Advantages – Concentrated Solar Thermal (CSP)

I attended the CSP Today conference last week in San Francisco. A well attended event with many industry gurus sharing their views about the state of CSP in US.

It seems to me that there are three main advantages that are often touted for CSP (over Photovoltaic let’s say…) – Storage, cost and predictability of output. Besides predictability, the other two seem to be subjective.

This is the only solar technology that allows for storage naturally. Since the solar radiation is indirectly converted to electricity, there is an opportunity to store the collected heat in molten salts, before converting the heat to electricity.

The cost of setting up the molten salt system is exorbitant. The financial viability of the storage option depends on the incentives. In Spain, the power companies are incentivized based on the total energy output (MWh) into the grid. So they try to maximize the energy produced and having storage allows for higher energy / capacity factors – thus more revenue. Also the feed-in-tariff is enough to justify the extension of the salt system.

In US the companies are incentivized for the installed capacity (MW) through the investment tax credits. The credit is independent of the total energy production. So in US, the additional investment in the storage technology is not financially viable currently. The scarcity of projects demonstrating the molten salt technology also leads to more risk, leading to financing hurdles. The whole industry is waiting to see Solana (280MW, 6 hours of storage) project in Arizona get financed and built to lead the pack.

The common understanding is CSP is cheaper than PV due to the use of off-the-shelf, commodity components like mirrors, turbine, etc. It also was known to have higher efficiencies in solar to electricity conversion (~15%).

Due to the global oversupply in PV panels and reduced demand due to the financial crisis, the prices of the panels have drastically reduced. On the efficiency front, the PV at 15-20% efficiency is typical now, further adding the cost parity. The result is that PV is now at parity or close to parity with CSP. One western region utility claimed that they pay 0.16 c/Kwh for CSP and 0.14 c/Kwh for PV. This difference was attributed to the timing of the PPAs, generally the difference is not significant anymore.

The ability to provide “firm power” is a clear advantage of CSP at this time. Due to the output being provided by a steam turbine (and not directly from the field) and a ~2 hour built-in buffer in the trough technology, small variations in the in insolation do not affect the turbine output – like a passing cloud. PV on the other hand can have a very sporadic output profile. The firmness of power is highly valued by the utilities. No other solar technology existing has this benefit. This benefit is unique and is valuable, and I believe would be discussed more in months to come.


3 thoughts on “Advantages – Concentrated Solar Thermal (CSP)

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