Air pollution levels drop markedly after switching to renewable energy sources
Workers install photovoltaic panels at a farm in Qingdao's West Coast New Area, Shandong province, in March 2022. (HAN JIAQUN / FOR CHINA DAILY)
Qingdao, a key export and economic hub in East China's Shandong province, has shown substantial improvement in air quality after switching its major heating source from coal to natural gas in key urban districts and developing a network of multiple clean energy resources.
In September, its PM2.5 level fell to 18 micrograms per cubic meter, while concentrations of inhalable particulate matter — sulfur dioxide, nitrogen dioxide and carbon monoxide — had all turned first-class by national standards on air quality.
PM2.5 is the average concentration of fine particles of less than 2.5 microns in diameter and is a common measure of air pollution levels.
While Qingdao's annual average concentration of fine particles was as high as 59 micrograms per cubic meter in 2014, it had dropped to 26 by 2022, data from the city government showed.
"In the past, the 44 coal-fired boilers in the main urban areas of Qingdao often operated at full capacity each winter, causing heavy environmental problems from coal transportation, spill of cinder, chimney discharge and coal storage," said Xu Bing, general manager of Qingdao Energy Group, a State-owned large-scale energy supplier. "Today, such a sight has disappeared forever."
In its energy development plan for the 14th Five-Year Plan (2021-25) period unveiled in late 2021, Qingdao vowed to expand the scale of clean energy utilization, increase the proportion of non-fossil energy in its energy consumption structure, and reduce coal consumption.
By 2025, coal is expected to account for 23.5 percent of primary energy use. Consumption of coal-fired power, clean energy and external power transmitted to Qingdao will be optimized, to account for 21.5 percent, 27 percent, and 51.5 percent, respectively, of total electricity consumption in the city, according to the plan.
To promote the use of clean energy, the city will carry out projects to supply natural gas for heating in urban areas, and steadily promote clean heating projects such as "coal-to-gas" and "coal-to-electricity" in rural areas in accordance with local conditions, the plan showed.
The city will also continue to expand the use of clean energy, such as solar energy, geothermal energy, biomass energy, and industrial waste heat, while promoting the integration of renewable energy-based and conventional fossil energy-based heating systems.
It is estimated that the coal-togas conversion project will help the city reduce consumption of around 1 million metric tons of coal per year, thereby cutting carbon emissions by 850,000 tons annually.
Thanks to loans worth about $130 million provided by the Asian Development Bank, the company started the three-year project in 2021, together with other initiatives to promote low-carbon and digital transformation of energy supplies in Qingdao.
The total investment for the project as well as for other initiatives is planned at 1.68 billion yuan ($230 million), which also includes special local government bonds and funds from Qingdao Energy, in addition to ADB loans.
Technicians inspect heating supply status at a natural gas power station in Qingdao in December. (PHOTO / XINHUA)
As of end-October, the first and second phases of the project had been completed, which can provide heating to an area of more than 11.43 million square meters, reducing coal consumption by 92,800 tons per year.
The project can also reduce emissions of ash and nitrogen oxide by 30,000 tons and 137.05 tons, respectively, per year.
The project, which upgrades the energy mix and improves the air quality in Qingdao, also aims to set an example for the rest of the country amid China's efforts to honor its dual-carbon goals.
According to Xu, switching to natural gas as a heating source has reduced pollution on multiple fronts.
For instance, natural gas is transported by pipeline, which means it seldom causes pollution from transportation.
The new boilers, which adopt a low nitrogen-based combustion method, no longer need external flue gas treatment facilities. Besides, the natural gas heating plants are also in harmony with the surrounding environment, unlike coal-fired heating plants that discharge white smoke.
After the coal-to-gas conversion revamp, the Jinze heating station in Shibei district can meet household heating demand from within 8 million square meters.
At the same time, the vacant coal storage facility has been turned into a community cultural and sports center with an area of more than 10,000 square meters, becoming a good place for community residents to refresh and exercise.
Ding Ruiping, deputy general manager of Qingdao Energy, said that the company's heating supply capability has surged more than 40 percent, thanks to the implementation of the project.
In addition, about 380 mu (25.3 hectares) of land has been saved from the renovation of the heating plants for other more productive uses.
A resident surnamed Han, who lives near the heating plant in Shibei district, said the coal-to-natural gas switching project has greatly benefited his neighborhood, as they no longer have to suffer from dust and smoke from the coal-fired unit.
Apart from natural gas, the city has also made use of other new and clean energies, mostly renewables like distributed photovoltaics and ocean thermal energy.
"To reduce carbon emissions, Qingdao needed to phase out coal-fired boilers and a centralized heating network and switch to a distributed system relying on natural gas and other renewable energies for heating," said Lu Lanlan, a senior project official of ADB.
To achieve this, ADB has facilitated the sharing of experiences between the Qingdao and Swedish industry associations in heating and cooling, Lu said.
The project design has fully taken into consideration that a single clean energy source alone cannot meet the growing heat demand in Qingdao, nor achieve overall low-carbon transformation of the heating system while the city phases out its coal-fired power plants.
Therefore, a "multienergy complementarity" approach — a combination of multiple clean and renewable energies — has become the core aspect in promoting a low-carbon transformation of Qingdao's heating system, she added.
For example, the Qingdao Olympic Sailing Center, a community of 10 buildings, has achieved zero CO2 emissions by improving energy efficiency, phasing out fossil fuels, reducing the use of natural gas, and increasing the use of renewable energies.
The distributive photovoltaic facilities on the roof of the Qingdao International Convention Center, part of the Olympic sailing center, not only generate power to meet demand from the convention center, but are also able to provide electricity to the Qingdao power grid.
Their average annual power generation is 760,000 kilowatt-hours, saving 224 tons of standard coal and reducing carbon dioxide emissions by 580 tons per year.
Apart from common renewable energy sources like solar photovoltaics and wind energy, the center also makes good use of clean energy technologies to heat or cool the buildings, such as industrial waste heat recovery and seawater source heat pumps.
The center can save 3.03 million kWh of electricity, 22,000 gigajoules of heat, and 5,500 standard cubic meters of natural gas every year, therefore slashing 8,663 tons of carbon emissions.
Wei Qingpeng, an associate professor at the school of architecture at Tsinghua University, said that buildings account for about 21.7 percent of China's energy consumption, and Qingdao's "multienergy complementarity" approach for heating and energy supply has accumulated valuable experience in developing an energy model centered on new energy sources.
