This was written in 2018 as part of course on being green and renewable energy sources in modern times.
Solar power as an alternative source of energy is still facing push back by those who stem to profit from not moving to photovoltaics as a source of electricity despite large number of active projects and movement in tends in research and development to solar power over the past 2 decades. Moreover, in this recent decade, the price of projects has decreased substantially in comparison to the projects that started in the early 2000s and late 1990s. In this paper we discuss and some arguments against the sue of solar power, and supply evidence the refutes them. Then we discuss the cost and feasibility of solar power and some projects that are being undertaken today.
What makes an energy source viable depends on a number of criterion including, cost of produc- tion and transportation, accessibility, availability, and feasibility. For these reasons, in conjunction with the already established infrastructure for it, fossil fuels, have been set as the standard as a viable energy sources to support a growing world population, agriculture, and business driven society. In this paper, we will discuss how such criterion apply to an alternative energy source, solar power, and possible implications, costs, and infrastructure involved with it. The advantages the fossil fuels have over solar power are generally the advantages that non- renewable resources have over renewable resources. Fossil fuels are in general less expensive than the materials required for solar power, they are more energy dense, they are easily transported by established infrastructure and they are already deeply integrated into society [1]. Solar power is a candidate for an alternative, renewable energy source because of the energy generated by it and because it is essentially unlimited. The energy collected from the sun is utilized in a number of different ways. The most well known is the collection electrons by the use of high energy waves through interfacing with photovoltaic (PV) cells as arrays. The sun’s energy is also actively harnessed by mirrors that focus the sun’s rays onto a transfer fluid or water and is then converted into electricity by other means [2]. This energy is green as no greenhouse gasses are emitted in this process. However, a reason that solar power hasn’t been more widely integrated is because of the high start up cost and the fact that solar power does not work as effectively at night [3] or during cloud cover [4]. Furthermore, the places where solar power is more geographically viable are often quite far from the areas of demand for the power [5]. For example, ideal places for larges ares of solar panels, solar farms, are flat areas with little coverage and a lot of sun [6]. This is why the first American commercial scale solar power companies were largely concentrated in the desert regions of California [7]. Unfortunately, such rich areas are often far from densely populated coastal regions of the United States [6]. This leads to the current debate about solar power and whether or not it should be adopted. Proponents of solar power note its greenness, its potential, the research and development that is currently being put into the area [8]. Furthermore, as of the last decade, the cost of solar production has decreased substantially due to competition in the sector required for the production of parts used in the balance of system (BOS) for the PV arrays [9]. Opponents of solar power note that it is expensive in the short run [3], and requires some supporting technology like that of an energy storage system to power cities or keep a grid active during the night time hours and when solar energy is not readily available [1], that it requires access to water resources, available and proximate transmission access to grids, and continuous land parcels [3]. In this paper, we will note some current technologies used by solar power and then discuss the viability of solar power.
Solar energy is either harnessed passively and or actively. When passive, the solar power is trans- formed directly into electricity by PV modules [2]. PV modules are simple devices that allow for electricity generation at a variety of scales [4]. PV cells are generally made out of a semiconductor, usually silicon (Si) and is placed into a glass for protection [4]. Because atoms are quantal, that is they are discrete and specific, PV cells are wavelength specific, that is they only work when a certain frequency of light is sufficient to knock off an electron [10]. This electron release is called to photovolatic effect, hence the name PV cell [10]. These cells are placed into an array which are then integrated with other balance-of-system hardware e.g. inverters, transformer, which are needed to convert the raw DC current into a more usable and AC current [4]. Once the electrons are induced to travel through an electrical circuit and also processed by the BOS, they can be used to power electrical devices or send electricity to a power grid [2].
Solar energy actively harnessed may be focused in order to fuel an auxiliary source as opposed to using the suns rays to generate electricity directly. This is the type used in places like California and China for example [5]. Concentrated solar power (CSP), also called solar thermal power, manifests in multiple forms, however, the governing principal is the same [11]. Solar power is used to heat a fluid which then goes to create steam that drives a turbine-generator set [4]. The light is directed and focused by mirrors on to a something, usually a fluid, to transfer heat [4]. This heat is subsequently used to vaporize water into steam to turn a generator. We will describe three CSP systems.
Parabolic trough concentrator (PTC) systems use curved mirrors to concentrate the solar energy onto a receiver tube. The tube contains a fluid capable of transferring high-temperature fluid that will be used to evaporate water to generate electricity [3]. This fluid is often stored in a two-tank storage system where the heat transfer fluid (HTF) also serves as storage medium [12]. This system is one of the most advanced thermal energy storage’s for solar thermal power plants and is used by solar power plants in California since the late 90s [12].
Compact linear Fresnel Reflectors (CLFR) use curved-mirror trough systems concentrate light directly onto the water to be evaporated in order to generate electricity [3]. These act as broken- up parabolic troughs consisting interleaving (segmented) mirrors. This design is said to be more efficient than the standard linear Fresnel reflector (LFR) [11]
Dish-engines or parabolic dish reflectors (PDR) have a solar concentrate consisting of concave mir- ror(s) distributed over a parabolic dish surface which concentrates sunlight on to a focal point [11]. This focused solar energy is the used to heat a fluid and then evaporate water in order to generate electricity. The dish is mounted on a structure that tracks the position of the sun continuously throughout the day [13].
Here we discuss the cost of solar power and of installing commercial scale solar power electrical systems along with some examples. We also cite current examples of cities in America using renewable energy. Finally, we conclude with future directions and speculation of solar power.
Since the long term goal is to replace fossil fuel based power plants with solar based ones, we first consider solar power at the scale of utilities. Utility-scale solar refers to large-scale PV, concentrating photovoltaic (CPV), and concentrating solar power (CSP) projects that usually sell electricity generated by solar power directly to utilities or other buyers, rather than displacing on site consumption like that of private or consumer mounted solar panels and PVs [14]. Due to the early mentioned advantages, PV have grown much more and are more prevalent than CSPs or CPVs [15] and is projected to grow even faster into the next decade [15]. What made PV so expensive in the early part of the 2000s were the BOS parts [9]. In particular, the inverter for a array of PV. The inverter loading ratio (ILR) has a large impact on the PV array’s DC capacity and in turn the PV array’s AC capacity [9]. The price of such parts has over the last decade [9], allowing for more optimum ILR ratios and a net increase in power generation [14]. This increase in power generation is directly proportional to the increase in revenue for PV solar generation at the utility-scale [14]. As a result, there has been a recent increase in the number of entities investing in solar power as well as an increase in the amount of power purchase agreements [15]. From the years 2007 to 2015, the median price of installed PV at the utility scale dropped from $2.70WDC to $2.10WDC 1 [14]. Furthermore, the project design costs have also dropped during this time period [14]. This was caused the by the decease in raw materials like crystalline silicon (c-Si) modules, the above mentioned BOS devices, and switching to fixed tilt projects as opposed to solar tracking projects [14]. Thus, both the up-front installation costs and cost of PV electricity generation have demonstrated a monotonically decreasing trend. It should be noted that there are outliers to this trend but these outliers correspond to much larger utility scale projects that were started before the decrease in the price BOS parts and are long ongoing projects.
We have mentioned already in our introduction that the problems faced by renewable sources of energy, in particular solar power, include the financing of these projects, access to water resources, available and proximate transmission access to grids, continuous land parcels with limited cloud cover and relatively flat, and they need areas of high direct normal solar radiation [3]. One place that has taken advantage of their geographical viability for solar power use is the state of Texas. Indeed, the Central Austin Utilities company of the city of Austin, Texas has done case studies on three different battery storage pilot projects to remedy the problem of energy storage the case of discontinuous sunlight, an important problem that impedes the argument for solar power [16]. 1The reported measurement is DC as that is the most commonly reported measurement for PV project capacity. Here we describe two of those projects. One solution is the integration of smarter technologies into the grid for power management and transmission. The Austin Sustainable and Holistic Integration of Energy Storage and Solar Photovoltatics (SHINES) is attempting this. The project was awarded four million three hundred US dollars to build two utility scale energy storage systems, multiple customer-suited energy storage systems at residential and commercial properties, smart inverters, real-time data feeds, and a distributed energy resource optimizer [17]. In sum we can see that approach is to store and transmit power at smart times in order to set the older costs that come with traditional method of electricity generation. The batteries being used in this projected at 1.5 MW/3 Mwh LG chem lithimum-ion battery. These batter will be co-located with a community solar array. Support batteries will also be installed in residential and commercial properties. This project has gained lot of traction and has attracted multiple partners uch as Pecan Street Incorporated, Doosan, Stem Incorporated, Clean Power Research, and others [18]. Another solution to the electricity storage problem has been proposed by Pedernales Electric Cooperative and is in in Johnson city. The project named battery energy storage solution project (BESS) is the anticipated approach to solving the energy storage problem, that is by energy storage and then release when it is later needed by consumers. Economically, the project edges the cost of a type of service obligation2 with self-procured storage. Additionally, the energy usage is shifted in order to avoid peak energy pricing. This is due to the flexible design configuration. The idea is that is the off peak times will charged for wholesale prices while during offsetting the the charge of electricity during peak times by load shifting [19]. This approach is beneficial in at least two ways. One the benefit is to the producer of the electricity service in that during peak-load hours, especially in the Summer months, electricity generation is often out-sourced to peaker plants [20], that is plants that are active during peak electricity hours. These plants are a heavy drain on utility companies as the price of the electricity they provide is quite high. So in moving to BESS the price of electricity for these utility companies decreases. Additionally, there is benefit for the consumer as with a decrease in the price of the supply, there is an expected increase in the supply of the electricity and a decrease in price for the consumer [21].
As we have demonstrated, research and development of PV has been active over the past decade. The problems of PV are well-known and are being actively researched and improved on. Further- more, the decrease in price coupled with reported increases in efficiency in some experimental PVs had made it more attractive investment [22]. In other words, the main arguments against the use 2Power Exchange Code (PEC) Ancillary Service Obligation which is mandatory as an Electric Reliability Council of Texas (ERCOT) Load Service Entity (LES) of solar power have been for all intents and purposes sufficiently solved. In fact, solar power as an means of electricity generation has seen a global trend as can be seen by the massive project being undertaken in India to move to solar power generation to support their electricity grids [23], China is considering doubling their solar power target from 110GW to 200GW of electricity by 2020 based off of research done by the China National Renewable Energy Centre (CNREC) and is already in the midst of a current energy transition to more sustainable mean [24]. Thus, it is no longer a question of whether or not we should be using solar power as a renewable energy source to supplant and eventually replace fossil fuels, but a question of how soon can we replace our primitive fossil fuel based energy economy with a more robust and sustainable one. We end with a quote by India’s Prime Minister Narendra Modi ”The world must turn to (the) sun to power our future. As the developing world lifts billions of people into prosperity, our hope for a sustainable planet rests on a bold, global initiative.”