The Asco I nuclear power station, center, is seen by a sign that reads "private property, nuclear association of Asco" in the small town of Asco, Spain. Photo by David Ramos: AP

Five years ago when Spain’s Socialist government promised that it would decommission the country’s nuclear power plants once their 40-year lifespan expired, it had no idea that it was painting itself into a corner.

By July 10 it must decide what to do with Garoña, its oldest and smallest nuclear power plant, a facility with 466 megawatts of much-needed power capacity. The Garoña plant’s license expires on that date, even though the 40-year lifespan of the plant doesn’t come around until 2011. And although the outdated, 1st- generation plant only accounts for 1.4 percent of the country’s electricity output, the decision -- whichever way it goes – may determine the future of nuclear energy in Spain.

The licenses of the remaining seven nuclear power plants, which together account for about 20 percent of the country’s power capacity, are all due for renewal in the next two years, all within the mandate of Spain’s prime minister, José Luis Rodríguez Zapatero, who has publicly declared that he is anti-nuclear. Zapatero’s decisions will have a long-term impact on the country’s energy mix and its carbon dioxide emissions. Indeed, while many European countries are planning to increase their nuclear capacity – the list includes the UK, Poland, Italy, Finland, and of course, France -- Spain could go the other way.

That said, many things have changed since Zapatero’s electoral promise. Spain is likely suffering more from the global recession than any of its European peers. Its unemployment of nearly 18 percent is more than double that of the levels in Europe and the OECD and the government has admitted that the economy will contract more and take longer to recover than most of its neighbors. In the meantime, Spain’s greenhouse gas emissions have increased faster than any country in Europe. Along with Greece, it was the only country in the EU-15 to see its annual emissions increase in 2007, the latest year tallied by the EU Commission.

Furthermore, since 1990, it has increased the amount of greenhouse gases by 53 percent, by far the biggest increase among its peers. And despite its efforts to boost renewable energy sources, which now account for more than 30 percent of generated electricity, it is still more dependent on fossil fuels than most of the EU. And last week, Spain’s Nuclear Security Council issued a non-binding report this week recommending a 10-year extension of the life of the Garoña plant, conditioned to several security upgrades. Most expected the go-ahead would clear the way for a swift government approval.

But then politics got in the way.

The Socialist Party suffered a huge setback during recent elections for the EU Parliament, losing votes to the main opposition party, as well as center-left and green parties. Going back on his word to shut down nuclear plants would be a risky bet for Zapatero. Almost 60 percent of Spaniards said they oppose nuclear power. That is by far the lowest level of support of any European country with operating nuclear plants, according to the latest Eurobarometer2008 survey (pdf) .

The survey also showed that support for atomic power generation in Spain has increased significantly since 2005, but it by no means is close to popular. Thus keeping the plant open could be politically dangerous given that the Socialists are facing growing dissent within its rank and file and the opposition party continues gaining ground at the expense of the government.

Garoña, owned by Endesa and Iberbrola, the country’s two biggest utilities, support keeping the plant open, as can be expected. And they are getting support from some political heavyweights. Former Socialist President Felipe Gonzalez, a party patriarch, supports keeping the plant open and Spains Minister of Industry, Miguel Sebastian, has a similar position.

Closing Garoña could cost Spanish companies an estimated $2.3 billion to pay for the natural gas needed to produce the electricity that could be lost during the 10-year proposed extension to the plants license. That gas would also produce 25 million tons of carbon dioxide in the same period, which depending on the price, could add close to another $1 billion in costly carbon credits under the EU trading scheme. In contrast, keeping the plant open would cost some $210 million over the 10-year period, the operator has said.

Then there is the fact that the plant directly employs some 700 people, on top of another 400 indirect jobs. That is about half the employment of Burgos, where the plant is located, according to a recent study. At a time when unemployment is the top concern for Spaniards, the decision to shut down Garoña would not go well either.

So what will Zapatero do? Will he go back on his electoral promise and risk shedding more votes at a time when polls are showing his support dwindling? Or will he risk the consequences of setting a precedent that could derail Spain’s nuclear future? So far, the prime minister hasn’t shown his hand. He said he will “try to keep” his electoral promise “unless there are major reasons” not to do so.