I have been keen to discuss the true carbon footprint of different renewable technologies for some time now. In this article I am looking to clarify a moral dilemma on Solar PV. Green "free" energy once it is installed but what carbon debt to you as a consumer inherit?
Today, it was heartening to see South Korea introduce Carbon Footprint Rules for solar panels, following a similar process in place in France which uses the lifetime carbon footprint as a prioritization metric in the permitting process for grid scale developments (great idea).
In Ireland we have great initiatives to track from field to fork, emissions per sector and emissions per km traveled/metres squared of a building, however there is no standard associated with informing and allowing consumers to understand the carbon footprint associated with the manufacture of technologies before they land on site.
I believe this is something we need to be able to assess. To enlighten myself, I reviewed what research was available on the realities on domestic PV installs.
Solar modules are made using a uniform energy intensive manufacturing process of no fewer than 200 steps using some very interesting hexafluorides and chemicals. I was looking for details surrounding - The Cumulative energy demand (CED) for the production of a PV-system. How much energy does it take to make a panel?
I found a number of sources for this which averaged at about 1300KWh of energy per metre squared.
Nawaz and Tiwari (2006) 1380kWh/m2 Roof-mounted
Nawaz and Tiwari (2006) 1710kWh/m2 Ground arrays
Lu and Yang (2010) 1237kWh/m2 Roof-mounted
Kannan et al. (2006) 1224kWh/m2 Roof-mounted
Kato et al. (1998) 1291kWh/m2 Only modules, no install
Ferroni (2014) 1287kWh/m2 2/3roof, 1/3 ground
Armed with this information it was easy to appreciate how much carbon the process generates. This is largely dependent on electricity grid which the manufacturer is connected to. If you are looking at some mass markets like China, a 305 watt panel will have a footprint of 2 Tonnes of Co2e plus shipping to your location.
Alternatively in low carbon intensive grids such as France, the footprint is closer to half.
What does all this mean?
While I am being Green for Ireland right now with solar PV in my garden, my Italian manufactured panels have an estimated installed carbon footprint of ...... 11 tonnes!
In the past year, I have generated 2300kWh of electricity and offset 920kg of Co2e, so in 11 years I may be carbon neutral from a life cycle perspective.
But wait, that's not it, to fully appreciate this we need to assess the end to end and life cycle of the assets and generation associated with the Irish grid. This is not an easy feat and not for today's discussion.
What is the correct thing to do? With daily increases in renewable penetration on our island and ever lowering gCo2e/kWh on the grid:
Install a sensible amount of solar - don't go wild!
Source panels manufactured in a jurisdiction with low C02e intensities on their grid (if i had sourced panels from outside the EU some manufactureres would have generated over 18 tonnes of Co2e to produce my 9 panels)
Open up this conversation with friends and colleagues. For global decarbonization to happen and be successful we need to look at full life cycle emissions and move away from the concept of it being green on our own doorstep.
Hope this brought some insight,