Evaluate the advantages and disadvantages of using direct solar energy to heat buildings and water, and to produce energy.
6 thoughts on “Evaluate the advantages and disadvantages of using direct solar energy ?”
Sergey P
Well, I think that the biggest disadvantage of using solar energy is that you can’r generate electricity at night or when the weather is very cloudy.
Tenacious B
Direct solar energy or passive solar energy as it is sometimes called has the capacity to reduce some of our current energy needs if incorporated into architecture in a meaningful way. I will discuss the advantages and disadvantages in the following paragraphs.
There are a number of ways passive solar energy can be used to ones advantage. Solar cookers or solar ovens as they have been called, have been experiencing a revival in public interest since the 1970’s as an alternative means of cooking food. Food is placed at the focus of a parabolic mirror. All of the sun’s rays pass through this point and as a result, the solar energy literally cooks the food. Another similar technology uses small mirrors that are focused upon one point several feet above a mirror array. The super intense energy from the sun at this point can be used to boil water in little as 10 minutes, depending upon the size of the array. (Google search solar furnace for more info) Once the water begins to boil, the steam can be used in a steam engine which can provide electricity if hooked up to an alternator and then rectified in a manner similar to DC converters found when using solar panels.
Another type of solar furnace uses aluminum cans (due to their low specific heat capacity) that are stacked, painted black and have holes cut through the bottom of each can. An array of 10 cans high and 12 cans wide (for example) is then placed into a box with a glass face. The sun will impinge upon the cans. Since they are painted black, the air will warm within the aluminum cans. This air is then vented into a room and during a cool autumn day, can warm a small room with no conventional furnace required. An array as described could be mounted on the southern wall of a house and a small solar powered fan can be used to blow the warm air into the building. This is only effective as long as the sun is shining however.
Another advantage of solar energy can be found in hot water heaters. A parabolic trough with a black pipe running along the focus can be used to heat water in a reservoir. By thermodynamic convection, the warm water will move through the pipes and circulate through the tank, eventually warming all of the water. Insulation surrounding the holding tank will serve to maintain constant temperatures. A drawback to such a system is that in colder climates, the water tank may have to be disconnected in order to prevent freezing and cracking of the pipes.
Passive solar heating through the use of incorporating thermal mass can serve to warm a house on cold winter days. Masonry and concrete is placed in such a manner inside one’s house that an extensive array of southernly exposed windows allow the sun’s light to enter the house and warm the mass. The stone warms by day and at night when the sun goes down, the stone re-radiates the heat back into the room, compensating for the temperature difference. To maximize this effect further, large barrels of water are sometimes embedded into walls. Water has a very high specific heat capacity so it will re-radiate this energy over a much longer period of time than masonry.
Despite all of these benefits, the major controlling factor of the aforementioned technologies is the sun itself. If the sun is not present, none of them will work so aside from the passive solar heating using masonry or water as a thermal sink, all other methods rely upon the sun immediately. This is not an excuse to not incorporate these technologies into building however. After the initial investments have been made, these sources of truly free energy will continue to pay for themselves many times over with very little maintenance. This will cause your hot water heater to work substantially less in the summer and your furnace to work less in the winter.
There are many pros and cons regarding the use of solar energy but the biggest beneficiaries of this technology can be mother nature and your wallet. Enjoy!
kipman118
Advantage is that we can make it our self’s, no co2 is released, it can never run out. New solar panels can work at night through lunar rays.
Disadvantage is expensive, the technology is not ready yet.
JOHNNIE B
That is natures way with petroleum . Plants store the oil in there seed and leaves ,which is the plants energy captures from the sun. Nature has the largest solar collectors there is but some are too dumb to know it.
peter.jungmann
Disadvantage. Doesn’t really work. If you get enough that it does work it’s obscenely expensive and still doesn’t work at night.
John S
The sun is providing free energy every day. How much energy depends mainly on the latitude and to some extent on climate. The question that you are asking is to evaluate our use of this energy to heat buildings and water and presumably other uses.
Advantages:
This energy is free at source and is totally renewable, as far as we know for thousands of years.
Disadvantages:
To harness this energy we need to employ materials and resources and to use our ingenuity to provide technical solutions appropriate to the economic and physical situation and location. There is a capital cost and possibly maintenance costs.
The actual harnessing of the energy can only happen in daylight hours so there may be problems of storing the energy at night.
The advantages are greatest in hot sunny climates but the need for energy is often greater in colder, northern or southern latitudes.
Methods
What are the methods that we can use? Where are the different methods most appropriate?
Buildings
For buildings we need to consider internal climate control and hot water supply and for both these we can use passive and active methods. It is also much easier to incorporate suitable provisions into new domestic, commercial and public construction, although significant improvements can be made to existing buildings.
Passive methods: The four methods for domestic construction in the northern hemisphere that make use of greenhouse effect are:
South facing windows (large windows on south, small or none on north side) other elevations as appropriate with solar shading or solar glazing and thermal insulation.
South facing roof space: usually pitched roof used as a solar collector. May need small fan and duct to circulate hot air.
Conservatory: South side glazed volume.
Trombe wall. South glazed wall with heavy masonry or concrete wall painted black.
And for larger buildings one might use a climate wall i.e. glazed external wall with significant air space between external and internal wall (internal wall can be fully or partially glazed or incorporate thermal mass for storage of heat)
Active methods use solar voltaic panels or solar collectors with water pumped to storage or direct use. Thermosiphon systems, where the storage tank is placed above the collector, do not need a pump and are therefore regarded as a passive system. Standard units are used for hot water supply throughout the Mediterranean countries and middle east. The use of thermal chimneys is also an anchient passive method of internal climate control with modern uses.
This is a very big subject and I have only touched on a brief outline. One could also discuss earth sheltering, construction methods, sustainability, low technology methods for emerging third world countries such as solar ovens and all sorts of related subjects.
Although all the above information is from my own personal knowledge, I have used references in the past such as Wikipedia, (on line encyclopaedia) the Energy Trust Website (a non- profit making Trust based in London) and for low cost energy saving
technology: http://www.energygreed.com/. This site offers a manual for building your own solar power array and wind turbine, with sources for free batteries and claims to save you 80% on electricity costs. In the future I think we will have better gas fired boilers that are not only more efficient like condensation boilers, but combine heating and power generation, so that you will be able to sell back your surplus electricity to the national grid in Britain or the power utility company in USA and Canada. Meanwhile we have to rely on the present technology and in cold climates improved insulation or more heavily insulated new construction, double or triple glazing. Solar methods can be quite useful depending on the payback period. Heat pumps with ground collection systems usually take longer to payback and depend on your having a large volume low energy heat source such as a large pond or coils in the ground. Wind energy is another useful method, and although intermittent can have an acceptable payback period.
Well, I think that the biggest disadvantage of using solar energy is that you can’r generate electricity at night or when the weather is very cloudy.
Direct solar energy or passive solar energy as it is sometimes called has the capacity to reduce some of our current energy needs if incorporated into architecture in a meaningful way. I will discuss the advantages and disadvantages in the following paragraphs.
There are a number of ways passive solar energy can be used to ones advantage. Solar cookers or solar ovens as they have been called, have been experiencing a revival in public interest since the 1970’s as an alternative means of cooking food. Food is placed at the focus of a parabolic mirror. All of the sun’s rays pass through this point and as a result, the solar energy literally cooks the food. Another similar technology uses small mirrors that are focused upon one point several feet above a mirror array. The super intense energy from the sun at this point can be used to boil water in little as 10 minutes, depending upon the size of the array. (Google search solar furnace for more info) Once the water begins to boil, the steam can be used in a steam engine which can provide electricity if hooked up to an alternator and then rectified in a manner similar to DC converters found when using solar panels.
Another type of solar furnace uses aluminum cans (due to their low specific heat capacity) that are stacked, painted black and have holes cut through the bottom of each can. An array of 10 cans high and 12 cans wide (for example) is then placed into a box with a glass face. The sun will impinge upon the cans. Since they are painted black, the air will warm within the aluminum cans. This air is then vented into a room and during a cool autumn day, can warm a small room with no conventional furnace required. An array as described could be mounted on the southern wall of a house and a small solar powered fan can be used to blow the warm air into the building. This is only effective as long as the sun is shining however.
Another advantage of solar energy can be found in hot water heaters. A parabolic trough with a black pipe running along the focus can be used to heat water in a reservoir. By thermodynamic convection, the warm water will move through the pipes and circulate through the tank, eventually warming all of the water. Insulation surrounding the holding tank will serve to maintain constant temperatures. A drawback to such a system is that in colder climates, the water tank may have to be disconnected in order to prevent freezing and cracking of the pipes.
Passive solar heating through the use of incorporating thermal mass can serve to warm a house on cold winter days. Masonry and concrete is placed in such a manner inside one’s house that an extensive array of southernly exposed windows allow the sun’s light to enter the house and warm the mass. The stone warms by day and at night when the sun goes down, the stone re-radiates the heat back into the room, compensating for the temperature difference. To maximize this effect further, large barrels of water are sometimes embedded into walls. Water has a very high specific heat capacity so it will re-radiate this energy over a much longer period of time than masonry.
Despite all of these benefits, the major controlling factor of the aforementioned technologies is the sun itself. If the sun is not present, none of them will work so aside from the passive solar heating using masonry or water as a thermal sink, all other methods rely upon the sun immediately. This is not an excuse to not incorporate these technologies into building however. After the initial investments have been made, these sources of truly free energy will continue to pay for themselves many times over with very little maintenance. This will cause your hot water heater to work substantially less in the summer and your furnace to work less in the winter.
There are many pros and cons regarding the use of solar energy but the biggest beneficiaries of this technology can be mother nature and your wallet. Enjoy!
Advantage is that we can make it our self’s, no co2 is released, it can never run out. New solar panels can work at night through lunar rays.
Disadvantage is expensive, the technology is not ready yet.
That is natures way with petroleum . Plants store the oil in there seed and leaves ,which is the plants energy captures from the sun. Nature has the largest solar collectors there is but some are too dumb to know it.
Disadvantage. Doesn’t really work. If you get enough that it does work it’s obscenely expensive and still doesn’t work at night.
The sun is providing free energy every day. How much energy depends mainly on the latitude and to some extent on climate. The question that you are asking is to evaluate our use of this energy to heat buildings and water and presumably other uses.
Advantages:
This energy is free at source and is totally renewable, as far as we know for thousands of years.
Disadvantages:
To harness this energy we need to employ materials and resources and to use our ingenuity to provide technical solutions appropriate to the economic and physical situation and location. There is a capital cost and possibly maintenance costs.
The actual harnessing of the energy can only happen in daylight hours so there may be problems of storing the energy at night.
The advantages are greatest in hot sunny climates but the need for energy is often greater in colder, northern or southern latitudes.
Methods
What are the methods that we can use? Where are the different methods most appropriate?
Buildings
For buildings we need to consider internal climate control and hot water supply and for both these we can use passive and active methods. It is also much easier to incorporate suitable provisions into new domestic, commercial and public construction, although significant improvements can be made to existing buildings.
Passive methods: The four methods for domestic construction in the northern hemisphere that make use of greenhouse effect are:
South facing windows (large windows on south, small or none on north side) other elevations as appropriate with solar shading or solar glazing and thermal insulation.
South facing roof space: usually pitched roof used as a solar collector. May need small fan and duct to circulate hot air.
Conservatory: South side glazed volume.
Trombe wall. South glazed wall with heavy masonry or concrete wall painted black.
And for larger buildings one might use a climate wall i.e. glazed external wall with significant air space between external and internal wall (internal wall can be fully or partially glazed or incorporate thermal mass for storage of heat)
Active methods use solar voltaic panels or solar collectors with water pumped to storage or direct use. Thermosiphon systems, where the storage tank is placed above the collector, do not need a pump and are therefore regarded as a passive system. Standard units are used for hot water supply throughout the Mediterranean countries and middle east. The use of thermal chimneys is also an anchient passive method of internal climate control with modern uses.
This is a very big subject and I have only touched on a brief outline. One could also discuss earth sheltering, construction methods, sustainability, low technology methods for emerging third world countries such as solar ovens and all sorts of related subjects.
Although all the above information is from my own personal knowledge, I have used references in the past such as Wikipedia, (on line encyclopaedia) the Energy Trust Website (a non- profit making Trust based in London) and for low cost energy saving
technology: http://www.energygreed.com/. This site offers a manual for building your own solar power array and wind turbine, with sources for free batteries and claims to save you 80% on electricity costs. In the future I think we will have better gas fired boilers that are not only more efficient like condensation boilers, but combine heating and power generation, so that you will be able to sell back your surplus electricity to the national grid in Britain or the power utility company in USA and Canada. Meanwhile we have to rely on the present technology and in cold climates improved insulation or more heavily insulated new construction, double or triple glazing. Solar methods can be quite useful depending on the payback period. Heat pumps with ground collection systems usually take longer to payback and depend on your having a large volume low energy heat source such as a large pond or coils in the ground. Wind energy is another useful method, and although intermittent can have an acceptable payback period.