Solar Thermal Systems
According to Mallik (2008), the technology that generates clean and sustainable energy from a number of sources such as water, sun, plants and wind is termed as renewable energy technology. In the year 2007, the Energy Information Administration reported that in the United States, around nine percent of the electricity generation and seven percent of whole energy consumption is due to the renewable energy technologies. There are numerous benefits of renewable energy technology. The prime and the foremost benefit is that it makes the energy economy of the country very strong and sustainable (Mallik, Bhave, & Mate, 2008, pg 45-48).
Biomass technology
It is the technology, which converts the animals waste and other types of wastes into productive use. It converts these wastes into fuels, power and chemicals. This technology takes the sun’s energy, which is stored in the organic matter through breaking it. There are different processes, which are used to break the organic, but the process is based on the form of organic matter and the final user.
Bio power
This technology is used for generating heat and electricity from the biomass resources. There are three main processes in the bio power, which are co-firing, anaerobic digestion and direct combustion.
Bio fuels
Mallik (2008) sated that these fuels are mostly used in vehicles but besides this, they are also used in the production of electricity. These fuels are also beneficial for the economic growth and environment of the country. Two main forms of bio fuels are the biodiesel and the ethanol.
Solar Photovoltaic cells
These cells are used to transform sunlight into electricity. Since 2002, the use of photovoltaic cells has been increasing at a rapid rate of twenty percent every year. This proves that this technology is growing very vastly. Up until now many photovoltaic plants has been built around the world and some are under construction. Many of these plants use tracking system to track the sun and produce more energy.
Affect on environment on the use of energy
Mallik (2008) wrote that in this modern age people are highly aware of the fact that the combustion of fossil fuels is very dangerous for the environment. Beside this, global change in the climate is also another factor. Carbon dioxide emission in the environment at a high rate is making matters worse. It is commonly seen that most of the industries, power plants and automobiles directly emit carbon dioxide in the environment.
In addition to this, Abbasi (2011) stated that lack of trees in the environment is also harmful because forests are being cut rapidly to avail the land for the construction of houses. The emission of carbon dioxide in the atmosphere and cutting of trees are the main causes of green house gases. These green house gases in turn results in global warming and according to a number of researchers, global warming is increasing at a rapid rate. However, on the other hand, the renewable energy technologies have no adverse affect on the environment (Abbasi., 2011,pg 34).
Nicholson (2009) recommended that in order to make the world a better place to live, we should adopt the usage of renewable energy technologies so that global warming can be stopped. There are numerous examples of these renewable energy technologies, for instance wind energy produces no harmful substance. Beside this, it does not produce either air or water pollution. In addition to this, solar power systems also do not produce any air pollution but there is a criticism about manufacturing of solar power systems. Though, its manufacturing requires some amount of energy but if comparison is made with the conventional systems, the solar power systems requires less energy. As far as combustion of bio mass is concerned, it produces air pollution. However, the amount of air pollution depends upon the type of process used in the combustion of bio mass.
Demand of renewable energy in the future
According to a recent report published by the UN, the prices of renewable energy technology will reduce in the coming future due to the latest developments. Because of this reduction in the prices and increase in demand for the clean and sustainable energy, it can be easily predicted that the demand for renewable energy will increase in the future. In addition to this, the report that since people is now much aware about global warming, they are taking keen interest in the development of renewable resource technologies (Nicholson, 2009, pg 39-47).
The demand for electricity is also increasing with the rapid increase in population. This also shows that the increased demand for renewable technology in future because it is a safer and clean method of generating electricity. Apart from this, as it is mentioned above that renewable energy plays a positive role in the development of an economy therefore it also predicts that its demand will increase rather than decreasing. Another recent report told that in 2050, renewable energy would control the entire world by seventy-seven percent.
Herring (1988) told that the Government of United Kingdom is taking major steps for a bright future of clean energy in the country. The Government is planning to establish a bank named as Green investing bank to assist in providing financial facilities in the development of renewable technologies.
As far as funds are concerned, around $US35 billion (a$32.7 billion) has been given by the department of energy of United States in order to assist the projects of clean energy.
Beside this, the government has also announced to give $10 billion for the Clean Energy Financial Corporation. The CEFC will contribute in a vital way for gaining investments from the private sector.
Usage of energy in the commercial sector of United Kingdom
According to research, the commercial sector of United Kingdom consumes three times more energy as compared to the domestic sector. This consumption in the commercial sector is likely to grow at a faster and constant rate. As far as the office sector is concerned, the demand in this sector for the air conditioners is very high and this results in heavy emission of car bon dioxide gas. Not only is this, but the workers are now looking for more comfort, ease and luxury. This demand for comfort by the workers results in the usage of technology. The growing rate of consumption of energy in the commercial sector of the United Kingdom clearly reveals the fact that there is an expansion in the lighting, floor space, heating, air conditioning and information technology (Herring, Hardcastle, Phillipson, & Energy, 1988, pg 107-117).
According to Quaschin (2005), growth in the floor space of commercial sector has been observed since the year 1970 and from this year to 1994, floor space for the ware house increased at a drastic rate of 114% whereas the floor space for offices were doubled and 54% increase occurred in the floor space of retail. The same trends were observed in the leisure industry but this industry did an agreement on reducing the energy consumption with the government. Leisure industry is the first to make such an agreement of energy consumption with the government. A large part of the leisure business is comprised of restaurants; medium and small size pubs etc.
In the year 1981, it was determined that the commercial sector consumed around 6.4 per cent of the total energy. The most significant fuel for the commercial sector is electricity and the consumption of electricity as well as other fuels depends upon the services rather than the number of employees.
There are certain techniques available for the energy conservation. The users as well as the owners of the business should be well aware about the cost and the outcome that will be generated by using the fuels. It is also imperative that fuel prices are clear to the owners of the buildings as it helps the decision makers in taking an appropriate and efficient decision (Quaschning, 2005, pg 67-73).
Energy can also be saved through the commercial buildings in a variety of ways. For instance, microprocessors can assist in informing the managers about the energy patterns and in this way, a sophisticated and organized control can be made in the business.
According to Probst (2011), commercial sector has a high demand of fuels but on the other hand, this sector also emits carbon dioxide in multiple ways. Some of the industries in the commercial sector are using latest technology to avoid the emission of CO2 but a large part of commercial sector is paying no attention to this side in spite of being aware about its dangers.
The Association for Energy Conservation has proposed legislation and according to the legislation, the main property freeholders that include pension funds, insurance companies etc. should make their buildings energy efficient. In addition to this, the legislation also requires that there should be an audit for energy after every five years and the audit will be done to ensure that the performance of the business in terms of energy is according to the standards or not. In this regard, some exceptions have been given to the insurance companies while the other companies should follow these principles.
In the year 2005, the commercial sector of the United Kingdom spent $16,500 million for fossil fuels of 350,000 GWh. On the other hand, researchers have reported that a decline of energy consumption has been observed in the tertiary sector of the United Kingdom (Probst & Roecker, 2011, pg 109-124).
Hot water consumption
Probst (2011) stated that hot water is consumed around three percent in industries and fifteen percent I the fossil energy. This shows that a total of 22,000GWh of hot water is consumed each year.
The high and low temperature hot water from the hot water boilers is used in a number of things such as apace heating, washing and in some industrial processes. The direct and straight use of hot water is in washing. Modern hot water boilers are coming day by day and the development in the production of these boiler systems shows the significance of it use.
The solar Thermal Market of the United Kingdom
However, international economic crises were going on in the year 2008, but still, in this year the United Kingdom was among those who had a great market for solar thermal systems. It has been reported by (STA) Solar Trade Association of British that in the year 2008, fifty percent increase occurred in the total amount of solar thermal systems installation around the world. There were a number of reasons for this rapid increase in the installation of solar thermal systems. These include huge publicity, changes in climate, government assistance and open-minded people who wanted to adopt this technology and use clean energy (Council, 2004,pg 220-234).
The government of British assists in the solar thermal projects and these ways are as follows in two ways:
1) Arrangement of Low Carbon Building campaigns
2) Appreciating the owners of homes to invest in the green technology.
An amount of thirty million were invested in the Low Carbon Building program and this program started in the year 2006, during the mid of June. Since many more applications were received which were above the expected ones, therefore, in the year2008, an increment of six million GBP was made in the budget.
According to Barnst (2000), almost fifty percent of the total demand of energy of the United Kingdom is for heat; therefore, it is probable that the market of solar thermal systems will grow at a faster rate. Recently a study named as the Potential of Solar Thermal in Europe was conducted and the results of the study determined that how the heating as well as the cooling sector of the solar thermal can contribute in the growth of the country (Voravate, Barnes, & Bogach, 2000, 183-190).
Beside this, a survey was also conducted in different countries such as Germany, Austria, Spain, Denmark and Poland so that the European Union and its other member states can be made aware about the contribution of the solar thermal industry and how the renewable energy technology can bring change in the country. In addition to this, the demand of heating and cooling was also calculated for the future years of 2020, 2050 and 2030.
Sukhatme (2008) said that further predictions were also made regarding the growth of solar thermal systems and it was estimated that around twenty six percent of growth will occur in the annual sector of Europe due to which the solar thermal will be able to fulfill 6.3% from the total of twenty percent of renewable energy target of the Europe. It was also told that in the year 2008, above fifty percent growth occurred in the solar thermal industry of Europe (Sukhatme, 2008, pg 56).
As it is mentioned, above that, this growth in the solar thermal market will continue at a constant rate and in the year 2050, forty-seven percent of the total demand for low temperature by the European nation will be fulfilled by the solar thermal systems. Since a growth of any sector results in providing job opportunities to the individuals of the country, therefore this dynamic growth in the solar thermal industry will also affect positively in the employment structure of the country.
If only the domestic market is considered than the employment, opportunities by the solar thermal market in this sector will be around four-lack and seventy-thousand.
According to the President of the ESTIF, the growth in the solar thermal market of the country will occur definitely due to the changing climate and high demand of renewable energy technology. Keeping this thing in mind some of the renowned manufacturers has already expanded their production plan for the upcoming years and is willing to further invest in this. At another occasion, the President said that solar thermal system is the need of today’s world. It helps people to get rid of harmful carbon and provides the best solution of using clean energy. Due to this solution, people are no more dependent on the limited fuels, which are imported from other countries. However, the country is facing some economic disorder, but, due to high demand of solar thermal systems, the President believed that the solar sector would not be affected by it (Ramlow & Nusz, 2010, pg 54-66).
The solar thermal industry is turning the society into a sustainable one and due to the growth in this sector; new markets are developing each day. As far as the international growth is concerned, this industry spread more vastly around the world in the year 2008. In the year 2008, the highest growth occurred in the market of Germany and it was observed that the demand of solar thermal systems increased around fifty percent over there.
On the other hand, some small markets also observed growth in this regard. In addition to this, in the year 2008, the turnover of the solar thermal products was more than €3 billion in the European market.
United Kingdom and the Solar Resources
Laughton (2010) told that United Kingdom has taken steps to adopt the renewable technologies in all of its sectors and these steps taken at private as well as government level are successful. It has been noticed that the country is involved in developing a solution to all of its energy related problems. This fact cannot be denied that in comparison with the other countries, the resources are less available in the United Kingdom, but, in order to overcome this, some projects are correctly going on. The government is hopeful that these projects will be successful and will answer the energy related problems of people (Laughton, 2010, pg 105-109).
The United Kingdom commonly produces three resources, which are petroleum, natural gas and coal. Among these three resources, the most imperative for the production of electricity is coal but unfortunately, United Kingdom faced a decline in its production since the year 1980. On the other hand, United Kingdom sufficiently produces natural gas and has a good gas network through which people can easily get gas at a low price.
In total, it can be said that United Kingdom has bulk of geothermal resources but beside this, it has a shortage of biomass resources as well as solar resources.
In the year 2007, an increase was observed in the market for heat pumps and this increase was due to increased prices of energy, but, before this increase, the markets for biomass as well as solar thermal systems were not so developed in the United Kingdom.
At present, due to government efforts, the market structure has been changed and development has occurred in this sector. A renewable heat incentive program was started in the year 2011 and providing the renewable heat to households, industries and communities was the basic aim of this program. It is still in process and positive results are coming each day (Sheet Metal and Air Conditioning Contractors National Association, 1978, pg 37-49).
Types of Solar Water Heating System:
There are two types of solar water heating system, which are active heating systems, and passive heating systems however, active heating systems are commonly more used. In active heating systems, the water is moved towards the collector from the storage tanks with the help of a pump while passive heating systems rely on the water to move towards the collector from the storage area naturally with the help of gravity where it has to be heated.
Hulstrom (1989) told that mostly active systems are preferred over passive systems as they are very convenient to install. The motor required to pump water is powered by solar cells thus making this system 100% solar powered. Apart from this, there is no need to build and maintain water storage tanks like the one used in passive heating systems thus making it look more attractive to eyes. Solar water heating systems may require backup in case of abnormal use or for days when it is cloudy. This system may be part of the solar water heating system purchased and in some cases; it has to be bought separately (Hulstrom, 1989, pg 303-309).
There are four types of solar collectors for residential purpose. They are as followed:
1. Flat-Plate collector:
Flat plate collectors are will insulated glazed boxes designed to with stand all types of weather conditions that has dark absorber plates covered with polymer.
2. Thermosyphon systems:
In Thermosyphon system, the water is heated, as a result cool water sinks, and warm water rises which then flow towards the collector, which is installed beneath the tank. Although Thermosyphon systems are reliable, the only major problem is that at the time of installation one must carefully pay attention to the roof where it is to be installed, as it weighs around 800 pounds when fully filled with water. As compared to integral collector-storage passive systems, Thermosyphon systems are more expensive.
3. ICS or Batch Systems:
According to DeWinter (1990), ICS systems that are also referred to as batch systems comprise of one and in some cases more then one black tanks this is inside fully insulated glazed box. In this system water move towards the solar collector where it is heated and from there, it moves towards the conventional backup water heater providing continuous source of hot water. ICS or Batch system should only be installed in areas where there are mild freeze climates as extreme cold conditions can block the water pipes as the ware storage is on the roof. Even in these systems one must take a close look on the roof where this system is to be installed because it weighs over 800 pounds (DeWinter, 1990, pg 183).
4. Evacuated-tube solar collectors:
Evacuated tube solar collectors are transparent glass tubes placed in rows in parallel positions. The glass tube contains metal absorber tube, which is attached to a fin. The fin helps to soak up solar energy and slow down loss of radioactive heat.
There are two kinds of Active Solar System. They are as follow:
1. Direct Open Loop Circulation Systems:
In Direct Open Loop Circulation System, the water is circulated from the collector into the house with the help of a motor. This system works well in mild climate conditions and is not recommended for extreme temperatures.
2. Indirect Closed Loop Circulation Systems:
Indirect Closed Loop Circulation Systems circulates the water from the collector towards a heat exchanger where the water gets heated and then flow towards the home. This system is not only workable in mild weather conditions but also works in extreme weather conditions. It happens because the fluid that is circulated contains an anti-freeze agent known as glycol-water mixture and its amount depends on the freezing conditions it has to work with.
Drain back Systems:
DeWinter (1989) also told that in Drain back system which is also referred to as indirect system moves the water from the collectors with the help of a pump towards a reservoir tank. The piping for this system should be done in a way that it forms a slope for the water to flow downwards easily and for bringing water up towards the roof larger motor is required in order to suck the water up.
The Main Components of Solar Thermal System:
There are five main components of Solar Thermal System. They are as follow:
1. Solar collector panel:
Solar collector panel is mostly installed on the roof where it can receive appropriate amount of sunlight. The panel absorbs the heat from the sun and then transfers the heat towards the liquid that is to be circulated from the panel. In some cases, this liquid is water and in some cases, it can be any type of special fluid that helps to transfer heat towards the storage tanks with the help of heat exchanger (DeWinter, 1990, pg 183).
2. Storage Tank:
Storage tank acts as an enclosed reservoir for incoming hot water to be stored and used for heating purposes.
3. Heat Exchanger:
Heat exchanger is responsible for transferring the captured heat from the solar panels towards the solar storage tanks where the water or any other fluid is stored for heating purposes.
4. Expansion Tank:
Expansion tank is responsible for ensuring that the pressure limit that has been set by the designer does not exceed the suggested limit.
5. Control Systems:
Control system includes a circulating pump and a controller that controls it. It is responsible for regulating temperature by comparing the difference between the exit point of heat exchanger and exit point of solar collector. In case the collector temperature is higher then the temperature of heat exchanger then liquid is circulated in order to equalize the temperature after which the pump turns off.
Solar Collector Governing Equations:
In the industry of solar energy, De Winter (1989) put great emphasis on the production of active solar energy systems, which includes many sub-systems that together are able to perform this function like solar collector, heat exchanger, storage tank and fluid distribution system. The most important part of the active solar systems is the solar collector. Solar collector is responsible to absorb sunlight and then converts it into heat, which is then transferred to any fluid usually water or air, which is later circulated through subsystems. All this makes it very difficult to accurately record and analyze the solar collector because there are many elements involved. In spite of it, an equation has been created to analyze and describe the thermal performance of solar collectors.
How to calculate energy production:
The sunlight from the sun has to travel through space, which means that it has to go through vacuum in order to enter earth hemisphere after which these solar energy falls on earth with differing concentration. This is also known as RFD, which stands for Radiant Flux Density. There are two types of Solar Irradiance which are beam gb and diffuse gd. Beam gb are those beams which comes directly from the sunlight into the solar panel where else Beam gd are those beams that comes from after being reflected by objects or by clouds in the sky (DeWinter, 1990, pg 183).
In this way, we can safely put this in this form of equation:
G = GB + GD
Solar collector is responsible for creating heat by absorbing solar energy with the help of an absorber. In order to determine the absorption rate it is very important to know that how good is an absorber in absorbing heat.
The following equation can help in energy calculation:
Qs = GA (tC AP) — UA (Tc — TA)
AP = absorption factor of collector plate
Tc = temperature of collector plate
A = area of solar collector
G = total iradiance
Qp = absorbed power
U = collector U. value
A = area of solar collector
TA = ambient air temperature
Mallik (2008) believes that energy coming from the sun = ES. Some of the light reflected back due to the surface reflection so it will be subtracted (ER) from ES which is the energy coming from the sun as a result we get the total energy absorbed by the solar receiver or the solar energy receiver that can be denoted by EA.
EA = Es — Er
Due to material physics only some part of this energy will be absorbed and this ratio is given by M, therefore E. absorbed * m = total energy available for heating Eh.
Eh*t equal to total energy available over t hours for heating water where t equals to time of available sunlight striking on the convertor. The result of this determines the temperature of the water, which gets heated by the solar energy. We can increase the energy efficiency by using more absorptive material and using less energy loss transfer means, which are prone to lesser losses (Mallik, Bhave, & Mate, 2008, pg 56).
Effective and Efficient:
There may be two reasons as to why these solar systems may be installed. The first reason may be in order save world’s fossil fuel ad the other may be the amount that would be saved in future after installing solar systems.
Following can be the cost of a thermal solar heater:
Cost of components
Cost of installation
The two costs mentioned above represents the initial cost of this system. It is estimated that if conditions were favorable the thermal solar system would be able to payback within eight to 10 years. Mostly the savings related to this system are meant for long run and not short run.
Conclusion:
According to Hulstrom (1989), solar energy is free of cost and the setup is relatively cheaper and to extract this energy is relatively cheaper then the renewable energy resources which help make our earth a better greener and a safer place to live in. If this type of system is produced at a large scale it will not be only relatively cheaper but also very cost effective but we need to use bigger and better receptors which can be strategically place in well lit areas which receives the maximum days light throughout the year and the angle of the light reception is also essential and with new technologies coming up it is relatively easier to gather more energy directly from the sun by utilizing sun rays from a wider angle and also using diffuse light from the surroundings.
How ever there are certain disadvantages of this system which is that it is directly dependant on sunlight intensity and the whole system can perform under power if not place strategically this also introduces another problem as cloud cover often diffuses most of the sunlight there by reducing efficiency of the system so it is very important that the system is only placed in areas where sunlight high intensity sunlight is available all year round and day time is maximum. Another evident disadvantage of this system is that it only works during daytime and is therefore limited to half-day productivity thus having lesser productivity to its counter parts (Hulstrom, 1989, pg 189-195).
References
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