Dr. Viet Hung NGUYEN,
VSSMGE; CTV Wind Civil Engineering.
Vietnam has been rapidly developing its renewable energy sector, including wind energy, to meet the growing demands for electricity and to reduce its reliance on fossil fuels. The country has great potential for wind energy due to its long coastline and favorable wind conditions, particularly in the central and southern regions. In this article, we will discuss the historical development of wind energy in Vietnam, the important role of Civil Engineering and Geotechnical Engineering, and the prospects for innovation in wind turbine foundation design.
Historical Development of Wind Energy in Vietnam
The development of wind energy in Vietnam can be traced back to 2007 when the first wind turbine was installed in Binh Thuan Province. This project had a capacity of only 30 MW and was considered experimental at the time. However, it paved the way for further development of wind energy in the country.
In the following years, several wind farms were built, including the 24 MW Phu Lac wind farm in 2014, and the 40 MW Dam Nai wind farm in 2015. These projects were all located in the southern region of Vietnam, which has the most favorable wind conditions.
Since then, Vietnam has continued to develop its wind energy sector, with more wind farms being built throughout the country. As of 2022, Vietnam has a total installed wind power capacity of 4000 MW (https://en.evn.com.vn, n.d.), accounting for 10% of the country’s total electricity generation capacity.
Role of Civil and Geotechnical Engineers in Wind Energy Development
The development of wind energy in Vietnam has been made possible through the efforts of various stakeholders, including the government, investors, and technical experts. Civil and geotechnical engineering have played a critical role in this development, particularly in the design and construction of wind turbine foundations and all infrastructure called Balance of Plant. The design and construction of wind turbines and their foundations require a high level of expertise in these fields.
Vietnam has a diverse range of geological conditions that pose unique challenges for Geotechnical Engineering. Two notable examples are the geotechnical conditions in the mountainous regions and the soft soil conditions in the Mekong Delta.
Geotechnical Conditions in the Mountains
Vietnam has a long mountainous region that spans from the north to the south of the country. This region is characterized by steep slopes, weathered rock, and soils prone to collapse. Weathering of rocks and soil can cause significant changes in their physical properties, including their strength and stiffness.
The weathered rock in mountainous regions can be challenging for foundation design, as it can be difficult to determine the strength and stiffness of the rock. The presence of cracks, fissures, and jointing in the rock can further complicate the design process. In addition, the steep slopes can lead to instability, requiring careful analysis and design to ensure the safety of structures built on or near them.
The collapse Soils are also a common geotechnical challenge in the mountainous regions. These soils are typically composed of clay, silt, and sand, and are characterized by their low shear strength and high compressibility. Its easly change the mechnical properties when there is the water. They can be particularly challenging for the design of embankments, retaining walls, and other structures that require stability.
Soft Soil Conditions in the Mekong Delta
The Mekong Delta is a low-lying region in southern Vietnam that is characterized by soft soil conditions. The region is prone to flooding, and the soils are often saturated, leading to low shear strength and high compressibility.
The soft soils in the Mekong Delta can pose significant challenges for foundation design, particularly for large structures such as wind turbines. The compressibility of the soils can cause differential settlement, which can lead to structural damage and failure. In addition, the high-water content in the soils can cause liquefaction during the wind turbine viration or earthquakes, which can also result in structural failure.
To overcome these challenges, Geotechnical Engineers play an important role. In the early stages of wind energy development in Vietnam, most wind farms used shallow foundations, which were sufficient for the relatively small turbines used at the time. However, as turbines grew larger and more powerful, deeper foundations were required to support them. This is where geotechnical engineering played a critical role in developing innovative foundation designs that could withstand the harsh environmental conditions of Vietnam’s coastal regions.
The dynamic analysis of the soil is critical in the design of wind turbine foundations to ensure that they can withstand the dynamic loads imposed by the turbine. Wind turbines are subject to various dynamic loads, including wind loads, rotor loads, and gravitational loads, among others. These loads can cause the turbine to vibrate, leading to the resonance effect.
The resonance effect occurs when the natural frequency of the wind turbine structure matches the frequency of the external loads. This can cause the structure to vibrate excessively, leading to fatigue failure of the structure and potential collapse. The dynamic properties of the soil play a crucial role in determining the natural frequency of the wind turbine foundation and its response to external loads.
To analyze the dynamic behavior of the soil, Geotechnical Engineers use specialized software to model the soil-structure interaction. These software packages can simulate the dynamic behavior of the soil and its response to external loads, such as those imposed by wind turbines. The analysis takes into account various factors, including the stiffness and damping properties of the soil, the geometry of the foundation, and the loads applied to the structure.
The dynamic analysis of the soil is crucial in determining the fatigue life of the wind turbine foundation. Fatigue failure occurs when a structure is subjected to repeated cyclic loading, causing cracks to develop and propagate until the structure fails. Wind turbines are subject to fatigue loads due to the cyclic nature of wind loads, which can cause stress concentrations and lead to crack initiation and propagation.
By analyzing the dynamic behavior of the soil and the loads imposed by the wind turbine, Geotechnical Engineers can design wind turbine foundations that can withstand the dynamic loads and avoid the resonance effect. This helps to ensure the long-term performance and safety of the wind turbine structure.
One company that has played a key role in the design of Balance of Plant of wind energy in Vietnam is CTV Wind Civil Engineering. The Engineering Firm specialize on the Civil Engineering Balance of plant of Wind power project. They have been involved in the design of over 80% of all wind farm projects in Vietnam and have contributed significantly to the development of innovative foundation designs for both onshore and offshore wind power project.
One of the most significant projects that CTV Wind has been involved in is the largest wind farm in Vietnam, the 252 MW BT Wind Farm in Quang Binh Province. CTV Wind has collaborated with the famous contractor in Vietnam, FECON Construction Corporation (NGUYEN & MARTIN, 2020), they have successfully applied different geotechnical technologies and foundation design concept for wind turbine foundation in Vietnam, including shallow foundation, concrete precast pile foundation, bored pile foundation, vibro-compaction soil improvement, and soft-spot foundation. These technologies have helped to ensure the stability and safety of wind turbine structures, even in challenging geological conditions.
It’s impressive to hear that CTV Wind has successfully implemented a new concept of offshore foundation in Vietnam using the Concrete Precast pile foundation (Vietnam Patent No. 1-2014-01963, 2014) . This innovative approach has allowed them to reduce the construction costs of offshore wind turbine foundations by about 30% compared to classical offshore wind turbine foundation solution This design was applied for more than 150 wind turbine foundations to difference wind turbine manufrature such Vestas, Siemens Gamesa, Gold wind, Mingyang … in the southend sea of Vietnam
One of the advantages of using the Concrete Precast pile foundation is that it can be manufactured offsite and transported to the installation site, reducing the time and cost of onsite construction. This approach also allows for more precise quality control of the foundation components, ensuring that the foundation meets the required design specifications.
Another advantage of the Concrete Precast pile foundation is that it can be designed to suit a range of soil conditions, including soft soil conditions. This is particularly important in Vietnam, where soft soil conditions are prevalent in the Mekong Delta region.
The success of this new concept of offshore foundation in Vietnam is a testament to the innovation and expertise of CTV Wind and the potential for further advancements in the design and construction of wind turbine foundations. The continued development of geotechnical engineering and the use of new materials and techniques will undoubtedly play a critical role in the future of wind energy in Vietnam and beyond.
The Concrete Precast pile foundation Concept can be adapted to suit soft soil conditions and the local construction, material, and human resources in Vietnam. The design of the foundation can be modified to suit the specific soil conditions at the installation site, including soft soil conditions. This helps to ensure that the foundation can provide the required support and stability for the wind turbine structure.
The use of locally available materials and resources can also help to reduce the cost of the foundation and support the local economy. The precast concrete components of the foundation can be manufactured using locally available materials and labor, reducing the need for expensive imports and providing employment opportunities for local workers.
The adaptation of this concept to suit local conditions in Vietnam highlights the importance of considering local factors in the design and construction of wind energy infrastructure. The unique environmental and geological conditions in Vietnam, including the prevalence of soft soil conditions, require innovative solutions that are tailored to the local context. The success of the Concrete Precast pile foundation in Vietnam demonstrates the potential for locally adapted solutions to drive the growth of wind energy in the country and contribute to sustainable development.
Future Role of Geotechnical Engineering continues to expand its wind energy capacity, geotechnical engineering will play a critical role in developing innovative foundation designs for onshore and offshore wind turbines. The increasing demand for renewable energy in Vietnam, coupled with the challenging soil conditions in coastal areas, presents an opportunity for geotechnical engineers to develop new techniques and technologies that can improve the performance and cost-effectiveness of wind turbine foundations.
In conclusion, the development of wind energy in Vietnam has come a long way since the first project in 2007. The growth of the wind energy sector in Vietnam is testament to the government’s commitment to renewable energy and the ingenuity of civil and geotechnical engineers in overcoming the challenges of foundation design. The project archive of the first wind farm in Vietnam provides valuable insights into the design, construction, and operation of wind energy projects in the country. Looking to the future, geotechnical engineering will continue to play a critical role in developing innovative foundation designs for onshore and offshore wind turbines, enabling Vietnam to achieve its ambitious renewable energy targets.
References
https://en.evn.com.vn. (n.d.). Retrieved from Vietnam Electrical : https://en.evn.com.vn/d6/news/The-status-of-commercial-operation-acceptance-COD-of-wind-power-plants-as-of-31-October2021-66-142-2562.aspx
NGUYEN, V., & MARTIN, A. (2020). Onshore and nearshore wind turbine foundation design and construction: Which way the designer can chose to optimize time and costs, based on International and Vietnamese experiences. 5th FECON Construction technoloy summit (p. 12). Hanoi: Fecon.
NGUYEN, V., & TRAN, D. (2014). Vietnam Patent No. 1-2014-01963.