 near term.
However, “negawatt” measures, those that reduce the need for electricity generation in the first place (such as energy-efficient buildings and appliances) not only save money and reduce GHG emissions, but also eliminate the corresponding water use.
PJZ: There is a trade off but recent technology progress also shows how to break the link between the two. In Northern China, many power plants have started employing air cooling technology that substitutes water for cooling. The other possibility is to use more efficient power generators, grids and pumps for water transport in cities. In the short term, the linkage between water and energy will remain but in the longer term it depends on technological change. This will involve looking at what we can do to fund better technology, introduce incentives and encourage new policies.
CWR: While aware of the need to diversify its energy sources and reduce greenhouse gas emissions, it seems China is starting to realize that alternatives to coal are running up against water limits as well. What are some of the issues here?
PJZ: There are several issues here related to the water-energy nexus. Let’s start from Concentrating Solar Power (CSP), which also needs water to produce, to store and, transform the energy into vapor. So for some specific solar technologies you need a lot of water. Nuclear power needs a lot of water for cooling. China has an ambitious target to expand total energy use and this needs complimentary water supply regardless of the energy source. So it doesn’t necessarily mean that when you diversify energy sources that you eliminate the water problem.
The partial answer to this is to introduce incentives – for example, correct water pricing or allocation of water quotas, which are measures we have already been using for a long time. The other is to develop water-saving technology. But this is all complicated. There are many factors to consider. If the price can reflect the real cost of energy generation that is fine but for some end users, the real cost of electricity generation and transmission is a problem. So the direction is right, these are all important to consider, but it is a matter of degree.
CWT: China has the fastest growing renewable capacity of any country in the world. Wind power and solar photovoltaic (SPV) are two bright spots of the new energy economy. Water is not a bottleneck for them—on-site water use is negligible and life cycle water consumption is only 1/7 to 1/5 of the most efficient coal-based technology. Reliability and grid accessibility, rather, are obstacles for wind and SPV.
Nuclear power, on the other hand, is among the most water-intensive energy generation technologies at 2.7 m3/MWh. Various sources indicate that China will significantly expand its nuclear power capacity in the coming decade, and at least 30 GW is expected to be completed by 2015. Though all existing Chinese nuclear power plants are based in the coastal region and use sea water for cooling, proposals on building inland nuclear units have been on the rise. In fact, three Yangtze provinces, Hubei, Hunan, and Jiangxi, are reportedly competing over the first permit from the central government. According to the Medium and Long-term Development Plan for Nuclear Power, several provinces facing water shortages (e.g., Henan and Gansu) are also on the list of potential sites. For those areas, a careful evaluation will be needed to ensure sustainable water supply for cooling, without sacrificing agricultural, human, and environmental water needs.
Likewise, some emerging and future energy generation technologies do pose a challenge for water availability. One example is CSP. Combined with thermal storage systems, this technology could be smoothly integrated into the current grid and even enhance its capacity to accommodate a larger share of variable energy sources. But solar thermal’s cooling water need is exceptionally high – considerably higher than that of nuclear (closed-loop) and almost double that of pulverized coal (PC) per unit of energy generation. Since China’s