China's construction machinery sector is expected to see stable export growth this year on the back of soaring overseas infrastructure projects and strong global orders for electric-powered excavators, loaders and other mining equipment, domestic manufacturers said on Tuesday.

A roll-on-roll-off vessel loading 500 excavators and a self-discharging truck produced by Xuzhou Construction Machinery Group Co Ltd (XCMG) left for Nigeria from a wharf of the Lianyungang Port in East China's Jiangsu province recently.

Sun Dong, manager of rolling transportation unit at a subsidiary owned by Lianyungang Port Group, said this is the 100th cargo ship loaded with construction machinery being exported this year.

Liu Jiansen, vice-president of XCMG Construction Machinery Co Ltd, a subsidiary of Jiangsu province-based XCMG, said the company's export orders mainly came from Asia, Africa and Latin America, but that it witnessed explosive growth in the European, Australian and North American markets this year.

The export orders for products from excavators and earth moving equipment, to mining machineries such as giant mining trucks and excavators, have all experienced between 300 percent and 400 percent growth year-on-year in the first four months, he said.

The country's major excavator manufacturers reported a sharp increase in exports in the first four months, as their exports surged by 78.9 percent year-on-year to 33,791 units during the period, said the Beijing-based China Construction Machinery Association (CCMA).

Since many foreign companies have adopted a "go green" approach to further reduce carbon emissions and save on the cost of diesel fuel, many domestic manufacturers have accelerated the pace of developing electric-powered construction machinery to secure an increased share in overseas markets.

Jiangsu Weiteli Motor Ltd, a Taizhou, Jiangsu province-based manufacturer of electric vehicle drive motors, saw orders for motors used on electric construction machinery rise between January and April, and they already exceed the total order volume logged last year. The company predicts the market in this category is expected to grow more than 300 percent on a yearly basis in 2022.

In South America for example, a 27-metric-ton electric excavator consumes about 100 kilowatt-hours (kWh) of electricity for an hour and costs less than $16 to operate. Under the same conditions, a fuel excavator consumes between 16 liters and 17 liters of diesel and costs over $23 to run, said Shi Hongliang, the company's vice-president.

"Assuming the operating time is 3,000 hours a year, costs of energy and maintenance of a 27-ton electric excavator can save about $25,000 per year," he said. "Since international crude oil prices have remained high this year, our motors used in electric construction machinery have sold well in both domestic and foreign markets."

The diesel-powered construction machinery market currently is finding increasing use by new energy products, especially in developed markets such as Germany, France and the United States, said Li Dongchun, general manager of the international business center at Guangxi Liugong Machinery Co Ltd, a Liuzhou, Guangxi Zhuang autonomous region-based construction machinery manufacturer.

Customers are also demanding longer battery lives and smarter control systems, pushing the company to continuously launch new products, he said.

The electrification trend of construction machinery with small operating radiuses and fixed activity is more obvious, such as electric-powered loaders and dump trucks used in factories, mines and ports, he added.

Li said the earliest start of electrification in the field of construction machinery is the electric forklift. Among the forklifts it currently exports, the proportion of electric forklifts has reached 62 percent.

Liuzhou exported 1.44 billion yuan ($216 million) worth of construction machinery in the first four months, while new energy loaders have become a pillar product for the city's exports in this category, according to Liuzhou Customs, a branch of Nanning Customs in Guangxi.

Wu Peiguo, secretary-general of CCMA, said with notable improvement of the technical level, quality and reliability of batteries, motors and electronic control systems in China, the nation's export volume and production capacity of electric-powered construction machinery will continue to rise this year.

Under China's coordinated regional growth strategy and ongoing establishment of a unified domestic market, Wu said demand for infrastructure construction remains appealing with continuous efforts to drive the development of the Beijing-Tianjin-Hebei region, the Yangtze River Economic Belt and the Guangdong-Hong Kong-Macao Greater Bay Area.

The Communist Party of China Central Committee and the State Council jointly released in April a guideline on accelerating the establishment of a unified domestic market. It said China will optimize the layout of commercial and trade circulation infrastructure, bolstering the integration of online and offline development.