Difference between revisions of "Essay"
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==Working title== | ==Working title== | ||
− | "April 6, 2012 - Information about | + | "April 6, 2012 - Information about the Cambridge Mosstable coming soon!"[https://biophotovoltaics.wordpress.com/] |
− | + | ||
+ | ==Motivation: relevance for the students of the WdKA== | ||
+ | The adventure of the moss table is relevant for the students of the WdkA because at least partly the curriculum is heading for conceptual design. In certain area's there is no objection to the approach of cenceptual design, for instance archictecture. But the moss table points to a type of project where an elaborated and convincing design is based on a mechanism which does not function. In that case the design becomes a convincing and powerfull suggestion of something which will never work. If you know about the field, you can appreciate the project on it's design value, but if you are unfamiliar with some specialized part of this hidden function you can easily be put on a wrong track.<BR> | ||
+ | <BR> | ||
+ | Is it possible to discuss where the boundaries are for designers to present futuristic and conceptual designs? The moss table will be used as a showcase of this designer dilemma.<BR> | ||
+ | |||
==Intro== | ==Intro== | ||
− | + | Students Spatial design of the WdKA visited the exhibition “Bio Design”[http://biodesign-online.hetnieuweinstituut.nl/] in the New Institute in Rotterdam. They were inspired by the presented ideas. One student incorporated the energy harvesting principle of the Cambridge Moss table in her design. She took the claim of the mosstable for real, that this amount of moss will light this lamp on the table. And why not? Scientists guarantee the truth of the statement and the designes produce a very communicating product. The public loved the moss table. | |
− | + | ||
+ | ==About the Cambridge Moss Table== | ||
+ | The Cambridge Moss Table is designed by a team of designers and scientists at Cambridge[http://eprints.brighton.ac.uk/12727/ ]. | ||
+ | It is called “a prototype table and a showcase of emerging technology”. [http://www.gizmag.com/living-furniture-moss-table/22397/] . | ||
+ | The science part is to show the possibility of moss plants to generate energy. The design part of this project is meant to convey the message of this scientific research effectively by giving the scientific result a shape as “table” inside a home and showing what can be done with energy: lighting a normal household lamp. | ||
+ | At the above-mentioned exhibition a leaflet was added that the lamp doesn’t function. Internet pictures show the lamp illuminated and even reflections of light on the wall. | ||
+ | Although the setup is not producing enough energy to power the lamp incorporated in the design in 2011 the technology is forecasted to be competitive with the solar cell within 5-10 years [http://www.catalyststudent.org.uk/dl/f1e65d9e2de4200b723fe4a7d2d78ea30afb3de3/18-catalyst_21_4_487.pdf]. | ||
− | == | + | ==Description of the Design== |
− | + | The moss table is a white round table with at one side a table lamp. Moss plants are orderly arranged in the table top under a glass cover. The tale top is multi-layered. A table light is part of the table. The plastic legs and the frame of the table are indistinguishable from a basic camping table. The design contribution is in the way the moss plants are growing under a glass table top and the way the table light is inserted in the circular shape. The nicely arranged fresh moss plants under the glass are very appealing for the eye. | |
− | == | + | ==The complexity of the Moss Table project== |
+ | The Moss Table turns out to be the result of a combination of a scientific research and a research about the way designers can present scientific research. | ||
"The moss table was produced as part of a research project called “Design in Science”, which set out to explore how designers might be able to support scientific research." [https://biophotovoltaics.wordpress.com/] | "The moss table was produced as part of a research project called “Design in Science”, which set out to explore how designers might be able to support scientific research." [https://biophotovoltaics.wordpress.com/] | ||
+ | The scientific research was about the possibility of generating energy from moss. The design research was about effectively communicating the scientific results to the public. But not yet "scientific results" - "early stage scientific results". | ||
+ | "Its aim is to explore how designers can play a role in early stage scientific research."[http://eprints.brighton.ac.uk/12727/] | ||
+ | This "early stage" can be interpreted in different ways. The designers had to imagine and even extrapolate the possibilities of this technique, "predicting" levels of energy which are not proven yet. | ||
− | == | + | ==What makes the moss table attractive?== |
− | + | The moss table incorporates everything we are looking for: The esthetics of the table is appreciated: | |
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
"As for the rest, it was more difficult to say. There were some beautiful aesthetic pieces, like the Meridian Audio M80, the Moss Table and the Prestige kettle, which drew the eye with their innovative design." | "As for the rest, it was more difficult to say. There were some beautiful aesthetic pieces, like the Meridian Audio M80, the Moss Table and the Prestige kettle, which drew the eye with their innovative design." | ||
[http://www.cabume.co.uk/the-cluster/heaven-sent-or-false-prophets-cambridges-design-icons-go-on-show.html]<BR> | [http://www.cabume.co.uk/the-cluster/heaven-sent-or-false-prophets-cambridges-design-icons-go-on-show.html]<BR> | ||
+ | The public understands the message of the design: | ||
"A moss table has won the People’s Choice poll to be included in the Design Icons: Cambridge Innovation Festival exhibition at Anglia Ruskin University from February 8 to 23." | "A moss table has won the People’s Choice poll to be included in the Design Icons: Cambridge Innovation Festival exhibition at Anglia Ruskin University from February 8 to 23." | ||
[http://www.cambridge-news.co.uk/20-Cambridge-Design-Icons-chosen/story-22505983-detail/story.html ]<BR> | [http://www.cambridge-news.co.uk/20-Cambridge-Design-Icons-chosen/story-22505983-detail/story.html ]<BR> | ||
+ | |||
+ | The table seems to provide nice, nearly "free" energy. | ||
+ | The plants generating the energy are conveying the feeling of "green uncontaminated energy". | ||
+ | Nobody, not even the moss plants seem to suffer for generating this energy. | ||
+ | The energy will be created "intimidly" in our home, at our table, without interference or energy companies sending a bill. | ||
+ | Generating this energy does not pollute the environment, we even add friendly environment by using moss plants. We don't need specially manufactured materials or technical complexity like very pure silicium needed for solar panels. | ||
+ | The temptation of the predicted 3W/m2 is huge: charging your cell phone... | ||
+ | The idea that these tiny lovely plants, growing in all forests will help us reduce the energy bill, while just growing inside our homes is a marvellous promise.<BR> | ||
+ | |||
+ | ==Absence of critical remarks== | ||
+ | On the Internet no critical remarks about the mosstable or the BPV research are found. | ||
+ | Making critical remarks about a complex project like this not easy. What could be criticized by whom? The scientists of the team are not in a position to criticize the specialized designer; likewise can the designer never challenge the scientist. The design is evidently pleasing. The design communicates the goal of harvesting energy from unforeseen sources– maybe even too well! The scientists present the measured data (see the last paragraph of this essay). A prediction that moss will generate even more energy in the future is acceptable – we know technology will improve always – but what is “more energy”. | ||
+ | Still, thinking about the moss - damp cold forest with moss in shady places - who can imagine this moss suddenly producing 3W per square meter? | ||
+ | |||
+ | ==Comparable scientific research== | ||
+ | Research of energy generated by moss can be categorized within the domain of biofuels [http://www.alternative-energy-news.info/headlines/biofuels/]. The pro’s and con’s of biofuels are clear. If plants are used to generate energy, expecially edible plants like potatoes, potential foodstocks could be transformed into energy plants. For the wealthy part of the world this is an advantage, for poor people it could mean a disaster. | ||
+ | The moss research is also part of solar power, because photosynthesis is the mechanism, which produces energy from sunlight. Two other studies are mentioned to analyse briefly the way they present their results and “claim” energy levels. | ||
+ | |||
+ | *Photosynthesis | ||
+ | A research from the University of Georgia (2013) is done directly inside the photosynthesis cycle of the plant. | ||
+ | [http://cleantechnica.com/2013/05/11/harvesting-electricity-from-plants-plant-based-energy-generation/]<BR> | ||
+ | The article states: "There is obviously a great deal that would still need to be done before such a technology could be commercialized, but it’s definitely an interesting one…." | ||
+ | The claims are modest: "In the near term, this technology might best be used for remote sensors or other portable electronic equipment that requires less power to run,” accoring to the scientist Ramasamy. | ||
+ | <BR> | ||
+ | |||
+ | *Potatoes | ||
+ | Potatoes are investigated as batteries by a team from the University of California, Berkeley.[http://www.alternative-energy-news.info/power-from-potatoes/] . The description is simple. It is stated that an LED can be lit on a potatoe. A LED is having a well known energy consumption. Energy domains of the LED and charging a cell phone are wide apart. In this study no over extended claims are made. | ||
+ | |||
+ | ==About conceptual or futuristic design== | ||
+ | Technical problems in these days, as experienced by the general public seem to be insignificant, because of the enormous advance of technology on all levels. The public is not impressed by low figures of generated energy and believes the promise of 3W of the moss table project immediately. There is also a will to believe this is possible, because this way of energy generation with moss seems humain and friendly. Design as a product must also have the aura of the “new”, exclusive, clean, of the future. Design plays a role in acceptance of technical inventions. By situating this moss table design in the future it seems to avoid any contemporary critical remarks. What can go wrong? Architects have always produced sketches of imaginary buildings. Science fiction films display a big array of events which will never happen or function with our current level technology even if this extended at the maximum, like time travel, making other planets habitable, communicating with people at the other end of the universe etc. This does not bother the public - often the fiction in a film has become reality in some decades. | ||
+ | |||
+ | ==Comparable Conceptual Design== | ||
+ | '''The Solar Fiber project'''<BR> | ||
+ | Comparable Design and design goal can be found in the solar fiber project [http://www.solarfiber.nl/en/]. The team of designers aimed for opening up a possibility of harvesting energy with fabrics. They did research on producing fabrics where optical fibers are woven or knitted next to normal fabric. The goal of the optical fibers is catching the energy of light and transmitting this energy to photo cell. The design research results are marvellous. | ||
+ | With a multimeter showing some voltage the designers claim without further research that the future development of this kind of fabric will generate enough energy to charge a cell phone. | ||
+ | The fact that the fibers at the moment do not capture light in any significant amount doesn't hinder the designers to make this promise. In private communication with one of the designers she stated her conviction that technology will lower the energy consumption of cell phones, and the energy which the solar fiber will harvest will be improved, thus matching the promise of charging the cell phone.<BR> | ||
+ | |||
+ | '''The Solar bike road '''<BR> | ||
+ | The idea to cover the surface of roads with solar cells seems very attractive. One experimental bike road of 70 meter length is now in use in the Netherlands[http://www.solaroad.nl/en/]. | ||
+ | Calculation[https://www.youtube.com/watch?v=HOZBrHqTJk4] and current results[http://mic.com/articles/117948/6-months-later-here-s-what-s-happened-to-the-netherland-s-solar-bike-paths] show that this bike road generates half the energy of solar panels at roof tops. This result combined with a much larger investment than solar cells on rooftops (special protective glass and maintenance) doesn't hinder people to firmly believe in the concept of covering all roads with solar panels.<BR> | ||
+ | |||
+ | The difference with the moss table is that the solar bike road is a prototype which is generating energy. If this is only half of solar panels on a roof and even if the investment are much larger than solar panels this kind of project is clearly different from the moss table. A solar bike road may be doomed because other ways of harvesting solar power are more efficient but it is clearly functioning and it is not suggesting to generate a multiple of the current energy “in the future”. | ||
+ | |||
+ | ==Conclusion== | ||
+ | The design part of the moss table generates a lot of attention for this way of generating energy. Designers are unconsciously suggesting possibilities by adding elements like the lamp which are demanding energy totally out of the domain of the moss plants. The argument that maybe in the future when cell phones or lamps consume less energy this would be possible is evading the fact that this kind of project only generates small amounts of energy and will never light our home nor charge our current kind of cell phone. <BR> | ||
+ | The firm conviction of the student mentioned in the introduction is evidence that designers and so the general public are easily put in a wrong state of mind, also because they believe that science is backing this claim. | ||
+ | Therefore I argue that even designers should study some scientific facts and use their common intuition before connecting domains of energy generation and energy consumption in a way that is very suggestive and currently just not true. A design over extending the claims will generate publicity, but on the long run it will make the claims of designers implausible and designers as persons unreliable, besides harming the image of science. | ||
+ | |||
+ | Only in recent times design and technology have met. The problem mentioned in this text must be seen as a positive challenge, not blaiming either designers or scientists. The misunderstanding is an unforeseen result of new collaborations. It asks for a new, more complex way of critical thinking, reaching out over several unrelated disciplines. | ||
+ | |||
+ | ==Added: Predictions Calculations== | ||
+ | |||
+ | Citing the numbers:<BR> | ||
+ | "Currently, the moss generates about 50 milliwatts per square metre (mW/m2). Scientists anticipate that future devices may be able to generate up to 3W/m2 (Strik at al., 2011). "[https://biophotovoltaics.wordpress.com/]<BR> | ||
+ | Each one (moss plant?)generates a potential of about 0.4-0.6 volts (V) and a current of 5-10 microamps (µA).[https://biophotovoltaics.wordpress.com/] | ||
+ | <BR> | ||
+ | In a comparable article [http://www.designboom.com/technology/bio-photovoltaic-panel/ ] on BPV is briefly mentioned the following: "voltage and amperage were measured in all the experiments, and even though voltage was always present, no amperes were observed.".<BR> | ||
+ | (In an added chapter, the numbers are compared with other ways for generating energy.)<BR> | ||
+ | |||
+ | |||
+ | The given figures about the moss table, compared with other sources and experiments.<BR> | ||
+ | <BR> | ||
+ | Mosstable: currently 50 mW/m2.[https://biophotovoltaics.wordpress.com/]<BR> | ||
+ | Currently the table can produce about 520 Joules (J) of energy per day = 0.006 J/s (Watt) [https://biophotovoltaics.wordpress.com/]<BR> | ||
+ | Predicted for moss: up to 3W/m2 = 3J/s. <BR> | ||
+ | <BR> | ||
+ | In the article, these values are compared to a laptop consuming 25W (J/s). <BR> | ||
+ | The lamp fitted in the design table can be estimated at 10 - 25W. <BR> | ||
+ | |||
+ | Comparison with a solar cell: 5.2W [https://www.sparkfun.com/products/9241 ], which is indicated to have enough power to charge your cell phone. | ||
+ | My samsung cell phone uses 700mA at 5V for 4 hours meaning 3.5W during 4 hour is needed with an adaptor). <BR> | ||
+ | |||
+ | Comparison with a standard battery: 2000 mAh at 1.6V = 3.2 W during 1 hour.<BR> | ||
+ | |||
+ | Compare to solar power on a roof top: for Rotterdam, panel facing South [ http://solarelectricityhandbook.com/solar-irradiance.html]<BR> | ||
+ | From 0.80 kWh/m2/day in January to 4.98 kWh/m2/day in June = 1.38 W/m2<BR> | ||
+ | |||
+ | [[Category:Research]] |
Latest revision as of 11:02, 21 November 2022
Work in Progress!
Working title
"April 6, 2012 - Information about the Cambridge Mosstable coming soon!"[1]
Motivation: relevance for the students of the WdKA
The adventure of the moss table is relevant for the students of the WdkA because at least partly the curriculum is heading for conceptual design. In certain area's there is no objection to the approach of cenceptual design, for instance archictecture. But the moss table points to a type of project where an elaborated and convincing design is based on a mechanism which does not function. In that case the design becomes a convincing and powerfull suggestion of something which will never work. If you know about the field, you can appreciate the project on it's design value, but if you are unfamiliar with some specialized part of this hidden function you can easily be put on a wrong track.
Is it possible to discuss where the boundaries are for designers to present futuristic and conceptual designs? The moss table will be used as a showcase of this designer dilemma.
Intro
Students Spatial design of the WdKA visited the exhibition “Bio Design”[2] in the New Institute in Rotterdam. They were inspired by the presented ideas. One student incorporated the energy harvesting principle of the Cambridge Moss table in her design. She took the claim of the mosstable for real, that this amount of moss will light this lamp on the table. And why not? Scientists guarantee the truth of the statement and the designes produce a very communicating product. The public loved the moss table.
About the Cambridge Moss Table
The Cambridge Moss Table is designed by a team of designers and scientists at Cambridge[3]. It is called “a prototype table and a showcase of emerging technology”. [4] . The science part is to show the possibility of moss plants to generate energy. The design part of this project is meant to convey the message of this scientific research effectively by giving the scientific result a shape as “table” inside a home and showing what can be done with energy: lighting a normal household lamp. At the above-mentioned exhibition a leaflet was added that the lamp doesn’t function. Internet pictures show the lamp illuminated and even reflections of light on the wall. Although the setup is not producing enough energy to power the lamp incorporated in the design in 2011 the technology is forecasted to be competitive with the solar cell within 5-10 years [5].
Description of the Design
The moss table is a white round table with at one side a table lamp. Moss plants are orderly arranged in the table top under a glass cover. The tale top is multi-layered. A table light is part of the table. The plastic legs and the frame of the table are indistinguishable from a basic camping table. The design contribution is in the way the moss plants are growing under a glass table top and the way the table light is inserted in the circular shape. The nicely arranged fresh moss plants under the glass are very appealing for the eye.
The complexity of the Moss Table project
The Moss Table turns out to be the result of a combination of a scientific research and a research about the way designers can present scientific research. "The moss table was produced as part of a research project called “Design in Science”, which set out to explore how designers might be able to support scientific research." [6] The scientific research was about the possibility of generating energy from moss. The design research was about effectively communicating the scientific results to the public. But not yet "scientific results" - "early stage scientific results". "Its aim is to explore how designers can play a role in early stage scientific research."[7] This "early stage" can be interpreted in different ways. The designers had to imagine and even extrapolate the possibilities of this technique, "predicting" levels of energy which are not proven yet.
What makes the moss table attractive?
The moss table incorporates everything we are looking for: The esthetics of the table is appreciated:
"As for the rest, it was more difficult to say. There were some beautiful aesthetic pieces, like the Meridian Audio M80, the Moss Table and the Prestige kettle, which drew the eye with their innovative design."
[8]
The public understands the message of the design:
"A moss table has won the People’s Choice poll to be included in the Design Icons: Cambridge Innovation Festival exhibition at Anglia Ruskin University from February 8 to 23."
[9]
The table seems to provide nice, nearly "free" energy.
The plants generating the energy are conveying the feeling of "green uncontaminated energy".
Nobody, not even the moss plants seem to suffer for generating this energy.
The energy will be created "intimidly" in our home, at our table, without interference or energy companies sending a bill.
Generating this energy does not pollute the environment, we even add friendly environment by using moss plants. We don't need specially manufactured materials or technical complexity like very pure silicium needed for solar panels.
The temptation of the predicted 3W/m2 is huge: charging your cell phone...
The idea that these tiny lovely plants, growing in all forests will help us reduce the energy bill, while just growing inside our homes is a marvellous promise.
Absence of critical remarks
On the Internet no critical remarks about the mosstable or the BPV research are found. Making critical remarks about a complex project like this not easy. What could be criticized by whom? The scientists of the team are not in a position to criticize the specialized designer; likewise can the designer never challenge the scientist. The design is evidently pleasing. The design communicates the goal of harvesting energy from unforeseen sources– maybe even too well! The scientists present the measured data (see the last paragraph of this essay). A prediction that moss will generate even more energy in the future is acceptable – we know technology will improve always – but what is “more energy”. Still, thinking about the moss - damp cold forest with moss in shady places - who can imagine this moss suddenly producing 3W per square meter?
Comparable scientific research
Research of energy generated by moss can be categorized within the domain of biofuels [10]. The pro’s and con’s of biofuels are clear. If plants are used to generate energy, expecially edible plants like potatoes, potential foodstocks could be transformed into energy plants. For the wealthy part of the world this is an advantage, for poor people it could mean a disaster. The moss research is also part of solar power, because photosynthesis is the mechanism, which produces energy from sunlight. Two other studies are mentioned to analyse briefly the way they present their results and “claim” energy levels.
- Photosynthesis
A research from the University of Georgia (2013) is done directly inside the photosynthesis cycle of the plant.
[11]
The article states: "There is obviously a great deal that would still need to be done before such a technology could be commercialized, but it’s definitely an interesting one…."
The claims are modest: "In the near term, this technology might best be used for remote sensors or other portable electronic equipment that requires less power to run,” accoring to the scientist Ramasamy.
- Potatoes
Potatoes are investigated as batteries by a team from the University of California, Berkeley.[12] . The description is simple. It is stated that an LED can be lit on a potatoe. A LED is having a well known energy consumption. Energy domains of the LED and charging a cell phone are wide apart. In this study no over extended claims are made.
About conceptual or futuristic design
Technical problems in these days, as experienced by the general public seem to be insignificant, because of the enormous advance of technology on all levels. The public is not impressed by low figures of generated energy and believes the promise of 3W of the moss table project immediately. There is also a will to believe this is possible, because this way of energy generation with moss seems humain and friendly. Design as a product must also have the aura of the “new”, exclusive, clean, of the future. Design plays a role in acceptance of technical inventions. By situating this moss table design in the future it seems to avoid any contemporary critical remarks. What can go wrong? Architects have always produced sketches of imaginary buildings. Science fiction films display a big array of events which will never happen or function with our current level technology even if this extended at the maximum, like time travel, making other planets habitable, communicating with people at the other end of the universe etc. This does not bother the public - often the fiction in a film has become reality in some decades.
Comparable Conceptual Design
The Solar Fiber project
Comparable Design and design goal can be found in the solar fiber project [13]. The team of designers aimed for opening up a possibility of harvesting energy with fabrics. They did research on producing fabrics where optical fibers are woven or knitted next to normal fabric. The goal of the optical fibers is catching the energy of light and transmitting this energy to photo cell. The design research results are marvellous.
With a multimeter showing some voltage the designers claim without further research that the future development of this kind of fabric will generate enough energy to charge a cell phone.
The fact that the fibers at the moment do not capture light in any significant amount doesn't hinder the designers to make this promise. In private communication with one of the designers she stated her conviction that technology will lower the energy consumption of cell phones, and the energy which the solar fiber will harvest will be improved, thus matching the promise of charging the cell phone.
The Solar bike road
The idea to cover the surface of roads with solar cells seems very attractive. One experimental bike road of 70 meter length is now in use in the Netherlands[14].
Calculation[15] and current results[16] show that this bike road generates half the energy of solar panels at roof tops. This result combined with a much larger investment than solar cells on rooftops (special protective glass and maintenance) doesn't hinder people to firmly believe in the concept of covering all roads with solar panels.
The difference with the moss table is that the solar bike road is a prototype which is generating energy. If this is only half of solar panels on a roof and even if the investment are much larger than solar panels this kind of project is clearly different from the moss table. A solar bike road may be doomed because other ways of harvesting solar power are more efficient but it is clearly functioning and it is not suggesting to generate a multiple of the current energy “in the future”.
Conclusion
The design part of the moss table generates a lot of attention for this way of generating energy. Designers are unconsciously suggesting possibilities by adding elements like the lamp which are demanding energy totally out of the domain of the moss plants. The argument that maybe in the future when cell phones or lamps consume less energy this would be possible is evading the fact that this kind of project only generates small amounts of energy and will never light our home nor charge our current kind of cell phone.
The firm conviction of the student mentioned in the introduction is evidence that designers and so the general public are easily put in a wrong state of mind, also because they believe that science is backing this claim.
Therefore I argue that even designers should study some scientific facts and use their common intuition before connecting domains of energy generation and energy consumption in a way that is very suggestive and currently just not true. A design over extending the claims will generate publicity, but on the long run it will make the claims of designers implausible and designers as persons unreliable, besides harming the image of science.
Only in recent times design and technology have met. The problem mentioned in this text must be seen as a positive challenge, not blaiming either designers or scientists. The misunderstanding is an unforeseen result of new collaborations. It asks for a new, more complex way of critical thinking, reaching out over several unrelated disciplines.
Added: Predictions Calculations
Citing the numbers:
"Currently, the moss generates about 50 milliwatts per square metre (mW/m2). Scientists anticipate that future devices may be able to generate up to 3W/m2 (Strik at al., 2011). "[17]
Each one (moss plant?)generates a potential of about 0.4-0.6 volts (V) and a current of 5-10 microamps (µA).[18]
In a comparable article [19] on BPV is briefly mentioned the following: "voltage and amperage were measured in all the experiments, and even though voltage was always present, no amperes were observed.".
(In an added chapter, the numbers are compared with other ways for generating energy.)
The given figures about the moss table, compared with other sources and experiments.
Mosstable: currently 50 mW/m2.[20]
Currently the table can produce about 520 Joules (J) of energy per day = 0.006 J/s (Watt) [21]
Predicted for moss: up to 3W/m2 = 3J/s.
In the article, these values are compared to a laptop consuming 25W (J/s).
The lamp fitted in the design table can be estimated at 10 - 25W.
Comparison with a solar cell: 5.2W [22], which is indicated to have enough power to charge your cell phone.
My samsung cell phone uses 700mA at 5V for 4 hours meaning 3.5W during 4 hour is needed with an adaptor).
Comparison with a standard battery: 2000 mAh at 1.6V = 3.2 W during 1 hour.
Compare to solar power on a roof top: for Rotterdam, panel facing South [ http://solarelectricityhandbook.com/solar-irradiance.html]
From 0.80 kWh/m2/day in January to 4.98 kWh/m2/day in June = 1.38 W/m2