

• Perform design certification

• Build prototype towers


45

Assembly video – 140-m tall Hexcrete Towers

Link: https://www.youtube.com/watch?v=2bKn9rtjLS0

https://www.youtube.com/watch?v=2bKn9rtjLS0


Next Step


Conclusions

• Global wind capacity will continue to grow and is likely to

exceed the targeted goals.

• Iowa has significant wind energy potential

• the suggested 2020 and 2035 targets can be easily

accomplished

• Tall wind turbine towers should be included in future wind

farms

• Hexcrete tower technology offers a competitive concrete

solution to reach new heights

design and testing of a new concrete wind turbine tower...wind power asce iowa section conclusions...

Documents