Concentrated Solar Power

1. Presentation

Solar power is the conversion of sunlight into electricity, either directly using photovoltaics (PV), or indirectly using concentrated solar power (CSP).
Photovoltaics convert light into electric current using the photoelectric effect. Concentrated solar power (CSP) systems use mirrors or lenses to concentrate a large area of sunlight, or solar thermal energy, onto a small area. The concentrated heat is then used as a heat source for a conventional power plant (ie: gas, oil, coal, nuclear): the heat drives a heat engine (usually a steam turbine) connected to an electrical power generator.

Various techniques are used to track the Sun and focus light but there are four main forms of concentrating technologies:

- Parabolic trough
- Fresnel reflector
- Solar power tower
- Dish Stirling

Difference between Photovoltaic and Concentrated Solar Power (CSP):

CSP plants produce more consistent power output (less 'spiky-ness'). These plants can produce power fairly consistently throughout the day because of the thermal inertia and the ability to burn natural gas when clouds roll in. When clouds blanket a PV plant, the output can drop off a cliff. CSP power plants fit naturally with storage systems and can even continue to produce power at night.

2. Market Analysis

The CSP market has seen about 740 MW added between 2007 and end-2010. More than half of this capacity (approximately 478 MW) was installed during 2010, bringing the global total to 1095 MW. Spain added 400 MW in 2010, taking the global lead with a total of 632 MW, while the US ended the year with 509 MW after adding 78 MW, including two fossil-CSP hybrid plants.

CSP growth is expected to continue at a rapid pace. As of April 2011, another 946 MW were under construction in Spain with total new capacity of 1,789 MW expected to be in operation by the end of 2013. In the US, a further 1.5 GW of parabolic trough and power-tower plants were under construction as of early 2011, and contracts signed for at least another 6.2 GW. Interest is also notable in North Africa and the Middle East, as well as India and China.

Although industry activity continued to focus in the two leading markets of Spain and the United States, the industry expanded its attention to other markets in Algeria, Australia, Egypt, Morocco, and even China. Still, most industry expansion took place in Europe and the United States. For example, Schott of Germany doubled its production of receiver tubes in its facility in Seville, Spain. Rio Glass of Spain, a relatively new company that has become a major producer in recent years, was building a manufacturing plant in the United States and also planning for plants in India and China.
The industry also saw several acquisitions by major energy players seeking to enter the CSP market. Siemens bought Solel (Israel), ABB bought Novatech, GE bought E-Solar, and Areva bought Ausra. Alstrom also entered into a joint venture with Bright Source. The industry remained vertically integrated, with individual companies involved in many parts of the value chain, but this was expected to change as markets expand and as companies specialize in specific parts of the value chain.

Leading project development firms worldwide include Abengoa (Spain), Acciona (Spain), BrightSource (United States), Schott (Germany), and Siemens (Germany). Leading mirror manufacturers include Saint-Gobain (France), Flabeg (Germany), and Rio Glass (Spain). Other notable CSP firms include Areva (Spain), eSolar (USA), Solar Millennium (Germany), and Solar Reserve (USA).

DESERTEC

One of the world largest ongoing project, is Desertec. This German based consortium of about 20 companies, including RWE AG, EON, Munich RE Siemens and Deutsche Bank is behind a hugely ambitious EUR 400 billion ($550 billion) project to build solar plants stretching across 6,000 square kilometres of the North African desert. The rollout is planned for the coming decades and will eventually supply up to 15% of all of Europe's electricity needs by 2050.

According to a study by the German Aerospace Center (DLR), a state agency that provided data used by Desertec, less than 1% of suitable land in the North Africa and the Middle East would be needed to cover the current electricity consumption of the region, as well as Europe. Many countries with intense sunshine also have large tracts of uninhabited land.

The consortium already has two plants in operation in Morocco and Egypt. Morocco hopes to upgrade its existing transmission line to Spain and install 2000 megawatts of solar power capacity to supply both its own needs and to tap into the lucrative European export market.

Desertec expects to see the first electricity flowing through undersea cables from Morocco to Spain as early as 2014. The technology that will initially be used in Morocco is concentrated solar power (CSP), allowing a secure supply even when the sun is not shining and at night.

3. Commercial Potential for the Carnot engine

Despite competitive photovoltaic prices and lingering environmental and financing concerns, CSP technologies are poised for gigawatt-scale adoption in 2011. Future growth will remain healthy as the generation stack increasingly incorporates CSP plants in excess of 100MW.

The CSP industry has finally reached a mature state where the less efficient technologies have been overtake by more competitive technologies.

FAIL: The SES's suncatcher: too complicated, too expensive. The company went bankrupt last setpember.

WIN: AREVA's compact linear fresnel reflector system. A simplified CSP with direct steam generation compatible with hybrid gas/coal/solar power plants.

What can the Carnot engine bring to CSP ?

As an efficient, simple and reliable technology, our goal is to implement the Carnot engine in low cost and low to medium temperature CSP systems such as:

- direct steam generation CSP (without the need for costly heated oil/heat exchangers);

- direct solar generation (low cost and small scale CSP systems)
- air cooled systems (no water needed)

Moreover, the flexibility and modular design allow us to produce a wide range of on demand power engines based on the same architecture. Since the Carnot engine is an external combustion engine, it can be plugged on mutiple heat flows coming from various sources (heated oil, steam, direct sun beam, etc.).

As the competition with photovoltaic technologies goes on, especially in term of costs, the CSP industry is leaning toward cheap and simple solutions. The Carnot engine is well suited for this market.



4. Conclusion

The latest international energy outlook from the US Energy Information Administration shows a strong growth of the world solar energy demand. For the next 10 years, the solar power generation should increase by at least 200%. The International Energy Agency forecasts are even more significant.
Despite the fact that the largest share comes from photovoltaic modules, the CSP market remains very dynamics with large projects under development. These projects are supported by big industrial and financial players. The CSP unique ability to produce consistent power output make it valuable in some power generation cases. It can also be interconnected with a traditional fossil fuel power plant to create hybrid fuel power facility.
The latest industrial trend to ensure CSP competitiveness is to lower the capital and operating costs by building simple systems and getting rid of costly technologies (complex reflectors, multiples stages heat exhangers, water cooling, etc.).
The characteristics of the Carnot engine make it a perfect candidate for these low costs standards: high efficiency at low to medium temperature, external combustion and multi-source.