This month, the Italian utility Enel unveiled “Archimede”, the first Concentrating Solar Power (CSP) plant in the world to use molten salts for heat transfer and storage, and the first to be fully integrated to an existing combined-cycle gas power plant. Archimede is a 5 MW plant located in Priolo Gargallo (Sicily), within Europe’s largest petrochemical district. The breakthrough project was co-developed by Enel, one of World’s largest utilities, and ENEA, the Italian National Agency for New Technologies, Energy and Sustainable Economic Development.
Several CSP plants already operate around the world, mainly in the US and Spain. They use synthetic oils to capture the Sun’s energy in the form of heat, by using mirrors that beam sunlight onto a pipe where pressurised oil heats up to around 390°C. A heat exchanger is then used to boil water and run a conventional steam turbine cycle. Older CSP plants can only operate at daytime – when direct sunlight is available -, an issue that has been dealt with in recent years by introducing heat storage, in the form of molten salts. Newer CSP plants, as the many under construction in Spain, use molten salts storage to extend the plants’ daily operating hours. Archimede is the first plant in the world to use molten salts not just to store heat but also to collect it from the sun in the first place.
This is a competitive advantage, for a variety of reasons. Molten salts can operate at higher temperatures than oils (up to 550°C instead of 390°C), therefore increasing efficiency and power output of a plant. With the higher-temperature heat storage allowed by the direct use of salts, the plant can also extend its operating hours well further than an oil-operated CSP plant with molten salt storage, thus working 24 hours a day for several days in the absence of sun or during rainy days. This feature also enables a simplified plant design, as it avoids the need for oil-to-salts heat exchangers, and eliminates the safety and environmental concerns related to the use of oils (molten salts are cheap, non-toxic common fertilizers and do not catch fire, as opposed to synthetic oils currently used in CSP plants around the World). Last but not least, the higher temperatures reached by the molten salts enable the use of steam turbines at the standard pressure/temperature parameters as used in most common gas-cycle fossil power plants. This means that conventional power plants can be integrated – or, in perspective, replaced – with this technology without expensive retrofits to the existing assets.
So why hasn’t this technology come before? There are both political and technical issues behind this. Let’s start with politics. The concept dates back to 2001, when Italian nuclear physicist and Nobel prize winner Carlo Rubbia, ENEA’s President at the time, first started Research & Development on molten salt technology in Italy. Rubbia has been a preminent CSP advocate for a long time, and was forced to leave ENEA in 2005 after strong disagreements with the Italian Government and its lack of convincing R&D policies. He then moved to CIEMAT, the Spanish equivalent of ENEA. Under his guidance, Spain has now become world leader in the CSP industry. Luckily for the Italian industry, the Archimede project was not abandoned and ENEA continued its development till completion.
There are also various technical reasons that have prevented an earlier development of this new technology. Salts tend to solidify at temperatures around 220°C, which is a serious issue for the continuous operation of a plant. ENEA and Archimede Solar Energy, a private company focusing on receiver pipes, developed several patents in order to improve the pipes’ ability to absorbe heat, and the parabolic mirrors’ reflectivity, therefore maximising the heat transfer to the fluid carrier. The result of these and several other technological improvements is a top-notch world’s first power plant with a price tag of around 60 million euros. It’s a hefty price for a 5 MW power plant, even compared to other CSP plants, but there is overwhelming scope for a massive roll-out of this new technology at utility scale in sunny regions like Northern Africa, the Middle East, Australia, the US.
The Italian CSP association ANEST claims Italy could host 3-5,000 MW of CSP plants by 2020, with huge benefits also in terms of jobs creation and industrial know-how. A lot more can be achieved in the sun belt south of the Mediterranean Sea, and in the Middle East. If the roll out of solar photovoltaics in Italy is to offer any guidance (second largest market in the World in 2009), exciting times are ahead for Concentrating Solar Power.
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You probably won’t hear it from columnist George F. Will, Fox News commentators or the plethora of conservative blogs that have claimed global warming essentially stopped in 1998, but recent figures released by the National Oceanic and Atmospheric Administration show that global land and ocean surface temperatures in June were the highest since record-keeping began in 1880. What’s more, the first half of 2010 was the hottest such period ever recorded, and Arctic sea ice melted at a record-setting pace in June.
The heat can probably be attributed at least in part to periodic and entirely natural changes in ocean temperatures and surface air pressure “” the El Ni±o/La Ni±a phenomena most likely played a role. But the fact that peak years are getting hotter while even relatively “cool” years now tend to remain above historical averages (the 10 warmest years on record all occurred within the last 15 years, according to the NOAA) shows that something else is at work. A consensus of climate scientists worldwide, including not only the United Nations‘ Intergovernmental Panel on Climate Change but the national scientific academies of the United States and the rest of the developed world, have identified that “something else” as anthropogenic (human-caused) greenhouse gases, which reflect the sun’s heat back onto the Earth rather than letting it escape into space.
Climate skeptics such as Will et al either deny that this warming is happening “” an increasingly untenable position in the face of overwhelming evidence that it is “” or insist that it doesn’t matter. They argue that it would be more expensive to try to solve the problem than to adapt to it, and that in any case, the effects of higher temperatures won’t be all that damaging. Climate modelers, who have accurately forecast the currently observed climate oscillations, sea-level rise and ice melting, do not agree. They predict catastrophic destruction in coastal cities, droughts, crop failure, forest loss, insect infestations and other woes.
For us, it’s not a difficult decision which side to believe: scientists who directly observe and measure climate changes and whose accuracy is rigorously tested by their peers, or pundits with little knowledge of climate science whose views are informed by a long-held resentment of environmentalists and government regulation. Yet the latter group, working hand in hand with big energy companies that profit from the filthy status quo, have injected enough doubt into the national debate to paralyze Congress “” which seems little closer to imposing greenhouse-gas limits or placing a market price on emissions than it was during the laissez-faire George W. Bush administration “” and confuse the public, who in recent polls are increasingly inclined to believe that the threat of climate change has been exaggerated.
Granted, scientists themselves deserve some blame for the shift in attitudes. Climatology, even more than other fields, is undergoing changes that are unsettling for those in the trenches. A relatively obscure line of work until policymakers started seriously considering carbon curbs in recent years, climate science is suddenly at the center of a raging international debate. Meanwhile, a sedate culture of publication and private peer review has been roiled by a new media environment; today, critics of a scientist’s work don’t have to publish a carefully reviewed study in a major journal, they just have to fire off an indignant blog post.
When scientists at the prestigious Climate Research Unit at the University of East Anglia responded to such critics by sending catty e-mails to their colleagues, and when those e-mails were made public by hackers last November, it did more to impede action on climate change than Big Oil could have achieved with an army of lobbyists. Yet investigations have shown that the e-mails amounted to little more than fits of pique. The most recent review, conducted by an independent team funded by the University of East Anglia, found no evidence that the researchers had undermined scientific findings by the Intergovernmental Panel on Climate Change or any other group, and that they neither withheld access to data nor tampered with it.
We’d love to hear climate skeptics explain away the results of such investigations and address the latest report from the NOAA. But we suspect they’ll do what they usually do when confronted with facts that contradict their worldview: ignore them.