Jul 23, 2019 in Exploratory

Solar Power

Introduction

In the recent past, environmentalists and climatologists have started issuing warnings about an impending global catastrophe caused by rapid industrialization and other environmentally harmful activities of humanity. Global warming has become the most feared enemy of the planet that should be defeated at any cost if people do not want to suffer from global climate changes and associated catastrophes. However, humanity has not been ready to give up its industrial activities and shift entirely to green technologies, which has given rise to countless researches and searches for a solution that would allow businesses and industries to function at their desirable capacities but with a less detrimental impact on the environment. One of the possible solutions concerns the development of renewable energy technologies, which would reduce the use of coal and the like responsible for emission of greenhouse gases. This search for green technologies has coincided with a need to diversify energy sectors of developed nations and decrease their dependency on such conventional energy sources as coal, gas, and oil since these natural resources are exhaustible and the planet can deplete their reserves in the future. Even though this future seems to be distant, businesses and governments view this situation as a significant risk in addition to a fear that future generations would be left with scarce and non-existent vital resources. Researchers working on both of these problems have come to a decision that renewable energy sources may be a valid solution since they can ensure sustainable development and are environmentally friendly. However, not all renewable energy sources are equally efficient and effective in providing the population with power and ensuring sustainable development at the same time. Solar power can be regarded as the most efficient and sustainable energy source on sunny territories. There are various solar power technologies with different capacities that offer in their turn various benefits and shortcomings. Hence, the current paper intends to provide a short overview and analysis of solar energy as a sustainable energy source, using  the example of the Arizona project entitled Solana. This project has been chosen for the analysis as it is one of the most sophisticated solar technologies in the world that has reached maximum power generation capacity among all solar power technologies so far. The raised issue is highly topical as innovations relating to solar power are gradually becoming more and more popular and cost-effective and seem to be a logical answer to the issue of green and sustainable energy source available to both the public and businesses at a reasonable price. 

Description of the Project 

Relatively recently, Arizona Public Service Co, which is the key supplier of electricity in the state of Arizona, has developed and started implementing its APS’AZ Sun program aimed at introducing renewable energy sources, in particular solar power, in the state. According to this initiative, Arizona has to comply with a new standard in the use of renewables in the amount of 15% from total electricity consumption by 2025. Solana has become a part of this program and received almost $1.4 billion in financing in the form of the DoE’s loan guarantee, which allowed to construct and launch the operation of this plant. The project has been developed and implemented by the Spanish company Abengoa that posits itself as a global innovative leader in the international solar power market. The company claims that its key mission consists in “contribution to sustainable development and the creation of jobs and benefits for the communities and regions where they are located”. Abengoa has been selected by the state officials for the Solana project because of its proven commitment to production of clean solar power with the help of innovative and constantly improving technologies and vast international experience relating to construction, operation, and maintenance of solar power plants all over the world, including Mojave Solar Project in the USA, Agua Prieta in Mexico, KaXu Solar One in South Africa, Shams-1 in the UAE, Solucar Complex in Spain, and some other.

Hence, the company has developed the project of “a 280-MW (gross) utility-scale solar thermal electric plant with six hours of molten-salt thermal energy storage”. It is situated near Gila Bend not far from Phoenix, Arizona. Pictures of the Solana plant are given in Appendix B. As evident from these pictures, this CSP plant is huge as the solar field covers about 3 square miles and contains 3,200 parabolic through collectors that have 2.2 million of sq.m. of reflective mirrored area in total. The overall cost of the Solana project amounts to approximately $2 billion. Gross predicted output is 280 MW, but about 10% has to be used for operation of the plant, which means that about 250 MW are produced for consumers. The plant started operating in October, 2013, and its first year of operation was connected with a slightly lower volume of produced power even though Abengoa’s and APS’s representatives claimed that such slow start was expected. 

Solana is said to be “one of the largest power plants of its kind in the world”, which is also special due to its ability to solve the intermittency problem and produce electricity for about six hours after the sunset due to the innovative technologies installed on the plant. However, this thermal storage system may be employed during summer seasons. Irrespective of this slight restriction, Solana is the first solar power plant in the world that can generate electricity at night, which makes it a unique and highly efficient renewable energy source. Besides, it can satisfy Arizonian’s peak power demands during the hottest seasons, which no other solar power plant in the world can do. Therefore, as the APS’s representative said, “Solana is a monumental step forward in solar energy production”.

 

Design

Figures 2 – 5 in Appendix B provide pictures of the complete Solana plant with Figure 6 being the schematic representation of the plant prior to its construction. It is evident  from these pictures that the design of the Solana project is a mixture of a parabolic through concentrating solar power and a molten salt energy storage, which referred to as “CSP + MSES” is in the company’s documentation. After its completion in October 2013, Solana has become the largest CSP plant in the world and the first utility-scale renewable energy plant in the USA. Solana’s generation technology is based on more than 3,000 of parabolic through collectors and 2 Rankin stream turbines with the capacity of 140 MW each. Design of the thermal storage is unique for a plant of this kind and presupposes the use of 2 molten salt tanks, each is 122 ft in diameter and 34 ft deep and ensures 6 hours of energy production after the sunset. 

Solana’s design is predicted to have 41% capacity and Abengoa’s representatives claim that despite the low capacity of the first year, Solana will improve its performance in the coming years. The lifecycle of the plant is said to last for 30 years. Solana’s solar field employs “Abengoa’s steel Phoenix collected design” that has been developed to ensure quick assembly and optimal performance. In addition, the improved Phoenix design has managed to achieve a reduction in cost in the amount of 10% as compared with the previous collector design entitled ASTR0. Under the current Solana’s design, the sun’s rays are concentrated by means of parabolic mirrored through collectors on tubes with synthetic oil that is then heated and used to produce electricity with the help of stream turbines. This design has proved to be efficient in comparison with some other solar power plants that show the capacity of 20-25% on average. 

Benefits of the Project 

The Solana project is characterized by multiple significant benefits. According to Abengoa, the project has benefitted the entire country thanks to $2 billion of investments during the period from 2011 to 2013. Also, the company claims to have ordered and purchased 75% of supplies and equipment within the US, hence assisting the economy of 29 states and 165 companies that have received more than $900 million in payments. The construction of the plant provided more than 2,000 people with employment, while the completed plant requires from 65 to 85 specialists who will receive decent salaries. According to the current tax rates, the projected 30-year lifecycle is likely to generate more than $400 in tax revenues. However, financial benefits are not the most important aspect of this project. 

Solana proves that renewable energy sources, in this particular case solar power, are suitable for utility-scale production of electricity. This is the first project that also solves intermittency issues even though this option is currently available during the summer season. According to APS and Abengoa, the Solana plant can provide about 70,000 households in Arizona with green and sustainable power, which is a huge benefit. Moreover, the plant contributes to energy sector diversification in Arizona and decreases dependence on conventional energy sources. One of the greatest benefits of the project concerns its sustainable nature and environmental safety. First of all, the plant has been constructed on land previously used for agricultural purposes. Today, the plant consumes 75% less water than this land plot required in the past. Secondly, carbon offset of the Solana plant amounts to 475,000 tons per annum, which is a considerable reduction of greenhouse gas emissions. 

Of course, the cost of the project is rather high, but with the government’s subsidy and loan the plant’s construction took slightly less than 3 years, which is a good result as compared to the construction of power plants using other sources of energy. Another advantage of the project is its relative safety. Even though fires and accidents involving plant employees may occur, they will not be of detrimental nature to the area like, for instance, accidents on nuclear plants that are currently propagated by the nuclear sector as environmentally friendly energy sources. Despite some fears that solar power may be more expensive than other power sources, recent researches of the US Energy Information Administration prove that “cost of solar has fallen to only about 2 cents per kilowatt-hour more than nuclear or coal”. Withal, the Solana project has proved to have numerous benefits that are evidently worth the cost of its construction.

Some Additional Facts about the Project 

Thanks to its advantages and a unique thermal storage capacity, the Solana project received the Energy Storage North America Innovation Award in the category entitled “Utility-Scale” on October 1, 2014. This innovation award was granted to the plant because of its excellence in terms of the project development. In addition to the votes of the experts, the public could vote on contestants via Twitter, and Solana received a 77% approval rate. 

Furthermore, the Solana project is interesting for some other additional facts. Thus, the liquid used in tubes is said to be non-toxic and environmentally friendly even though the APS’s representative does not recommend tasting it because of its unpleasant taste and high temperatures reaching above 530 degrees Fahrenheit. Solana’s operation should have started several months earlier, but it is not a significant delay. CSP is said to be more dangerous than SPV, but they both are less dangerous than conventional energy sources. As of now, Solana project has increased consumers’ bills by $1.28 per month, but this figure is going to drop to $0.94 within 10 years.  However, this project has proved that sustainability is attainable within the energy sector and that renewable energy sources can become a viable and cost-effective substitution for conventional environmentally harmful energy sources like coal.

Results and Conclusion

The current paper has attempted to provide a brief overview and analysis of solar power as an efficient means of sustainable development, citing  the example of the Solana project developed and implemented in Arizona, the USA. It has been shown that solar power should be considered as an efficient and viable alternative to conventional energy sources, which is highly beneficial thanks to its capacity to produce clean energy without a detrimental impact on the surrounding environment and contribution to greenhouse gasses emission. Moreover, the Solana project demonstrates that renewables can be employed on a large scale with only a slight increase in the cost for consumers. A great shortcoming of a solar power project similar to Solana stems from the total cost of its construction. In the case under consideration, the plant would not have been built without the government’s loan. However, at the same time, the plant can be constructed within less than three years and solve the intermittency issue, which is an essential benefit. Overall, it may be concluded that environmentally friendly technologies and sustainability are worth paying a little more than people are currently spending on power since they receive clean energy and less polluted environment instead, which presents fewer health hazards. The Solana project is a bright example of how solar power contributes to sustainability and rescue attempts to save the planet from potentially catastrophic climatic changes.

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