Shiny Rocks May Be Good For Solar Energy

Fools Gold
Fool's Gold (image by Clearly Ambiguous, CC 2.0 licensed)

Interesting note flying around the blogosphere yesterday (see here, here, and here, amongst many websites featuring the news) about a research project done at Berkeley. It found that, based on material cost and availability, solar photovoltaics made with iron pyrites (aka Fool’s Gold) are more likely to solve our energy crisis than PV made with silicon or CIGS thinfilms. This is due to both the cost of the raw materials and their availability – both crystalline silicon and the CIGS precursors are relatively expensive and relatively rare. Iron pyrite and its precursors are among the most common elements on earth, in contrast.

What we’ve found is that some leading thin films may be difficult to scale as high as global electricity consumption… if our objective is to supply the majority of electricity in this way, we must quickly consider alternative materials that are Earth-abundant, non-toxic and cheap. These are the materials that can get us to our goals more rapidly.

The paper noted that PV cells made with iron pyrite are not as efficient as those made with silicon, but here’s where it gets interesting. I did a Google search yesterday to find out just how efficient those iron pyrite solar cells are – and I can’t find them. There are a handful of papers about iron pyrite solar cells, but none that indicate it’s anywhere near being ready to compete even on the low-efficiency end. (E.g., see here, in a paper from 2000.)

So, that may mean I’m just not any good at searching on Google, and be that as it may. The other side of the coin is that this report lines up with what I’ve [intlink id=”119″ type=”post”]been saying since October[/intlink] – it’s not about the efficiency of the cells, it’s about the [intlink id=”194″ type=”post”]price/performance[/intlink]. We have plenty of surface area on which to put solar cells, even if they aren’t very efficient. What we don’t have is lots of extra money to pay for them – so low-efficiency cells that have a good price performance ratio – $1-2/kw or $0.10-0.30/kwh – are what we’re looking for.

(And of course, we need to be a lot more efficient in our energy usage, and be able to store that good sun power we’ve generated.)

In any case, I’m now looking forward to hearing about iron pyrite-based solar cells – if you know of any post-2000 research on this topic, definitely let me know!

Zero Net Energy Homes Part 4 – Honda Accord Versus Solar Panels

El �ºltimo de los mohicanos
Money ('El Altimo de los Mohicanos' - photo by wakalani, CC 2.0 licensed)

One of the biggest problems for residential solar electricity generation is that it just costs too darn much to install those panels on your roof. Over the next five and ten years this will change significantly as new developments from the labs make it into large-scale production. Eventually houses will be generating all their own electricity using photovoltaics as a matter of course.

But is there a way to think about the cost today that makes the cost even seem reasonable?

Well, if you’re thinking about buying a new car, you should read on. Each year you don’t buy a new car and continue to drive the one that you’ve already paid for, you pays for another year of your solar panels. At the end of the loan period (seven years in my example below), you’re getting free electricity from a system that increases the value of your home and has another 20 years of life at the minimum. If you’d bought a car, in seven years you’d be driving a rapidly depreciating vehicle that you’d probably have to replace soon.

For my house, after rebates, putting up solar panels today would cost about $22,000. This would be a 4kw system, offsetting about 92% of my electric bill, according to the solar power calculator at Clean Power Estimator. With a $3,000 down payment, and using SunPower’s “Smart Financing” with a seven year term, my monthly net cost would be about $250, after subtracting out my electric bill.

So, $22,000 total cost, $3,000 down payment, $250 monthly – that sounds just about exactly like buying a new car, doesn’t it? In fact, if I go to carsdirect.com and price out a new Honda Accord EX, that comes out to $22,372. My current car, a 2000 Honda Accord, is worth $4,000. So I need to finance $18,000. With a four year loan, I’ll be paying about $420 per month.

Netting it out, for each year that I make the decision to buy solar panels versus a new car, I actually save about $170 per month. At the same time, according to the solar power calculator, I eliminate almost four tons of CO2 (worth an additional $320 at the currently accepted value of $80/ton). After seven years, all that electricity will be free to me, for at least the rated life of the panels. And I’ll get most or all of the cost of the panels back when I sell my house. When I sell the new Honda, I’ll get a lot less than I paid for it.

As an additional note, if you’re thinking about buying a new BMW, such as an M3. If you chose a BMW 335i with Sport Package instead, you could put up the solar panels with the difference in cost: 1 BMW M3 = 1 BMW 330i + Sport Package + solar panels. You’d get nearly the same performance – much more than you can effectively use anywhere in the U.S. except on a race track – and you’d offset all the CO2 you’d be generating with your new car.

Definitely let me know if I’ve convinced you to put up solar panels instead of buying a car this year! Or if you have any other comments on this topic – I’d love to hear from you.

The Answer Is Blowing In The Wind

Windmill and old houses in Schipluiden
Old Windmill (image by waterwin, CC 2.0 license)

The results of this study on solutions to global warming, air pollution, and energy security, by Stanford professor Mark Z. Jacobson, are somewhat surprising, given the drumbeat from many areas on both nuclear and biofuels as necessary for the salvation of the world.

Jacobson analyzes 12 energy sources for their beneficial impact on global warming, air pollution, and energy security – the ten electricity sources are solar-photovoltaics (PV), concentrated solar power (CSP), wind, geothermal, hydroelectric, wave, tidal, nuclear, and coal with carbon capture and storage (CCS) technology; the two liquid fuel options are corn-ethanol (E85) and cellulosic-E85.

An article in Science Daily summarizes one of Jacobson’s conclusions:

Jacobson said that while some people are under the impression that wind and wave power are too variable to provide steady amounts of electricity, his research group has already shown in previous research that by properly coordinating the energy output from wind farms in different locations, the potential problem with variability can be overcome and a steady supply of baseline power delivered to users.

As the bottom line in the study, Jacobson writes:

In summary, the use of wind, CSP, geothermal, tidal, solar, wave, and hydroelectric to provide electricity for BEVs [battery electric vehicles] and HFCVs [hydrogen fuel cell vehicles] result in the most benefit and least impact among the options considered. Coal-CCS and nuclear provide less benefit with greater negative impacts. The biofuel options provide no certain benefit and result in significant negative impacts. Because sufficient clean natural resources (e.g., wind, sunlight, hot water, ocean energy, gravitational energy) exists to power all energy for the world, the results here suggest that the diversion of attention to the less efficient or non-efficient options represents an opportunity cost that delays solutions to climate and air pollution health problems.

Note that the study ranks the various energy alternatives without regard to cost. That’s going to be controversial. Jacobson says:

Costs are not examined since policy decisions should be based on the ability of a technology to address a problem rather than costs (e.g., the U.S. Clean Air Act Amendments of 1970 prohibit the use of cost as a basis for determining regulations required to meet air pollution standards) and because costs of new technologies will change over time, particularly as they are used on a large scale.

In the real world, costs do have a major impact, especially given that we do not have a Clean Air Act regarding carbon today. This is why it’s so important that the price/kW of solar panels, for example, is dropping and will continue to drop.

In fact, when you leave cost out of the equation, is it surprising which energy sources came out on top? Let me know your thoughts.

30-fold Increase In Solar Energy By 2016 – Moore’s Law, Anyone?

Solar Power International Logo
Solar Power International Logo

The opening keynotes at the Solar Power International trade show last week were eye-opening. (See the Tuesday Keynotes video on this page – Resch at 20 minutes, Hamm at 37 minutes.)

Rhone Resch of the Solar Energy Industries Association first told the story of getting the investment tax credit for solar renewed – 17 failed votes before it finally passed with the Paulson Bailout bill. He then outlined the benefits to the solar industry of the ITC – stability for solar energy businesses, creation of thousands of new business opportunities due to the remove of the residential solar cap, and a return to leadership of the US in solar. “Solar energy is going to create 440k new jobs, 1.2 million new solar installations, and 28 gigawatts of new capacity – enough to power seven million homes throughout the U.S.”

To achieve the 28 gigawatts of new solar electric generation capacity predicted by Resch in the next eight years, Julia Hamm of the Solar Electric Power Association (SEPA) threw down a challenge to the attendees. The industry must “be bold, be innovative, be strategic.” In particular, she outlined four key policy guidelines the industry must embrace to achieve this goal.

Utility Ownership of Solar Power Projects

The utility and solar industries must collaborate to find program structures, such as utility ownership of distributed photovoltaics, that provide a winning scenario for both industries, as well as for customers at large. The solar industry can utilize this new market segment as a buffer until home and small business owners are back on more solid financial footing.

Increased Utility Engagement in Solar Markets

The utility and solar industries must work together to get more utilities engaged, starting by increasing the solar knowledge base of utility employees, from top executives down to distribution engineers. We must move beyond having ninety seven percent of all grid-connected solar installations in just 10 utilities’ service territories.

Greased Wheels

The utility and solar industries must work in partnership with regulators and investors to push for approval and funding of new transmission projects and the development of smart grid configurations to expedite the timeframe in which new utility-scale and distributed solar projects can come on line and provide maximum value.

Development of Innovative Approaches

By working in collaboration, the utility and solar industries can make great strides towards modernizing today’s electricity infrastructure and offering customers affordable and clean power. But the status quo will not cut it. We need bold new ideas developed in tandem for the mutual benefit of both industries, and society at large.

(A press release version of this challenge is here.)

The 28 gigawatt figure represents an increase in solar capacity of more than thirty fold between 2009 and 2016. This is approximately three times the estimated amount of generation predicted to come online as a result of existing renewable portfolio standards and policies in states with existing solar carve outs.

However, not only does 30-fold growth far outstrip most predictions for solar energy capacity in the next eight years, it has another interesting property. It corresponds to a “Moore’s Law-type” of growth, with a doubling period of about every 18 months. This is the first time I’ve heard a solar energy organization step up to a prediction of a Moore’s Law-type growth rate. And it means that in 18 years, if the doubling rate stays constant, solar would be responsible for over 400 gigawatts of capacity, or just about equal to our current energy usage in the U.S. Solar could be providing nearly 100 percent of our energy by 2026, or even more if our overall energy usage goes down due to efficiency, as is possible given California’s example.

And if our solar capacity keeps on doubling every year and half after that? What will we do with all that energy? Your comments welcome, of course!

Expanding Options In Solar Energy and Electric Cars

Mission Peak (L), Mount Allison (C) and Monume...
Mission Peak in Fremont, CA. Image via Wikipedia

A roundup of a few stories that came out this week that I found particularly interesting.

  • Solyndra, a startup in Fremont, CA (just down the street from my office), is using a new form factor for thin film solar cells:

    Unlike conventional solar panels, which are made of flat solar cells, the new panels comprise rows of cylindrical solar cells made of a thin film of semiconductor material. The material is made of copper, indium, gallium, and selenium. To make the cells, the company deposits the semiconductor material on a glass tube. That’s then encapsulated within another glass tube with electrical connections that resemble those on fluorescent lightbulbs. The new shape allows the system to absorb more light over the course of a day than conventional solar panels do, and therefore generate more power.

    Not only do they not need trackers, but because they are mounted with space between each tube, they aren’t susceptible to wind and they can collect light reflected off the building’s roof and ambient light coming in obliquely.

    What I like about this story is that it shows that there’s still a lot more innovation to be done in all areas of alternative energy design – yesterday I saw another report about a new fuel cell membrane made of a cheap material instead of platinum, and there’s practically a new wind energy device every week. They’re not all going to be winners, but it’s the kind of design ferment that’s going to lead to big cost and practicality improvements in every area.

  • The EPA provides an interactive analysis (using Google Earth) of marginal and contaminated land that could be used for renewable energy farms – wind and/or solar:

    According to the EPA, many lands tracked by the agency, such as large Superfund sites, and mining sites offer thousands of acres of land, and may be situated in areas where the presence of wind and solar structures are less likely to be met with aesthetic, and therefore political, opposition.

    One stumbling block for a massive transition to solar power in the U.S. has been the land use question. I’m not saying we want to build our power on contaminated lands, but it’s interesting to see this as an option.

    Via CleanTechnica.com

  • Renault commits to electric vehicles. Saying that:

    “EVs are a necessity because hybrids cannot deliver the level of gasoline use and emissions reductions that governments and customers are demanding of automakers”

    Renault unveiled two zero-emission concept cars at the Paris autoshow Mondiale de l’Automobile, both of which are pure electric. The cars have a range of 160-200 kilometers (95-120 miles) and are designed for day-to-day use and short weekend trips, “not vacations” as Renault admits.

    Renault is committing to EVs because they believe that’s the only they’ll be able to deliver the gasoline economy and emissions reductions being demanded by both the market and governments.

These stories caught my eye as not just “more of the same” this week. What green energy stories got your interest up recently?

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Running Some Numbers On Rooftop Solar Energy in 2018

Solar power systems installed in the areas def...
Solar power systems covering the areas defined by the dark disks could provide more than the world total primary energy demand in 2006 (assuming a conversion efficiency of 8%). Image from Wikipedia.

I recently asked physicist Richard Muller whether he thought the price-performance of solar electricity generation would follow a Moore’s Law-type curve. He said that this would not occur due to improving the efficiency of solar collection, as the current levels of efficiency – 20-40% – are reasonably high. However, he added

“I do expect the price to drop by a factor of 10, so we will have lots of solar.”

Well, in the nature of things, there’s definitely a limit to how much energy a solar PV collector can get from a square meter of sunlight. (There’s about 1kw of energy in a square meter – as I learned in Physics For Future Presidents, by Professor Muller – so we can expect to get 400 watts or less.) The amount of this energy per square meter we can collect will go up, but asymptotically approach (at best) the physical limits.

On the other hand, I’d argue that the cost of collecting it can go down a nearly unlimited amount – certainly multiple orders of magnitude. So what will solar PV look like in 2018 – ten years from now?

Continue reading “Running Some Numbers On Rooftop Solar Energy in 2018”

DoE Solar Energy Report On Market Penetration Outlook for Solar PV

A laundromat in California with solar collecto...
A laundromat in California with rooftop solar collectors (Image via Wikipedia)

As we contemplate the future of energy, and the combination of utility-level and distributed energy, and of different types – solar PV, solar thermal (heat your own hot water for showers), wind, etc., one question I have asked myself is how much energy can realistically be produced by the solar collectors on the roofs of our houses and office buildings in the U.S.?

It turns out the United States government has done some research on this! There’s a very interesting set of Department Of Energy reports, including one (PDF) on the market opportunities for grid-tied distributed solar PV. It figures out, state by state, how much roof surface is available, how attractive the incentives and infrastructure are (e.g., is there net metering?) and uses some simple algorithms to come up with an expected market penetration for solar PV on commercial and residential roofs. The resulting amount of electricity generated in this distributed fashion is amazingly high. Their best case scenario has installed MWs of rooftop solar PVs rising from about 2,000 in 2008 to almost 25,000 in 2015, more than a factor of ten increase over seven years.

Influence of system pricing, net metering policy, federal tax credits, and  interconnection policy on cumulative installations
Influence of system pricing, net metering policy, federal tax credits, and interconnection policy on cumulative installations

The report uses conservative numbers for solar PV cost improvements – breakthoughs and innovations like the ones mentioned in Technology Review every week (like this one), will make the market penetration even faster (and higher) as they come to market.

I was pleased to see that our government has done this kind of research. Think what could be done if funding for renewable energy research and development was an order of magnitude higher!

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Top Green Energy Stories For August 2008

Top Fivewoodleywonderworks
Top Five Stories

August was a great month for energy storage breakthroughs! In addition, a big talking head talks big, and a business-of-green-energy announcement make my list of top stories.

1. Hydrogen from water
2. Fuel cell breakthrough #1: cheap catalyst
3. Fuel cell breakthrough #2: better cathode
4. Al Gore’s call to action: The U.S. should “produce all electricity from carbon-free sources by 2018.” (Actually from late July, but my blog didn’t start until August!)
5. Green energy investment up 60% YoY in 2007, on target for 60% YoY growth in 2008

Moore’s Law depended (and still depends) on a constant flow of breakthrough technologies, processes, scale, and designs. You can’t necessarily predict how Moore’s Law will continue to hold two years from now, or five years from now, but you can be confident that through some combination of technologies, processes, and designs, the price/performance of IT will continue to decline at an exponential rate.

The top five green energy stories of 2008 give an indication that the same types of forces are at play in the green energy world. Numbers 1, 2, and 3 each represent a potential 10x reduction in the cost of the most expensive part of a particular energy flow. For number 4, Gore used the bully pulpit of a Nobel Prize and Oscar (and, oh yeah, he was nearly president) in a most constructive way. And number 5 illustrates that green energy technologies are on a growth rate of doubling about every 18 months.

Did these stories excite you as much as they did me? Were there other green energy stories in August that you feel are more important?

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Another Analysis (More Detailed) Of Gore’s Call To Action on Renewable Energy

Wicked Barrel, by batintherain (Creative Commons license)
Wicked Barrel, by batintherain (Creative Commons license)

My very basic analysis of Al Gore’s call to action for “100% carbon free electricity” yesterday had the virtue of being dead simple. Jerome a Paris of The Oil Drum did a more detailed analysis back in July, based on wind energy generation, that reaches a similar conclusion to mine:

The short answer is: while 100% is probably unrealistic, it’s not unreasonable to expect to be able to get pretty close to that number (say, in the 50-90% range) in that timeframe, and it is very likely that it makes a LOT of sense economically.

As you’ll notice Jerome has made somewhat different assumptions from mine, particular in regard to the total electricity demand. As I mentioned, I plan to drill down more into my analysis and take it from the “zero-order” to “first-order”. I’ll also revisit my assumptions to make sure we’re comparing apples to apples.

Running Gore’s Numbers: An Edifying, If Simplistic, Analysis

Photo: Bill Gantz
Photo: Bill Gantz (Creative Commons License: Some Rights Reserved)

In his galvanizing speech a few weeks ago Academy Award and Nobel Prize-winner Al Gore exhorted the United States to “produce all electricity from “carbon-free sources” by 2018.” This is a pretty abstract goal, in those terms – Gore (appropriately) didn’t go into great detail about how this should be done or even what it means in specific practical steps. Depending on your point of view and background knowledge about energy, the goal may seem easy or incredibly difficult, or even impossible, especially without further analysis.

So I thought it would be interesting to run some numbers on the goal. The idea is not to define how it should be done, but to look at some very simple scenarios for how it could be done to get a sense of the scale involved. The calculation is based on the Topaz Solar Farm project, which California’s PG&E utility just contracted for – a 550 megawatt solar generating station.

My initial calculations makes some gigantic simplifying assumptions, so it’s not “correct” – but it should be the right order of magnitude. For details of the calculation, see the analysis below. The conclusion is as follows:

As a very rough estimate, we would need about 800 Topaz-sized plants, total cost about $1 trillion, to meet the U.S. electricity demand. And it would require about 8,000 square miles of sunny land.

The Key Parameter

Gore’s goal is equivalent to saying “We need to be able to generate on the order of 400 GW of electricity from carbon free sources.”

A few other useful or interesting numbers:

  • 550 megawatts: Generating capacity of the Topaz Solar Farm, one of two new solar electric plants PG&E is building in the California desert, announced a few weeks ago
  • 9.5 square miles: Size of the Topaz Solar Farm
  • $1 billion: Cost of the Topaz Solar Farm
  • 1 gigawatt: Generating capacity for a “large” coal-fired generating plant
  • 50 GW: California’s typical peak energy demand
  • 24%: portion of PG&E’s currently contracted generating capacity that is renewable

Assumptions

For the purposes of this analysis, I’m making a few simplifying assumptions. These make the analysis “invalid” from a technical sense, but allow us to quickly see the big picture:

  • Electricity demand will stay constant: This may or may not happen – in California energy intensity (the energy used per person) is going down, and this summer absolute energy use went down. Amory Lovins of the Rocky Mountain Institute believes we can cut energy intensity by 50% via efficiency, which would definitely cut energy use. On the other hand, most scenarios dealing with energy use assume it will continue to grow.
  • Disregard base load issues: The sun don’t shine at night, but people still use electricity then. This is called “base load.” You often hear that “solar can’t provide base load,” which may or may not be true in the future, depending on storage technologies that might be developed. In any case, I’m not considering it in this analysis – I’m assuming “a megawatt is a megawatt.”
  • Disregard transmission issues: We’ll assume that if the energy is generated somewhere in the U.S., it can be used anywhere else it’s needed.
  • Disregard technology improvements – this calculation is based on the technology planned for the Topaz Solar Farm

First cut

We now have enough data to make the most simplistic conceivable analysis. How many Topaz Solar Farm equivalents (TSFs) would we need to supply total U.S. energy demand (given the assumptions above)?

Total demand = 400 GW

TSF = 550 MW

Demand/capacity = 400 GW/550 MW = 800 (number of plants needed)

Cost = 800 * $1 billion = $1 trillion (approximately)

Conclusion: In our simplified energy world, we’d need about 800 Topaz-sized plants, total cost about $1 trillion, to meet the U.S. electricity demand. And it would require about 8,000 square miles of sunny land.

Now, there are many ways that this analysis is “wrong” – since my assumptions simplify the world quite a bit. So it could easy be off by a factor of 50% or more. But, because the assumptions also tend to cancel each other out, it’s not off by a factor of five, say. For example, I’m not considering base load (which solar PV today can’t provide effectively), but on the other hand, solar PV is the most expensive energy source. We will probably need more than 800 plants, but a lot of them will be cheaper, per megawatt, than the Topaz Solar Farm.

In future posts I will expand this model to make it less simplistic and more realistic, and to take into account technology improvements, base load requirements, the ability of energy efficiency to change the demand line, and lots of other details that are just dropped on the floor for this analysis.

I’m very interested to hear your comments on this analysis. In particular, I hope for some constructive guidance on the next steps for making it more realistic. I want a simple model that’s easy for the layperson to understand, but which doesn’t over-simplify too much (as this model does). I’d consider this a “zero-order” approximation – the next one should be a “first-order” approximation.

Other reading

  • The New York Times’ Dot Earth blog posted the text of Gore’s speech and allowed commenters to annotate it – interesting reading if you have a few hours to get through all the comments!
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