Lifecycle Costs of Photovoltaics

Treehugger had a squib about a recent Brookhaven Labs analysis of lifecycle cost assessment for photovoltaic panels. There wasn't a direct link so I had to do a little digging to find it but the conclusion alone is worth it:

Using data compiled from the original records of twelve PV manufacturers, we quantified the emissions from the life cycle of four major commercial photovoltaic technologies and showed that they are insignificant in comparison to the emissions that they replace when introduced in average European and U.S. grids. According to our analysis, replacing grid electricity with central PV systems presents significant environmental benefits, which for CdTe PV amounts to 89–98% reductions of GHG emissions, criteria pollutants, heavy metals, and radioactive species. For roof-top dispersed installations, such pollution reductions are expected to be even greater as the loads on the transmission and distribution networks are reduced, and part of the emissions related to the life cycle of these networks are avoided.

It is interesting that emissions of heavy metals are greatly reduced even for the types of PV technologies that make direct use of related compounds. For example the emissions of Cd from the life cycle of CdTe PV are 90−300 times lower than those from coal power plants with optimally functioning particulate control devices. In fact, life-cycle Cd emissions are even lower in CdTe PV than in crystalline Si PV, because the former use less energy in their life cycle than the later. In general, thin-film photovoltaics require less energy in their manufacturing than crystalline Si photovoltaics, and this translates to lower emissions of heavy metals, SOx, NOx, PM, and CO2. In any case, emissions from any type of PV system are expected to be lower than those from conventional energy systems because PV does not require fuel to operate. PV technologies provide the benefits of significantly curbing air emissions harmful to human and ecological health. It is noted that the environmental profiles of photovoltaics are further improving as efficiencies and material utilization rates increase and this kind of analysis needs to be updated periodically. Also, future very large penetrations of PV would alter the grid composition and this has to be accounted for in future analyses.

The four types of PV examined were multicrystalline silicon, monocrystalline silicon, ribbon silicon, and thin-film cadmium telluride.

Cadmium telluride was best overall but

At least 89% of air emissions associated with electricity generation could be prevented if electricity from photovoltaics displaces electricity from the grid.

The estimated energy payback time (EPBT) for PV ranges from 6 years to 1.1 years, depending upon the type of PV, the insolation, and the installation. PV panels are usually rated to have a lifetime of 25 to 30 years. Now you know what to say when anybody questions whether PV's produce more energy than it takes to make them.

originally posted at http://www.dailykos.com/storyonly/2008/2/28/232952/333/722/466075

Solar Fountain Harvard Square

Harvard Square, November 2007

Ecological Design Principles
by Bill McDonough

Waste equals food
Use only available solar income
Respect diversity
Love all the children







Harvard Square, October 2007

This is a Solar IS Civil Defense arrangement.

The posters around the fountain include A South-Facing Window Is Already a Solar Collector and reproductions of historic WWII posters:



Ambrose Spencer has a larger solar fountain that he displays from time to time and I just read about Charles Goldman's portable solar fountain that he walked from Brooklyn to the Bronx.

click for movie
Ambrose Spencer and SunToys at AltWheels 2005

Video courtesy of http://energyvison.blogspot.com

For years, I've been recommending that people take these things to the public squares and most especially the farmers' markets, a core constituency of any green movement, as in the story "Mr Franklin's Folks".

It's all part of a Solar Survival Show and the sooner we start performing it the more likely we are to survive.

Invisibility of Solar Power

We swim in sunlight and solar power every day and every minute of daylight. We just don't recognize it as btu's, lumens, or watts. We don't count the calories in our solar diet and include no accounting in our energy budget for all the sunlight we already use.

Part and parcel of this invisibility is our inability to see actual working solar when it is right in front of our eyes. Probably the most common solar electric device around your town is the portable electric sign powered by PV panels. It's that orange thing behind the tree.



Can you see the PV panels on this health center in Brookline, MA? Would you recognize it as solar, glancing up from the street or your car window as you passed by?



This is the Porter Square Shopping Center in Cambridge, MA. The story I heard, is that the owners, one of whom was John O'Connor, author of _Who Owns the Sun?_ and an environmental activist, wanted people to see the PV panels so they raised them up on steel girders, an investment more costly than the panels themselves. I always thought they should have included some legend on the steel like "Solar Energy at Work" or "Solar Energy Works!" I think that might be a good idea on other public solar installations too. [The Porter Square Shopping Center has a geothermal heating system in addition to PV solar.]




This is one of those poles with PV panels you can see by the side of many highways. They are monitoring traffic, counting cars, sending congestion alerts. I've seen some powering emergency equipment too. They are all over the place once you recognize them.


This trash container is a solar powered trash compactor. They were invented in Jamaica Plain and Boston is testing out 50 around the city. This one is in Davis Square in Somerville. The first one I saw was on Spectacle Island last summer.



Boston is also trying out solar powered parking meters. As a bicyclist, I think there are still some design issues to be worked out.

Keep your eyes open. At least when the sun is shining.

Cross-posted at dailykos as an entry in my diary there.

Cell Phone Solar: The Video

I wrote about Cell Phone Solar before at solarray and in one of my diaries at dailykos.


What I wrote a few months ago and what I learned in Jamaica is still true:

Cell phones change everything
Cell phone solar with AA/D battery charging is a useful minimum scale
The price point should be $10 American or less

Solar Boston - Boston Harbor Islands

I like to visit the Boston Harbor Islands at least once every summer. Last year, I noticed all the wind and solar in use out there. The Hull wind turbines dominate one section of the horizon and the skyline of Boston rises like some science fiction Oz from another. On the islands there is quiet and distance, a magic place only a ferry ride away.

This year my friend Werner and Julie of Videosphere joined me to island hop and produce a video about what we've seen. There are solar assisted composting toilets, solar electric panels, solar hot water heaters, small and large wind turbines, and even solar vehicles. The future is already here. All we have to do is recognize it.

Solar Triple Decker

Ambrose Spencer has been going over the figures for the current state of the art of PV electricity on for example, a Boston "triple decker," three family house. As Ambrose has been thinking about and working on these issues for decades now, I'd trust his numbers.



THREE FAMILY HOUSING

In Dorchester and other parts of Boston there are thousands of triple deckers. While some midatlantic cities are filled with attached row housing, aka terrace housing which has less surface area per unit available solar estate, the predominant housing in Boston is the triple decker. These have full basements which are starting to be converted into a fourth apartment. They have three flats one over another and their floor plate is 40 to 50 feet deep from the street and the width is 25 to 28 feet. The triple deckers are in all different orientations depending on the street. The narrow face is to the street. The separation runs from 20 feet to just three feet, and is usually large enough for a narrow driveway.

For a triple decker, long dimension east and west, on the roof you can erect a solar collector 10 to 12 feet high before you start to shade the solar estate next door. Having laid out solar thermal on a couple of these I know that you can put 400 to 500 square feet before the shading next door is too much of a problem .

EXISTING TRIPLE DECKER
SOLAR ELECTRIC SOURCE 10 Mwhrs.
Using your numbers: 500 square feet at about 16 percent, 8 kw
and using 3.5 hours per day annualized is 1266 hours of collection
and 10 megawatt hours.

LOADS
HEATING 17 Mwhrs
An insulated triple decker uses about 1500 gallons of oil for the three units. This is 210 mmbtu per year gross, or 50 Mwhrs net. Using a heat pump with fan coils and a cop of 3 the annual electric load for space heat is 17 Mwhrs; this does not include domestic hot water or air conditioning.

LIGHT, PLUG LOADS, APPLIANCES AND DRIVES 7.5 Mwhrs
I used 2 kw of pv allocated for a family of four. 1266 hours of collection is 2.5 Mwhrs per apartment times 3 is 7.5 Mwhrs

THREE AUTOMOBILES. 7.5 Mwhrs
I reduced my use to 10,000 miles per year at 250whrs /mile. This gives 2.5 Mwrhs times 3 is 7.5 Mwhrs. This is for battery electric vehicles.

EXISTING TRIPLE DECKER SUMMARY
On an annual basis 32 Megawatt hours is needed of which the on site solar electric, 10 Megawatt hours, can only supply one third.

IMPROVED TRIPLE DECKER
SOLAR ELECTRIC SOURCE 10 Mwhrs
The supply is the same 10 Mwhrs per year

HEATING 6.2 Mwhrs
Super insulation retrofit can cut the heat load in half, and radiant ceiling heat can raise the cop from 3 to 4. These two changes reduce the heating load to 6.2 Mwhrs.

LIGHT, PLUG LOADS, APPLIANCES AND DRIVES 5 Mwhrs
Using additional efficiency, task area illumination and higher efficiency appliances these electric loads can be cut by a third. to 5 Mwhrs.

THREE AUTOMOBILES. 7.5 Mwhrs
This load remains unchanged.

IMPROVED TRIPLE DECKER SUMMARY
The load has been reduced to 18.7 Mwhrs of which the solar electric can carry more than half

CONCLUSION
I have briefly explored a realistic application of solar electricity to the type of housing most common in Boston's older neighborhoods, in the context of a likely necessity of a 50 year schedule for accelerated climate change mitigation, although the schedule will likely be more demanding as a result of climate induced positive feedback.

I have found that to supply a typical triple decker on a Net Zero Energy basis the efficiency of the photovoltaic efficiency would need to be raised by 2 to 3 times. That is 32 percent efficiency for the superinsulated, radiant heated improved building and 48 percent efficiency needed for the unimproved building.

In a zero carbon future, all of the triple decker load not supplied on site will need to be supplied by Wind, Biofuels and other sustainable forms of renewables. Each of these carry attendant development problems like the siting of wind farms, bird kill, and the difficulties of achieving sustainable forestry on privately held lands.

Hybrid thermal electric collectors being developed by Shell in collaboration with the Dutch government and other partners can help reduce the heating load still further, but even another reduction in electric part of the heating load by one half will only affect the total electric load by 10 percent for the existing building case. .