Posts Tagged ‘Carbon Footprint’
Southern Liberties, LLC, recently completed a massive overhaul of this Philadelphia rowhouse and documented the process on the blog, Building Green on Montrose. The 100-year old, 1,850 square foot home now has three bedrooms and two and a half bathrooms, and the owners hope to obtain LEED Platinum certification for their efforts. It’s listed for sale at $565,000 and incorporates some of the following green strategies:
- Vegetated green roof;
- Salvage of part / deconstruction of the rest of the original structure;
- Waste recycling during construction;
- FSC Certified woods used throughout;
- Recycled content metals used throughout;
- Pervious paving and rain water catchment system;
- High efficiency HVAC system;
- Energy-efficient windows placed to allow natural lighting;
- Zero VOC paints and stains, no carpet;
- Efficient spray foam insulation used on exterior walls; and
- Low-flow fixtures and Energy Star appliances.
First noticed at Re-nest.
Photo credits: Building Green on Montrose.
Keep it Green
It is our desire to always be open and transparent. We at Greencon have always been a little concerned about the actual carbon cost of PV . I have searched far and wide to get a conclusive answer. I stumbled upon this, give me your thoughts:
The environmental cost is Negative in the production of most PV panels. This is a very common misconception about solar panels. Everyone thinks that because they don’t create any waste by themselves that they are this ultimate clean energy source. None thinks about where the materials for the panel came from. The glass, metal, and all the little connectors used in assembling a solar panel don’t take much energy to build but the actual Photovoltaic material DOES!
The vast majority of PV panels are made from silicon that is created in High pressure, high temperature (1650 degrees C) machines. This method is very energy intensive and unfortunately the amount of energy it takes to produce that high quality silicon is more than the solar panels made from the silicon will ever be able to recover. Add on top of that all of the other processes to “dope” the silicon so it will transfer electrons and the cost just keep rising.
To really understand you would need to look into the production of semiconductors. I don’t have any exact numbers because semiconductor manufacturers don’t tell us how much energy they consume so you would have to get a hold of one of their bills to really find out. But my semiconductor professor in college gave us an estimate that was a magnitude larger than the life time capacity of your average solar panel.
Sadly, overall right now PV solar panels are not efficient enough to be used as an energy production method except in cases in of extreme remote locations like Space, at sea, or other places away from a power grid.
Of course Thermal Solar systems are totally different, using the sun’s heat creates steam to generate electricity or to transfer that heat for some other use is a great use of free energy. Production of mirrors or dark glass materials is cheap compared to PV panels.
When it comes to solar cells, there is good news and there is bad news. First the bad news. Installing photovoltaic solar panels on your roof will cost you more than you save on electricity bills before the panels have to be replaced. The good news is that you will reduce your carbon footprint and save energy. That is the conclusion drawn from a study published in Inderscience International Journal of Environmental Technology and Management.
Solar and wind power, and other renewable sources, such as wave and tidal power, represent an energy source that could underpin a sustainable energy policy by minimizing our reliance on fossil fuels and at the same time reducing carbon dioxide and other pollutant emissions. The main barrier that has so far hindered the development of a steady market for such “renewable” systems has been their cost.
According to Giacomo Bizzarri of the University of Ferrara and Gianluca Morini of the University of Bologna, the amount of electricity that can be saved over the lifetime of a domestic PV panel is about 2000 kWh per square meter for thin film modules, with an expected life of 20 years, single-crystalline silicon devices with an anticipated lifespan of 25 years fare better producing 4400 kWh per square metre. However, the initial costs are about 2.5 times the value of the electricity produced, the researchers say.
The pair carried out a cost-benefit analysis and found that the total energy produced over a two-year period outweighs the energy used in manufacture, installation, and maintenance. Their analysis also shows that the manufacture and use of PV panels produces less pollution than fossil fuel based electricity generation.
The researchers say that their analysis holds even in countries with medium sunshine. This makes PV panels a viable alternative energy supply but will not save you money, unless the price of electricity rises three to four times, which will give a positive internal rate of return.
Bizzarri and Morini point out that cost should not be the only consideration. The total energy and pollution involved in sourcing the raw materials, manufacturing, installing, and maintaining any particular system should also be considered. After all, if it uses far more energy to build a wind farm or install solar panels than the energy they can produce during their lifetime then it does not make environmental or economic sense to install them.
With this in mind, the researchers analysed all the costs from cradle to grave – in terms of energy use, pollution and carbon footprint, and economic – to find out whether photovoltaic cells are a truly viable alternative energy source.
Three different kinds of PV devices were assessed: single-crystalline silicon, polycrystalline silicon, and thin film copper indium diselenide. The team considered the costs from the point of manufacture to end-of-life disposal. “Our study considers the systems through the whole of their life cycle, “from cradle to grave”, the researchers explain, “leading to the estimation of the energy, economic and emission payback times.”
In their assessment of the three different PV panel types on the south-facing roof of a school in Ferrara, northern Italy, the team found that the energy produced by the panels over their lifetimes considerably overcomes the energy needed during manufacture. In fact, energy costs are recovered within two years in this medium sunshine climate. The team also showed that carbon dioxide emissions are significantly lower over the PV panel lifetime from cradle-to-grave compared with conventional electricity generation. Economic costs, the team found, would only be recouped if the panels remained fully functional for more than twenty years.
The researchers suggest that their study, which takes into account all the hidden costs in terms of energy, pollution, and money, could provide a role model for policy makers considering renewable energy sources.”
Well it does seem to pay it self back, and although there is a manufacturing cost to the environment it seems far reduced from coal fired energy costs.
Keep it Green