Beyond Recycling: Using Photonics to Save the Planet

Marie Freebody, Contributing Editor, marie.freebody@photonics.com

Historically, the environment has paid a heavy price whenever innovation or technological advances have taken place. But times are changing, and today, modernization seldom occurs without the environment being considered.

The public’s consciousness of the importance of preserving our planet plays an ever-greater role in forging the direction of photonics innovation – and, conversely, photonics is having a huge impact on the environment.

Osram GmbH in Munich has found that people today care more about the environment and sustainability, which is crucial for future products but also strongly influences photonics. Here, safety and aesthetics are combined in time for the 2012 European Football Championships: The steps at the Kiev stadium are enhanced by state-of-the-art LED technology from Osram Opto Semiconductors.

Ensuring a healthy environment for future generations hinges on reducing environmental pollution through renewable energy sources and on using more energy-efficient systems. At the same time, advanced tools must be developed for environmental monitoring. Photonics plays a vital role in achieving these aims through sensing and instrumentation tools for environmental monitoring; increasing the energy efficiency of photovoltaic systems; and adopting energy-efficient lighting such as LEDs.

The increasing role that environmental issues has played in shaping photonics in recent years has not been lost on Alan Kost, research professor of optical sciences at the University of Arizona and program chair at OSA’s Optics for Solar Energy meeting held in November 2012. He highlights solar energy as one of photonics’ biggest influences.

SolarCity installations at Arizona’s largest solar-powered community, Lend Lease Soaring Heights Communities at Davis-Monthan Air Force Base, in Tucson. SolarCity is a national leader in clean energy services.

“This is partly because environmental issues have more emphasis in recent years and play a larger role in all technology,” Kost said. “Also, solar energy, a photonics technology, has been seen as a way to address an important environmental issue.”

Global warming and pollution from fossil fuels have spurred an interest in solar energy and energy conservation, prompting growth in the research and development of solar concentrators and the optics associated with flat solar panels.

But while solar energy is less environmentally damaging than burning fossil fuels, it is not without its adverse effects. For example, solar panels take up lots of space, and solar concentrator arrays use lots of water. There are also considerations when it comes to sourcing the raw materials needed for fabrication, to energy costs in processing, to waste materials and to disposing of a solar cell at the end of its lifetime.

Several studies have investigated the environmental footprint of various solar cell technologies. The US Office of Energy Efficiency and Renewable Energy and the Bureau of Land Management have prepared a Programmatic Environmental Impact Statement (PEIS) to describe some of these effects.

Other organizations have carried out life-cycle analysis investigations that track environmental impact from cradle to grave. Such research provides policy makers with a greater understanding of the value of solar technology and of its considerations.

Environmental policy, policing

In the European Union, new emissions legislation has been introduced in a bid to limit the release of sulfur from ships. The problem is that there is no way to ensure that ships obey such legislation. The European Commission’s Institute for Environment and Sustainability (IES) was tasked with finding a way to remotely measure ship emissions of SO₂ and NO_x to identify those that do not comply with the limits.

Up for the challenge was Johan Mellqvist at Chalmers University of Technology in Gothenburg, Sweden, who believes that optical measurement techniques are the best way to tackle the problem. In his approach, Mellqvist employs differential optical absorption spectroscopy (DOAS) using the Andor Shamrock 303i Czerny-Turner spectrograph and Andor Newton spectroscopy detector.

“It is relatively light and small and can be carried onboard an airplane, in contrast to laser-based methods, such as [differential absorption lidar],” Mellqvist said.

“Sulfur dioxide absorbs light in the UV range at certain frequencies. In the DOAS technique, the absorption of light at such frequencies [is] compared to the background absorption, and from this the concentration of SO₂ molecules along the light path can be determined,” said Jens Hjorth of the Air and Climate Unit at IES.

An upward-looking telescope is shown onboard a patrol vessel during a field campaign at Rotterdam, Netherlands, harbor. With the agile patrol, vessel plumes of the passing cargo vessels and tankers were traversed, and plume cross sections were obtained. Hence, sulfur-dioxide emission can be characterized as mass of sulfur dioxide per unit time for individual ships.

In another approach, a UV camera can provide a two-dimensional picture of the absorption of UV light at the frequencies typical of SO₂, producing a kind of “picture” of the ship plume using the sun as a light source.

The truth is out there

Climate change is a tricky beast to quantify. With so many influences and subtle effects to measure, it is no surprise that scientific opinion differs – in some cases, greatly. And without definitive measurements, questions from skeptics remain unanswered.

Dr. Nigel Fox, head of Earth Observation and Climate from the Centre for Carbon Measurement at the National Physical Laboratory in Teddington, UK, is exploring numerous ways of gauging man’s impact on the environment.

A project dubbed TRUTHS (Traceable Radiometry Underpinning Terrestrial and Helio Studies) proposes launching a satellite that will orbit the globe, providing full coverage of the Earth. The satellite will continuously measure the full spectral radiance (reflected sunlight) of the Earth in a bid to not only determine effects of temperature change, but also to build a climate forecast model quicker than would be possible from any existing mission.

Artistic representation of the TRUTHS concept. The TRUTHS satellite is shown orbiting the Earth and providing reference SI-traceable calibrations of the sun, Earth and moon for both decadal climate change and cross-calibration of other sensors. The improved accuracy of TRUTHS allows much more certainty and confidence in the model-based forecasts of temperature rise.

Currently, the forecast of what the Earth’s temperature will be as a function of increasing levels of greenhouse gases is performed using complex computer models, based on extensions of those used today for weather forecasting.

The problem is that different groups make different assumptions, resulting in answers ranging from 2 °C to around 10 °C. Such a wide range has enormous consequences in terms of potential effects, and it leaves policy makers with questionable evidence on which to base decisions.

It was clear to Fox that there is a great need to improve the performance of spectrally resolving radiometers, which has led to the development of new calibration facilities and concepts partially funded from an EU FP7 project called MetEOC. This includes the use of tunable photonic fiber lasers, which Fox said are much more portable than the conventional tunable lasers used previously.

To make energy-efficient lighting solutions for supermarkets, Arquiled fits its LED luminaires with Oslon SSL light-emitting diodes.

“Similarly, the next generation of satellite-based spectroscopic sensors looking at atmospheric composition – e.g., ozone – requires the use of tunable lasers to determine their spectral bands and stray light,” he said.

When it comes to detecting and quantifying man-made influences on the environment, size, cost and, above all, reliability, are key.

“As many of the environmental issues require spectrally resolved information of varying degrees of resolution, the ability to do this is one of the drivers,” Fox said. “The need to have technology to allow accurate characterization and calibration is also a trigger and one which I am directly involved in. In space applications, there is a drive to make full use of the electromagnetic spectrum and to do this in an imaging mode.” With the technology set to go, all that remains is to secure the approximately £50 million (about $80 million) needed to get the satellite launched. If achieved, the TRUTHS satellite could take orbit in about three years.

Lidar boosts wind farm efficiency

Long before a forest of wind turbines can be installed at a site, a number of suitcase-size devices are deployed in the area for up to 12 months. These modest-looking units are bursting with photonic equipment and are used to monitor the wind speed and shear over seasonal variations to help assess a site for wind farm suitability. This feasibility study is known as micrositing.

ZephIR can be used from heights down to 10 m and up to 200 m from the unit’s installed position. Shown here is the ZephIR (DM) Dual Mode system in a turbine-mounted application.

In 2003, ZephIR Lidar of Ledbury, UK, released the first commercial wind lidar, exploiting decades of research at UK government R&D company QinetiQ. Designed specifically for the wind industry, the ZephIR has enabled world firsts such as taking measurements from a wind turbine spinner and being the first to be deployed at offshore wind farms, both in fixed and floating variations.

The lidar device sends out an infrared beam, a small fraction of which is reflected by natural particles in the air such as dust, pollen and water droplets. The returning light is detected by a receiver within ZephIR. Using the Doppler technique, ZephIR measures wind speed and direction, air temperature and pressure, and the presence of rain and turbulence intensity, to name a few, from heights down to 10 m and up to 200 m from the unit’s installed position.

The ZephIR was designed specifically for the wind industry, enabling wind speed, wind direction, air temperature and air pressure measurements as well as detection of the presence of rain and turbulence intensity. Here, ZephIR 300s are deployed at UK Lidar & Sodar test site.

“Conventional techniques for measuring wind speed include tall meteorological masts, typically up to 90 m in height, with cup anemometers mounted at various fixed heights across the mast,” said Alex Woodward, head of marketing at ZephIR Lidar. “Limitations with masts include access and installation at remote sites, ability to measure at hub height as modern turbines continue to increase in size, and flow distortions caused by the mast itself, which are then measured by the cup anemometers rather than the free-flowing wind flow.”

There are more than 650 onshore ZephIR deployments globally, and the technology is fast becoming the new standard in wind measurement.

When moving offshore, cost often is a prohibitive factor; ZephIR Lidar recently teamed up with marine engineering sister company SeaRoc of Brighton, UK, to deliver an innovative floating lidar system: SeaZephIR.

ZephIR Lidar recently partnered with marine engineering sister company SeaRoc of Brighton, UK, to produce the floating lidar system SeaZephIR. Here, SeaZephIR is deployed in the US.

“One of the key drivers with the development of SeaZephIR was to reduce the cost of offshore wind farm development through reducing the capital expenditure currently required in installing fixed meteorological masts on platforms (about £6 million) by up to 50 percent,” Woodward said. “First commercial sales have been delivered, and the next five years will see a rapid increase in SeaZephIR data being used to facilitate the development of offshore wind farms globally.”

Lidar technology also can be used to predict the wind that will be incident on turbine blades. Because they can be used in the area in front of a turbine, the blades can be optimized to make best use of the incoming wind and to protect themselves from heavy turbulence.

“The area of turbine optimization is very exciting, and ZephIR Lidar is in discussion with many of the leading turbine manufacturers to incorporate ZephIR into the turbine to both increase performance and reduce life-cycle costs from manufacture to operation and maintenance,” Woodward said. “The next five years will see a rapid increase in the delivery [of] turbine-mounted ZephIR systems to the industry globally.”

Sensors detect particulate emission

As the world’s population increases, so does demand on agricultural production; at the same time, farmland is becoming increasingly lost to urban sprawl. Emission plumes from agricultural facilities have been elevated to international attention. However, the task of accurately measuring the aerosol emissions from organic matter from whole facilities is not easy.

In the US, regulations of Concentrated Agricultural Feeding Operations and other particulate emission sources are based on multiple point-sampled measurements taken near these facilities and combined in models to account for wind and time variation. This combination makes it difficult to determine the effectiveness of specific conservation and management practices.

Although investment in chemical and particulate emission detection remains relatively low, scientists are harnessing photonics technologies to move the field forward.

Dr. Michael Wojcik, senior scientist for electro-optical sensor systems in the Space Dynamics Laboratory at Utah State University in Logan, is using remote optical sensors to map and track the evolution of emission plumes from agricultural facilities.

Wojcik, in conjunction with the US Department of Agriculture’s Agricultural Research Service, has developed and deployed lidar instruments and sensors based on tunable diode laser spectroscopy. The result is a multiwavelength lidar known as Aglite, which is calibrated in real time using a suite of standard point sensors.

The multiwavelength Aglite lidar instrument combines three laser wavelengths with an array of point sensors to distinguish between various types and sizes of particulate emissions. Here, Aglite makes measurements at an agricultural site.

Aglite uses three laser wavelengths in combination with information derived from an array of point sensors to distinguish between various types and sizes of particulate emissions. The resulting combination of point samplers and scanning lidar provides near-real-time measurements of facility operations, which can be used to evaluate emission fluxes.

Although it can typically cost about $5 million to develop a bare-bones deployable mobile lidar instrument from scratch, sophisticated lidar systems such as Aglite cost substantially more. But Aglite can generate near-real-time imagery of particle-size distribution and size-segregated mass concentration and can calculate whole facility emission rates.

“Aglite is housed in a small trailer, can be operated on a 5-kW generator and can be towed by a conventional 3/4-ton pickup truck,” Wojcik said. “Aglite has a useful range of 10 km with 6-m-range resolution and has been used to measure particulate emissions for the USDA, the DoD [Department of Defense] and for petroleum producers.”

Up next for development is a mobile infrared DIAL, which Wojcik hopes to demonstrate by March. DIAL can provide range-resolved (typically 6 million voxels) greenhouse gas concentrations over ranges of up to several kilometers.

“We have developed several new laser transmitters based on novel OPO [optical parametric oscillator] technologies. We have invented several new OPO configurations which allow for rapid pulse-to-pulse, nonmechanical wavelength tuning of 250 mJ/pulse of eye-safe 1550- to 1600-nm-wavelength light,” Wojcik said. “Future DIAL instruments will also operate in the UV spectral range.”

Energy-efficient lighting

The global lighting market is expected to generate revenue of around €100 billion (about $127 billion) in 2020, with 5 percent growth predicted per year from 2010 to 2016 and 3 percent growth from 2016 to 2020, based on McKinsey’s Global Lighting Market Model.

The public’s increasing interest in preserving the environment is being felt at lighting giant Osram GmbH in Munich. Dr. Berit Wessler of Osram’s Strategic Technology Cooperation has found that people and politics care more about the environment and sustainability, which is not only crucial for all future products, but also exerts a strong influence on photonics.

“If lighting is considered, about 20 percent of electricity consumption is used for lighting applications worldwide, and 70 percent of this is being consumed by very inefficient lamps,” Wessler said. “Companies like Osram have joined forces to create awareness for the enormous saving potential in this field. As a result, we have recorded increased demand for energy-efficient lighting products such as LEDs.”

There is still some R&D effort needed to fully exploit the potential of LED technology in terms of its energy efficiency and light quality. And despite attractive return-on-investment periods, people still are hesitant about buying LED lighting because of higher initial costs compared with traditional light sources (the price of an LED lamp today is up to 40 times higher).

“Osram’s experts work continuously … to improve LED lighting technologies and to customize them to different application needs,” Wessler said. “For example, we offer intelligent light-management systems where efficient LED lighting is coupled to a sensor network that controls the light according to people’s presence and the ambient light situation.”

Photonics not only is helping to reduce the world’s lighting energy consumption, but it also is earmarked to revolutionize data transfer and its associated energy needs.

“Currently, the total energy required to power the Internet, including data centers, network nodes and user terminals, amounts to about 3 percent of today’s energy generation capacity – more than is used for global air traffic,” Wessler said. “With Internet traffic growing at nearly 50 percent each year, this demand for energy will increase relentlessly, amounting to a doubling of the required total capacity for global electricity generation in less than 10 years.”

Advanced photonics technologies offer significant opportunities for reducing the resulting consumption. Transmitting data in the form of light allows it to be guided with very low loss and high capacity: A single optical fiber already carries the data equivalent to that of more than 1000 copper cables, and the use of improved materials and new data transport methods offers considerable further decreases in energy demand for data transfer.

The impacts of solar

The PEIS summary of findings for utility-scale solar energy facilities (generation capacity of 20 MW or greater) in six western US states (Arizona, California, Colorado, New Mexico, Nevada and Utah):

• Land disturbance/land use: Solar facilities may interfere with existing land uses, such as grazing, wild horse and burro management, mineral production and military.

• Soil, water and air resources: Construction of solar facilities on large areas of land requires clearing and grading and results in soil compaction, potential alteration of drainage channels and increased runoff and erosion.

• Ecological: The clearing and use of large areas of land for solar power facilities can adversely affect native vegetation and wildlife in many ways, including loss of habitat, interference with rainfall and drainage, or direct contact causing injury or death.

• Other: These include aesthetic issues and hazardous materials; concentrating solar power systems could potentially cause interference with aircraft operations if reflected light beams become misdirected into aircraft pathways.

For more information on PEIS, visit http://solareis.anl.gov/guide/environment/index.cfm.