According to Navigant Research, the global building stock is expected to grow from 151.8 billion m2 in 2014 to 171.6 billion m2 in 2024. Most of the new growth is expected to occur in China, where approximately 1 billion m2 of space is forecast to be added to the total commercial and residential building stock every year. North America and Western Europe each represent significant portions of the total building stock.
Commercial, residential, and industrial buildings are responsible for 47% of global greenhouse gas emissions and 49% of the world’s energy consumption. Much of the energy associated with the power used in operating these buildings is consumed needlessly and can be reduced through cost-effective measures. Knowledge of the size and composition of the global building stock is essential for understanding the built environment and the potential market for new energy efficiency technologies, as well as the impact those technologies can have in helping to achieve significant reductions in energy consumption and carbon emissions on a global scale.
China’s district heat network – which supplies heat from central locations – is the world’s largest: in 2015, it consumed more energy than all of the United Kingdom. But district heating is also major source of air pollution in many Chinese cities. The beginning of the winter season usually coincides with a surge in air pollution, mostly due to coal-fired boilers used in commercial heat production.
On an annual basis, pollutant emissions from coal-fired district heating represent between 3% and 5% of total energy-related pollutants nationwide. But northern cities are much more affected, as pollution from heating is concentrated there.
District energy systems are currently mostly fueled by coal. In 2016, 33% of total floor area was heated by coal-fired boilers for commercial heat production, and co-generation (mostly coal) accounted for 51%, the rest coming from gas and other sources.
China had the world’s largest district energy system in 2015, covering 192 721 kilometres (km) of hot water networks and 11 692 km of steam networks.
• District heat generation in China consumed more than 185 million tonnes of coalequivalent (Mtce) in 2015, higher than national energy consumption of United Kingdom.
• The district heat network in China currently covers around 8.5 billion square metres (m2) of buildings floor area, having nearly tripled since 2005, and it continues to expand.
• Total buildings floor area covered by the district heating network in Northern China tripled over the last decade, representing nearly all the floor area growth in the northern urban heating (NUH) area since 2005.
China’s government agencies, the National Development and Reform Commission (NDRC) and the National Energy Administration have announced a five-year plan to convert 70% of northern cities to mostly natural gas heating instead of coal.
The government has made “concrete arrangements” regarding geothermal heating, biomass heating, solar heating, gas heating, electric heating, industrial waste heating, and clean coal-fired central heating.
Half of northern China should be converted to clean heating by 2019, reducing bulk coal burning by 74 million tonnes, the reports said. That reduction should reach 150 million tonnes by 2021.
China consumed more than 200 billion cubic meters of natural gas annually and nearly 40 percent of that came from imports. China would continue to rely on imports for a “very considerable period”, according to the magazine.
According to recent media reports, pupils at schools in some rural areas whose coal-fired heaters had been dismantled were forced to study outside – as it was warmer than inside – or run around to generate body heat.
In a “double urgent” letter two weeks ago, the Chinese Ministry of Environmental Protection told authorities in 28 cities to relax the coal ban at places where the conversion process had not been completed.
China already has massive district heating networks
China will be able to develop low-cost, safe nuclear deep pool heating reactors and drop them in and replace the coal heating.
Super low-cost nuclear heating option could be possible in a few years
On November 28, 2017, China National Nuclear Corporation officially launched a project to create a 400-Megawatt Yanlong deep pool-type low-temperature heating reactor. A 400-megawatt Yanlong low-temperature heating reactor could heat as much as 20 million square meters, the equivalent of 200,000 three-bedroom homes.
A demonstration reactor was already used to (49-2 heap) to heat 10,000 square meters of buildings (about 50 three bedroom homes) in the institute for 168 hours. This proved the feasibility of the pool-type low-temperature heating reactor and marked important progress for the China National Nuclear Corporation in the field of nuclear heating technology. It provided strong technical support for the follow-up of pool type low temperature heating reactor model development. China National Nuclear Corporation also established a research center for nuclear energy heating technology.
The models of the pool type low-temperature heating reactor as “Yanlong” and “DHR-400” respectively. The heating reactor was developed in Yan, so its name included a “Yan.” The Dragon Series of reactors was researched and developed by China National Nuclear Corporation. Since the Chinese word for dragon is “long,” the reactor was named Yanlong. DHR-400 means district heating reactors, and “400” refers to the thermal power of the reactor, which is 400 megawatts.
Pool type research reactors have been tested and safely operated for more than 50 years.
Hundreds will be made to provide heat in Northern Chinese cities in the winter. This will prevent the burning of 500 million tons of coal every winter.
District heating is fairly common in Northern Europe and Russia.
District heating systems can vary in size. Some systems cover entire cities such as Stockholm or Flensburg, using a network of large 1000 mm diameter primary pipes linked to secondary pipes – 200 mm diameter perhaps, which in turn link to tertiary pipes of perhaps 25 mm diameter which might connect to 10 to 50 houses.
The first DH system in Sweden was in operation in 1948, but the more rapid build-up of these systems started in the 1960s. Now virtually all Swedish towns have a DH system. District heating accounted for 86% and 69%, respectively, of the energy use for heating
of multi-dwelling buildings and non-residential premises, while the corresponding proportion was 10% in one- and two-dwelling buildings Total DH production in 2007 amounted to 56.3 TWh (47.5 TWh was delivered) and was dominated by biomass, which accounted for 44% of the production.
Typical annual loss of thermal energy through distribution is around 10%, as seen in Norway’s district heating network.
Waste heat from nuclear power plants is sometimes used for district heating. The principles for a conventional combination of cogeneration and district heating applies the same for nuclear as it does for a thermal power station. Russia has several cogeneration nuclear plants which together provided 11.4 PJ of district heat in 2005. Russian nuclear district heating was planned to triple by 2015. Other nuclear-powered heating from cogeneration plants are in Ukraine, the Czech Republic, Slovakia, Hungary, Bulgaria, and Switzerland, producing up to about 100 MW per power station.
China’s deep pool system will generate no electricity, but is designed for ultra low cost heat production.
Each of the proposed heating plants would cost about 1.3 billion to 1.4 billion yuan (US$197 million to US$212 million) to build, a fraction of the price of a commercial nuclear power plan. The feasibility studies of DPR in some cities in China show that heating cost using nuclear energy is only one third of that by coal and only one tenth of that by nature gas.
China uses 4 billion tons of coal each year to produce 3900 TWh of electricity. China uses 1000 GW of coal plants. They are talking about getting rid of 12.5% of the coal with these systems. Displacing 125 GW of coal usage for heating would require about 300 of the 400 MW thermal plants. It would cost about $60 billion.
Each steel-and-concrete reactor pool measures about 10 meters in diameter and 20 meters deep, and holds up to 1,800 tonnes of water. A nuclear core is submerged in the water and can create up to 400 megawatts of heat to water to about 90 degrees Celsius for distribution through the city’s public heating network.
A single reactor can produce enough energy to heat 10 million square meters of living space within a 35km (22 mile) range. Two or three reactors would be enough heat a mid-sized city, though bigger metropolitan centers like Beijing would require more units.
The reactor core is placed in the depths of a normal pressure pool, and the water temperature of the core is heated with the static pressure of the water layer to meet heating requirements. Heat is transferred through a two-stage exchange to heating circuit, which can then be transferred to thousands of homes on a heat network.
The reactor is equipped with a high pressure isolation circuit, which ensures that radiation is isolated from the heat supply network. The pool type low temperature heating reactor is flexible in site selection, available in both inland and coastal areas and it suits northern China. The service life of a pool-type low-temperature heating reactor is 60 years.
Brian Wang is a Futurist Thought Leader and a popular Science blogger with 1 million readers per month. His blog Nextbigfuture.com is ranked #1 Science News Blog. It covers many disruptive technology and trends including Space, Robotics, Artificial Intelligence, Medicine, Anti-aging Biotechnology, and Nanotechnology.
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