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Check out China's first carbon-free desert highway

In the vast hinterland of the Taklamakan Desert, a 522-kilometer-long Tarim Desert Highway stretches majestically from north to south. The luxuriant ecological shelter forest on both sides of the highway adds a vibrant touch, resembling an emerald belt encircling this desert oasis. In 2022, following an upgrade by China National Petroleum Corporation's Tarim Oilfield Company, the scattered water well houses along the forest belt are now adorned with glistening photovoltaic panels that radiate resplendently under the sun.

Photo shows a distant view of the photovoltaic panels next to the water well houses on China's first carbon-free desert highway (partial view) shine brilliantly under the sunlight. (Photo provided by Tarim Oilfield Company of China National Petroleum Corporation)

The transformation project, known as the Tarim Desert Highway Zero Carbon Demonstration Project (hereinafter referred to as the "Zero Carbon Demonstration Project"), stands as China's most extensive photovoltaic irrigation and desert control initiative. It serves as a vibrant embodiment of China Petroleum Tarim Oilfield Company's commitment to the dual carbon goal and its unwavering dedication to green development. Building upon the previous integration of 11 water wells into grid electricity and pilot construction of photovoltaic power stations for 12 wells, the remaining 86 well houses will be powered by photovoltaic generation. This endeavor will enable ecological shelter forest pumping irrigation to be powered by electricity instead of oil, thereby pioneering a new paradigm of nurturing greenery with sunshine.

What transformations has the novel model brought forth in the Taklamakan Desert? What kind of extraordinary experience does it entail to construct a photovoltaic power station amidst this expansive desert? Join the journalist on an expedition to explore the nation's inaugural carbon-neutral desert road.

Sunlight-powered irrigation ensures uninterrupted water supply, with 109 families taking turns to guard the water wells along the route for 24 hours without power outage

The Taklamakan Desert, stretching approximately 1000 kilometers from east to west and spanning about 400 kilometers from north to south, stands as China's largest desert. Following the completion of the Tarim Desert Highway in 1995, it effectively dismantled the transportation barrier between the northern and southern regions of the Tarim Basin, thereby reducing the distance from Hotan to Urumqi by over 500 kilometers.

The Taklamakan Desert, the world's second largest mobile desert, perpetually shifts under the influence of prevailing winds. Consequently, the Tarim Desert Highway has earned its reputation as "the longest highway through a dynamic desert on Earth," yet it constantly faces the looming threat of being engulfed by sand and dust.

Given the insurmountable challenge of halting the relentless onslaught of sandstorms, a solution was sought in the form of fixing the ever-shifting sands. After years of unwavering dedication and perseverance, in April 2006, an astounding number exceeding 20 million salt-tolerant and drought-resistant plants such as tamarisk and red willow were meticulously planted on both sides of the desert highway, giving rise to an awe-inspiring ecological shelter forest. From that moment onward, this remarkable 'Green Great Wall' not only shielded drivers from being engulfed by blinding sandstorms but also left tourists who specifically ventured here utterly astounded by witnessing such an extraordinary spectacle - a true testament to human's miraculous ability to transform barren deserts into flourishing oases.

Photo shows staff maintain and repair the photovoltaic power generation system to ensure stable electricity production. (Photo provided by Tarim Oilfield Company of China National Petroleum Corporation)

With the launch of the zero-carbon demonstration project, changes are constantly occurring.

While driving along the Tarim Desert Highway, one can behold a water well house gracefully adorning the landscape every 4 kilometers, serving as an essential source of irrigation. A grand total of 109 houses embellish the entire route, each diligently manned by a dedicated family. Throughout the span of over 8 months during the annual plant growth period, these families reside here to meticulously nurture and safeguard the protective forest within a radius of 4 kilometers.

The stationed workers elucidated that their daily labor commences with the act of unsealing the main valve and pipeline switches for irrigation. In addition to this, they also undertake the maintenance and reparation of drip irrigation pipelines, whilst regularly administering fertilizers and pest control measures. For them, exposure to gusts of wind, scorching sun rays, and swirling dust is a familiar occurrence; however, what truly invigorates them is witnessing the palpable transformation brought forth by the three rows of photovoltaic panels adjacent to the water well house.

According to the information, the desert highway photovoltaic power station boasts a total installed capacity of 3800 kilowatts, enabling it to generate approximately 11,000 kilowatt-hours of electricity daily and around 3.6 million kilowatt-hours annually. Not only does it cater to the daily electricity consumption for water pumping and irrigation along the wells, but it also serves as an unwavering power source guaranteeing the everyday needs of stationed workers.

"In the past, when we relied on diesel engines for power generation, we would continuously pump water for 12 hours during the day. However, as night fell upon the pitch-black desert, a void of electricity enveloped us and forced workers to endure its darkness," expressed Li Jian, a senior supervisor at Tarim Oilfield Company's Tazhong Oil and Gas Management Zone. Nevertheless, with the implementation of zero-carbon demonstration projects, an unprecedented transformation has occurred after 16 long years - water wells are now blessed with an uninterrupted power supply that spans across 24 hours. Furthermore, air conditioning units, televisions and refrigerators have gradually found their way into our duty stations.

Changes extend beyond this.

"The working environment has now become much quieter. In the bygone era, diesel generators emitted deafening clamor, necessitating us to raise our voices. Presently, the noise level emanating from photovoltaic power generation equipment resembles that of a tranquil air conditioner," articulated the stationed worker.

The maintenance cost has been significantly reduced. Li Jian elaborated that upon completion and implementation of the zero-carbon demonstration project, it will result in an annual savings of nearly 4 million yuan in operating costs through a reduction of approximately 1000 tons in diesel consumption, deduction of equipment depreciation expenses, and a substantial decrease in diesel engine repair costs amounting to 1.8 million yuan annually.

The most remarkable transformation lies in the carbon emissions. According to Li Jian's calculations, the reduction in diesel consumption alone could annually mitigate 3,410 tons of carbon dioxide emissions. Moreover, through water pumping irrigation, 'zero emissions' are achieved while the ecological shelter forest has the capacity to absorb approximately 20,000 tons of carbon dioxide each year - effectively offsetting the carbon emissions from around 90,000 passing vehicles. In essence, this signifies that the operation of the entire desert highway will no longer contribute to atmospheric carbon dioxide levels; thus constituting a pivotal step towards attaining 'zero carbon'.

Photo shows a staff member installs and debugs photovoltaic panels. (Photo provided by Tarim Oilfield Company of China National Petroleum Corporation)

Zero-carbon demonstration project completed in 140 days using optimized techniques

Constructing roads in mobile deserts is challenging, and the same goes for building photovoltaic power stations.

As a crucial component of photovoltaic power stations, the outdoor power generation performance of photovoltaic modules is often influenced by factors such as material aging, operating temperature, solar radiation intensity, module surface reflectivity, and local climate conditions.

The zero-carbon demonstration project is situated in the heart of the desert, where the climate is extremely dry, the ground structure is loose, and sand dunes are highly mobile, making construction more complex than in conventional locations.

"During June and July, the temperature can reach as high as 45 degrees Celsius, with the sand surface temperature exceeding 70 degrees Celsius, making the ground feel like a griddle." Additionally, sandstorms are frequent in the spring and autumn, with intense storms occurring every three to five days on average.

According to Li Jian, to overcome these challenges, the project utilizes monocrystalline single-sided photovoltaic modules and lithium iron phosphate battery storage units, which have been carefully selected for their exceptional durability, drought resistance, and ability to withstand windblown sand.

As the desert sun sets, a dramatic temperature shift occurs: the scorching heat gives way to freezing cold, with temperatures sometimes plummeting to as low as minus twenty to thirty degrees Celsius. This extreme temperature fluctuation poses a significant challenge to photovoltaic power stations, which not only face the challenge of huge temperature variations but also lose their “power” for operation. This is particularly detrimental to the stable and continuous operation of the equipment.

To address this challenge, tailored solutions have been developed to enhance the photovoltaic power station's resilience. The first approach involves using the electricity generated by the photovoltaic panels on sunny days to power the load, with emergency diesel generators serving as a backup during periods of weak or no sunlight.

The second solution involves the integration of energy storage batteries, which are replenished by the excess electricity generated by the photovoltaic panels during the day. And when sunlight is limited, the energy storage unit discharges to meet the load's power demands. In extreme conditions such as sandstorms or rainy days with no sunlight, the diesel generators are activated as a last resort to provide emergency power to the load.

According to Li Jian, the customized solutions have yielded significant benefits in terms of carbon emissions. The energy storage unit, in particular, boasts a substantial storage capacity, enabling it to provide electricity for up to seven hours, thereby meeting the minimum sunshine duration required for irrigation during periods of weak sunlight. Additionally, it fulfills the electricity needs of on-duty workers during the night. Notably, when there is no sunlight, irrigation will be suspended, achieving a complete elimination of carbon emissions.

To ensure the stable operation of equipment, the zero-carbon demonstration project adopts a process that can not only creates a temperature-controlled operating environment, but also enhances dust resistance, as well as extends the lifespan of critical equipment.

"The entire construction line vertically spans 343 kilometers. To facilitate on-site work and boost efficiency, we optimized the foundation design of the solar panels, thereby minimizing the need for back-and-forth transportation, lowering the amount of excavation work required for the foundation pit, and significantly reducing construction costs," said Li Jian.

Thanks to the optimization exploration of technical routes and construction methods, the zero-carbon demonstration project was completed in just over 140 days from start to finish.

Photo shows the construction site of the zero-carbon demonstration project in northwest China’s Xinjiang Uygur Autonomous Region. (Photo provided by Tarim Oilfield Company of China National Petroleum Corporation)

A new eco-friendly approach for sand control

The zero-carbon demonstration project, China's longest photovoltaic irrigation and sand control project, provides "green" power for irrigation in the vast sandy desert, sowing seeds of hope for the environment.

Building a photovoltaic power station in the Taklamakan Desert requires preventing both the hollowing around the piles and the burial of solar panels by sand. This is a challenge brought by the erosion of shifting sands.

The "problem-solving approach" was clarified from the very beginning of the zero-carbon demonstration project design - to fully utilize the "inherent advantages" of the solar panels.

Li Jian explained, "The solar panels, which are about 2.8 meters tall, have a windbreak height that is five to nine times that of most desert vegetation, which can disrupt wind direction and reduce wind speed. Therefore, whether it's for local sand fixation or the interception of passing sand, its role is far greater than that of various sand barriers. Adhering to the principle of 'minimum land occupation and avoidance of tall trees,' while constructing the solar panels, we also use reed grass checkerboard sand barriers with good sand control effects around the solar panels within a certain range, greatly slowing down the advancement of sand dunes."

In desert areas, where the land is vast and the population sparse, the power consumption of water wells is low, and the photovoltaic (PV) installed capacity is small. PV panels can be flexibly arranged according to the terrain of sand dunes and the distribution of forest belts. As long as they maintain an inclination of 37 to 41 degrees, it will not only facilitate the self-cleaning of sand, but also ensure that there is no mutual shading from nine a.m. to three p.m. throughout the year.

"The shaded areas created by the PV panels can reduce the evaporation of moisture in the desert soil, thereby improving the growing environment for seedlings to a certain extent. The growth and proliferation of vegetation can, in turn, reduce the dust around the PV panels, increasing the power generation efficiency of the solar cells, thus forming a virtuous cycle of ecological patterns," added Li Jian.

Generating power on the panels, while providing shade underneath for green planting, the zero-carbon demonstration project has achieved an organic integration of photovoltaic power generation, sand prevention and fixation, and desert management, providing the "Tarim Plan" for national desertification control and the operation and maintenance of desert highways.

Over the past two years, under the "guardianship" of the zero-carbon demonstration project, an ecological micro-environment has gradually taken shape: the protective forests on both sides of the highway are lush and green, with an average "height" exceeding two meters, and many wild rabbits, sand foxes, and birds have made their homes here, adding a touch of vitality to the vast desert.

Photo shows an aerial view of the photovoltaic power station in the heart of the Taklamakan Desert in northwest China’s Xinjiang Uygur Autonomous Region. (Photo provided by Tarim Oilfield Company of China National Petroleum Corporation)

Green hope is actively growing, while the comprehensive benefits continue to emerge.

The Taklamakan Desert has transformed into a "hotbed of green energy." To date, the zero-carbon demonstration project has generated over six million kWh of green electricity, achieving the dual effects of desert control and environmental protection.

In the same expanse of sand, four photovoltaic power stations with a total installed capacity of 1.3 million kW have taken root in the heart of the desert, producing over 600 million kWh of green electricity this year, providing security for power supply during peak summer demand and supporting the green development of the economy and society.

Meanwhile, a photovoltaic power generation project, the size of which is equivalent to 3,285 football fields and with an annual designed power generation of 2.1 billion kWh, is gradually moving from planning to reality.

Oil and gas resources are "gushing" forth. Leveraging the desert highway, 32 modern large and medium-sized oil and gas fields in the Tarim Basin have sprung up rapidly like mushrooms after rain, becoming China's largest ultra-deep oil and gas production base and the main source of natural gas for the West-East Gas Pipeline Project.

The launch of the zero-carbon demonstration project has sown the seeds of green hope in the "Sea of Death." Now, this path of green, low-carbon development, which emerges from the vast desert, continues to extend deeper into the desert.

"Oil and gas development is a high-carbon-emitting industry, and to achieve the dual carbon goals, we must strive to reduce carbon emissions. At present, we are working on the development of carbon capture and related technologies, capturing carbon dioxide for direct use or storage to reduce carbon emissions," said Zhang Bo, Party branch secretary and deputy director of the Geological Research Institute of the Lunnan Oil and Gas Field.

He introduced that the next step will be to coordinate carbon dioxide capture for enhanced oil recovery, effectively reducing carbon emissions while comprehensively promoting the development of new energy businesses, ensuring the continuous vitality of the oasis that keeps creating "miracles."

Source : Central Commission for Discipline Inspection and National Supervisory Commission Website, Editor Chen Yao