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Energy the nexus of everything: December 2010 Archives


A recent story in the domain of the water-energy nexus caught my eye. The story describes the Oyster Creek nuclear power plant in New Jersey will be shutting down in 2019, 10 years earlier than planned, because it otherwise would have had to install cooling towers as a retrofit to the power plant. Environmental groups seem mostly behind the decision, but the Sierra Club is an example of one group that is far from satisfied. From the website of Exelon, the power plant owner, "Oyster Creek began operating in December 1969 as the first large-scale commercial nuclear power plant in the United States. Its single boiling water reactor produces 645 net megawatts (MW), enough electricity to power 600,000 average American homes."

The reason for the decision to shut down the plant instead of retrofitting it with cooling towers stems from an US Environmental Protection Agency (EPA) rule. This rule calls for existing power plants that use "once-through" or open-loop cooling to cease using that design in replacement of wet cooling towers that withdraw less water. The reason this rule exists is that that once-through and open-loop cooling systems withdraw high flow rates of water (up to tens of thousands of liters per kWh) into the power plant to cool the steam cycle, and then discharge that water, now heated, back to the water source. Cooling tower systems withdraw much less 1-5 liters per kWh. In the case of Oyster Creek the water source is Barnegat Bay seawater, and the plant has been blamed for depletion of much of the marine life of the bay.

This EPA ruling that demands conversion of cooling systems from once-through to cooling towers is meant to mitigate impacts upon marine life from sucking in marine animals into the water intake, impinging larger animals onto filter screens, and discharging warm water that disrupts the ecosystem's normal temperature balance. The drawbacks to this retrofitting are increased capital costs, slightly less net power output, and higher water consumption. Cooling towers are generally not used with intake of seawater because the cooling mechanism is via evaporation of the water. Thus, after the water evaporates, salt and other minerals deposit onto the cooling fins of the cooling tower creating a maintenance issue. The costs of chemicals and maintenance are generally not worth using cooling towers with seawater, although the use of cooling towers with freshwater is very common.

It is not clear if the 10-year early close down of Oyster Creek nuclear station is the beginning of a trend or one of a few to be highly affected by the cooling tower ruling. Given that Oyster Creek was the first large nuclear power plant in the US, it perhaps was destined to be one of the first to be retired. Any power plant using once-through cooling with seawater and that is planning on operating more than 5 more years will have a difficult decision to make. For power plants using seawater for cooling, I think it is likely that cooling tower retrofits will benefit the environment via less impacts on marine environments and lower profits (and/or higher electricity costs) of the power plant operator passing on to consumers to lower electricity consumption. Conversions of once-through to cooling tower on rivers and freshwater lakes will have lower economic impacts and the higher water consumption will affect water flows downstream. Thus, the environmental benefits are less clear, but lean toward more beneficial.

Unbeknown to most lay people and many energy insiders, Iran has more going on in the energy industry than nuclear controversy. Given the global location of Iran provides it with some of the world's highest solar insolation, there is actually solar research occurring. Much of the research involved concentrating solar-power technologies and the Iranian scientists were working to ensure that Iran had the domestic expertise to design and install solar CSP systems.

To support much of this solar research, Iran has a government-sponsored Renewable Energy Organization of Iran (SUNA) that is part of the Ministry of Energy. The objective of this organization is to develop applications for renewable energy. The staff includes 300 persons with 150 of those engineers and scientists. The budget is approximately $60 m. Iran even has a feed-in tariff for wind and biomass energy of approximately 13 cents/kWh. Additionally, Iran has a renewable-portfolio standard to meet 10% of its electricity from non-hydro renewable-electricity technologies.

I had the privilege of learning of some of these details while joining a workshop this November between Iranian and US energy and solar-energy scientists and engineers. Joining the Iranians was the head of their National Academy. This workshop was arranged by the US State Department with assistance of the US National Academies. As the US and Iranian governments are officially not on speaking terms, it is nice to know that some parts of the governments are finding ways to keep some communication channels open. Sharing ideas on solar- and renewable-energy technologies may help us find a way to share ideas and shed light on renewing cordial relations. Kudos to the US State Department for finding ways to have international relations using science.