Green projects, especially for individuals, have a cashflow problem. Essentially, the upfront expense, whether for new lightbulbs or a solar roof, are large and these projects only pay off over the longer run. In some cases, you are also taking on a maintenance liability with the new system.
There have been in the solar industry arrangements called PPA (Purchased Power Agreements) for several years. In these deals, a third party installs and owns the facility on a rooftop, secures financing, and collects a guaranteed revenue stream from the building owner as he purchases power. Furthermore, any subsidies and tax benefits accrue to the PPA provider, who is also responsible for system maintenance.
There is a similar model being proposed in the lighting industry. Solid state lighting has the potential to greatly exceed the efficiency of existing lighting and could save 15% of national electrical use eventually. But the 'light bulbs' (LEDs) are substantially more expensive than traditional lighting. However, they will last for 20 years. Furthermore, the efficiency of the technology is still improving rapidly. This presents three problems: lighting companies today are in the light bulb replacement business. They will need to change business models if they are to succeed when replacement cycles reach 20 years. And facility owners are not willing to up-front the costs of SSL, especially if two years later even better technology becomes available. Enter a new business model: 'leased light'. Instead of purchasing light bulbs and fixtures, the lighting manufacturer or provider enters a contract to provide light at certain specifications for a certain price (perhaps tied to electricity prices). The lighting provider collects a revenue stream for light, and decides when to install the next generation based on long-term payback of the improved technology vs. the view on electricity prices. Efficiency improvements then accrue to the provider in reduced electrical costs.
Both of these models, while useful for businesses, break down in the residential market. The problem is that homeowners (need to) sell their houses with relative impunity. So any long term agreement or financing can't be guaranteed. In essence, what is needed is an agreement attached to the house, not the owner. Enter the Berkely First project. In this scenario, the city floats a bond to finance solar roofing for residences. The owners install the roofing with city money, and the owner pays for it long term by an additional line item on his property tax bill. If the owner sells, the new owner will continue to pay on the property tax line item until the bond is repaid. So the financing is attached to the building, not the person. The owner is still responsible for maintenance, as with the rest of his house, and it is in his interest as the benefits of reduce electricity bills depend on it.
I've often thought that the biggest problem in going green is going to be financing, not technology. Creative solutions like these will provide relatively painless avenues for people to install the technology.
h/t The Vine
Thursday, November 6, 2008
Monday, August 18, 2008
Solar hydrogen
One of the biggest problems in moving to a renewable energy portfolio is the transportability question. In fixed plant, you can afford to have acres of solar capture material, for instance, but not in a car or plane (yes there are exceptions!) In addition, we need to store the energy for nighttime or cloudy day use. So batteries, ultracapacitors, underground pressurized caverns, water columns, etc. are all being explored for storage. One method getting some attention is cracking water to make hydrogen and oxygen, the hydrogen being a useful fuel, which burned makes pure (ish) water. It has a great mass energy density around 120MJ/kg and and marginal volumetric density of 8.5MJ/l in liquid form (gasoline by comparison is 45MJ/kg and 31MJ/l.) So we would need 4x the gas tank size, and at high pressure, to move us the same distance. Of course, engineering the car for better mileage could make up a lot of that difference. And for fixed installations, this doesn't necessarily present a problem.
So I was intrigued when this landed on my inbox. What IS good is they have apparently made cracking hydrogen a much less energy intensive process. This is important. But they have committed a foul in claiming the technology is inherently 'solar'. This is common now as solar energy is such a hot field that any way to connect ones work to that field is a way to raise its profile. However, any energy source will work fine as long as it produces electrons. Perhaps it is enabling for a home fuel cell driven by solar power, but it really is 'electron agnostic'. As opposed to this finding. Here, unlike the claims in the MIT finding, the technology is inherently solar. And it yields hydrogen. It may not be strictly photonic technology, but it is still quite interesting.
The hydrogen production question is being approached electrochemically as above, as well as biologically. But I wonder if this is fool's gold. The volumetric density is still low, much lower than hydrocarbons. Using this for a plane fuel for instance might be prohibitive. If we are doing something with water and CO2, maybe we should be making long-chain hydrocarbons [sub req]. They can be pumped straight into our existing energy infrastructure, refined like any oil, and transported without a massive investment in new handling and tranport mechanisms. Of course, if they are solar driven (e.g. algae), they will also have the scale problem
So I was intrigued when this landed on my inbox. What IS good is they have apparently made cracking hydrogen a much less energy intensive process. This is important. But they have committed a foul in claiming the technology is inherently 'solar'. This is common now as solar energy is such a hot field that any way to connect ones work to that field is a way to raise its profile. However, any energy source will work fine as long as it produces electrons. Perhaps it is enabling for a home fuel cell driven by solar power, but it really is 'electron agnostic'. As opposed to this finding. Here, unlike the claims in the MIT finding, the technology is inherently solar. And it yields hydrogen. It may not be strictly photonic technology, but it is still quite interesting.
The hydrogen production question is being approached electrochemically as above, as well as biologically. But I wonder if this is fool's gold. The volumetric density is still low, much lower than hydrocarbons. Using this for a plane fuel for instance might be prohibitive. If we are doing something with water and CO2, maybe we should be making long-chain hydrocarbons [sub req]. They can be pumped straight into our existing energy infrastructure, refined like any oil, and transported without a massive investment in new handling and tranport mechanisms. Of course, if they are solar driven (e.g. algae), they will also have the scale problem
Solar scale
I wanted to spend a few minutes talking about the scale of the problem. It is important to consider this when making arguments about the technologies involved. Lets start with an assertion that is useful: it would take 10,000 sunny sq miles to replace current electrical demand with photovoltaic generated by silicon cells at 20% or so efficiency. This number is reasonable though I'm sure there are arguments. Current electrical usage in the US is about 20% of total energy usage (again, round number) so for all energy at 20% efficiency, we are talking about 50,000 sq miles of silicon (32 M acres). Another point to make is that 50k sq-mi is today's number, if we are talking about a renewable portfolio that really addresses the problem in say 30 years, we have to factor in the growth rate of 1.9%pa (hopefully reduced by conservation).
Now one myth going around is that we could do that with Walmart stores, maybe throw in some other big box stores. Walmart according to Wikipedia has about 500M sq ft of stores in the US. This is 18 sq miles. Off by three orders of magnitude. In other words we would need to have 1000 Walmart-sized chains completely converted, oh by the way, all in sunny climates like AZ. How about roads? Roughly 4M miles or roads by an average width of 50ft would give us 20,000 sq miles, getting close. But a road is a LOT easier to make in bulk than a solar cell. Even with oil and asphalt prices going up.
My point isn't that 50,000 square miles is a lot (it is), but that it is a large area to cover with manufactured materials. In the end, all forms of solar energy require capturing solar flux. Most of the really scalable technologies seem to have an efficiency problem which would double or more the amount required, and since half the cost of the silicon systems is in balance of system costs, the BOS cost would essentially double as well. Not to mention the power transmission infrastructure and power storage infrastructure needed to make it really viable. So efficiency is key, you can't just 'make it up in volume'. The flip side it that IF you can make it economically attractive in comparison to existing tech, with carbon tax/C&T and/or by reducing the cost, then you have a HUGE market.
BTW, this applies to all solar driven technologies. For instance corn ethanol is fundamentally solar energy, but at much less efficiency. Biofuels from algae are also solar derived, and suffer the same scale problem. Although we are talking about much simpler scalable technologies since they are 'self assembling' of a sort.
So maybe the approach is different. We really do need to be looking for a solar roofing material, or road material, or parking lot cover. And we need to conserve. Alot. That is where solid state lighting, OLED displays and other optoelectronic technologies can help.
Now one myth going around is that we could do that with Walmart stores, maybe throw in some other big box stores. Walmart according to Wikipedia has about 500M sq ft of stores in the US. This is 18 sq miles. Off by three orders of magnitude. In other words we would need to have 1000 Walmart-sized chains completely converted, oh by the way, all in sunny climates like AZ. How about roads? Roughly 4M miles or roads by an average width of 50ft would give us 20,000 sq miles, getting close. But a road is a LOT easier to make in bulk than a solar cell. Even with oil and asphalt prices going up.
My point isn't that 50,000 square miles is a lot (it is), but that it is a large area to cover with manufactured materials. In the end, all forms of solar energy require capturing solar flux. Most of the really scalable technologies seem to have an efficiency problem which would double or more the amount required, and since half the cost of the silicon systems is in balance of system costs, the BOS cost would essentially double as well. Not to mention the power transmission infrastructure and power storage infrastructure needed to make it really viable. So efficiency is key, you can't just 'make it up in volume'. The flip side it that IF you can make it economically attractive in comparison to existing tech, with carbon tax/C&T and/or by reducing the cost, then you have a HUGE market.
BTW, this applies to all solar driven technologies. For instance corn ethanol is fundamentally solar energy, but at much less efficiency. Biofuels from algae are also solar derived, and suffer the same scale problem. Although we are talking about much simpler scalable technologies since they are 'self assembling' of a sort.
So maybe the approach is different. We really do need to be looking for a solar roofing material, or road material, or parking lot cover. And we need to conserve. Alot. That is where solid state lighting, OLED displays and other optoelectronic technologies can help.
Sunday, July 20, 2008
New 'concentrator windows' for solar?
Well, research continues apace. Here's an interesting idea for a dye sensitized window that reradiates laterally into cells placed around a window frame. http://www.sciencedaily.com/releases/2008/07/080710142927.htm If is important to think of two things when evaluating new technologies: 1) what is the installed system cost, and 2) is it something people want? Re: cost, the issue really boils down to cell efficiency. In a typical solar roof and field, about 60% of the installed system cost is "balance of system" today. That means, if the solar cells were free, the system would still cost 60% of what it costs today. However, thats for a typical silicon system at ~18% efficiency. Start using lower efficiency systems, even with the same layout, and ... that balance of system cost (connectors, wires, inverters, pedastals, etc) goes UP inversely with the drop in efficiency. Conversely, the approach of CPV or Concentrated PhotoVoltaic is to use complex optical systems to provide high concentration (500x or more) onto very efficient cells (>38%). Here the hope is that the balance of system costs of this complex optical approch will be less than the savings of a typical cell vs the fancy triple junction cell. In the end, the amount of energy delivered per square meter is a (relative) constant, and what differs is the areal efficiency of the system.
Now, to our windows. They provide some nice features: the dyes absorb over a wide range of angles, given the intercepted solar flux, and still transport the power to the edges. But they also still allow some light to be transmitted. So the conversion efficiency is unknown. Then they talk about putting solar cells around the edge of the window. This is not the most efficient from a manufacturing point of view, and electrical connections -- "balance of system" -- costs could be high. Furthermore, since windows are rarely oriented towards the sun, there's a raw loss of intercepted solar flux. So the real question about when these windows would be economic is much more complex than the authors would have you believe.
As to the second question, would consumers really want them? Lets presume that the tint of the window is acceptable, and that the maintenance of these glass panels with 'paint' on them is nominal, and then lets assume that the electrical system is robust as well, with these strangely mounted cells and complex electrical connection to a window, and that installation is similarly easy, only then does it become a question of cost to the builder. Hmm, a lot of preconditions.
The long point of this post is that just because some one releases an item promising a new low cost way to use solar power, the economics of most decisions are in fact not in the cost of the technology. In fact, the dirty little secret of the solar industry is that the most effective way to create utility scale power from the sun is solar thermal techniques, in otherwords use the sun to make steam and power a standard turbine with that. Not only is the conversion efficiency higher, but the steam can be stored until needed relieving some of the day/night problems of solar power.
Often the better use of a technology might in fact not be the sexy comercial that a scientist might hope. For instance, I could see this technology being very helpful with work going on at the University of Deleware on extremely high efficiency solar cells (>60%). The key innovation there is the splitting of light into separate bands that are individually absorbed by optimized cells. This dye approach could provide such splitting and concentrating, if it is highly efficient.
Now, to our windows. They provide some nice features: the dyes absorb over a wide range of angles, given the intercepted solar flux, and still transport the power to the edges. But they also still allow some light to be transmitted. So the conversion efficiency is unknown. Then they talk about putting solar cells around the edge of the window. This is not the most efficient from a manufacturing point of view, and electrical connections -- "balance of system" -- costs could be high. Furthermore, since windows are rarely oriented towards the sun, there's a raw loss of intercepted solar flux. So the real question about when these windows would be economic is much more complex than the authors would have you believe.
As to the second question, would consumers really want them? Lets presume that the tint of the window is acceptable, and that the maintenance of these glass panels with 'paint' on them is nominal, and then lets assume that the electrical system is robust as well, with these strangely mounted cells and complex electrical connection to a window, and that installation is similarly easy, only then does it become a question of cost to the builder. Hmm, a lot of preconditions.
The long point of this post is that just because some one releases an item promising a new low cost way to use solar power, the economics of most decisions are in fact not in the cost of the technology. In fact, the dirty little secret of the solar industry is that the most effective way to create utility scale power from the sun is solar thermal techniques, in otherwords use the sun to make steam and power a standard turbine with that. Not only is the conversion efficiency higher, but the steam can be stored until needed relieving some of the day/night problems of solar power.
Often the better use of a technology might in fact not be the sexy comercial that a scientist might hope. For instance, I could see this technology being very helpful with work going on at the University of Deleware on extremely high efficiency solar cells (>60%). The key innovation there is the splitting of light into separate bands that are individually absorbed by optimized cells. This dye approach could provide such splitting and concentrating, if it is highly efficient.
Tuesday, July 8, 2008
SSL and Energy Star
On June 2, EPA released a revised Energy Star (TM) requirement for residential light fixtures, with immediate effectivity. This standard allows LEDs to be used in residential light fixtures with an Energy Star label. Great right?
Well, not so fast. DOE has been working with the Solid State Lighting (SSL) community since 2000 to advance the SSL industry. In the process, legislation was passed authorizing DOE to work with an industry group, the Next Generation Lighting Initiative Association (NGLIA), to develop programs to assist SSL technology development and deployment. From this collaboration have come programs that ensure better measurements of the light quality 'on task', funding for developments of technology, workshops and conferences on the issues associated with integrating this technology into the existing value chain for lighting, etc. DOE also developed, in long concert with the industry, an Energy Star Criteria, released in September 2007 for effectivity in September 2008. Note, this was developed over the course of a couple of years, was intended to promote real energy savings, and built on the standards and test methods developed with industry. In contrast, the EPA "technical ammendment" was developed in relative secrecy with little outside input and uses unproven test methods.
So why is this important? In the 1980s the first compact flourescent bulbs hit the market. Unfortunately, these products suffered from a variety of problems which we all probably remember. The colors were often too harsh, some complained of flicker, light generated by the devices was often less bright or less useful that similarly-rated incandescent bulbs, etc. These problems had the effect of slowing down the adoption of CFL bulbs, increasing energy consumption, and slowing the change of the industry. In the end, if the product doesn't provide satisfactory results to consumers, it will not be adopted.
Energy Star (TM) is not only an efficiency label, but also a de-facto quality label. Products carrying this rating are assumed by consumers to at a minimum meet the expectations for performance of traditional products. However, in the case of LEDs, there are significant issues related to the nature of the light generated in order to make that light useful. If you were to take an emitter (light engine) and test its light output vs. energy input, you could have an erroneous representation of the actual useful light generated. This is because light emits from the top of the chip, and from the sides, and the radiation pattern may not be well used by the fixture into which the light engine is installed.
Unfortunately, the EPA only chose to measure the efficiency of the light engine. DOE's CALIBER program which performs calibrated measurements of LED lighting products has shown repeatably that this is insufficient for determining useful light and thus useful efficiency. If you had to replace a fixture with two LED fixtures to get the same amount of light, it would halve the efficiency. Furthermore, other characteristics of the light have not been considered or are very loosely specified. For instance, 'color temperature' or the apparent color of the white light is acceptable up to a rating of 6500 deg-K. This is a very harsh bluish color, familiar if you have one of those early LED flashlights, and, per the CFL experience, totally unacceptable to consumers. By comparison the warm yellowish light of a 100W bulb is about 2800 deg-K.
By contrast, DOE's Energy Star criteria include a wide variety of quality metrics including actual light on tast, acceptable color temperature ranges, and efficiency metrics that improve over time. This last is especially important because LEDs are getting better every year, and fixture design is improving rapidly as well. While the standards are more explicit, they are not onerous, and should serve to provide at least a minimum qulaity level to product bearing the Energy Star label. Furthermore, with the one-year run-up to the standard release, manufacturers have time to bring their products into compliance and have them tested at a certified lab.
So why is EPA doing this? It isn't clear, but one problem with the Energy Star program all along has been the dual ownership of the program between EPA and DOE. DOE would seem to be the better stakeholder since its interest are in energy conservation, even though the pollution impact is also important. This could be, then, a classic 'turf war' between the two departments. Ultimately, programs mean money and power for a Department.
The Solid State Lighting Industry Trade Association (SSLITA), under the auspices of the Optoelectronics Industry Development Association (OIDA) filed a grievance with the EPA Office fo Inspector General, claiming that the duplication of effort side-stepped protocol and wasted government resources.
Well, not so fast. DOE has been working with the Solid State Lighting (SSL) community since 2000 to advance the SSL industry. In the process, legislation was passed authorizing DOE to work with an industry group, the Next Generation Lighting Initiative Association (NGLIA), to develop programs to assist SSL technology development and deployment. From this collaboration have come programs that ensure better measurements of the light quality 'on task', funding for developments of technology, workshops and conferences on the issues associated with integrating this technology into the existing value chain for lighting, etc. DOE also developed, in long concert with the industry, an Energy Star Criteria, released in September 2007 for effectivity in September 2008. Note, this was developed over the course of a couple of years, was intended to promote real energy savings, and built on the standards and test methods developed with industry. In contrast, the EPA "technical ammendment" was developed in relative secrecy with little outside input and uses unproven test methods.
So why is this important? In the 1980s the first compact flourescent bulbs hit the market. Unfortunately, these products suffered from a variety of problems which we all probably remember. The colors were often too harsh, some complained of flicker, light generated by the devices was often less bright or less useful that similarly-rated incandescent bulbs, etc. These problems had the effect of slowing down the adoption of CFL bulbs, increasing energy consumption, and slowing the change of the industry. In the end, if the product doesn't provide satisfactory results to consumers, it will not be adopted.
Energy Star (TM) is not only an efficiency label, but also a de-facto quality label. Products carrying this rating are assumed by consumers to at a minimum meet the expectations for performance of traditional products. However, in the case of LEDs, there are significant issues related to the nature of the light generated in order to make that light useful. If you were to take an emitter (light engine) and test its light output vs. energy input, you could have an erroneous representation of the actual useful light generated. This is because light emits from the top of the chip, and from the sides, and the radiation pattern may not be well used by the fixture into which the light engine is installed.
Unfortunately, the EPA only chose to measure the efficiency of the light engine. DOE's CALIBER program which performs calibrated measurements of LED lighting products has shown repeatably that this is insufficient for determining useful light and thus useful efficiency. If you had to replace a fixture with two LED fixtures to get the same amount of light, it would halve the efficiency. Furthermore, other characteristics of the light have not been considered or are very loosely specified. For instance, 'color temperature' or the apparent color of the white light is acceptable up to a rating of 6500 deg-K. This is a very harsh bluish color, familiar if you have one of those early LED flashlights, and, per the CFL experience, totally unacceptable to consumers. By comparison the warm yellowish light of a 100W bulb is about 2800 deg-K.
By contrast, DOE's Energy Star criteria include a wide variety of quality metrics including actual light on tast, acceptable color temperature ranges, and efficiency metrics that improve over time. This last is especially important because LEDs are getting better every year, and fixture design is improving rapidly as well. While the standards are more explicit, they are not onerous, and should serve to provide at least a minimum qulaity level to product bearing the Energy Star label. Furthermore, with the one-year run-up to the standard release, manufacturers have time to bring their products into compliance and have them tested at a certified lab.
So why is EPA doing this? It isn't clear, but one problem with the Energy Star program all along has been the dual ownership of the program between EPA and DOE. DOE would seem to be the better stakeholder since its interest are in energy conservation, even though the pollution impact is also important. This could be, then, a classic 'turf war' between the two departments. Ultimately, programs mean money and power for a Department.
The Solid State Lighting Industry Trade Association (SSLITA), under the auspices of the Optoelectronics Industry Development Association (OIDA) filed a grievance with the EPA Office fo Inspector General, claiming that the duplication of effort side-stepped protocol and wasted government resources.
Tuesday, July 1, 2008
CFl recycling
This is a key development from the Times. One of the major selling points of new types of photonic lighting (LED, OLED) has been that the current standard of high efficiency bulb, the Compact FLorescent bulb has mercury in it. Recycling rates are pitiful which means many are broken in trash cans or put in landfills. Comprehensive recycling programs have not been available, so recycling rates have been about 2%. This should raise the rate significantly, but also raise the awareness of mercury in the units and possibly raise awareness of the dangers of an in-home breakage. Considering the stir about mercury in vaccines, this could counter-intuitively have a positive effect of comparably efficient replacements promissing "NO Mercury!" I suspect that's why the major manufacturers of CFLs have not introduced their own lifecycle programs, and have discounted the mercury danger.
I'll admit that the amount of mercury is minute, but in some situations, say a baby's nursery, the concentration could be significant. Of course, there's a lot more mercury in an old-style thermometer, and people probably didn't know how to dispose of them either. Still, this is fundamentally a marketing game, and LEDs and OLEDs do not 'break' and do not emit toxic substances when mishandled (unless you actually ate one anyway.)
I'll admit that the amount of mercury is minute, but in some situations, say a baby's nursery, the concentration could be significant. Of course, there's a lot more mercury in an old-style thermometer, and people probably didn't know how to dispose of them either. Still, this is fundamentally a marketing game, and LEDs and OLEDs do not 'break' and do not emit toxic substances when mishandled (unless you actually ate one anyway.)
Thursday, June 26, 2008
Solar economics
Here's a new report on the economics of solar power generation. This chart is unique in that it shows where and how solar will be an economically attractive option. Specifically, this chart
shows us how and when solar will be a significant factor. If you haven't checked out Grist before, I highly recommend it for environmental discussion with an economics awareness. (h/t Sully)
shows us how and when solar will be a significant factor. If you haven't checked out Grist before, I highly recommend it for environmental discussion with an economics awareness. (h/t Sully)
Why am I doing this blog?
I've worked in this industry for many years, but have also been an environmentalist at heart. Not a crazy, tree-hugger, but one who looks for economic solutions to green problems. The Nature Conservancy was my first environmental charity. So what does that have to do with Green Light?
The logo for this site is the photopic response curve, that is the response of the human eye to light. As our world gets faster and more information dense, we need our eyes more and more because it is the highest bandwidth connection to the brain. Photonic technologies work at the intersection of photons and electrons, creating one from the other depending on need. Typcially, these technologies work in solid-state modes, meaning that there is negligible waste heat produced and the light generated can be very efficient. There are other technologies such as electric discharge and plasma techniques that can do some of the things I will discuss, and ultimately they will have a place in our need to achieve sustainability, but I will focus here on solid-state technologies.
Photonics and optoelectronics impact every facet of our lives. These technologies provide light, both useful and artistic. They provide power from photovoltaic technologies. They provide information display in computers and signs as well as entertainment in televisions and projection systems. And they tie all this information together with wicked fast fiber-optic lines carrying terabits of information. As time goes on, photonics will provide interconnections between chip, and ultimately interconnections between processing units on a single chip. And as the world goes more information intense, the use of these technologies will grow geometrically.
Some of these technologies are just being adopted but are inherently 'green'. Solid state lighting can produce white light today with the efficiency of flourescent bulbs, with a continued improvement curve that will probably double that efficiency in 10 years. Solar photovoltaic technology today can convert about 20% of the sun's energy to electricity. What limits adoption of these technologies are economic concerns, not technological ones. Can the economic problems be solved technologically? Sometimes.
What is clear: the grid power drawn by lighting, display, and communications is growing quickly in an information economy. Lighting alone is ~20% of electrical demand. New computer and router installations are being measured in 10s of megawatts, enough power for a small city. And the use of these technologies has not been optimal for efficiency. One example, the average LCD flatpanel today only transmits 7% of the light generated by its backlight unit to the user's eye.
It is time for this industry to start to consider both the economic and technological impediments and progress to enable sustainable, economically attractive solutions. I hope to highlight developments, data, and discussion about using photonics and optoelectronics technologies to advance the 'green revolution'.
The logo for this site is the photopic response curve, that is the response of the human eye to light. As our world gets faster and more information dense, we need our eyes more and more because it is the highest bandwidth connection to the brain. Photonic technologies work at the intersection of photons and electrons, creating one from the other depending on need. Typcially, these technologies work in solid-state modes, meaning that there is negligible waste heat produced and the light generated can be very efficient. There are other technologies such as electric discharge and plasma techniques that can do some of the things I will discuss, and ultimately they will have a place in our need to achieve sustainability, but I will focus here on solid-state technologies.
Photonics and optoelectronics impact every facet of our lives. These technologies provide light, both useful and artistic. They provide power from photovoltaic technologies. They provide information display in computers and signs as well as entertainment in televisions and projection systems. And they tie all this information together with wicked fast fiber-optic lines carrying terabits of information. As time goes on, photonics will provide interconnections between chip, and ultimately interconnections between processing units on a single chip. And as the world goes more information intense, the use of these technologies will grow geometrically.
Some of these technologies are just being adopted but are inherently 'green'. Solid state lighting can produce white light today with the efficiency of flourescent bulbs, with a continued improvement curve that will probably double that efficiency in 10 years. Solar photovoltaic technology today can convert about 20% of the sun's energy to electricity. What limits adoption of these technologies are economic concerns, not technological ones. Can the economic problems be solved technologically? Sometimes.
What is clear: the grid power drawn by lighting, display, and communications is growing quickly in an information economy. Lighting alone is ~20% of electrical demand. New computer and router installations are being measured in 10s of megawatts, enough power for a small city. And the use of these technologies has not been optimal for efficiency. One example, the average LCD flatpanel today only transmits 7% of the light generated by its backlight unit to the user's eye.
It is time for this industry to start to consider both the economic and technological impediments and progress to enable sustainable, economically attractive solutions. I hope to highlight developments, data, and discussion about using photonics and optoelectronics technologies to advance the 'green revolution'.
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