Some Skepticism on Solar Thermal Power’s Storage Potential

Date: 3 Jan 2012 | posted in: Energy, Energy Self Reliant States | 2 Facebooktwitterredditmail

Yesterday New York Times reporter Matt Wald had a piece on the role of energy storage in supporting the expansion of renewable energy.  However, his specific focus on solar thermal power generation overlooks the potentially high costs of relying on solar thermal power as well as the potential for distributed “storehousing” of renewable energy. Solar thermal … Read More

Bigger Subsidies Make Bigger Solar a Bad Bet

Date: 18 Nov 2011 | posted in: Energy, Energy Self Reliant States | 0 Facebooktwitterredditmail

Americans seem unable to resist big things, and solar power plants are no exception. There may be no reasoning with an affinity for all things “super sized,” but the economics of large scale solar projects (and the unwelcome public scrutiny) should bury the notion that bigger is better for solar. In fact, smaller scale solar and … Read More

Solar Diseconomies of Scale

Date: 14 Jun 2011 | posted in: Energy | 0 Facebooktwitterredditmail

PV projects, which ranged in size from 1-kilowatt residential installations to 48-megawatt power plants, have much shorter planning horizons and project completion times, along with lesser siting, permitting, financing and transmission requirements at these small- and medium-sized scales.

However, larger PV and CSP projects (those greater than 50 MW) require overcoming financing, siting/permitting, and transmission barriers that might emerge at these larger sizes. [emphasis added]

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Water Use May Decide Future of Centralized Solar Power

Date: 27 May 2011 | posted in: Energy, Energy Self Reliant States | 0 Facebooktwitterredditmail

Power plants use a stunning amount of water.  In 2005, thermoelectric power (e.g. coal, natural gas) accounted for half of all water use in the United States.  Across the country and particularly in the arid West, the water savings from renewable energy are as important as the pollution-free energy.

That makes the distinction in water use between centralized solar and decentralized solar a big deal, especially since centralized solar is only planned for the dry Southwest.

The following graphic illustrates water consumption for common types of power generation per MWh of electricity produced (additional reference here):

Traditional power generators are water hogs.  For example, a nuclear power plant consumes 720 gallons of water for each megawatt-hour of electricity produced.  Powering a single 75-watt incandescent light bulb for an two hours on nuclear-generated electricity would consume 14 ounces of water (more than a can of pop).  

While most of that water is returned to the environment, this report by the Alliance for Water Efficiency and ACEEE notes that it’s not undamaged:

Water is returned to its original source, even though its qualities have changed, especially temperature and pollutant levels. 

Nuclear and coal may be big offenders, but wet-cooled concentrating solar power uses even more water per MWh of electricity generated.  Dry-cooled CSP cuts water consumption significantly, but it’s still far more than solar power from photovoltaics (or wind power).  

If it were solely a question of cost, CSP and PV come out relatively close (see updated chart below) despite the former’s frequent need for transmission access. 

But if the tradeoff is significant water consumption versus none, then decentralized PV may make more sense everywhere, including the sunny Southwest.

Photo credit: Flickr user Shovelling Son

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Concentrating PV a Cost-Effective Option for Distributed Solar

Date: 23 Feb 2011 | posted in: Energy, Energy Self Reliant States | 0 Facebooktwitterredditmail

Concentrating solar typically fills people energy nerds with visions of large fields of mirrors focusing sunlight to make heat/steam/electricity, but concentration technology is also available for photovoltaics (PV).  In fact, using lenses to focus sun onto PV cells – concentrated PV or CPV – may prove to be a more cost-effective (and compact) strategy of doing solar power than either concentrating solar thermal power or traditional solar PV.

For this analysis, we compared a real-life, 1 megawatt (MW) concentrated PV installation in Victorville, CA (just outside Los Angeles) to Southern California Edison’s 250 MW distributed PV installation (in 1-2 MW projects).  Since SCE’s project likely involves fixed-tilt or flat PV panels, we also included a hypothetical ground-mounted single-axis tracking PV project for comparison.

The data suggests that CPV has a lower levelized cost of operation, even as both technologies have a levelized cost (with federal incentives) below the peak local retail electricity rate.

  CPV PV Fixed Tilt PV 1-axis tracking
Installation size 1 MW
Cost per Watt (AC) $4.55 $4.38 $6.56
Cost of capital 5%
% debt financed 80%
Debt term 10 years
Project life 25 years
Levelized Cost      
Unsubsidized $0.199 $0.215 $0.253
With ITC/MACRS $0.117 $0.125 $0.147
Capacity factor 24% 17% 22%

The comparison is not just about lowest cost, because CPV offers other advantages.  The concentrating lenses are less expensive that the actual solar cells, and thus CPV can potentially offer lower cost for the same kilowatt hour output.  Additionally, a CPV can offer higher output per square foot of occupied space. 

CPV appears to already be in a strong position to compete with traditional solar PV options, a promising position for a product just entering the commercial market.

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Addressing Frequently Asked Questions About Solar PV v. Concentrating Solar

Date: 21 Jan 2011 | posted in: Energy, Energy Self Reliant States | 0 Facebooktwitterredditmail

Although both produce electricity from the sun, there are significant differences between solar PV and concentrating solar thermal electricity generation.  This FAQ provides answers to the most pressing questions about the two solar technologies. 1. Isn’t concentrating solar power cheaper? No.  Five years ago the two technologies were relatively comparable, but in 2011 there’s no doubt … Read More

Rapid Distributed PV Outstrips Lumbering Solar Thermal

Date: 20 Jan 2011 | posted in: Energy, Energy Self Reliant States | 0 Facebooktwitterredditmail

While California lumbers forward with a high-cost, controversial solar strategy built around remote utility-scale solar thermal plants, with the hope that 10,000 megawatts can be built in ten years, Germany is demonstrating now that 10,000 megawatts of distributed PV can be added in only three years.

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Home Solar Cheaper Than Every Concentrating Solar Power Plant

Date: 13 Jan 2011 | posted in: Energy, Energy Self Reliant States | 3 Facebooktwitterredditmail

A residential rooftop solar PV system in Los Angeles, CA, has a cheaper cost per kilowatt-hour of electricity delivered than the most cost effective, utility-scale concentrating solar power plant. 

In 2010, a buying group called Open Neighborhoods openly advertised an opportunity to get a solar PV system installed for $4.78 per Watt (not including any tax credits, rebates, or grants), a system that would produce approximately 1,492 kilowatt-hours (kWh) per year (AC) for each kilowatt of capacity (DC). 

Based on the best available public information about the costs and performance of operational concentrating solar thermal power plants, the PS10 solar power tower – an 11 MW installation in Spain – has the lowest levelized cost of operation of any concentrating solar power plant that produces electricity.  PS10 had an installed cost of $4.15 per Watt and produces 2,127 kWh per kW of capacity. 

However, due to higher operations costs and a higher cost of capital (8% rather than 5%) for a concentrating solar power plant, the levelized cost of the residential rooftop system (17.3 cents per kWh) is less than that of the power tower (19.9 cents per kWh).

This analysis also does not include any transmission infrastructure or efficiency losses, either of which would increase the levelized cost of the concentrating solar power plant.  It also did not include the lower price point from Open Neighborhoods, which advertised a possibility of driving the price down to $4.22 per Watt (driving the levelized cost down to 15.3 cents per kWh).

The Southern California Edison project, also featured in the chart, is another example of low-cost distributed solar PV, with the 250 MW project spread across commercial rooftops in 1-2 MW increments but still achieving large scale. 

Ultimately, this data further confirms that distributed solar can be delivered less expensively than centralized solar power. 

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Failure of 663 MW Stirling solar power plant another blow for centralized solar

Date: 3 Jan 2011 | posted in: Energy, Energy Self Reliant States | 0 Facebooktwitterredditmail

Southern California Edison recently canceled a 663 MW power purchase agreement for a Stirling dish powered concentrating solar power plant.  It’s the latest blow for centralized solar as the economics have continued to favor decentralized solar.  There were other issues, too:

Stirling and Tessera…also needed millions in equity investments and big honking loans from the government and others.

When modular, decentralized solar PV is easy to finance and less expensive than centralized solar thermal electricity, the decentralized power is going to win.

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