CSP is typically used in generating electricity. However the generation of heat and steam would seem to make purely thermal applications a natural outlet for its energy.
CSP Today examines the use of CSP as process heat and steam in micro-applications for industrial processes.
By Susan Kraemer
Heat or steam is needed in many kinds of industrial processing, including nearly all food and chemicals. These industrial applications need smaller plants generating lower temperatures, so plants for this market are known as micro CSP.
A small but growing sector
BrightSource is one of the few large CSP companies with at least one plant in both micro and macro markets. Recently there has been growth in the micro and modular CSP market, with firms such as protarget and Global CSP being established in the past few years.
Two firms that have been making waves focusing squarely on Micro CSP are Australia’s NEP Solar and Hawaii’s Sopogy, which has been selling steam and heat since 2002.
Sopogy manufactures everything in-house, from troughs to trackers, and markets the resulting steam heat production to foodservice and other industrial users globally, selling either just the steam or heat (for some US projects) or just the collectors, or complete finished CSP plants, as turnkey operations.
Starting up in 2002, founder Darren Kimura built one of the very few CSP firms not focused on the electricity market. Now Chairman of the Board of Directors, no longer acting CEO, but one of the firm’s bigger investors, serial entrepreneur Kimura spoke with CSP Today about the thinking behind that decision.
“My vision for micro CSP was really different from large scale CSP that’s going after power plants at 50 MW, 100 MW,” he explains. “That space was very busy, there were a lot of companies in that sector. I saw the opportunity to really go after the thermal market, because they were being completely ignored, yet they were massive.”
Even though their product is heat, not electricity, both firms quote it in megawatts and kilowatts for ease of translation internationally into local heat metrics.
A market niche
Sopogy’s micro CSP projects range from 5 MW to as high as 50 MW, and occupy a middle ground between solar thermal and CSP for power generation at well above the size range of the solar thermal industry, while well below the size range of some of the new CSP plants now being built for power generation.
Their plants make heat and steam from 100 to 250 ˚C, higher temperatures than solar thermal which produces heat at 50 to 75˚C, but at much lower temperatures than full scale CSP plants for generating electricity.
However, this middle range is right at the sweet spot for the largest thermal market in the world - purely thermal processes, according to Kimura.
“If you look at all the industrial processes out there, that range covers more than 80% of them,” he says. “Pasteurisation, pretty much all foods are treated by steam, hot water, whatever it might be. That’s all in that range. Textiles, pharmaceuticals, chemicals, all of that stuff.”
Each modular collector is “about the size of a Prius car,” he says. “About 5 or 6 ft wide, and 12 ft long: about 1/3 the size of a regular parabolic trough.” Each unit generates 2 KW of heat, and so they are assembled in series to supply the amount of heat the customer needs up to 50 MW.
Generating each megawatt takes a bit over two acres of land in total, he says.
Each collector is very light, about 125 - 150 pounds, so if an industrial user owns enough roof space, these can be roof-mounted. Reinforcing structures to withstand high speed wind is not necessary.
“Because it’s smaller, it’s lower to the ground,” explains Kimura. “So we get less exposure to the wind. But we also flip the collector upside down into a “wind slow mode”, where the c-shape of the trough faces the earth.”
Australian air conditioning market
NEP Solar, with offices in Australia and Switzerland is focused on using micro CSP for chilling at commercial sites. Much closer to the startup stage than Sopogy, they have built just a few solar cooling projects, all in Australia, and are currently developing solar air conditioning for a shopping mall in the state of Victoria, running the heat into an absorption chiller.
“The market is huge in Australia, we have very hot sun,” says Johan Dreyer, CEO of NEP Solar. “The need for cooling is quite dramatic here. There’s a good overlap between solar radiation and the need for cooling. But it’s just one of the markets we can use our collectors for to provide industrial heat.”
Their collectors produce in a similar range at 130 degrees C to 250 C. Their two models are 20 (and 24) metres long, and 1.2 (and 1.8) metres wide. “Each weighs approximately 1,000 kg per collector,” he says. “That’s not too heavy for these roofs because it’s spread out over quite a large area.”
Dreyer estimates that generating half a megawatt would take between 2,500 and 3,000 square metres including the rows between the troughs, but he is not yet generating in the megawatts.
Like Kimura, he is not interested in competing with the lower temperature market of solar thermal. It is a more difficult market segment for NEP Solar, with no PPAs.
“To date we haven’t sold heat; only the complete capital investment,” he says. “But PPAs are a market we are looking at as the clients don’t necessarily want to take on the risk of the capital investment and are happy to provide their roof, and supply the energy, the heat for their process.”
There are constraints in the relationship between a potential user's thermal energy needs and their roof space.
“Typically if we look at something like a food processor, they would use significant amounts of energy, but their floor area is generally quite large. “Somebody in the mineral industry needs huge amounts of heat but are very concentrated in a small floor area,” he says.
But while there are constraints on the Micro CSP market, at 11 years old, Sopogy is now cost competitive with the traditional thermal industry.
“It’s a lot cheaper to do it from the sun,” says Kimura. “The economics stand for itself. You pay for the technology upfront, but there’s no fuel cost, and when you run it over a life of ten, maybe as long as twenty years, if you take the blended cost of the capital, divided by the amount of energy produced over the time, you get a cost that’s probably about 25 - 50 percent lower than a fossil fuelled plant.”
He estimates the size of the purely thermal market at $3 to $5 billion annually in terms of what customers within this niche are now paying for thermal energy each year.