Tag Archives: CPV

What Is the Best Solar Power Plant Technology to Cut Land Costs?

CSP costs more, but PV developers pay more for real estate.

Herman K. Trabish: August 8, 2013

As the price of photovoltaic solar levels out and the value of concentrating solar power’s storage improves, it is possible that the price of land could become a decisive factor in a solar project’s overall energy costs. A new land-use analysis demonstrates the choice of technology could be crucial. 

Researchers at NREL drew on acreage data from 72 percent of the 6.7 gigawatts of operating and under-construction photovoltaic and concentrating solar power solar capacity in 3Q 2012. The list of projects surveyed include those from major PV developers First Solar (FSLR) and SunPower (SPWR) as well as major CSP developers BrightSource Energy, SolarReserve and Abengoa.

The research team that produced the report Land-Use Requirements for Solar Power Plants in the United States used two land-use measurements. The total area was taken as the typically fenced offsite boundaries on blueprints. The direct-impact area was smaller. It included only the land on which there were solar arrays, access roads, substations, service buildings, and other infrastructure.  

The most efficient total land use was the 2.8 acres per gigawatt-hour per year associated with two-axis CPV installations of more than 20 megawatts. The least efficient use of land was the 5.5 acres per gigawatt-hour per year associated with two-axis flat-panel PV projects of less than 20 megawatts.

The most efficient direct land use was the 1.5 acres per gigawatt-hour per year for dish Stirling CSP technology. The least efficient was, again, two-axis flat-panel PV projects of less than 20 megawatts, with 4.1 acres per gigawatt-hour per year.

The caveat — and it is important — is that only one dish Stirling project, from Tessera Solar, was analyzed. And only six CPV installations, including those from Tenaska and Cogentrix, were analyzed. Four of the CPV projects were less than 20 megawatts and only two were over 20 megawatts. Other relevant findings in the analysis included:

  • Nine tower projects analyzed for direct land use came in at 2.8 acres per gigawatt-hour per year and seven parabolic trough CSP projects used 2.5 acres per gigawatt-hour per year, both better than the 43 smaller fixed PV projects’ 3.2 acres per gigawatt-hour per year and the 41 smaller single-axis 2.9 acres per gigawatt-hour per year.
  • Fourteen tower projects analyzed for total land use came in at 3.2 acres per gigawatt-hour per year and eight parabolic trough projects used 3.9 acres per gigawatt-hour per year. The 52 smaller fixed PV projects used 4.4 acres per gigawatt-hour per year and 55 smaller single-axis PV projects used 3.8 acres per gigawatt-hour per year.

Larger PV projects, though currently falling out of favor with utility-scale solar developers and financiers, showed improved direct and total land use.

  • Seven 20-megawatt-plus fixed and seven single-axis PV projects were analyzed. Fixed came in at 2.8 acres per gigawatt-hour per year in direct land use and single axis used 3.5 acres per gigawatt-hour per year.
  • Fourteen 20-megawatt-plus fixed PV projects used 3.7 acres per gigawatt-hour per year in total land and sixteen 20-megawatt-plus single-axis projects used 3.3 acres per gigawatt-hour per year.

The smart use of infrastructure in PV projects had more to do with efficient land use than module efficiency, according to lead researcher Sean Ong.

The value of the numbers and conclusions, the study acknowledged, was limited by relatively small sample sizes, and the best quality data was not always available for analysis. Often, the researchers could not get data from developers and were forced to use third-party sources.

Also, over 26 gigawatts of utility-scale PV and CSP projects were in development in February 2013. “Owing to the rapid evolution of solar technologies, as well as land-use practices and regulations,” the NREL study noted, “the results reported here reflect past performance and not necessarily future trends.

Source: GreenTechSolar.

Who will be the next solar energy supplier for PG&E?

Following 535 MWe parabolic trough systems supposed to be built by Israeli Solel Solar Systems (if they succeed to join forces with the right strategic partners and raise the required 2BnUSD), and about 500MWe Power Towers systems to be built by BrightSource -LuzII (if they succeed to build their first pilot plant to provide heat from the sun, early next year), and the today announced 177MWe deal based on Ausra Inc.’s linear fresnel reflectors, –  it seems that parabolic dish and/or CPV are in line.    

 It is understandable why PG&E decided on the parabolic trough systems, as they are considered commercially available, and Solel has the know-how of the primary developers of this technology. Moreover, Solel, did not rest on Luz’s laurels, and enhanced the performance of their linear receivers. However, it seems that they have already pushed the envelope of these single-axis trackers….….. and does not have the long term commercial potential. 

 Until lately it was taken for granted that troughs and towers were having potential advantage for providing electric power to utilities, having high dispatchability capabilities, that gives them the ability to more closely match the utility load profile,  over dish and CPV systems, which were having potential advantage for decentralized energy and mainly for remote areas, due to their modularity. 

It seems that the coast is clear now for solar systems based on dish with high concentrators, based on enhanced two-axis tracking systems and with inherent storage and hybrid fossil capabilities. The remaining question is what will the PCU be based on? There are no operating commercial dish-Stirling power plants; from the development of viable Stirling engines there is ‘nothing to write home about'; and storage is currently not a considered viable option for dish-Stirling. Hence, it seems that there is room for PCU based on CPV or an innovative receiver feeding a gas/air turbine with very high temperature flux.  

Moreover, there is room for doubt if all the above three – Solel’s trough, Ausra’s Fresnel and Bright Source’s towers – will really get under way in due time and provide electricity to PG&E as soon as 2010 (as suppliers claim). 

Hence, Solar Dish, high temperatures receivers and CPV providers – buckle down!