In China, the application of renewable energy witnesses rapid development. In the near future, a lot of demonstration projects will be built and thus it is urgent to know the economics of renewable energy building application technologies. Based on the renewable energy demonstration projects in Chongqing city, the author discussed the economy issue of water-source heat pump system (WSHPs) in order to provide suggestions for the application projects. According to the design information of demonstration projects, the average incremental investment, allowance, and payback period are calculated in this paper. Comparing WSHPs with traditional heating, ventilation, and air conditioning (HVAC) system, the saved energy of WSHPs is estimated in the current paper. The author calculated the amount of saved energy in unit applied area and unit intake water. Besides, the economy and efficiency of WSHPs project is analyzed at the end of this paper.
China is an energy consumption power. The shortage of energy resources is a big problem. Nowadays, conventional energy resources cannot meet the current huge energy demand and thus it is urgent to apply renewable energy technologies to solve the problems of energy shortage. In China, about 1/3 of total consumed energy is used in building, and HVAC systems account for more than 50% building energy consumption [
Chongqing city (located at Western China, upper reaches of Yangzi River) belongs to typical hot summer and cold winter climate. The average temperature of Yangzi River and Jialing River is about 19–26°C in summer and 9–16°C in winter. Tests show that (1) both of the two rivers have an inconspicuous effect on vertical temperature stratification, (2) in addition to turbidity and sediment concentration, the water quality of two rivers can meet engineering requirements [
In Chongqing, pilot programs of WSHPs have been carried out since 2006. There are three projects including Yangzi River, Jialing River, and reservoir WSHPs. The three projects run well and then the first batch of renewable energy demonstration projects was organized in 2007 (six projects, 500,000 m2 building application in total). In 2008, the second batch of renewable energy demonstration projects was started. In 2009, Chongqing city successfully declared a national renewable energy demonstration city of China and needs to complete nearly 3.2 million m2 renewable energy applications. In recent years, more and more WSHPs demonstration projects have been invested. The author collected and sorted out data resources of those projects and got design information of eight WSHPs projects. Based on the information of those eight projects (including design system EER, investment payback period, energy savings, etc.), this paper presents an analysis of the operating efficiency, the increase investment, the investment payback period, and technological economy of WSHPs.
The water intake equipment and water treatment system are the essential components of WSHPs. Water intake equipment transport water into the host. And water treatment system improves water quality to meet the operation requirements of WSHPs. Due to the water intake equipment and water treatment system, the initial investment of WSHPs is higher than traditional HVAC system (water-cooled chillers in summer and boiler in winter). Thus, many countries including China use policy incentives to promote the development of heat pump system [
The average incremental investment and allowance of WSHPs project.
Building function | Building area |
Incremental investment |
Allowance |
Average building area allowance |
Payback period | |
---|---|---|---|---|---|---|
1 | Hotel | 2.6 | 195 | 119.92 | 46.12 | 12.4 |
2 | Hotel | 1.18 | 247 | 108.96 | 92.34 | 9 |
3 | Office | 5.4 | 95.07 | 468.48 | 86.76 | 12.4 |
4 | Office | 3.8 | 166.14 | 279 | 73.42 | 15 |
5 | Commercial and residential | 35 | 221.7 | 951 | 27.17 | 8.26 |
6 | Commercial and residential | 7 | 76.9 | 468.56 | 66.94 | 18 |
7 | Commercial and residential | 5.4 | 292.41 | 843 | 156.11 | 13.5 |
8 | Commercial and residential | 30 | 249.6 | 2272 | 75.73 | 7.29 |
| ||||||
Average | 193.01 | 78.07 | 11.98 |
The average incremental investment of WSHPs is CNY 193.01/m2 and the average allowance is CNY 78.07/m2, which is about 40.5% of the average incremental investment. Without the allowance from government, the average payback period of WSHPs is about 11.98 years, while the average working life of the HVAC system is between 15 and 20 years. If allowance is considered, the average payback period declines to 7.13 years, a reasonable payback period. It is obviously that the payback period of WSHPs is too long to be wildly used without the support of the government.
Previous studies collected and sorted the system EER of traditional HVAC system of public building in Chongqing city [
The design system EER of traditional HVAC system.
Building function | Building number | Average design system EER in summer* | Average design system EER in winter* |
---|---|---|---|
Market | 26 | 2.9 | — |
Hotel | 12 | 2.56 | 1.62 |
Office | 122 | 2.71 | 1.58 |
| |||
Average | 2.72 | 1.6 |
The design system EER of WSHPs.
Building function | Rated cooling capacity (kw) | Average design system EER in summer | Average design system EER in winter | Actual operational EER | |
---|---|---|---|---|---|
1 | Hotel | 1499 | 3.57 | 2.93 | — |
2 | Hotel | 1362 | 4.11 | 3.17 | 3.4 in summer |
3 | Office | 5856 | 3.26 | 3.13 | — |
4 | Hospital | 3489 | 3.3 | 3.3 | 2.9 in summer and 3.1 in winter |
5 | Commercial and residential | 11887.5 | 4.13 | 3.62 | 3.6 in summer |
6 | Commercial and residential | 3888.2 | 4.5 | 4.1 | — |
7 | Commercial and residential | 10548 | 3.77 | 3.65 | 3.1 in summer |
8 | Commercial and residential | 28400 | 4.15 | 3.29 | — |
| |||||
Average | 3.85 | 3.40 |
In Chongqing, the average design system EER of traditional HVAC system is 2.72 in summer and 1.6 in winter (shown in Table
According to the design information of the eight WSHPs projects, the author calculated the average amount of saved energy in unit applied area and in unit quantity of water, shown in Tables
The average design saved energy amount in unit applied area.
Building area (10,000 m2) | Design amount of saved energy (Tce*/year) | Amount of saved energy in unit applied area (Tce/10,000 m2) | |
---|---|---|---|
1 | 2.6 | 307 | 118.08 |
2 | 1.18 | 141.6 | 120 |
3 | 5.4 | 189.6 | 35.11 |
4 | 3.8 | 160 | 42.11 |
5 | 35 | 1234.22 | 35.26 |
6 | 7 | 315.23 | 45.03 |
7 | 5.4 | 777.9 | 114.06 |
8 | 30 | 8550 | 285 |
| |||
Average | 99.33 |
The average design saved energy amount in unit intake water.
Water intake amount (m3/h) | Design amount of saved energy (Tce/year) | Design performance period of HVAC system per year (h) | Amount of saved energy in unit water (Tce/m3) | |
---|---|---|---|---|
1 | 328.3 | 307 | 2400 | 3.896 × 10−4 |
2 | 489 | 141.6 | 2400 | 1.21 × 10−4 |
3 | 1200 | 189.6 | 2400 | 6.58 × 10−5 |
4 | 750 | 160 | 1600 | 1.333 × 10−4 |
5 | 5600 | 1234.22 | 3048 | 7.23 × 10−5 |
6 | 439 | 315.23 | 1600 | 4.488 × 10−4 |
7 | 1908 | 777.9 | 2400 | 1.699 × 10−4 |
8 | 3235 | 8550 | 3650 | 7.241 × 10−4 |
| ||||
Average | 2.656 × 10−4 |
The average design saved energy amount in unit applied area is 99.33 Tce per 10,000 m2 per year and the average design saved energy amount in unit water is
According to the above statement, if the government invests CNY 50 million to support WSHPs, projects may achieve great economic and environmental benefits (as shown in Table
The economic and environmental benefit of every 50 million.
Value | |
---|---|
Invested money | 50,000,000 (CNY) |
Average building area allowance | 78.07 (CNY/m2) |
Demonstration area | 64.05 (10,000 m2) |
Coal saving amount per year | 6362.09 (Tce) |
Electricity saving amount per year | 1574.78 (10,000 Kwh) |
Reducing CO2 emission per year | 14486.48 (Tons) |
As the average building area allowance is CNY 78.07/m2, the demonstration area of WSHPs projects will be 0.6405 million m2 if CNY 50 million is invested. These projects will possibly save 6362.09 Tce, a reduction of 14486.48 tons of CO2 emissions and save 15.7478 million Kw energy consumption per year. CNY 50 million invested to support heat pump system projects makes a significant contribution to environmental protection. Also, these projects can relieve the increasing pressure on the power grid and reduce the investment in electric power plants. The economy and efficiency of WSHPs is remarkable.
WSHPs can hardly be popularized without the support of the government as the initial investment is too high at present in China. The design system EER of WSHPs is 3.85 in summer and 3.40 in winter, a rise of 41.54% and 112.5% form those of traditional HVAC system, respectively. However, the incremental investment is up to CNY 193.01/m2. It is estimated that the payback period will be nearly 12 years without allowance. The average allowance is CNY 78.07/m2, nearly 40.5% of incremental investment, so if the allowance of government is considered, the payback period of WSHPs project will be declined to nearly 7 years. The economy and efficiency of WSHPs is remarkable. According to the above estimation, if CNY 50 million is invested to support WSHPs applications, these projects will bring great benefits. One-off subsidy will possibly reduce the consumption of Tce and achieve a reduction of CO2 emission, so it will contribute to reduce greenhouse emissions and protect the environment.
The authors would like to thank the Chongqing Municipal Commission of Urban-Rural Development for providing project material and technical support for this study. The paper received Project (2010DFA72740-03, 2010DFA72740-06-06) support from US-China Clean Energy Research Center.