Aims
Water use and consumption for thermal power generation has had several estimation attempts regionally, by country and globally. However, all the previous estimations had fallen short of reality, as sources for data and ratios in each previously reported case have shown instances of unfeasibly low water consumption. This is because water use and consumption are often not reported, and agencies in charge of monitoring water use are scarce, independent of each other and do not use standardised methods for measurement of water use. Therefore, the main target of this work was to develop a new method to estimate on a per power plant basis the global water use and water consumption by thermal power stations. Furthermore, the per power plant basis of the study allowed to make projections of water released from cooling systems at the decommissioning point at a global level.
Methods
With the database of Publication I used as a base for the work, a satellite survey of the registered thermal power plant units of 50 MW and higher was carried out in order to identify their exact location and their cooling system type. Then, according to their identified location and distance to the nearest water body, water source was assigned as fresh water or saline water. Then, an extensive review was conducted to find the specific ratios of water use and consumption assigned to different combinations of generation technology and cooling system type. For the next step, the water use and consumption were distributed and geographically allocated to countries, regions and rivers of the world. Finally, two scenarios for power plant decommissioning were created to present the potential reduction in water, as thermal power plants are phased out and replaced with renewable energy power generation.
Results
Globally, water use for cooling by the power sector adds up to 500 km3 of water, 290 km3 of which are freshwater for the thermal power plant fleet active in 2014. For the same year, water consumption for cooling was estimated to be 25 km3 globally, 18 km3 of which was freshwater. The countries with the highest water losses were China, the United States, India and Russia, with China experiencing the highest water consumption and the United States showing the highest water use. Worldwide, the rivers most affected by water consumption are the Ohio River, the Yellow River and the Mississippi River, while water withdrawals experience their highest numbers in the Yangtze River, the Mississippi River and the Tennessee River. Depending on the decommissioning strategy, by 2030, an 85%
reduction in water consumption can be achieved globally, and by 2050 it can by further reduced to up to 97% if energy generation transitions to renewables, such as solar PV and wind.
6 Discussion
6.1
General discussion of the presented resultsThe global energy system has been changing and evolving from its inception and will continue to do so in order to adapt to the growing demand and shifting needs of society.
Over the decades, power generation technologies have shifted roles from non-existent, sometimes to a top player, and in some cases back down to a diminished presence in the global energy system.
Noticeably, over the past two decades, the global power generation capacities have been experiencing a clear tendency favouring solar PV and wind over other generation technologies. This evolutionary tendency is likely the result of three main factors: the unanimous message from the scientific community showing the correlation between carbon emissions and climate change, the increased societal awareness of that message and the exponential increase in the cost-competitiveness of wind and solar PV in comparison with other technologies.
Ultimately, and by definition, non-renewable power generation technologies are destined to eventually collapse, as their fuel source under constant use will eventually be depleted.
Therefore, a global energy system evolving towards renewables not only makes sense but is indeed inevitable.
However, the “when” and “how” this transition is completed is still under discussion and development, and the short- and medium-term future of the energy system depends on the decisions being taken today. These decisions, whether to go to renewables or fossil or nuclear, will inevitably shape the local, and in an aggregated manner also the global energy system, for the next three to four decades.
Furthermore, despite climate change being a global issue, different regions, sometimes within countries, are evolving at different paces towards renewables. Moreover, this phenomenon seems not to always follow technical developments, scientific guidelines or availability of resources. Instead, there is still a strong influence of politics. A good example case of this phenomenon is nowadays the United States, where the federal government is rolling back environmental regulations, but states and cities within the country have become more invested in reaching carbon neutrality.
On the other hand, society is a factor that can significantly accelerate the transition towards renewables. An informed society is able to pressure governments to move faster towards sustainability. Over time and through democracy, an informed society is able to shape governments and promote environmental targets.
Ultimately, just as currently the factors affecting the decision-making on capacity installations vary widely across countries and regions, these factors and their priorities are likely to also change over time. For example, non-hydro renewables started
development after the oil crisis of the 1970s, over the realisation that fuel dependency is a threat to energy security. Similarly, in the mid-1980s, it was the concern of safety that drove the global energy sector away from the then dominating nuclear energy after the Chernobyl nuclear disaster. Likewise, new factors may arise, or current factors may shift relevance in their shaping of the global energy sector.