Archive for photovoltaics

National (and Colorado) Tour of Solar Homes, October 6

Note: This post was originally for the 2006 Tour. The 2007 Tour of Solar Homes will be on October 6, 2007. See the original post after the break.

———————Info about 2007 Tour of Solar homes————————

Colorado Solar Tour link
Colorado Tour of Solar Home Flyer
For Southwest Colorado, there’s some info on the SWCRES website.
For Fort Collins area tour, see NCRES Website
For other states, go to the National Solar Tour link

———————Info about 2006 Tour————————
Read the rest of this entry »

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Water and energy

Last month, several nuclear power stations in Europe had to shut down during a heat wave (and consequent period of extreme electricity demand) to avoid releasing overheated water back into the environment.  As many other astute observers have pointed out, this pokes another big hole in the arguments that nuclear is our best choice of carbon-neutral generating technology.  A power plant that goes down precisely when you need the most power is almost useless for the current grid.

It also brings up the broader point of the role of water in electricity generation.  Nuclear is not the only technology that uses water for cooling.  Coal plants, including “next generation” IGCC plants mostly use water for cooling (air cooling can be used, but it makes them less efficient, and hence more expensive to run, and is seldom used in practice.)

This is a problem because water, in most countries is under-priced.  Resources that are under-priced tend to be overused, since the user does not have to bear the full cost of supply.  This is the cause of a large number of ills, such as the drying up of the Aral sea due to irrigation for cotton farming.  It is not only poor countries who don’t have enough water.  In the US, mispricing means that almost every aquifer is being pumped at much faster than sustainable levels.  In this context, it seems certain that power plants are also paying too little for the water they use for cooling.

 With a looming need to increase farming to supply biofuels, it is more important than ever that water be priced appropriately, especially in planning scenarios for power plants.  When water is under-priced, generation technologies which use more water are likely to be inappropriately favored in comparison to technologies which use little or no water for generation.

 Like nuclear, thermal electric systems are usually water cooled.  Fossil-fueled power plants account for approximately 39 percent of the water used in the United States, second only to agriculture. For coal plants, this typically amounts to 3 gallons of water (Texas study) or 0.5 gallons (NREL study) for every kWh produced (25 gallons are used for cooling, but only 3 evaporate in the process).  Nuclear, Biomass, and Oil fired plants also require large amounts of water lost as steam in the cooling process.   Some Solar thermal technologies also require significant water for cooling.

Water use by large hydropower projects is more complex, since water in reservoirs is more useful for some purposes (recreation) but often less useful for wildlife.  However, there is no question that reservoirs increase evaporative losses.  An NREL study quantifies these losses in the US.  Overall, in the US evaporative losses average over 18.2 gallons per kWh of hydroelectric power generated.  These numbers vary widely depending on the reservoir, from 2-3 gallons per kWh in cool northern states, up to over 100 gallons per kWh in KY, OK, SD, and WY.  Keep in mind that a lot of these reservoirs have other uses besides power generation, such as storing water for dry seasons, but the numbers can be mind-boggling.

Technologies which use little water include gas turbines (both natural gas and gas from renewable sources such as landfill gas), and geothermal (the water is typically re-injected into the ground).

Wind, photovoltaic, and wave power require no water to generate electricity. 

Energy efficiency, by its nature, uses no water.  Readers will recognize that as an ongoing theme: Given the choice, it is better to avoid using a kWh than it is to generate a kWh (regardless of source… even renewables have environmental impact.)

Renewable energy advocates should also be advocating for more rational water pricing, especially in planning scenarios.  Water use in generation will eventually come to be recognized as a significant cost (and source of uncertainty, as France found out last month).  The sooner this happens, the better for everyone.  Pricing water properly will not only save water, it will help move us to renewable energy technologies.

Investors may do well by concentrating their investments on low water use technologies, especially in parts of the world where water is (or will soon be) scarce.

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John Turner’s Renewable Energy Future; renewable technologies compared.

When you want an informed, but unbiased opinion, it’s usually best to ask someone John A Turnerwhose livelihood does not depend on coming back with the “right” answer.  When it comes to comparing different renewable energy technologies, one of the best experts I’ve heard from is John Turner.   Dr. Turner is a principal scientist for the Center for Electric & Hydrogen Technologies & Systems at the National Renewable Energy Laboratory (NREL), in Golden, Colorado.

The Hydrogen economy is that long hoped for world in which one day our cars will fill up at the corner hydrogen station, and combine that fuel with oxygen in the air, a process which will create electricity for the car’s motor, and with the only emissions being water.  It all sounds wonderful, but to reach that nirvana of zero emissions, the hydrogen itself needs to be produced with non-emitting technology.  That is because, contrary to oversimplified hype from politicians, hydrogen is not an energy source, but rather an energy carrier.  Like a battery, it has to be produced (charged) before it can be used.

Dr. Turner’s goal is to guide us to the hydrogen economy with as few missteps as possible, with missteps in his mind being the used of unsustainable technologies to get there.  Since he wrote his visionary 1999 article in Science, outlining a path to a “Renewable Energy Future” in which hydrogen serves as portable energy storage for an economy fueled solely by renewable sources of power.  The weak link in this chain is fuel cell technology.  Fuel cells are used to efficiently convert hydrogen and oxygen to electricity and water.  They have been around for well over a century, but are still too expensive for use in cars, although they are practical in some military and larger scale civilian operations.  A similar problem exists for hydrogen storage.

In contrast, hydrogen as a storage medium for electricity from intermittent power sources such as wind is a technology whose time has come. Norsk Hydro is currently doing a trial run of a wind/hydrogen combination system on a small Norwegian island, powering 10 homes.

What is most interesting to me about his presentation, is his unbiased comparison of different renewable technologies, along with nuclear, and Internal Gasification Coal Combustion (IGCC) with carbon sequestration.

He compares these technologies for robustness: the ability to meet our future energy needs; for expense, and for Energy Payback.  Energy payback and the related measure EREOI (Energy Return on Energy Invested) give us an idea of how much of our energy will have to be devoted to making more energy.

Here’s the run-down (with some additions of my own):

Technology

Energy Payback/ EROEI Robust? Price per kWh (approximate 2003 prices) Long term?
Wind

3-4 months; 20-30x

Yes

5-8 cents

Yes

Solar PV

3-4 years; 8x

Very

21-24 cents

Yes

Concentrating Solar

5 months; 40x

Very

8 cents

Yes

Biomass

varies

No

7 cents

Yes

Geothermal

varies by source

No

4-7 cents

Yes

Nuclear

1 year, not counting waste disposal. <20x

Yes

13-18 cents

?

Coal (w/ carbon sequestration)

16% of energy required for sequestration.

For now

5-6 cents

70 yrs, at current growth rates.

Energy efficiency

months; 50x +

Can never get all energy from efficiency

1-2 cents

Yes

(Items with links are from linked sources)

We’ll need all these energy sources, but Wind and concentrating Solar (CSP) stand out as near-term, robust, economical solutions, while Energy Efficiency and Geothermal will give us the most bang for our buck as we try to get started down the road.

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To PV, or not to PV, that is the question.

Are you thinking about installing a photovoltaic (PV) system on your house?  Do you think to yourself, “It will be great to have my meter run backwards and have the electric company pay me for a change”?  “And I’ll be doing something to save our environment.”

The statement above that really bothers me is the part about doing something to save our environment.  My problem with it is the number of resources required: you’re going to have to give something up to buy that PV system, and the thing you are giving up could easily do a whole heck of a lot more good for the environment.  

Suppose you buy a PV system for $20,000 (rebates may halve the price of this, but you’ll see that that won’t make much difference in my argument.)  There’s a lot of argument over the precise numbers, but that system will produce 3,000 kWh (price $9/watt installed, 15% capacity factor) to 4,500 kWh a year ($7 per watt, 18% capacity factor.)   For electricity prices at a balmy Hawaiian $.24 per kWh, that system will then pay for itself (before maintenance) in a minimum of 18.5 years, and generate 83 MWh over that time, or around 150 MWh over the life of the system (30 years.)

Before anyone starts arguing about rising energy prices, let’s compare that PV system to something else we can do with the same money, at the same electricity prices. Suppose we take that same $20,000 and invest it in a 1 year CD at 5%.  After a year, we will get $1,000 in interest, which we will use to buy 500 25watt compact fluorescent light bulbs (in bulk) at $2 each.  We give these away to people who are currently using 100w incandescents.  Over the next several years, those CFLs will save a total of 300,000 kWh (8000h bulb life x 75w per hour saved x 500 bulbs). 

After only a year, we still have $20,000 so we can still buy a PV system if we want to (and take advantage of any rebates we missed out on the year before), we have avoided someone using over 300 MWh of electricity, which is about twice as much as the PV system will generate in its rated 30 year life (and don’t forget the cost of maintenance.)  Plus, most of the energy savings from the CFLs will happen over the next 8 years, rather than the 30 years it will take the PV system to generate half as much.  Most importantly, we have our initial investment of $20,000 back after one year, even though we are giving the CFLs away, while it will take over 18 years to get our money back from the PV system. 

 Because I believe in putting my money where my mouth is, anyone who mails me a receipt for the purchase of CFLs, I will PayPal them up to $5 or $2 per bulb, whichever is less (no more than once per person.)  Household LED bulbs also qualify for the same rebate.  I’ve uploaded a form to fill out, and plan to keep track of the number of bulbs, and the Negawatts generated on my website (as soon as my web guys get to it.)   This will be good for up to $1000 of total payments, or until December 31, 2006 (postmark), whichever comes first.  

Please note: I have withdrawn this offer as of 7/16/07. I have given out about $1,500 worth of rebates for over 750 CFLs, saving approximately 44 kWh per day.

For comparison, a PV system to offset the same amount of power on a daily basis would have to be over 7.5 kW, and would cost about $67,500, or 45 times as much (although it would last about 6 times as long as the CFLs, and it might only cost 20 times as much after rebates.)

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The silicon wafer industry

At Solar 2006, the annual meeting of the American Solar Energy Society there was much talk  of the shortage of polysilicon wafers, which are used to make the dominant type (crystalline) of solar Photovoltaic panels.  The other major use of polysilicon is for computer chips, which has been the dominant use until recently. 

I sat in on the following panels where the industry was discussed:

The CEO spotlight, where Goran Bye, the CEO of REC Silicon; as well as the “Market Status and Trends” panel, where several of the panelists discussed the polysilicon supply.  In particular, Hilary Flynn presented a paper by herself and Travis Bradford entitled “An assessment of global silicon production capacity and implications for the PV industry.”

According to Flynn and Bradford, the silicon wafer industry is highly consolidated, with the following major players: Hemlock, Wacker, REC Silicon, Tokuyama, MEMC Semiconductor, Mitsubishi, and Sumitomo having about 99% of the market in 2005.   Demand currently far exceeds supply, with more polysilicon being used in 2005 than was produced, with the excess being a drawdown of inventories, recycling, or an artefact of inaccuracies in the sampling method, or a combination of those factors.

From my own reading, there is much anecdotal evidence of the polysilicon supply shortage, with PV manufacturers scrambling to tie up contradts for supplies sufficient for their projected production, and even some failing to do so, with MEMC even reneging on an agreement with Evergreen Solar to supply them.

However, the silicon processing is extremely capital intensive, with long lead times, and all the major manufacturers are announcing large planned expansions to investment, and several new players are also entering the industry.  There is a long lead time between when a plant is announced, and when it come on line, so the silicon market is likely to remain out of balance, with extremely high prices and profits for silicon processers through both 2006 and 2007, assuming 30% growth in PV production.

It seems unlikely to me that PV manufacturers will be able to continue to make up the polysilicon shortfall in 2006 and 2007 from inventory (although no one seems to know what inventories are, except that they’re small, hence supply of PV growth will be constrained below 30%.

Hence I expect all polysilicon manufacturers to be very profitable through 2007, with prices beginning to subside (and perhaps crash) in 2008-9.  A crash of polysilicon prices would be facilitated by overbuilding of producers, combined with less than anticipated demand from PV manufacturers.  This might be aggravated if one of the other PV technologies (CIGS, CdTe, or Amorphous silicon) were to grab market share from crystaline silicon due to price breaktroughs and constraint in the supply for polysilicon.  Both CIGS and CdTe have the potential to be cost competitive with crystalline silicon (“PV value chain supply and demand challenges” Booz Allen Hamilton, presented at the conference), but will probably be constrained by the limited supply of Indium (CIGS) and Tellurium (CdTe) both of which are very rare.  As an aside, this might produce a large opportunity for investment in mining companies with large proven reserves of Tellurium or Indium– if one of these technolgies make much more rapid strides than crystalline PV.

There are two technologies in use by polysilicon manufacturers.  The most common is the Siemens process on which the majority of production facilities are based.  This process is extremely energy intensive, about 10x more so than the other technology, fluidized bed, which is currently used by MEMC and REC Silicon plans to use in it’s new capacity.  Most other manufacturers seem to be sticking with the Siemens process, most likely due to patent issues.  For this reason, my favorite silicon manufacturer is MEMC, since their less expensive process is likely to make them better able to weather a crash in the price of processed silicon in 2008 or 2009.  In the next year or two, I think most players in the industry will probably continue to benefit in terms of profits, although much of this may already be reflected in their stock prices.

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