the future of more cities, more nuclear energy, and water management

1. There are 22 cities with a population over 10 million people today, according to the United Nations. By 2040 there should be 31 more cities with over 10 million people based on current projections. They will predominantly in China with nine and India with eight. The numbers also show that the world is becoming more urban. For example, whereas only about 25 percent of the people in China lived in urban areas in 1990, that figure grew to 50 percent in 2010, and is expected to reach 75 percent by 2040. India and Africa are following similar tracks. Urbanization is closely associated with energy demand, and greater urbanization is projected to lead to greater electrification around the world.

The link between urbanization and energy demand is tied to several factors:
* The expansion of urban infrastructure creates demand for iron, steel, cement and other industrial goods that are energy intensive.
* Urban income levels tend to be higher than in rural areas
* Energy-intense manufacturing and other industries cluster around cities
* The number of people per household is usually lower in urban settings, which leads to a higher number of actual households.
* Urbanization results in sizable, “lumpy” demands for energy and electricity, which augur well for nuclear power. Urbanization tends to track to higher levels of air pollution, which should help nuclear power as well since it’s a carbon-free generation source.

Large scale nuclear energy construction will be in China and India and to a lesser extent some other emerging countries with urbanization surges. The developed countries in the US and Europe would only do this if they chose to phase out coal and replace it with nuclear but the trend is to shift to natural gas and some solar and wind.

2. China should vigorously develop nuclear energy and restart the plan to build nuclear power stations inland to reduce the nation’s high energy consumption per unit of gross domestic product and clear smog and haze, said The Report on the Development of China’s Eco-Cities (2014). China’s primary energy consumption in 2012 was 3.62 billion metric tons of standard coal, or 20 percent of the world’s total energy consumption.

China creates 14,000 yuan ($2,250) of GDP when burning one ton of standard coal. The figure is the equivalent of 25,000 yuan for the global average, 31,000 yuan for the Unites States, and 50,000 yuan for Japan, the report said

It provided the ranking of 116 major Chinese cities based on their energy consumption per unit of GDP in 2012. Urumqi, capital of the Xinjiang Uygur autonomous region, is at the bottom of the list, generating only 4,184 yuan of GDP per ton of standard coal. Huangshan, Anhui province, tops the list at 22,371 yuan, which is still below the global average.

China consumed about half of the world’s coal in 2012. Half of the consumption was at its thermal power stations, a major discharger of airborne pollutants. As for hydropower, the country has already developed 46 percent of the 500 million kilowatts that is considered the total that can be exploited.

In consequence, the report suggests restarting the plan to build nuclear power stations inland and reducing the number of thermal power stations to achieve greener urbanization.

“Setting up nuclear reactors only along the coast cannot fulfill inland cities’ growing thirst for green energy and the sustainability of the power network during extreme weather,” said Chen Xiaoqiu, deputy chief engineer of the Nuclear and Radiation Safety Center in the Ministry of Environmental Protection.

Chen said developing inland nuclear power plants would be an effective method for optimizing energy distribution and should be considered a necessity for clearing smog and improving air quality in many regions.

China’s per capita share of freshwater resources is one-fourth of the world average.

China may have to look at nuclear reactor designs and cooling designs that use less water.

Cooling Power Plants

Many nuclear power plants have once-through cooling, since their location is not at all determined by the source of the fuel, and depends first on where the power is needed and secondly on water availability for cooling. Using seawater means that higher-grade materials must be used to prevent corrosion, but cooling is often more efficient. In a 2008 French government study, siting an EPR on a river instead of the coast would decrease its output by 0.9% and increase the kWh cost by 3%.

If you sequester CO2 then coal plants use more water than once through nuclear

Dry cooling
Where access to water is even more restricted, or environmental and aesthetic considerations are prioritized, dry cooling techniques may be chosen. As the name suggests, this relies on air as the medium of heat transfer, rather than evaporation from the cooling circuit. Dry cooling means that minimal water loss is achieved. There are two basic types of dry cooling techniques available.

One design works like an automobile radiator and employs high-flow forced draft past a system of finned tubes in the condenser through which the steam passes, simply transferring its heat to the ambient air directly. The whole power plant then uses less than 10% of the water required for a wet-cooled plant,but a lot of power (around one to 1.5 percent of power station’s output) is consumed by the large fans required. This is direct dry cooling, using air-cooled condenser (ACC) and it is not currently in use on any nuclear power plant.

Alternatively there may still be a condenser cooling circuit as with wet recirculating cooling, but the water in it is enclosed and cooled by a flow of air past finned tubes in a cooling tower.* Heat is transferred to the air, but inefficiently. This technology is not favored if wet cooling depending on evaporation is possible, but energy use is only 0.5% of output. This appears to be the back-up system planned for Loviisa in Finland in 2014.

An August 2010 report from DOE’s National Energy Technology Laboratory (NETL) analysed the implications of new environmental regulations for coal-fired plants in the USA. An impending Environmental Protection Agency rulemaking in February 2011 was expected to mandate the use of cooling towers as “best available technology” to minimise environmental impacts from water intakes, rather than allowing site‐specific assessments and cost‐benefit analyses to determine the best option from a range of proven technologies to protect aquatic species. This could mean that all new plants—and perhaps many existing units—need to install cooling towers instead of using once-through direct cooling which do involve a lot of water, but about 96% of it is returned, slightly warmer. Cooling towers, as well as being more expensive, work by evaporating a lot of water, placing stress on supplies of fresh water – they use 1.8 L/kWh according to the report, compared with less than 0.4 L/kWh for once-through cooling. The NETL report noted that the projected increase in coal-plant water use over the next two decades if direct cooling is no longer allowed on new plants does not factor in the likelihood that many coal plants will add carbon capture and storage (CCS) technology to constrain US carbon emissions, thereby increasing water consumption by a further 30-40%.

A 2010 study by the Electric Power Research Institute (EPRI) found that the total cost of retrofitting US power plants with cooling towers would exceed $95 billion. The cost for 39 nuclear power plants (63 reactors) alone would be almost $32 billion. EPRI’s study encompassed 428 US power plants with once‐through cooling systems which were potentially subject to revised US Environmental Protection Agency regulations ostensibly to protect aquatic life from being caught up in the cooling water intake structures. As noted above, under proposed revisions to the Clean Water Act, EPA could have mandated that closed‐cycle cooling is the “best available technology” to minimise adverse environmental impact to aquatic life. EPRI’s study considered capital costs, revenue losses from extended outages required to change the systems, and costs associated with losses in plant efficiency including increases in energy use for fans and pumps in closed‐cycle cooling systems. Such a change would cost $305 per head for 311 million US citizens to retrofit all once‐through cooling system power plants “in order to remedy a virtually nonexistent environmental impact, according to scientific studies of aquatic life populations at these plants,” according to the Nuclear Energy Institute, the US industry association.

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