Building Green: Chapter 15 – Creating a Connection
Homegrown Revolution
March 9th, 2009 by brinkerPV Under $1 per Watt
February 27th, 2009 by SeldomFirst Solar announced that they have reached $1/watt for solar panels, within spitting distance of grid parity.
First Solar’s eventual goal is “grid parity,” a phrase that refers to making solar power cost the same as competing conventional power sources without subsidies. Right now the cost of making panels accounts for a little less than half the total cost of installation. The company estimates that it needs to get manufacturing costs down to $0.65 to $0.70 per watt, and other installation costs down to $1 a watt in order to reach grid parity—goals First Solar plans to reach by 2012.
The question, though, is whether First Solar or any other solar manufacturer would be able to handle the flood of orders that would ensue if they reached competitive cost. At that point, it comes down to a matter of having enough of raw materials. That is where the real limitations come to bear, according to a paper that will appear in the March issue of the journal Environmental Science & Technology. In the paper, Wadia and colleagues Paul Alivisatos and Daniel Kammen evaluated the global supplies and extraction costs for 23 promising photovoltaic semiconductor materials and found that the three materials that currently dominate the market—silicon, CdTe and another thin-film technology based on copper indium gallium selenide (CIGS)—all have limitations when ordered in mass. While silicon is the second-most abundant element in the Earth’s crust, it requires enormous amounts of energy to convert into a usable crystalline form. This is a fundamental thermodynamic barrier that will keep silicon costs comparatively high. Both CIGS and First Solar’s CdTe rank poorly in abundance and extraction cost, with CdTe ranking dead last in long-term potential based on current annual extraction rates.
Nanosolar also said they were able to produce their panels for $1/watt when they debuted last year.
Permaflow P-Trap
February 26th, 2009 by SeldomFour Steps to a More Efficient Shower
February 19th, 2009 by SeldomThis Instructables article has some good info:
- Enclose the stall.
- Install a foot pedal controller
- Add a check valve to make sure the hot water and cold water don’t backfeed when the flow to the head is off.
- Shower head (Recommendations).
Roof Materials for Rainwater Harvesting
February 7th, 2009 by SeldomTexas Rainwater Harvesting Manual:
For potable systems, a plain galvanized
roof or a metal roof with epoxy or latex
paint is recommended. Composite or
asphalt shingles are not advisable, as
toxic components can be leached out by
rainwater. See Chapter 2 for more
information on roofing material.
On the other hand, this research makes me question galvanized because of metals in the water: Link
The Texas Manual also has costs starting on page 50.
Composting Greenhouse
February 5th, 2009 by SeldomThis is the composting greenhouse built by the New Alchemy Institute in the early 80s.
Commercial greenhouses rely on fossil fuel heating rather than using passive solar design because they want as much light as possible for maximum growth rate. Blocking the north with insulation and mass results in a significant reduction. This design has the benefits of more light, but uses the compost process to provide the heat.
There are series of compost compartments along the north wall of this greenhouse accessible from outside. The compost provides CO2 for plant photosynthesis and helps heat the greenhouse. However, it also elevates the nitrogen level and the ammonia given off can burn the plant leaves. Therefore, they used small (40 watt) fans to blow the compost off-gasses thru 4″ perforated pipes and up thru the soil to use it as a biofilter. Bacteria in the soil turn the ammonia into nitrates which the plants then turn into amino acids.




