Concentrating solar power: It’s a good bet for the future

Over the last two and a half years or so, it has been my great pleasure and privilege to have had the opportunity, along with my close friend and colleague Wes Stein, to have acted as editor for a new book that has just been published – Concentrating Solar Power Technology: Principles Developments and Applications.

It is quite a technical read, not necessarily ideal for the Christmas list for elderly grandparents or young children (but one shouldn’t generalise). It is, however, an ideal book for engineers and scientists seeking an in depth technical introduction to the field and it also introduces the technologies and approaches in a way that is accessible to those with a non-technical background. It was not the remit of this book to make the detailed commercial case for why we should bother with concentrating solar power (CSP) at all.

In all fields of human endeavour, some lead and some follow fashion. Nations, companies, individuals who have the highest probability of the greatest success are those that successfully pick the trend before the main crowd. My hypothesis here is that CSP represents such an opportunity for Australia.

Readers of RenewEconomy will be very aware of the revolutionary changes the world’s energy industry is experiencing. At the forefront of those changes is the massive and continuing growth of wind and PV. In 2011, global financial turnover in these was around $US230 billion in roughly equal shares. CSP on the other hand was the proverbial mosquito bite on the bum of this sector. However it was a $US2 billion mosquito bite, and it has also been experiencing compound growth of 40 per cent/year for the last six years.

CSP’s current competitive advantage is the ability to build in large scale commercially proven thermal energy storage systems. The majority of the CSP systems built in the last few years incorporate thermal storage. A good example to point to is Abengoa’s “Solana” project that is nearing completion in Arizona. It is a 280MW system with storage for 6 hours operation at full power. Such thermal storage systems, being an integral part of the system, have the happy consequence of actually improving system efficiency, since less energy is dumped during high sun periods. 1-2 hours of storage can actually produce cheaper electricity than no storage. Higher levels of storage offer the potential to preferentially target times of higher demand/price.

In terms of cost, the current situation is that without storage, CSP electricity is at least 30 per cent more costly than PV. But a CSP plant with six hours storage is considerably less than half the cost of a PV plant combined with the same level of battery storage. CSP is also at the top of its cost curve and projected to reduce with deployment, as PV has done.

Is storage needed at all? If Australian and the world aspires to nothing more than 20 per cent renewables the answer is in most situations, no. However the only logic of 20 per cent renewables targets really, is as the first step towards 100 per cent clean energy. I believe that is where we are headed, it may just take a while for public policy to catch up with an unstoppable global industry trend.

Work by UNSW and others, into 100 per cent renewable scenarios, finds a geographical spread of wind and solar across an interconnected network do very well, but a significant level of energy storage and dispatchability is a very valuable/essential asset in the system.

The current debate around what has been called the “death spiral” scenario facing our retail electricity market is interesting. Ever higher retail prices needed to recover network expenses, encouraging more domestic PV and energy efficiency responses, leading to even higher prices for network electricity. From an engineer’s perspective, it is rather implausible to imagine that in a country with large cities, it could prove cost optimal to abolish the electricity network and make every house self-sufficient. To do so would be to forgo cost effective wind power, the benefits of geographical interconnection, the benefits of higher levels of solar radiation in inland areas and the benefits of utility scale CSP plants with energy storage. Optimal solutions are usually a mix. Rooftop PV makes a lot of sense, I struggle with the idea that significant amounts of battery storage in the home would be part of an optimal least-cost mix. The fact that some are seriously suggesting it is, to me, evidence of market failure.

One of the features of CSP that should make it attractive to countries like Australia, is that the manufacturing does not require highly capital intensive facilities and much of the manufactured components are bulky and not ideal for international shipping, thus there is a greater chance of holding on to a larger fraction of the value chain in the country and region of installation.

There is potentially an even bigger reason for Australia to engage in concentrating solar. The last chapter of our book looks at the use of concentrating solar to produce fuels. Making this the last chapter was a conscious editorial choice. We wished to end the book with a discussion of an application that may well be of the largest future importance. Concentrating solar systems are being tested to use high temperatures to; decompose natural gas, biomass or coal into the building blocks for oil substitutes and ultimately directly split water and/or CO2 to hydrogen and carbon as well as a range of other imaginative ideas.

Whilst in countries like Australia, our stationary energy sector is responsible for the majority of greenhouse gas emissions, we should not forget that in Australia and globally, more than 30 per cent of our primary energy comes from oil and it is responsible for over 70 per cent of the cash flows, reflecting its higher value. The recently released federal government Energy White Paper, clearly acknowledges the imperative of moving to clean energy and it acknowledges the possibility of a much greater growth and contribution from renewables than previous such documents have. The elephant in the room however is that even as a carbon constrained world is discussed, Australia is projected to continue to grow its exports of coal and gas indefinitely.

Based on recent numbers, the Australian economy is quite dependant on exporting coal at $3.50/GJ and smaller amounts of gas at $7/GJ. We also sell a lot of energy in the form of uranium but derive little revenue from it at 20c/GJ. At the same time we import a growing amount of oil (due to growing demand and declining domestic production) at around $19/GJ and with the impending closure of refining capacity, we will move more towards more direct imports of diesel and petrol at an even higher value of around $25/GJ.

Liquid fuels have a lot of advantages. The energy and financial cost of moving energy as a liquid combustible hydrocarbon across half the planet is only around 2 per cent of the energy moved. The energy density by volume or mass including the containment is many times higher than other forms of energy other than nuclear fuel. Handling by pumping, piping and storage vessel is convenient and low cost. The speed of re-fueling transport vehicles is high. However international oil production is moving increasingly to options such as deep water drilling, tar sands and shale oil, all of which are more costly and result in substantially higher greenhouse gas emissions and other environmental costs. Key energy customer countries Japan and South Korea are unavoidably dependant on energy imports to sustain themselves, but are trying to move to lower carbon intensity.

Putting all these observations together I suggest that it is quite a good bet that liquid fuels will continue to play a major role in world energy supply and use well into the future and probably indefinitely. Australia would be better off economically if it moves its energy exports up the value scale towards liquids rather than down towards uranium. Using concentrating solar technologies to achieve a reduction in carbon intensity of the fuel would be both an economic and environmental win. A future world where energy is exchanged via totally emission free fuels would be the long term vision.

Dr Keith Lovegrove is a senior consultant in solar thermal at IT Power. He is a world leading expert in Concentrating Solar Thermal (CST) technology and has more than 20 years experience in leading solar thermal research – including 15 years teaching at the Australian National University (ANU) as head of the Solar Thermal Group. Keith led the design and construction of the ANU Big Dish, the largest concentrating solar dish in the world (at 500m2). He is a key contributor to the IEA Solar PACES program, which is an international cooperative network developing CST and chemical energy systems.