Analysis and Prediction of Noise Pollution from Wind Turbines: A Case Study of Loi Hai Wind Power Plant (Ninh Thuan, Vietnam)45216

Analysis and Prediction of Noise Pollution from Wind Turbines: A Case Study of Loi Hai Wind Power Plant Ninh Thuan, Vietnam Cuong Tran Thien 1* , Huan Nguyen Quoc 1 , An Thinh Nguyen 2

Analysis and Prediction of Noise Pollution from

Wind Turbines: A Case Study of Loi Hai Wind Power Plant (Ninh Thuan, Vietnam)

Cuong Tran Thien 1(*) , Huan Nguyen Quoc 1 , An Thinh Nguyen 2 , Minh Tran 1

(1) Faculty of Environmental Sciences, VNU University of Science, Vietnam National University, Hanoi, Vietnam

(2) VNU University of Economics and Business, Vietnam National University, Hanoi, Vietnam

* Correspondence: tranthiencuong@hus.edu.vn

Abstract: The demand for electric power in Vietnam has increased over the past five years at annual growth rates of 10% to 12%, and the challenge is to promote renewable energy sector One of these sustainable energy sources is to harness energy from the wind through wind turbines However, a significant hindrance preventing the widespread use of wind turbines

in Vietnam is the noise they produce, because noise significantly contributes to the annoyance experienced by residents living near wind farms The prediction of noise impacts for new wind farms is one of the many aspects of the environmental impact assessment process in Vietnam This paper deals with a predictive software approach for the calculation and simulation of the acoustical noise produced by 11 wind turbines of Loi Hai wind power plant in Ninh Thuan Province, Vietnam In the software framework, several noise resonance simulations of 11 wind turbines and National Highway No.1A have been performed, and giving a first description of the results that can be achieved in terms of noise mapping in more complex configurations of wind farm

Keywords: Wind farms; noise pollution of wind turbine; noise impacts; prediction model; modeling

1 Introduction

With the potential and advantages of wind resource, Vietnam is placing a center role

on this vital one of the alternative energy sources in the energy development strategy The country is currently focusing on mobilizing resources, creating favorable conditions to attract investors who have experience, financial capacity and modern technology in developing wind power plants This process helps contribute to ensuring national energy security, create a breakthrough to promote socio-economic development as well as realizing

Vietnam's green development and environmental protection strategy (VG 2015)

In response to the Vietnamese Government 's commitment in the 21st Conference of the Parties to the United Nations Framework Convention on Climate Change (COP21) November 2015, Decision No 2068/QD-TTg dated 25/11/2015 of the Prime Minister approving Vietnam's renewable energy development strategy to 2030, and a vision to 2050 (VG 2015), stressed that "Development priority sources of electricity from renewable energy, creating a breakthrough in energy security assurance, contributing to the conservation of energy resources and minimizing environmental pollution”

According to the Revised Vietnam Power Plan for the period of 2011-2020, with a vision to 2030 approved by the Prime Minister in Decision No 428/QD-TTg dated March 18,

2016 (VG 2016), the development of wind power is set to total wind power capacity of 800

MW in 2020, 2,000 MW in 2025 and 6,000 MW in 2030 Wind power will account for 0.8% of

the total in 2020, about 1% in 2025 and about 2.1% in 2030 (VG 2016)

In short, the development of wind power brings great benefits in terms of energy and socio-economy, becoming the main driving force for the development of this industry

in many countries around the world, as well as in Vietnam (VG 2015) However, one of the

significant obstacles preventing wind power development is the noise generated by wind turbines and its impacts on local communities where the wind power project are located

(Ofelia Jianu et al., 2011), besides other obstacles on the policy mechanism and electricity tariff in Vietnam (MoIT of Vietnam, 2018) In fact, the development speed of wind power in

Vietnam still slow; only 7 wind power projects with a total capacity of about 190MW have

been put into operation (Ministry of Industry and Trade of Vietnam, 2019)

Noise generated by the operation of wind turbines comprises two main sources:

1 Mechanical noise generated during the working of mechanical components such as gearboxes, generators, drives, cooling fans and ancillary equipment

(Rogers et al., 2006)

2 Aerodynamic noise generated during the interaction of turbine blades and wind turbine towers with blowing air The level of noise generated by wind

turbines also increases with the wind speed, usually from 4 to 12 m/s (Tickell

et al 2004)

Residents at a distance of 3 km or more from the nearest wind turbine can hear

low-frequency noise emitted from wind farms (Hansen et al., 2017, Hansen et al., 2013, Rogers et

al., 2006, Vladislovas et al., 2016)

It has been proven that people exposed to excessive noise will suffer from health problems such as hearing impairment, headaches and fatigue (due to sleep disorders)

(Alberts, 2006, Robert J et al., 2014) Extremely high noise exposure may even cause constricted arteries and a weakened immune system (Alberts, 2006)

According to a research by the Institute of the Counties & Municipalities in Denmark

(AKF-lnstitute of Local Government Studies, 1996), based on interviews with people living near

wind power plants, the medical costs incurred by noise are estimated at nearly 0.0012 Euro/kWh

Overall, in recent years, with the progress of science and technology, while wind turbines have been designed and manufactured with much lower noise level, the noise from wind turbines is still a serious problem It is necessary to quantify and evaluate the extent and extent of its impact on the local community as well as the workers operating the wind power plants

2 Methodology

2.1 Wind farm location

Figure 2 Location of the project in Vietnam

Loi Hai Wind Power Plant is located in Loi Hai

Commune, Thuan Bac District, Ninh Thuan Province,

Vietnam; Plant location is located in an area of 523ha,

near the North - South railway and National Highway

1A

The plant has a capacity of 30MW, including 11

turbines (capacity of 2,625MW) manufactured by

Gamesa firm (Spain) with a noise level at rotor of

102.9dB (according to the manufacturer's catalog) The

height of the turbine tower is 102m (PECC3, 2017)

Table 1 Frequency of wind appearance toward 16 directions in the project area

Frequency (%) 33.7 5.13 6.00 20.9 1.28 2.38 1.11 6.44 0.609

Remark: N: North, NNE: North Northeast, NE: Northeast, ENE: East Northeast, E: East, ESE: East Southeast, SE: Southeast, SSE: South Southeast, S: South, SSW: South Southwest, SW: Southwest, WSW: West Southwest, W: West, WNW: West Northwest, NW: Northwest (PECC3, 2017)

N NNE NE ENE

E

ESE SE SSE S SSW SW WSW W WNW NW NNW

33.7

Figure 3 Wind roses summarizing 16

wind directions (PECC3, 2017).

Figure 4 Wind speed frequency distribution (PECC3, 2017)

Figure 5 Monthly and diurnal wind speed profile (PECC3, 2017)

Table 2 A summary of wind farm information

capacity (MW)

The height of the turbine tower (m)

Noise at rotor (dBA)

(Source: Feasibility study report of Loi Hai wind power plant project) (PECC3, 2017)

Table 3: Noise level of wind turbines by 1 octave frequency

5

6

3

12

5

25

0

50

0

100

0

200

0

400

0

800

0

LWA(eq) (dBA)/C Noise level (dBA)

(Turbine Gamesa G126

2.625MW)

95 8

5

10

4

10

2

10

5

The average wind speed at the height of 50m in the project area is 6.85m/s (NASA), with the prevailing wind direction being the Northeast Noise levels measured in the project

center area and National Road 1A are 52dBA and 68.4dBA respectively (PECC3, 2017)

2.2 Methodology

This study was conducted on the basis of applying a modeling method to calculate and simulate the noise level generated from 11 wind turbines of Loi Hai wind power plant and National Highway 1A (the road section running through the project), simultaneously simulating sound resonance between sources using a combination of German Cadna/A

software (Computer Aided Noise Abatement) (https://www.datakustik.com), and Dutch Inoise software (https://dgmrsoftware.com)

The calculation and prediction methods in both Cadna/A and Inoise software applied to wind turbines are based on the international standards of acoustic transmission: ISO 9613-2 (1996), and ISO 17534-3 (2015)

Accordingly, each wind turbine is a noise source and is considered a point source The sound pressure level at a position is determined by subtracting the sound pressured drop from the external elements from the noise source (wind turbine) in the octave frequency range The noise level in the octave range is shown by the following equation:

SPLTurbine = LW(eq) + D - Ageo - Aatm - Agr - Abar - Amisc - 2dB

SPL: Sound pressure

LW(eq): Noise level at source (rotor)

Ageo : Decreased noise level due to the spread of sound waves in spherical form in the free field from the sound source {Ageo = 20 x Logd + 11 (d: Distance from turbine to the recipient point)}

D : For wind turbines, the noise level is measured and calculated following the wind direction, so there is no need to adjust the amount of noise Therefore, D is usually equal to 0

Aatm : Noise level reduction by atmospheric absorption = d (Distance from wind turbine) x a (atmospheric absorption coefficient 0,003dB/m)

Agr : Noise level decrease due to absorption by earth surface = 0,5dB (absorbing mixed earth)

Abar : Noise level decrease due to absorption by obstructing objects (Depends on the size of the object)

Amisc : Additional noise reduction level (Spreading effect through foliage, plants, houses ) 2dB is the corrected noise level, used to convert the Lweq levels according to the background intensity parameter LA90

Of which, the resonant noise level of the whole wind power plant is calculated as follows: SPLWind farm = ∑(SPLTurbine within a radius of 3km from the wind turbine)

3 Results

We have selected 3 noise sensitive points (NSP) to quantitatively calculate the level

of resonant noise level from wind turbines of Loi Hai wind power plant

- NSP1: Ba Rau Primary School, Loi Hai Commune, 2km from the wind power plant

to the South;

- NSP2: Boundary of Nui Chua National Park, 1km to the East from the plant;

- NSP3: Residential area of Suoi Da village, Loi Hai commune, 1.3km northeast of the plant

Calculation results are presented in the following tables and figures:

Table 4: Noise levels at three noise sensitive spots during the day Noise

calculation

point

VN-2000 coordinate system (Projection 3 0 )

Wind velocity (m/s)

Noise level due to wind turbines (dBA)

Resonance noise level (dBA)

Figure 6: Noise level due to traffic activities on

turbines

Table 5: Noise level at three noise sensitive spots at night Noise

calculation

point

VN-2000 coordinate system (Projection 3 0 )

Wind velocity (m/s)

Noise level due

to wind turbines (dBA)

Resonance noise level (dBA)

NSP 3 1300100.32 589760.69 6.85 45.1 52.3

Figure 8: Resonance noise level between 11 wind turbines of the plant and NH1A

Research results demonstrate that:

 Each wind turbine is considered a source of continuous noise, in point form, and NH1A is considered as a discontinuous noise source, and is in line form

 The noise intensity generated by wind turbines depends mainly on aerodynamic phenomena and the processes that generate mechanical noise Wind turbine noise increases due to the negative reflection processes and the ground surface of surrounding buildings, while its absorption is affected by air density, humidity and by airflow kinetics of ambient elements

 Noise level at rotor of wind turbines and along National Road 1A exceeds the permissible standards (QCVN 26: 2010/BTNMT regulation of noise limits

in normal areas from 6am - 9pm is 70 dBA and from 21h - 6h is 55dBA

(National technical regulation on noise QCVN 26:2010/BTNMT, 2010) The noise

level at the base of the wind turbine tower meets QCVN 26: 2010/BTNMT during the daytime while exceeds the permissible limit in QCVN 26: 2010/BTNMT at night Outside the range of 130-150m from the base of the tower, the noise level generated from the turbines is considered within

QCVN 26: 2010/BTNMT (National technical regulation on noise QCVN

26:2010/BTNMT, 2010)

 When there is a resonance between 11 turbines and NH1A road, the noise level increases from 6.3-7.3 dBA

 The diffusion of noise in general depends on many factors, especially the speed and wind direction

 The resonant noise level at night is usually 0.3 - 0.5dBA higher than that in daytime

 In case the project applies World Bank standards (limited to 45dBA), people and livestock are not allowed to live permanently within the contour of 45dBA Households living within the yellow area must be relocated and resettled

 Indeed, for the Loi Hai wind power plant project, due to the large number of affected households (197) due to the scope of the isoline noise of 45dBA, so the project was not entitled to preferential loans from international financial institutions

 Wind power projects are generally opposed by the local community for the reason that people are at risk of adverse physiological and psychological symptoms related to wind turbine noise And it is because of the current acoustic nuisance that has caused a backlash from residents in social and health impact surveys on people living near wind turbines

 To minimize the negative impacts due to the noise from wind turbines to the environment and human health, it is necessary to apply a number of synchronous solutions such as: technological solutions (using new modern turbines with generating low noise and regularly servicing turbines, etc.), managerial solution (recommended for local people not to live in areas with

a noise level of 45dBA or higher, etc.) and to implement a well prepared plan

on compensation and resettlement for 197 local households to help them feel secure to live in their new resettlement sites

4 Conclusions

In this paper, the authors presented a summary of scientific basis, modeling methods and results of calculation, prediction and simulation of the noise intensity distribution due

to wind turbines of Loi Hai wind power plant in Vietnam, also considered the case of acoustical resonance with other sources in the region

The application of the modeling method to quantify the noise level from wind turbines in particular and the combination of noise sources in general is highly feasible, presenting visual results This correspondingly serves as an important basis for the environmental authorities and project investors in decision making right from the project screening stage

Acknowledgments: The authors extend their thanks to the Faculty of Environmental

Sciences, VNU University of Science, Vietnam National University, Hanoi for their invaluable support for this research

References

AKF-lnstitute of Local Government Studies, Denmark, April 1996

Research Institute of the Counties & Municipalities in Denmark (AKF), April 1996 Robert J McCunney, MD, MPH, Kenneth A Mundt, PhD, W David Colby, MD, Robert Dobie, MD, Kenneth Kaliski, BE, PE, and Mark Blais, PsyD (2014) Wind Turbines and Health - A Critical Review of the Scientific Literature American College of Occupational and Environmental Medicine, Volume 56

The United Nations Framework Convention on Climate Change (UNFCCC/COP21) Alberts, D.J (2006) Primer for Addressing Wind Turbine Noise Report from Lawrence Technological University, 19 pages

Evans, T., and Cooper, J (2012) Comparison of predicted and measured wind farm noise levels and implications for assessments of new wind farms Acoustics Australia, 40, 28-36

G Leventhall, A Bullmore, M Jiggins, M Hayes, A McKenzie, R Bowdler and R Davis (2009) Prediction and assessment of wind turbine noise, Agreement about theabout the relevant factors for noise assessment fromassessment windfrom energywind projectsenergy projects Acoustics BulletinAcoustics Bulletin 34(2), 35-37

F W Gsveld, F.W (1984) Prediction of broadband noise from horizontal axis wind turbine, J Propulsion 1, 4, 292-299

Colin H Hansen, C.H., Con J Doolan, C.J., and Kristy L Hansen, K.L (2017) Wind farm noise: measurement, assessment and control: John Wiley & Sons, 624 pages

Colin H Hansen, C.H., K L., B Zajamsek, K.L.B (2017) The Occurrence of Nocturnal Wind Farm Rumbling Noise 7th International Conference on Wind Turbine Noise Rotterdam, Thethe Netherlands, 2nd - 5th May 2017 pp 123-130

Hayes McKenzieHayes PartnershipMcKenzie LtdPartnership Ltd (2011) Analysis of how noise impacts are considered in the determination of wind farm planning applicationsplanning applications Report 2293Report 2293/R1, UK,

UK Department ofDepartment of Energy and Climate Change 49 pages

International Standard ISO 17534-3 (2015) Acoustics - Software for the calculation

of sound outdoors - Part 3: Recommendations for quality assured implementation of ISO 9613-2 in software according to ISO 17534-1

International Standard ISO 9613 (1996) Acoustics - Attenuation of sound during propagation outdoors - Part 2: General method of calculation

International Standard ISO 9613 (1996) Acoustics - attenuation of sound during propagation outdoors - Part 1: calculation of the absorption of sound by the atmosphere Geneva

Ofelia Jianu, O., Marc A Rosen, M.A., and Greg Naterer, G (2011) Noise Pollution Prevention in Wind Turbines: Status and Recent Advances 14 pages

Vladislovas Katinas, V., Mantas Marčiukaitis, M., Marijona Tamašauskienė, M (2016) Analysis of the wind turbine noise emissions and impact on the environment Renewable and Sustainable Energy Reviews Renewable and Sustainable Energy Reviews

58 (2016), 825-831

Klug, H (2002) Noise from Wind Turbines (2002): Standards and Noise Reduction Procedures Paper presented on the Forum Acusticum, 2002, Sevilla, Spain 7 pages

Hansen, Kristy, H., Branko Zajamsek, B., and Colin Hansen, C (2013) Analysis of unweighted low frequency noise and infrasound measured at a residence in the vicinity of

a wind farm Australian Acoustical Society, Proceedings of Acoustics, 17 - 20 November

2013 9 pages

Mihaila, J M., C Bigan, C., V Panduru, V (2014) Mathematical modelling of noise mapping at wind turbine farms, Balkan Society of Geometers, Geometry Balkan Press Applied Sciences, Vol 16, 2, 014, pp 48-55

Møller, H., and C.S Pedersen, C.S (2011) Low-frequency noise from large wind turbines Journal of the Acoustical SocietyAcoustical ofSociety of America, 129(6), 3727-3744

National technical regulation QCVN 26:2010/BTNMT dated December 16th, 2010 of the Minister of Natural Resources and Environment on noise

Power Engineering Consulting Joint Stock Company 3 (PECC3) (2017) Feasibility study report of Loi Hai wind power plant project 111 pages

Rogers A.L, Manwell J.F and Wright S (2006) Wind Turbine Acoustic Noise Renewable Energy Research Laboratory, Department of Mechanical and Industrial Engineering University of Massachusetts at Amherst, Amended