Green and Clean Drying Equipment to Assist Grain Storage

In the Green Grain Drying Center on Shuangshan Island in Zhangjiagang, Jiangsu province, eight ground-source heat pump grain electric drying pieces of equipment are operating, accompanied by the rumbling sound of machinery.

Workers were occasionally seen operating the machinery to feed the drying equipment. This center is the first ground-source heat pump grain electric drying project in Jiangsu and the daily grain drying capacity can reach 96 metric tons.

Shuangshan Island is a small island located in the center of the Yangtze River, covering an area of about 20 square kilometers. There are 5000 mu (about 333 hectares) of high-standard farmland on the island. Currently, the wheat on the island has entered the mature stage, and the golden wheat sways in the wind, presenting a bustling scene of harvesting, transportation, drying and storage.

Drying and storage are critical processes after grain harvesting. Insufficient drying of grain can lead to losses such as mold and germination. "In the past, traditional coal or oil-fired hot air furnaces were used for grain drying, which had high drying costs and environmental pollution," said Weng Xiaoping, general manager of Zhangjiagang Shuangshan Agricultural Investment and Development Co Ltd.

To accelerate the transformation and upgrading of agricultural machinery and equipment, China Suzhou Zhangjiagang Power Supply Co of the State Grid Corp enhanced services and collaborated with the local agricultural and rural bureau to promote green and efficient agricultural machinery and equipment, such as drying, brewing and planting, throughout the city. They advocate clean heat source substitution technology and continuously improve the power supply service capabilities and electrification level in rural areas.

The geographical location of Shuangshan Island leads to inadequate supply of steam and natural gas through pipelines. To achieve clean energy drying, ground-source heat pump grain drying technology, which utilizes the earth as an "energy reservoir" and uses electricity to transport "energy," became the preferred choice. Last March, Zhangjiagang Agricultural and Rural Bureau took Shuangshan Island as a pilot and built the Green Grain Drying Center to explore the application of ground-source heat pump technology in grain drying. The center covers an area of 3,700 square meters and has 8 newly-built ground-source heat pump grain drying pieces of equipment, with a total investment of 2.5 million yuan ($350 thousand).

"In simple terms, ground-source heat pump is a heating, cooling and air conditioning system that utilizes geothermal resources stored in the ground and converts them into energy, enabling efficient utilization of geothermal resources," said Lyu Bin, director of the marketing department of the China Suzhou Power Supply Co of the State Grid Corp. The Shuangshan Island Green Grain Drying Center uses underground pipes buried 100 meters deep to absorb underground heat and transports the heat to the grain drying equipment through a heat pump circulation system, using high temperatures to evaporate the moisture in the grain.

"The heat pump needs electricity to 'transport' heat, so we have simultaneously strengthened the construction of supporting power facilities. We have built a dedicated transformer with a capacity of 500 kVA for the center and installed more than 50 meters of cables to ensure stable power supply to the drying center," said Zhou Jun, deputy director of the marketing department of the Zhangjiagang Power Supply.

Compared to traditional drying equipment, ground-source heat pump grain drying offers advantages in terms of space efficiency, high productivity and low carbon emissions. "This technology primarily harnesses geothermal resources, allowing the ground-source heat pump drying equipment to produce around 5 times the heat energy for every 1 kilowatt-hour of electricity consumed," said Lyu.

Moreover, the proximity of the heating evaporator in the ground-source heat pump grain drying equipment to the grain dryer enables the direct transfer of heat into the drying chamber, resulting in increased energy efficiency.

Compared to conventional methods, it can save over 30 percent in electricity consumption, significantly reducing production costs.

"After the project's implementation, the drying cost per ton of grain has decreased from around 240 yuan using fuel to approximately 60 yuan, resulting in a cost reduction of about 75 percent. Moreover, the entire drying process only requires one or two operators, relieving local farmers of significant burdens," said Huang Longhu, the agricultural machinery administrator of Shuangshan Xiangshan Tourist Resort. Considering an annual drying volume of 4,500 tons of wheat and rice, the drying center can save nearly 800,000 yuan in expenses.

In recent years, Suzhou Power Supply has focused on promoting the green transformation and development of agriculture, actively advocating for green and clean grain drying equipment and technologies, and promoting energy-efficient and environmentally friendly upgrades as well as the adoption of clean heat sources for grain drying. To date, Suzhou has invested in a total of 683 sets of various types of clean heat source drying equipment, accounting for over 40 percent of the total, effectively ensuring the green and secure storage of grain.