Today, we welcome for a guest post (and video…eco-rapping included!) Sustainable John of China’s Green Beat, which is back after a seven month hiatus with this excellent expose on geothermal energy in the Middle Kingdom’s capital.
You may not know it looking around Beijing, but not all of the buildings you see are heated with natural gas and coal. Some are heated (and some cooled as well) using geothermal energy. Two main technologies are currently being employed in Beijing to this end:
- Deep well geothermal
- Ground source heat pumps
Deep well geothermal 深层地热井
Beijing has some unique geothermal resources. Far below the Earth’s surface underneath Beijing’s skyscrapers, apartments, and parks, there is an enormous amount of water at a natural temperature of 60-70 degrees. This is the reason why Beijing has a lot of hot spring hotels and spas. The process of using this energy involves drilling down deep into the earth and then pumping the water up so it can flow through the piping of a building, providing natural heat. Some environmental concerns have been raised about the technology, since when the water is pumped up, there are a lot of heavy metals in it. The water is treated before used for heating, but some say there is long-term damage to underground water resources, even though the water is reused.
The process for building deep geothermal well systems takes a long time and a large amount of upfront investment, but many companies and residential developments are taking advantage of this resource not just to save on lifecycle energy costs but also to market their product to a consumer looking for some natural hot springs. It’s a selling point used in the advertisements for these apartment complexes.
Right now, Beijing has about 300 such deep wells for using this unique resource, and every year about 20 new wells are being drilled.
Ground source heat pumps 地源热泵
Ground source heat pumps are a technology used all over the world. The technology is based off the fact that the earth’s temperature 25-100 meters below the surface is usually constant around 20 degrees Celsius, no matter what season it is. This constant, natural temperature can help cool our buildings in the summer and heat our buildings in the winter. Using technology similar to refrigerators and air conditioners, a heat pump extracts the ground’s heat in the winter (heating) and exhausts heat back into the ground in the summer (cooling).
The way Green Beat found out that Beijing was using a great deal of this technology was through the critically acclaimed Linked Hybrid, a new 11 building apartment complex near the northeast second ring road in Beijing. Linked Hybrid is using ground source heat pumps to meet over 2/3 of its heating and cooling needs. In addition to using clean energy, however, the architects and engineers emphasized lowering the demand for heating and cooling in the first place. Two very simple and effective ways they did this was buy using top grade wall insulation and window systems. The technologies (mostly imported from Germany) not only offer energy benefits, but also benefits in comfort, noise and pollution control, and aesthetics. For instance, all the piping for heating and cooling is placed in the floors and walls for radiant heating, so visually there is no stack or wall air conditioning units with improves both indoor and outdoor aesthetics. However, this complicated and added cost to the construction process. They also had to drill a couple hundred mini wells for the ground source heat pump piping. Add to this the fact that there is a parking lot under the entire complex, and let’s just say this construction wasn’t for any old migrant worker. The end result: some of Beijing’s most pricey real estate. One nice thing about the complex was that it isn’t gated like most of Chinese real estate development these days. You can approach it from a number of directions on foot, although there isn’t much nearby in the way of shopping or errands.
Ground source heat pump technology is being used elsewhere. At the end of 2007, the amount of building space in Beijing using ground source heat pumps amounted to 10.5 million square meters. By 2010, the government plans this number to grow to 35 million square meters. To you, that may or may not sound like a lot, but keep in mind, China has over 40 billion square meters of buildings already, growing by 6% per annum. Geothermal is also growing in other parts of the country. The Zhejiang provincial government has a target for 5 million square meters of building space to use ground source heat pump technology by 2012.
Geothermal power 地热发电
Well, it seems the use of geothermal energy for heating and cooling is growing in China. How about power? Is there any hope for China to power any part of its grid with geothermal the way Iceland (26.5% of electricity generation), Philippines (23% of electricity generation capacity), and the US (only 1% of electricity generation, although most installed electrical generation capacity worldwide with over 3GW now) do?
To easily produce electricity, water temperatures of over 150°C are needed, so these are usually concentrated around volcanic activity. China’s geothermal resource belt is mostly in Tibet, with parts in Western Sichuan and Yunnan as well. There are additional low temperature (<150°C) resources found in southeast China (Hunan, Jiangxi, Fujian, and Guangdong provinces).
Some of the resources in Tibet have been explored and developed. In 1988, 1993 and 1996, three boreholes in the northern hydrothermal alteration area of Yangbajan Geothermal Field in Tibet reached depths of 970, 2007 and 1459 m with measured temperatures of 202, 330 and 251°C, respectively. Eventually power plant equipment was installed in this area. At the end of 2003, China had a 24MW plant installed at Yangbajan which annually produces 100GWh, a significant chunk (between 1/4 and 1/3) of Lhasa’s requirements. Total capacity as of 2004 was 28.18MW, with other small plants/pilot projects installed in western Tibet, Guangdong, and Hunan. Given that the best resources are where the least needs are, China’s long term plan is not that ambitious: 75MW by 2020, 200MW by 2030, and 500MW by 2050.