The University of Hong Kong

Research and Development of Wind Turbine Technologies for Harnessing Wind Energy

Prof. Dennis Y.C. LeungDept. of Mechanical Engineering

The University of Hong Kong

HKU Engineering Faculty Seminar13 December 2010

Outline

● The needs for using renewable energies

● The status of renewable and clean energy research.

● Wind power development status in the world

● Micro-wind turbine for harnessing wind power

● Summary remarks

There is an obvious trend of increasing temperature all over the world.

The whole world has been threatened under the influence of global warming.

Global warming & Climate change

From: http://scienceblogs.com/framing-science/2006/12/melting_metaphors_new_study_on.php

We have to action immediately in order to improve our air quality, alleviate the global warming and climate change.

The use of more non-conventional or renewable energy to replace the conventional fossil fuels is a common approach adopted by many countries to reduce the carbon emission intensity.

Climate change – need actions

EU passed its energy-climate change package in 2007of which the proposed target of RE is 20% by 2020.

In the US its RE target is 25% by 2025.

In China, the Renewable Energy Act had passed in 2006 and revised in 2009 with target at 15% RE in 2020.

HK Gov. has set a target of 1-2% RE by 2012 and 10% biofuels for road transport by 2020.

All the above policies triggered the blooming of RE industries in the world.

Renewable energy policies

•`Solar

• Wind

• Hydro

• Tidal and Wave

• Geothermal

• Biofuels

• Nuclear

Non-conventional and Renewable energy resources

Solar – research on-going

Wind – mature technology for conventional wind turbine, R&D for new design

Hydro – mature technology

Tidal & Wave – R&D

Geothermal – R&D

Biofuels – mature technology for certain biofuels

Nuclear – Nuclear fission mature but controversial in usage

Status of renewable and clean energy research in the world

Renewable energy resources in ChinaHydro power● 400GW, 1700TWh (210Mtce); (~150GW at present)

Wind● 1000GW (250GW on shore + 750GW offshore); (~5GW at present)● 2500TWh (307Mtce)

Solar PV● 520GW, 1000TWh (130Mtce)

Biomass (for electricity generation and biofuels for vehicles)● 500Mtce

Totally: 1.15Btce (17% of energy demand in 2050, 6.5Btce)

Wind Power

Wind energy is identified to have great potential for development in many parts of the world.

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Nuclear Biomass Hydro Coal-fired Wind Natural gas

Cos

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Electricity cost for different energy sources

Data from Lester Russell Brown

Source: Global Wind Energy Council

Global cumulative installed capacity 1996-2009

200 GW in 2010

Source: Global Wind Energy Council

Annual Installed Capacity by Region 2003-2009

• In 2009, China’s total installed capacity is 25 GW and will increase to 150 GW in 2020. Annual growth rate: ~116%

• EU will increase its wind power to 20% of its total electric power by 2020.

• USA will increase its wind power to 30% of its total electric power by 2030.

• According to the Global Wind Energy Council , wind could meet 12% of global power demand by 2020, and up to 22% to 2300 GW by 2030, saving a total of 34 billion tons of CO2.

Future development

Windfarmmap

China has 190 wind farms with more than 10 wind turbines

Development of wind turbines

A 19th-century American knock-off of the Persian

panemone that probably made a wonderful clothes dryer.

Water pumping sailwing machines

Water pumping sailwingmachines

A Dutch horizontal-axis windmill

Modern wind turbines

World’s Largest wind turbine 7 MW

Details:

• Model Enercon E-126• Rotor dia.: 126 m• Energy produced: 20 million kWh/year• For 5000 household of four in Europe• Installed in Emden, Germany in 2008

Wind turbine development trend

Year 1985 1989 1992 1995 1999 2002 2005 2008

Capacity 0.05MW 0.3MW 0.5MW 1.3MW 2.0MW 4.5MW 5.0MW 7.0MW

Rotor dia. 15 m 30 m 40 m 60 m 80 m 120 m 120 m 126 m

World’s largest wind farm

• Roscoe Wind Farm in Texas

• Consists of 627 wind turbines

• Total capacity: 782 MW

• Total area: 400 km2

• Capacity/area: 2 MW/ km2

• HEC proposed wind farm: 17 MW / km2

• HEC Lamma Power Station: 7500 MW/ km2

Wind power development in Hong Kong

HEC proposed 100 MW offshore wind farm

CLP proposed 200 MW offshore wind farm

Wind turbine research

• Efficiency enhancement- blade design (shape)- pitch actuator control- generator

• Small wind turbine

• Wind resource mapping- onshore- offshore

Main problems with conventional wind turbines

• High cost: the cost of power generation is higher than we expected;

• Long lead time: the time from planning to commissioning needs several years;

• Complexity: installation and maintenance of large wind turbine are rather complex;

Main problems with conventional wind turbines(cont’d)

• Low availability: start up wind speed: 4 to 5 m/s;maximum ~25 m/s

e.g. The wind turbines in Dongshan Island (FujianProvince) are active for roughly 35% of the year,which is a typical figure for an onshore site. Theavailability of the wind turbine in Lamma Island isless than 30%.

• Small size wind generators (that can work with lowwind speeds and that are easy to install andmaintain) are much costly.

Performances of one of the biggest wind turbine manufacturers: Windpower of Denmark

Wind speed in Hong Kong and in the world in general

Average wind speed in urban areas of Hong KongAverage wind speed of Hong Kong

Innovative small wind turbine systems

Modular Micro-wind turbine

Modular Micro-wind turbine

Governing equations

Aerodynamics on a blade of the static micro wind turbine.

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RSs air drdS]×cos×sin × ) U× U- (U×[ windpassrel

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Optimization using CFD simulation

Modular Micro-wind turbine

Computational grids of moving zone and wind turbine in a dynamic and static model

Modular Micro-wind turbine

Computation mesh

Wind turbine measurement

Modeling and Experimental Results

Modeling and Experimental Results(cont’d)

Pow

er

Wind Speed

Performances(wind speed in m/s and power in watts)

0.5 m21.25 m2

C) performances comparison for same surface area and kW

B) operating range

A) Efficiency

Advantages of the modular microwind turbines

• Low cost – 40-50% the cost of conventional wind turbine with the same capacity

• Low start up speed – as low as 1 m/s, conventional wind turbine can only be start up at 4 to 5 m/s.

• Modular : easy to install and maintain, and flexible for expansion

A demonstration unit at HKU

Other advantages

(Beijing)

Other wind turbines installations

Summary remarks● Air pollution and global warming problems asked for

the adoption of cleaner renewable and non-conventional energy;

● Wind power has been identified to have great potential to be widely adopted;

● Micro-wind turbines are found to have advantages over conventional ones in urban environment.

● A special micro-wind turbine was designed and its performance was found not only suitable for the low wind speed urban environment but also for higher wind speed suburban and rural environment. This serves as an alternative for engineers to consider when installing wind turbines.

The University of Hong Kong

Thanks for your attention!

HKU Engineering Faculty Seminar13 December 2010