Quite a few years ago, some of us became acquainted with a rather interesting way of generating energy from solar power. Various variations of gigantic solar towers were conceptually presented and some projects where very well founded. However, until today these towers have not really delivered as promised and the development has oftentimes been hampered by unforeseen factors. Now, the time has come to evaluate the progress this far – and take a look at a company (or more) that ensures that they have built a working solar tower that delivers what it is promising.
What then, is a solar tower? Well, actually the towers are real power plants, preferably operating in deserts and similar flat, open and sunshine intensive places. However, there are some variations where it comes to the concepts. One kind work by using what could simply be called green-houses, where the air in underground collectors is heated directly by sunshine. This type of solar tower is correctly named a solar updraft tower:
What is central to the concept is that the heated air needs somewhere to go. By utilizing a very tall chimney tower as a central point of the plant, the air flows from the collectors up the tower and puts wind turbines placed in the chimney to work. This updraft is caused by what is called the chimney effect, and facilitates for significant power generation. We will begin by taking a look at a company utilizing this type of solar tower technology (though not yet constructed) and later in this article we will get to projects using another type (and are up and running)
Despite the promising outlooks on creating large amount of green energy, a solar tower comes at a price – a high one. The large initial investments needed to create these novel structures have in many cases not been made, since the risks have been considered too imminent. However, some concepts stand out as being more than mere fantasies. One of the most hyped ones comes from an Australian firm called EnviroMission. The company became quite recognized some years ago when they released some Youtube-videos and got covered in some science magazines.
EnviroMission uses the “green-house technology” described earlier, as opposed to regular solar panels- Actually, according to SeeNews, the company owns the global license for this specific solar tower technology (with exception from China). The firm has announced the up-start of several solar towers around the world, but none of them has ever been constructed since the first solar tower announcement in 2001. However, the company reported a few days ago that they are close to begin producing solar towers in India, and have signed an agreement with “a leading power company” to purchase the electricity from the towers. Below is a picture of EnviroMission’s proposed tower:
Another type of solar tower technology uses large amounts of big mirrors to reflect rays of sun at towers. The most recent project, called Crescent Dunes, takes advantage of 17,500 heliostat mirrors that collect and focus the sun’s thermal energy to heat molten salt (a type solid during standard temperature, but becomes liquid when exposed to heat) flowing through a 540-foot (160 m) tall tower. The heated salt then circulates from the tower to a storage tank, where it is then used to produce steam and generate electricity. The tower is going to begin producing energy next month and power up to 75,000 homes during peak electricity periods, according to Breaking Energy.
The Crescent Dunes project has received federal loan guarantees of a staggering $737 million. However, some people are skeptic against the initiative. This skepticism stems from the outcome of a similar project called Ivanpah, which got an outstanding $1.6 billion in federal loan guarantees. The owners are heavyweights NRG Energy, Google Inc and BrightSource Energy. The initiative is currently running, but “only” produces 411,000 megawatt hours as compared to the promised 1 million megawatt hours. In any case, International Business Times reports that the operators of the Ivanpah plant have experienced a series of setbacks since opening (such as unexpectedly cloudy skies), while the owners of the Crescent Dunes plant swear their prospects of success are far greater. The Crescent Dunes plant in Nevada, expected to generate 500,000 megawatt-hours per year, is displayed below:
Another interesting initiative utilizing the exact same technology as the Crescent Dunes project is brought about by the Spanish company Abengoa Solar. This company currently operates at smaller scale, but has a lot of bigger and very promising initiatives up the sleeve. Abengoa owns Europe’s first commercially operating concentrating solar power plant, and the solar tower is generating 11 megawatt-hours annually in Sevilla. Below is a short and descriptive video illustration of how the technology works (if you did not fully get it from our text):
Conclusively, even though the technology used in a solar tower is quite novel (and of different kinds), the great plans and hugely backed initiatives undoubtedly show promise. The large energy generating capacity is key to a more sustainable world, and the sun is as free as it is clean. If just one company managed to pull it off large scale, it could count for a lot in terms of increased interest and additional investments. This is truly one of the few technologies that could take on global warming for real, but as for all commercially viable energy options, it must function and deliver on the promises.