Part 2 - Life Cycle Assessment of PVs

Alright, so, one of the things that we can consider is this just this general life cycle of a technology and its component materials inside of the scope of how it is manufactured, used, where it is sourced from. Those--that arc of life is often termed as a cradle to an end-of-life like a grave stage, and what we would like to ultimately consider is a cradle to cradle concept where you’re actually considering the technology and the core elements-- the materials from which it was made-- how did you source them, how did you process them and is there a creative way to up cycle them to do to basically recycle them with the same or higher quality of character that they had when you were first sourcing them and that cycle, that closed loop cycle of materials processing is termed cradle to cradle. This was actually popularized by an architect named William McDonough who ultimately wrote text on the same term. So, when we look at this in the terms of life cycle assessment, it actually fits within the framework of life cycle assessment. We think of it in terms of stages and it’s kind of the stages of the life cycle are something that we could box into our own bins and conveniently will break this up into raw materials sourcing so that could be mining, or that could be processing a polymer material from petroleum distillates or, you know, ultimately getting maybe even wood materials if we’re talking about other types of technologies. But let’s focus on something like a silicon photovoltaic. We are going to source the material from SIO2 from quartz or sand and we’re going take that raw material and we’re going to convert it into silicon metal from a silicon oxide to a silicon semiconductor metal that will ultimately serve as our source materials, our raw or refined material that will ultimately be used to make our silicon technology. So, we go from raw materials stage to a technical processing stage -- stage of the life cycle where we’re taking this refined silicon and we are using a process in industry to turn it into wafers and process that wafer ultimately into a photovoltaic cell and incorporate that into a photovoltaic module. And then, from the technical processing, we are going to pass that into a use stage and that’s where you would buy or the or your installer would buy a photovoltaic module. They’d install it. Once it’s installed, it’s in use and as we’ve probably heard before, photovoltaic models have a rather long lifetime; so, maybe, that photovoltaic module is in use for 25 to 40 years and then it reaches its end of use so it goes across that stage of use and then it reaches this final stage, could be final, of end-of-life which could be a disposal which means we’re ultimately going to turn into a waste pile or if we’re thinking cradle to cradle, we think in terms of recycling so that last stage could be a recycling step that basically turns it back into a subset of raw materials that we can process and the technical stage, deliver back to the use stage and then continue to cycle it around in a cradle to cradle fashion.

Alright, so we have technologies, like a photovoltaic, they are installed in your house. And you know at that point, when they are installed in your house, that they are being used. And so, if we are think about like cycle assessment, we could actually address that there’s very likely a way to bin stages of a life cycle, n a way that we, the team of analysts, could ultimately look and inventory the different stages, the different parts, steps, of the life cycle of a photovoltaic module, from raw materials, through technical processing, to use, and ultimately to recycling or disposal. We could follow those and break those up and effectively really help to define our scope inside of the life cycle framework. So each stage can effectively be thought of us bin of time where a certain type of process is happening, and we just talked about the use stage. And at either side of that time window we are going to have a gate. Right. So we have a gate that opens into a new stage and an end gate that transfers our type of life for, say the photovoltaic module, to the next stage. And when we’re doing a lifecycle assessment we are essentially doing a full assessment that takes it from sourcing of raw materials, through the gate to the next stage of technical processing, through another gate to the stage of use, and through another gate to either disposal or recycling, looping back again. So, if I’m doing a lifecycle assessment, but I’m only containing a part of that lifecycle, usually we title that something along the lines of cradle, which is the beginning of the lifecycle, to gate. Or, if we are taking just a window, like the use phase in our analysis, we do a gate-to-gate analysis. So cradle-to-gate, gate-to-gate. And if I was doing a lifecycle where I was considering how would I recycle, how would I even up-cycle a process, I would do a cradle-to-cradle lifecycle assessment. And cradle-to-cradle is a term that was actually coined by architect William McDonough and he has a text by the same name. The Interesting thing here is that we’ve found ways to break our assessment, our inventory analysis, into chunks. And we’ve even found ways where we could bound a time horizon to really dig into an unknown part of a life cycle. And that gives us a lot of ability to tune in our life cycle assessment, a lot of ability to add to a life cycle assessment. And it also provides us with a cautionary note that lifecycle might be only a very short portion of the analysis. Maybe they are doing a gate-to-gate study that doesn’t incorporate transportation energies, doesn’t incorporate broader environmental impacts because it’s not within the stage that is currently being analyzed. It’s good to know what are the boundaries of a life cycle assessment. And usually it should be clearly stated in review of that assessment.

Within photovoltaics, you know, we have a culture of life cycle assessment. We are actually a type of technology that has been using life cycle assessment for a number of years, and so we have new pressures that are changing the way that we both address life cycle assessment and compare lifecycle assessments between different researchers, and we have new challenges for things like future technologies. So, let’s start out with comparing different lifecycle assessments. Within photovoltaics, you can have an array that’s deployed in a use stage in southwestern United States. You can have another array that is deployed within the Netherlands, a great deal farther north in latitude, and having a very different insulation condition, a different degree of light that’s reaching the panels. And so, it really does affect the energetic payback. It affects how quickly a lot of the payback aspects of photovoltaics is determined. And so, we have, so the industry has developed a process called harmonization, where we are effectively finding ways to combine data sets and be able to do a comparative analysis between those different data sets, regardless of the fact that they’re in different locations. And that’s really kind of a transformative step for the photovoltaic industry. Now there are other things happening in photovoltaics, which is that the technologies are shifting. They’re changing. New materials are being incorporated, and yet we know that within the lifecycle of photovoltaics, inside the use stage, we’ve got a very long period of time. It could be up to 25, 40 years of time. So, what did we do if we can’t immediately document what are the inventory analysis of the use stage? We have to think about how we can address using life cycle assessment as a future technology indicator, as, you know, to assess whether or not this is a good decision using a new material to incorporate into photovoltaic technologies, in which case it’s really being used as a decision-making tool. So that’s changing, and then the third thing that’s really popping up is that life cycle assessment follows the flows of mass and energy. And it’s really just determined to do that. However, we know that finances are an important part of paybacks for photovoltaics and so we need to think about ways to tie together both life cycle assessment with financial returns, and so we see a stitching together of life cycle assessment and what could be called life cycle costing analysis.

The thing about life cycle assessment is that it’s very systems based it’s really meshed together with many other things beyond just a collection of data and an interpretation of the data. I mean we have to think about how are we guided to arrive at our particular goals and our scoping within the life cycle framework and we have to think about what is and we have to interpret what is an important impact and to whom and to what? So, there are some issues that are embedded within life cycle assessment that are really tied to the values that we hold, why we’re doing this as a life cycle assessment in the first place is really to better understand what is happening in the entire arc of developing and using and ultimately either recycling or disposing of the technology. You know why do we want to know these things? Ultimately we want to know them because we’d like to know if we’re having a detrimental impact on society, a detrimental effect on the biome that supporting us, are we going to have ultimately in the long term of the technology are we going have a detrimental impact to future generations? So, these are major drivers that are tied into life cycle assessment and that really shape the goal of life cycle assessment and you life cycle assessment framework really is hinged on goals and scope and it’s also that scoping that we want to be careful about that we want to have a kind of social recognition among the groups of people doing life cycle assessment and the society that’s reviewing the results of our assessment. We would like to know that the scope of this is encompassing enough that it actually reflects what is happening in nature because we’re really you know creating a sample of what is happening in large scale and we really want to be representative of what’s actually happening rather than say in the case of scope capturing just a small Gate to gate stage that might not be reflective of a much larger energetic or environmental impact in maybe an earlier stage or end-of-life stage so to be aware that the scoping the problem in life cycle assessment is -- needs to be representative of the real major impacts and that it actually has-- you run the risk in a life cycle assessment of being to contained of an assessment, and actually not capturing hat is really happening out in reality. That you have to be careful of and that actually ties back to the very process of life cycle assessment which is that it needs to be transparent process and in needs to be a process that is actually vetted by peers. So, much like an article, a science article, is very by peer review so is a true life cycle assessment, once you’ve gone through the process you really do-- you really are expected to have the life cycle assessment vetted, to be understood and then to be potentially replicated by any other peer in your cohort. So, these obligations, right these are really guiding the way that you are forming a life cycle assessment and you’re really expected to go beyond that you have some kind of deeper obligations that are embedded into life cycle process that are effectively guided by our social values which will direct that process of the life cycle framework and will ultimately continue in that process as we iterate through each successive cycle of life cycle assessment.