By Richard Johnson
Against the backdrop of the Fukushima disaster, Mexico has decided to tango nuclear and wind power to meet 23% of the country’s electricity needs by 2026. The new energy plan also envisages connecting the Mexico’s entire population to the grid, cutting back transmission losses and developing abundant shale gas reserves.
Energy minister Jordy Herrera presented the government’s national energy strategy on March 1, 2012 in Mexico City. On top of his priority list was strengthening of the hydrocarbon sector by increasing production of natural gas by 73% and characterising shale gas reserves fast enough to maintain a steady reserve.
Mexico has two nuclear reactors generating almost 5% of its electricity. The country’s first commercial nuclear power reactor began operating in 1989. According to the World Nuclear Association, there is some government support for expanding nuclear energy to reduce reliance on natural gas, but recent low gas prices have overshadowed this.
In 2011, 258,128 GWh (Gigawatt Hour) of electricity were produced in Mexico, with about 10,000 GWh of this coming from nuclear. By 2026 the total amount of electrical power used is foreseen at some 479,650 GWh. Apart from 4% nuclear and the hydro sector that generates about 10% of electricity, Mexico’s power mix is fossil-heavy: coal provides 12.5%; oil, 20%; and gas already some 49%.
But, as the World Nuclear News (WNN) reports, Mexico does not want to rely too much on gas: It expects 35% of electricity to come from non-fossil sources, up from 20% now. However, hydro, biomass and solar can only expand to keep pace with growth in demand, leaving nuclear and wind as the only options to meet this goal. Three different scenarios were put forward where the two favoured low-carbon technologies divide up a 23% share of electricity supply.
The most pessimistic scenario for nuclear sees it meeting 2.5% of demand, which at about 11,991 GWh represents virtually no growth in the country’s only nuclear power plant, Laguna Verde, which hosts two boiling water reactors producing about 800 MWe each and licensed to operate until 2029 and 2034.
The middle scenario puts nuclear at 6.6%. This would be a tripling from current production to 31,656 GWh and would require a little over 4 GWe of nuclear capacity in total, assuming a capacity factor of 90%.
The last scenario envisages 18.1% of power coming from nuclear plants – some 86,816 GWh and about equivalent to the output from 11 GWe of nuclear generating capacity.
The new energy strategy document took note of last year’s Fukushima accident and stressed Mexico’s involvement in international forums to secure on-going improvement of nuclear safety. It said nuclear power “continues to be a viable option to meet growing demand for energy” and noted it as “among the best options” for power generation thanks to low external costs and minimal damage to public health and the environment.
According to WNN, Mexico had long-prepared nuclear expansion plans beyond its single Laguna Verde plant, but these faltered in recent years and looked unlikely to resurface given discovery of large reserves of shale gas.
Shale gas is natural gas formed from being trapped within shale formations. Shale is a fine-grained, clastic sedimentary rock composed of mud that is a mix of flakes of clay minerals and tiny fragments (silt-sized particles) of other minerals, especially quartz and calcite.
Shale gas has become an increasingly important source of natural gas in the United States over the past decade, and interest has spread to potential gas shales in the rest of the world. One analyst expects shale gas to supply as much as half the natural gas production in North America by 2020.
Mexico’s March 1 policy document, however, explained that the government will develop a specific program, through coordinated efforts of the Federal Electricity Commission, the National Institute of Nuclear Research, National Commission of Nuclear Safety and Safeguards and the US-based Electric Power Research Institute to develop a safe and competitive route for nuclear development. They will “conduct studies to determine the financial, political and social viability, as well as the environmental implications of the gradual incorporation of new nuclear power plants.”
It was noted that nuclear developments have long lead times, and the definition of these projects would need to be agreed quickly. There will also be an effort, the government said, to engage in dialogue with local governments to reach consensus on the possibility of new nuclear.
Emissions set to rise
Apart from building new power plants, the Mexican plans also call for increases in energy efficiency of 15% by 2026. In parallel it wants to make better use of existing power plants by reducing losses in the grid from some 17.3% last year to more like 8.0% in 2026. Achieving that would allow Mexico to reduce its reserve margin in generation from 26.0% to 12.9%, said the government.
Nevertheless, WNN reports, the sheer growth in energy demand from all sectors will see carbon dioxide emissions rise by 40% to 567 million tonnes per year. The business-as-usual projection was for 52% growth to 619 million tonnes per year.
History of nuclear energy
Mexico’s interest in nuclear energy was made official in 1956 with the establishment of the National Commission for Nuclear Energy (CNEN). That organisation took general responsibility for all nuclear activities in the country except the use of radioisotopes and the generation of electric power. The Federal Electricity Commission (CFE), one of the two state-owned electricity companies, was assigned the role of future nuclear generator.
Preliminary investigations to identify potential sites for nuclear power plants were begun in 1966 by CNEN and CFE and in 1969 CFE invited bids for proven power plant designs with a capacity of around 600 MWe. In 1972 a decision to build was made, and in 1976 construction began at Laguna Verde on two 654 MWe General Electric boiling-water reactors (BWRs).
Although Mexican industry did not supply major components for the Laguna Verde plant, Mexican companies undertook the civil engineering work and Mexican staff maintain the reactor and train to operate it at CFE’s simulator.
CNEN was later transformed into the National Institute on Nuclear Energy (INEN), which in turn was split in 1979 into the National Institute of Nuclear Research (ININ), Mexican Uranium (Uramex) and the National Commission on Nuclear Safety and Safeguards (CNSNS). Uramex’s functions were taken over by the Ministry of Energy in 1985.
In February 2007 CFE signed contracts with Spain’s Iberdrola Engineering and also Alstom to fit new turbines and generators to the Laguna Verde plant at a cost of US$ 605 million. The main modifications consist of a turbine and condenser retrofit and the replacement of the electric generator, main steam reheater and the feedwater heater.
With approval from the CNSNS, the reactors were uprated progressively by 138 MWe each from 2008 to January 2011. As a first step, 11.6 MWe uprates to both units were achieved in 2007 through better flow control. In February 2011 Iberdrola announced that both units were operating at 820 MWe gross, about 800 MWe net, a 20% increase from the previous 665.5 MWe net. Their operating life was also extended to 40 years.