Past Projects

Protocrystalline Silicon Materials and Photovoltaic Devices


Protocrystalline Si:H growth as a function of hydrogen concentration


Hydrogenated amorphous silicon (a-Si:H) based solar cells are less expensive than traditional crystalline silicon based solar cells and posses an excellent ecological balance sheet. The ecological and economic promise of a-Si:H solar cells is incomplete because of the light induced degradation of its electronic properties known as the Staebler-Wronski Effect (SWE) -- as they are exposed to sunlight their efficiency drops. Dr. Pearce's previous research engineered the material to obtain a superior steady state by the use of deposition phase diagrams developed by real time spectroscopic ellipsometry, which have led to the concept of the protocrystalline hydrogenated silicon (Si:H) growth regime, shaded in yellow in the figure. The key feature of the protocrystalline Si:H material is its relative stability to light induced degradation as observed in the electron-mobility lifetime product and similarly in the solar cell fill factor.


There are five important characteristics of the protocrystalline Si:H regime:

1. Phase Evolution
2. Substrate Dependence
3. Increased Nuclei Coalescence

4. Unique Optical Properties
5. Unique Electrical Properties


For a detailed review article on protocrystalline growth see:

R.W. Collins, A.S. Ferlauto, G.M. Ferreira, C. Chen, J. Koh, R.J. Koval, Y. Lee, J.M. Pearce, and C. R. Wronski, “Evolution of microstructure and phase in amorphous, protocrystalline, and microcrystalline silicon studied by real time spectroscopic ellipsometry”, Solar Energy Materials and Solar Cells, 78(1-4), pp. 143-180, 2003.


More info:


Indium Gallium Nitride Materials and Photovoltaic Devices


SEM image of nanocolumns of InGaN

This research intends to radically reduce the cost of PV by developing an ultra-high efficiency indium gallium nitride (InGaN) solar cell. The primary reason InGaN shows such incredible promise as a photovoltaic material is the ability to modify its band gap by adjusting the ratio of indium and gallium in the film. A multi-layered cell of InGaN can be made with band gaps ranging from 0.7eV (InN) to 3.4eV (GaN) which covers the entire range of the solar spectrum. Thus, a well-designed InGaN solar cell can absorb and convert a much higher fraction of the sun’s light energy into electricity. In addition to band gap engineering, PV device performance can be improved by engineering the microstructure of the material to increase the optical path length and provide light trapping. For this purpose, nano-columns are candidates for the ideal microstructure as it has been shown that when their diameters  are optimized, resonant behavior is observed.  Our research has shown this is possible with an inexpensive scalable deposition process.

PV System Modeling over Large Areas


The use of open source GIS to determine solar radiation in SE Ontario

This was an investigation of the capacity and capabilities of the module r.sun, one of the utilities of the Geographical Resources Analysis Support System (GRASS). Using Southeastern Ontario as case study, insolation, including temporal and spatial variation of albedo, was computed to output reliable solar energy for large scale solar PV farm development in the region.


Sample automatic roof extraction

In addition to regional analysis for ground mounted systems, understanding the rooftop PV potential is critical for utility planning, accommodating grid capacity, deploying financing schemes and formulating future adaptive energy policies. This project demonstrated techniques to merge the capabilities of geographic information systems and object-specific image recognition to determine the available rooftop area for PV deployment in an example large-scale region in south eastern Ontario. A five-step procedure has been developed for estimating total rooftop PV potential which involves geographical division of the region; sampling using the Feature Analyst extraction software; extrapolation using roof area-population relationships; reduction for shading, other uses and orientation; and conversion to power and energy outputs.

We have also developed methods to automate roof and PV placement using LiDAR and to handle partial shading of the PV systems.

Industrial Symbiosis for Photovoltaics


Detail of Schematic of Industrial symbiosis in PV manufacturing

This project explores utilizing industrial symbiosis to obtain economies of scale and increased manufacturing efficiencies for solar PV cells in order for solar electricity to compete economically with fossil fuel-fired electricity.

The eco-industrial park has been designed to be made up of at least 8 symbiotic factories. The study found that by co-locating these factories in the eco-industrial park, the transportation costs and energy between them can be minimized and many of the inputs for the solar PV plant can literally come from waste products in the surrounding population centers. It should be noted that each factory will be scaled appropriately for the symbiotic system and should be individually profitable so that independent businesses can replicate this model by co-locating and benefit from industrial symbiosis in future facilities.

This study was then built upon by looking specifically at the relationship between (1) the recycling facility and (2) the glass factory to provide the necessary substrate glass for (3) the PV factory.This article quantified the inputs and outputs for the glass manufacturing component of such a system using standard manufacturing techniques and found that utilizing industrial symbiosis in this way, potential reductions for such a plant were found to be about 30,000 tons/year in raw materials and over 220,000 GJ/year in embodied energy.


Coupling of a greenhouse and glass factory

All industrial processes generate waste. The form of this waste can be in discarded items, unused materials, or waste energy which is not used for the creation of the end product. However, items that are seen as waste and a liability to one company are in many cases seen as useful inputs to other industrial processes. An industrial system which takes advantage of this principle can go by many names but is generally described as industrial ecology, or industrial symbiosis, wherein traditionally disparate industries can work together to produce environmental and financial benefits for both companies. There have been many successful industrial symbiosis projects worldwide, and the purpose of this project is to highlight another potential symbiosis, with the combination of flat glass manufacturing and tomato greenhouse agriculture.

In addition, recycling silane in the PV production itself was found to futher improve the environmental impact of a-Si:H-based PV.


Open Source Industrial Symbiosis


Google Earth Interface for looking at waste products in Pennsylvania.

As you can see from the figure - any waste stream can be chosen for the entire state and the geographic position at which the waste is created is shown. The large the column the greater the waste in tons. The white lines show the "as a bird flies" distance between waste source and sink.

Several proprietary industrial symbiosis software tools have been developed, however, without long term financial commitments these endeavors fall short of creating generalizable and sustainable tools. The recent development of virtual globes such as Google Earth (GE), an information service that provides imagery and three dimensional data depicting the entire physical earth, provides an opportunity to use a new sustainable method of navigating information to save energy and use materials more efficiently in the real world. To test this open source methodology, a data set was used from the Department of Environmental Protection in Pennsylvania, which has mandated reporting the location of disposal and type of residual waste from sources producing more than one ton per month. This data set was integrated into the GE interface to identify and quantify opportunities for materials and energy efficiency improvements. This investigation found that virtual globes coupled with open source waste information can be used to:

  1. reduce embodied transport energy by reducing distances to recycling facilities,
  2. choose end of life at recycling facilities rather than landfills, and
  3. establish industrial symbiosis and eco-industrial parks on known by-product synergies.

For one waste category, a potential 70% reduction in ton-kilometers was identified by simply observing closer disposal locations than currently utilized; similar reductions are achievable in other categories. It is concluded that the open source sharing of information in virtual globes provide a means to identify economically and environmentally beneficial opportunities for waste management if the data have been made available.

Collaboration

If you are interested in obtaining either the raw data used in this project or the kml files to search for additional opportunities to reduce waste in Pennsylvania - please contact Dr. Pearce.  We really have just scratched the surface with what can be done by coupling GIS and industrial symbiosis even with this data set.

Green IT/S



Video detailing the features of iViro an app developed by a spin off company 
Envirolytics

Green ITS Research is committed to the research, education and use of information technologies and systems to support environmental sustainability. For a full list of  papers, courses and energy conservation measures to support your own Green information technology and systems initiatives go here.

For example, consider the use of smartphone technology as a tool to implement building energy audit programs to increase energy conservation measure (ECM) uptake and concomitant environmental and economic benefits. The smartphone audit analyzed provides a energy audit platform with: i) quasi-real time analysis, ii) continuous user engagement, iii) geospatial customization, iv) additional ECMs, v) ECM ranking and user education, and vi) the ability to constantly evolve. A case study of 157,000 homes in Southeastern Ontario shows that 55 years is needed to complete energy audits for all dwellings in the region following a traditional energy audit model. However, the results of the smartphone based audit program accelerates this in both terms of audits completed and cumulative carbon dioxide savings over a sensitivity range of audit effectivenesses. It is concluded that an advanced and expanded home energy auditing program that uses smartphone technology could provide significant economic and environmental benefits.


Energy Cannibalism


Modeled global electricity supply capacity (GW), 2010–2050.

As the unacceptable results of continued fossil fuel combustion on climate change become ever clearer, a need to dramatically reduce greenhouse gas (GHG) emissions by aggressive energy conservation and immediate transitioning of global civilizations to alternative energy  sources has become evident. Many energy technologies are capable replacing significant volumes of fossil fuels. Unfortunately, neither the enormous scale of the current fossil fuel energy system nor the necessary growth rate of these technologies is well understood within the limits imposed by the net energy produced for a growing industry.

This technical limitation is known as energy cannibalism, which we developed, and refers to an effect where rapid growth of an entire energy producing or energy efficiency industry creates a need for energy that uses (or cannibalizes) the energy of existing power plants or production plants.

Thus during rapid growth, the industry as a whole produces no net energy because new energy (or conserved energy) is used to fuel the embodied energy of future power plants or production facilities. Such life cycle analysis is also valid for GHG emissions. All current technologies are dependent to some degree on fossil fuel energy and thus also contribute to emissions.

To provide quantitative solutions to this problem, this paper introduces the concept of dynamic carbon life-cycle analyses, which generate carbon-neutral growth rates. These conceptual tools become increasingly important as the world transitions to a low-carbon economy by reducing fossil fuel combustion. In choosing this method of evaluation it was possible to focus uniquely on reducing carbon emissions to the recommended levels by outlining the most carbon-effective approach to climate change mitigation. The results of using dynamic life-cycle analysis provide policy makers with standardized information that will drive the optimization of electricity generation for effective climate change mitigation.



P2P Financing of Renewable Energy Technologies


P2P-FIT-RET Network with PV example

Despite the clear need to reduce greenhouse gas emissions, lack of access to capital and appropriate financing mechanisms has limited the deployment of renewable energy technologies (RETs). Feed-in tariff (FIT) programmes have been used successfully in many countries to make RETs more economically feasible. Unfortunately, the large capital costs of RETs can result both in the slow uptake of FIT programmes and incomplete capture of deployment potential. Subsidies are concentrated in financial institutions rather than the greater population as traditional bank loans are required to fund RET projects. This project considered the political, financial and logistical risks of an innovative peer-to-peer (P2P) financing mechanism. This mechanism has the goal of increasing RET deployment capacity under an FIT programme in an effort to equitably distribute both the environmental and economic advantages throughout the entire population.



Using Salt to Make Drinking Water Safe

How adding salt to drinking water - can in some cases make it safe to drink

Solar water disinfection (SODIS) has proven to be effective at reducing diarrheal incidence in epidemiological intervention studies. However, the SODIS method is limited to waters of low turbidity (<30 NTU). Our work investigated the use of common table salt (NaCl) to reduce the turbidity of water containing suspended colloidal clay particles for use in the SODIS method. Three representative clays found in tropical soils (kaolinite, illite and bentonite) were tested at three levels of turbidity (50, 100 and 200 NTU) for their flocculating behavior with multiple NaCl concentrations to find the optimum. Supernatants were tested for sodium concentration for comparison against health and taste thresholds. Results show that unlike kaolinite and illite, pure bentonite solutions were shown to be very responsive to NaCl and produced supernatants with as low as 4 NTU (98% particle removal efficiency). Our work has shown that NaCl, in combination with high-activity clay particles in solution, may effectively reduce turbidity to levels suitable for SODIS treatment, thereby expanding the number of people who can utilize the technology effectively.


How adding salt to drinking water - can in some cases make it safe to drink.  --  Clean Drinking Water for Everyone


Overcoming Barriers to Open Source Appropriate Technology


Appropedia is the web's largest user developed provider of OSAT

Open source appropriate technology (OSAT) refers to technologies that provide for sustainable development while being designed in the same fashion as free and open-source software. Facilitated by advances in information technology software and hardware, new ways to disseminate information such as wikis and Internet-enabled mobile phones, the global development of OSAT has emerged as a reality.

This research investigates how the sharing of design processes, appropriate tools, and technical information enables more effective and rapid development of appropriate technologies for both industrialized and non-industrialized regions. This sharing will require the appropriate technology community to adopt open standards/licenses, document knowledge, and build on previous work. The group's work offers not only OSAT itself but also solutions in the form of platforms and software necessary on which to share and build knowledge about appropriate technologies. These solutions are open, easily accessible for those in need, have a low barrier to entry for both users and information creators, and must be vetted in order to utilized as a trustworthy source on critical information needs.


Open Source Research


Despite a well-established gift culture similar to that of the open source software movement in academic publishing and the tenure process many academics fail to openly provide the “source” (e.g. data sets, literature reviews, detailed experimental methodologies, designs, and open access to results) of their research. Closed research is particularly egregious when it could be used to accelerate the transition to a sustainable world and this transition is hobbled by antiquated research methodologies that slow the diffusion of innovation. To overcome this challenge, MOST has embraced the use of open source methodologies in research for applied sustainability. Open-access and open-edit Internet technologies are used as both real-time research tools and a means of disseminating findings on appropriate technology and sustainability-related research to the broadest possible audience. The results of experiments on open source research found that more rapid deployment of sustainability technologies is possible by building on the foundations of the hacker ethic with i) massive peer-review in the development of background material and experimental design, ii) increased visibility, which leads to iii) increased funding opportunities and improved student recruitment, and iv) improved student research-related training and education. In addition, we have started to use open source hardware (OSHW), which consists of physical artifacts of technology designed and offered in the same manner as free and open-source software (FOSS). MOST is working on open-source scientific hardware using Arduino microcontrollers and RepRaps in addition to our standard work in OSAT.


Amorphous Silicon Solar Photovoltaic and Thermal Hybrids


More Heat, More Light: A Step Toward Better Solar Energy Systems




Joshua M. Pearce (CC-BY-SA) MTU MSE ECE