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Solar thermal and storage could offer best value for money

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In late December 2013, I was in India and had the privilege to be given an in depth guided tour of the Godawari Green Energy 50MW Concentrating Solar Power plant. This trough concentrator based system is India’s first complete CSP plant, it was commissioned back in May 2013.

csp indiaI am pleased to report that it appears extremely well built, to be working perfectly and is operated by a competent well qualified local team. Sensibly, this first Indian CSP plant replicates a proven model implemented in Spain and incorporates a European design and many key components are imported.

With a construction time of just 19 months, it came close to matching the best ever construction time achieved in Spain. The next cab of the rank for CSP in India, is Reliance Industry’s 100MW plant based on AREVA Solar’s Linear Fresnel technology. This I drove past and could see over the fence a hive of activity and a well progressed mirror field stretching into the distance.

India has delivered on these projects under its National Solar Mission (20GW of solar by 2022) on the same time frame that Australia managed to achieve nothing much under its Solar Flagships program. Oh, what could have been. It is not a bed of roses though, several announced CSP projects in India have failed to get off the ground and the country is struggling with the debate around why bother with CSP if the Levelised Cost of Energy of PV is less.

Globally, the Concentrating Solar Power sector continues to grow very strongly, with total deployed capacity of over 3GW by the end of 2013. The majority of the systems now in operation incorporate several hours of built in thermal energy storage. With construction slowing in Spain due to the removal of tariff support policies, the spotlight has shifted to the US, where the 400MW Ivanpah tower system, the Solana project (280MW trough system with 6 hours storage) and the soon to be completed 100MW Crescent dunes tower system with 10 hours energy storage, are receiving much attention. South Africa now has 4 projects under construction. Arguably, India and South Africa are vying for the new second place. Other market places offer huge potential but it is still early days on deployment.

Despite all of this, if CSP is acknowledged as being around 50% more costly on Levelised Cost of Energy than PV and total global deployment at 3GW is only about 3% of PV’s 100GW, does it have a future?

Those of us who work in the field believe it does and this stems in part from the fact that whilst the energy may cost 50% more, the total economic value delivered may be up to 150% more. A key observation is that now most CSP systems incorporate energy storage as standard practice and doing so comes at no increase in the cost of the energy. The currently dominating approach to achieving this, is storing heat in tanks of high temperature liquid salts (up to close to 600oC). This heat is then used to raise steam for power generation as needed.

In early February the Australian Solar Thermal Energy Association (AUSTELA), and the Institute for Sustainable Futures at UTS are organising a series of workshops to introduce new tools developed for evaluation of the potential network benefits of Concentrating Solar Power systems in the NEM.  ( Brisbane 6th Feb, Sydney 11th Feb and Adelaide 12th Feb.).

The workshops will also introduce new tools, developed by IT Power Aust for AUSTELA, enabling easier economic and performance assessment of CSP projects in Australia, using the well-known ‘System Advisor Model,’ for which we have developed Australian solar resource and economic models.

CSP systems, particularly where they incorporate thermal energy storage, offer a number of key sources of value in addition to providing green electrons as other renewable generation does. The extra sources of value include:

  • moving energy sales to high demand periods;
  • whole electrical system avoided cost;
  • ancillary services.

IT Power’s 2012 study on the Potential for CSP in Australia for the Australian Solar Institute, modelled CSP plants configured for “peaking” operation using historical price data in the NEM and indicated that such energy could be up to 100% more valuable than random generation. Other studies have found similar effects. The possibility of heating the salt tanks in CSP systems electrically at times when PV or wind generation is in excess and might otherwise be wasted also exists and has yet to be fully exploited.

Much has been written in recent times on the extent to which major upgrades to our electrical network are contributing to the cost of consumer’s electricity bills in Australia. The case can be made that CSP systems with energy storage can be sufficiently reliable that if installed at constrained locations in the network, they can avoid the need for expensive network upgrades.

The AUSTELA-Institute for Sustainable Futures project to be launched at the February workshops examined this hypothesis at constrained sites across the NEM, using data provided by the electricity network operators.  The study identified $0.8 billion of potentially avoidable network investment, and 533MW of cost effective CSP, which could be installed at grid constrained locations in the next ten years.

Ancillary services are needed to keep an electrical system functioning smoothly; they include things like voltage and frequency support and the ability to ramp up and ramp down generation on request.  CSP with thermal storage can provide such services as a matter of course. Studies of 100% renewable electricity scenarios consequently identify CSP with storage as a key ingredient of an optimal generation mix. AEMO’s recent modelling of 100% renewable electricity scenario’s for Australia, took a technology and cost based bottom up approach and predicted that CSP with storage might provide around 20% of the electricity generation in 2030.

In addition to these directly quantifiable sources of value, CSP offers some substantial but less obvious value to Australia’s economy. By its very nature, more of the manufacturing and construction value resides in the country and region of construction – international experience suggests around 70% local content in CSP projects. CSP is a large utility scale technology best built in high solar resource inland regions in Australia, with associated benefits in regional employment and economic activity.

For a nation like Australia there is also a significant “option” value of an involvement in the CSP value chain at a time when it is gaining pace. A key example of this, is that a strong capability in CSP for electric power, could lead on to future involvement in large scale solar concentrator processing of hydrogen rich fuels for export.

Complete cost benefit analysis of CSP systems must be carried out on a case by case basis – by specific location and time.  But there is enough evidence to suggest that, in Australia as in other markets, there are many circumstances where rational analysis of the all the value provided by CSP suggests a strong net positive benefit.  Internationally, continued industry growth seems assured, and it is really a question of when Australia will act to take its place in the growing global CSP market.  We certainly have the technical, research and industrial capabilities to act if we choose to.

So far green electricity policy measures around the world have almost universally treated kWh generated as having the same value irrespective of the time of generation.  This is not an approach that logically leads to the most cost effective mix of renewable generation types, for stable operation of a 100% clean electricity system.  Globally we need new policy measures that are designed to guide an optimal trajectory to 100% renewable electricity by, for example, differentiating on time of generation and rewarding other values appropriately.  

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  • Askgerbil Now

    Concentrated solar thermal may be even more cost-effective in a hybrid power station using alternate fuels when solar thermal energy is not available.

    Cost savings for the hybrid power station include the solar thermal energy store and the heliostats / mirrors that are used to add energy to the thermal energy store and not generate power. Depending on the amount of thermal storage in the design, perhaps half of the heliostats serve no other purpose than collecting thermal energy for storage. This is a substantial fraction of the capital cost.

    Suitable candidate technologies for a hybrid concentrated solar thermal power station include CSIRO’s Solar Air Turbine and an indirectly fired gas turbine (IFGT) such as that developed by BTOLA. Both of these technologies are able to share the turbine and electricity generator – maximising the return on the investment on these components: “Combining Technologies to Cut Energy Costs” ( http://blog.gerbilnow.com/2014/01/combining-technologies-to-cut-energy.html )

    • wideEyedPupil

      Where are you getting your ?methane gas from AN? Natural Gas, CSG or Shale Gas? Fugitive emission around these extraction methods (especially fracking) are as bad from a GHG footprint perspective as burning coal to produce energy when measured on the twenty year time frame and using a factor of 84x CO2-e for methane (IPCC AR 5 other paper rate is as high as 105x). Twenty years is significant given climatic tipping points of frozen methane in the Polar regions that is starting to melt and may ‘burp’ our entire carbon budget and more in a short time period.