Monday, December 31, 2012

Cleantech News from CleanTechnica

Cleantech News from CleanTechnica

Link to CleanTechnica

Using An EV To Power A Home

Posted: 30 Dec 2012 10:00 AM PST

Here’s a useful repost from the Electric Vehicle Association of Greater Washington, DC. This is quite a nice little advantage of EVs.

Over 8 million people were left without electricity in the wake of Hurricane Sandy and last summer's derecho storm left many without power for a week or more. Some resourceful electric vehicle owners in the DC area have figured out how to use the big battery in their cars for emergency power. Television station WUSA, channel 9 in Washington, DC did a story on EVA/DC member Doron Shalvi who used his Nissan Leaf to power his refrigeratorwhen the lights went out at his house during Sandy.

This could have been you, and it is something to think about when you shop for your next car.  Could an EV or a Plug-in Hybrid (PHEV) fulfill your needs, stroke your desires and enhance your shelter requirements — all at the same time?  The answer, of course, is "Yes!"   Whether it is the next power outage — and there WILL be a "next power outage" –  rising prices at the pump, concerns about America's energy security and/or a strong desire to contribute to the planet, EVs and PHEVs offer advantages that are unmatched by internal combustion vehicles or even by non-plug-in hybrids.

"Well, couldn't I just put an inverter on any car and have the same advantage?" you might ask. You could, but it wouldn't work nearly as well, as Doron Shalvi points out.  And you might have to leave your ICE vehicle idling for days at a time until the power came back on — something that you definitely would not want to do in an enclosed garage.

Would you like to learn more?  Why not attend the next meeting of the Electric Vehicle Association of Greater Washington, D.C. and meet friendly people who have "been there, done that," and are delighted to share what they know! EVA/DC member Scott Wilson will give a live demonstration of one of these EV inverter systems at the November meeting. He plans to brew us some coffee from the power coming off of his Nissan Leaf. We will also have pizza and soft drinks.

The public is invited to all EVA/DC meetings which are usually held at the Silver Spring Library on the third Wednesday of each month. See our Meetings page for map and details.

Using An EV To Power A Home was originally published on: CleanTechnica

Solar PV’s 44% Efficiency Record, Thanks To NREL & Solar Junction

Posted: 30 Dec 2012 08:52 AM PST

Here’s a great solar PV story from the good folks over at NREL (note that we’ve already covered Solar Junction’s 44% solar cell efficiency record, but this post below goes above & beyond that first one):

An operator inspects a photolithography tool used to manufacture high-efficiency Solar Junction concentrator solar cells. NREL’s pioneering multijunction work led to the Solar Junction SJ3 solar cell with tunable bandgaps, lattice-matched architecture, and ultra-concentrated tunnel junctions. Credit: Daniel Derkacs/Solar Junction

It takes outside-the-box thinking to outsmart the solar spectrum and set a world record for solar cell efficiency. The solar spectrum has boundaries and immutable rules. No matter how much solar cell manufacturers want to bend those rules, they can’t.

So how can we make a solar cell that has a higher efficiency than the rules allow?

That’s the question scientists in the III-V Multijunction Photovoltaics Group at the U.S. Department of Energy’s (DOE) National Renewable Energy Laboratory (NREL) faced 15 years ago as they searched for materials they could grow easily that also have the ideal combinations of band gaps for converting photons from the sun into electricity with unprecedented efficiency.

A band gap is an energy that characterizes how a semiconductor material absorbs photons, and how efficiently a solar cell made from that material can extract the useful energy from those photons.

“The ideal band gaps for a solar cell are determined by the solar spectrum,” said Daniel Friedman, manager of the NREL III-V Multijunction Photovoltaics Group. “There’s no way around that.”

But this year, Friedman’s team succeeded so spectacularly in bending the rules of the solar spectrum that NREL and its industry partner, Solar Junction, won a coveted R&D 100 award from R&D Magazine for a world-record multijunction solar cell. The three-layered cell, SJ3, converted 43.5% of the energy in sunlight into electrical energy — a rate that has stimulated demand for the cell to be used in concentrator photovoltaic (CPV) arrays for utility-scale energy production.

Last month, that record of 43.5% efficiency at 415 suns was eclipsed with a 44% efficiency at 947 suns. Both records were verified by NREL. This is NREL’s third R&D 100 award for advances in ultra-high-efficiency multijunction cells. CPV technology gains efficiency by using low-cost lenses to multiply the sun’s intensity, which scientists refer to as numbers of suns.

Friedman says earlier success with multijunction cells — layered semiconductors each optimized to capture different wavelengths of light at their junctions — gave NREL a head start.

The SJ3 cells fit into the market for utility-scale CPV projects. They’re designed for application under sunlight concentrated to 1,000 times its normal intensity by low-cost lenses that gather the light and direct it at each cell. In regions of clear atmosphere and intense sunlight, such as the U.S. desert Southwest, CPV has outstanding potential for lowest-cost solar electricity. There is enough available sunlight in these areas to supply the electrical energy needs of the entire United States many times over.

Bending Material to the Band Gaps on the Solar Spectrum

NREL Principal Scientist Jerry Olson holds examples of the first multijunction cells that were developed in the 1980s based on his scientific breakthrough.

Sunlight is made up of photons of a wide range of energies from roughly zero to four electron volts (eV). This broad range of energies presents a fundamental challenge to conventional solar cells, which have a single photovoltaic junction with a single characteristic band gap energy.

Conventional cells most efficiently convert those photons that very nearly match the band gap of the semiconductors in the cell. Higher-energy photons give up their excess energy to the solar cell as waste heat, while lower-energy photons are not collected by the solar cell, and their energy is completely lost.

This behavior sets a fundamental limit on the efficiency of a conventional solar cell. Scientists overcome this limitation by using multijunction solar cells. Using multiple layers of materials in the cells, they create multiple junctions, each with different band gap energies. Each converts a different energy range of the solar spectrum. An invention in the mid-1980s by NREL’s Jerry Olson and Sarah Kurtz led to the first practical, commercial multijunction solar cell, a GaInP/GaAs two-junction cell with 1.85-eV and 1.4-eV bandgaps that was recognized with an R&D 100 award in 1990, and later to the three-junction commercial cell based on GaInP/GaAs/Ge that won an R&D 100 award in 2001.

The researchers at NREL knew that if they could replace the 0.67-eV third junction with one better tuned to the solar spectrum, the resulting cell would capture more of the sun’s light throughout the day. But they needed a material that had an atomic structure that matched the lattice of the layer above it — and that also had the ideal band gap.

“We knew from the shape of the solar spectrum and modeling solar cells that what we wanted was a third junction that has a band gap of about 1.0 electron volt, lattice-matched to gallium arsenide,” Friedman said. “The lattice match makes materials easier to grow.”

They concentrated on materials from the third and fifth columns of the periodic table because these so-called III-V semiconductors have similar crystal structures and ideal diffusion, absorption, and mobility properties for solar cells.

But there was seemingly no way to capture the benefits of the gallium arsenide material while matching the lattice of the layer below, because no known III-V material compatible with gallium arsenide growth had both the desired 1-eV band gap and the lattice-constant match to gallium arsenide.

That changed in the early 1990s, when a research group at NTT Laboratories in Tokyo working on an unrelated problem made an unexpected discovery. Even though gallium nitride has a higher band gap than gallium arsenide, when you add a bit of nitrogen to gallium arsenide, the band gap shrinks — exactly the opposite of what was expected to happen.

“That was very surprising, and it stimulated a great deal of work all over the world, including here at NREL,” Friedman said. “It helped push us to start making solar cells with this new dilute nitride material.”

Good Band Gaps, but Not So Good Solar Material

The NREL team that shared the 2012 R&D 100 award for the world-record SJ3 multijunction solar cell include, from left, Aaron Ptak, John Geisz, Sarah Kurtz, Brian Keyes, Bob Reedy, and Daniel Friedman; unpictured team members are Jerry Olson and Steve Johnston. Credit: Dennis Schroeder / NREL

The new solar cells NREL developed had two things going for them — and one big issue.

“The good things were that we could make the material very easily, and we did get the band gap and the lattice match that we wanted,” Friedman said. “The bad thing was that it wasn’t a good solar cell material. It wasn’t very good at converting absorbed photons into electrical energy. Materials quality is critical for high-performance solar cells, so this was a big problem.”

Still, NREL continued to search for a solution.

“We worked on it for quite a while, and we got to a point where we realized we had to choose between two ways of collecting current from a solar cell,” Friedman said. “One way is to let the electrical carriers just diffuse along without the aid of an electric field. That’s what you do if you have good material.”

If the material isn’t good, though, “you have to introduce an electric field to sweep the carriers out before they recombine and are lost,” Friedman said.

But to do that, virtually all impurities would have to be removed. And the only way to remove the impurities would be to use a different growth technique.

Using Molecular Beam Epitaxy to Virtually Eliminate Impurities

Solar cells are typically grown using metalorganic vapor-phase epitaxy, or MOVPE.

“It works great, except you always get a certain level of impurities in the material. That’s usually not a problem, but it would be an issue for this novel material, with the gallium arsenide diluted with nitrogen,” Friedman said.

A different growth technique, molecular beam epitaxy (MBE), is done in such an ultra-high vacuum — 10 to the minus 13 atmospheres — that it can lower the impurities to the point where an electric field can be created in the resulting photovoltaic junction. And that would make the otherwise promising gallium-arsenide-dilute-nitride material work as a solar cell.

“The only problem was that there was no one in the entire world manufacturing solar cells by MBE,” Friedman said.

But that was soon to change.

Partnering with a Startup out of Stanford University: Solar Junction

A Stanford University research group with expertise in the use of MBE for other electronic devices saw an opportunity, and around 2007, they spun out a startup company they named Solar Junction.

Because Solar Junction was a mix of enthusiastic recent Ph.D.s and experienced hands from outside the established solar cell field, “they weren’t tied to the constraints of thinking this couldn’t be done, that the only economically viable way to make solar cells was with MOVPE,” Friedman said.

The federal lab and the startup got together. Solar Junction won a $3 million DOE/NREL Photovoltaic Technology Incubator contract to develop a commercial multijunction cell using dilute nitrides, and also received more than $30 million of venture-capital funding for this commercialization effort. To see more about NREL’s Incubator projects, see the NREL news release.

“So Solar Junction had this good idea. But now they had to prove that you could actually make a high-efficiency solar cell with this,” Friedman said. “Otherwise, who cares? People can make a lot of claims, but it’s very simple to know whether you have a good solar cell or not — you just measure it.”

It didn’t take that long, Friedman said. By 2011, NREL had certified a new efficiency record for Solar Junction’s SJ3 cell. The cell achieved an efficiency of 43.5% under concentrated sunlight, a significant step beyond the previous multijunction efficiency record of 41.6%, and far beyond the maximum theoretical efficiency of 34% for traditional one-sun single-junction cells.

Dilute-Nitride Junction Eliminates Need for Heavy Germanium Layer

With the new dilute-nitride junction, the germanium layer, which constitutes about 90% of the weight of the cell, is no longer needed. That may not be a big deal when it’s part of a huge fixed utility-scale array. But when solar cells are used to power satellites, reduction in weight means a smaller rocket is needed to launch into space, potentially reducing costs significantly. The lighter weight is also essential for the military, which is increasingly asking soldiers to carry backpacks that include solar devices to power electronics.

Serendipitously, if the germanium substrate is retained, it has essentially the ideal band gap of 0.7 eV for a fourth junction, perfect for capturing longer wavelengths of the solar spectrum. That paves the way for a 50%-efficient solar cell in the not-distant future.

The cost to manufacture the SJ3 cell is competitive with that of the industry-standard GaInP/GaAs/Ge cell, according to Solar Junction. Its greater efficiency translates to significant cost-of-energy savings.

According to a report released this fall from IMS Research, the CPV market is forecast to double in 2012 and reach almost 90 megawatts. The World Market for Concentrated PV (CPV) — 2012 predicts installations of CPV will grow rapidly over the next five years to reach 1.2 gigawatts by 2016.

Because of its design and size, SJ3 is an instant plug-in replacement for the standard cell now used by the space and CPV industries. So, for example, if a 40%-efficient cell were replaced with a 44%-efficient cell, this would instantly increase the entire system power output by close to 10%.

“This is really a classic example of NREL developing something and then industry picking it up and running with it and making it a great commercial success,” Friedman said. “We started with some very basic materials research. We took it to the point where it made sense for industry to take over and take it to the marketplace.”

“We conceived the cell, demonstrated the individual parts, and let the world know about it,” Friedman said. “But Solar Junction put all the parts together with record-breaking results, made it work with MBE, and commercialized it at a time when no one else seemed to be interested in or able to do it.”

And now, utilities are ordering the SJ3 cells so fast that Solar Junction has depleted its pilot-scale stock and gone into partnership with manufacturer IQE to ramp up to full manufacturing scale.

Learn more about NREL’s photovoltaic research.

— Bill Scanlon

Solar PV’s 44% Efficiency Record, Thanks To NREL & Solar Junction was originally published on: CleanTechnica

UK Electric Vehicle Sales To Double In 2013?

Posted: 30 Dec 2012 07:47 AM PST


Cheaper models and more charging stations are reasons to expect UK electric vehicle sales to double in 2013.

If you’re jumping for joy, hold your horses — there are currently only about 3,000 electric cars in Britain, and most of those are part of company fleets. But any increase is a good thing, and the Guardian reports that British companies will continue to be major EV buyers.

Cheaper models with increased range and battery life (such as the Renault Zoe) will add on to sales of the Nissan Leaf and the “love it or leave it” Vauxhall Ampera, and the national EV charging network is sure to encourage British buyers to seriously consider electric cars.

Source: The Guardian
Image: Ampera via Shutterstock 

UK Electric Vehicle Sales To Double In 2013? was originally published on: CleanTechnica

Imagine If Everything Were Powered How Our Cars Are (VIDEO)

Posted: 30 Dec 2012 07:00 AM PST

Here’s a great video that puts gas-powered vehicles (vs electric vehicles) into perspective a bit:

Can you imagine if all of our machines were powered with gas? Oh my….

Alternatively, can you imagine if we powered our cars with electricity instead of gas.

(In case you missed it, that video was an ad for the Renault Z.E. brand.)

Imagine If Everything Were Powered How Our Cars Are (VIDEO) was originally published on: CleanTechnica

Sunday, December 30, 2012

Cleantech News from CleanTechnica

Cleantech News from CleanTechnica

Link to CleanTechnica

Show Me The (Fossil Fuel) Money

Posted: 29 Dec 2012 09:13 AM PST

Have you ever read news coverage of an energy or climate issue and thought to yourself, "Why is that spokesperson defending fossil fuels, slamming clean energy, and denying climate change?" As you may suspect, it's because they receive financial support from pro-fossil fuel interests – a fact rarely mentioned in media coverage.

"Fossil Fuel Front Groups on the Front Page," a new report from the Checks and Balances Project, reveals financial ties between pro–fossil fuel think tanks and the world's biggest fossil fuel interests, with a transactional relationship of funding for national media coverage.

According to the report, fossil fuel interests gave at least $16.3 million dollars in direct funding to the ten most-quoted pro–fossil fuel advocacy organizations from 2006-2010. Internal materials suggest a strategy of targeting funds from those with the most to lose by a shift toward the clean energy economy.

"Contributions will be pursued for this work, especially from corporations whose interests are threatened by climate (change) policies." -Heartland Institute fundraising document

Fossil Fuel Funds Buy Fossil-Friendly Quotes

So what does all that cash buy? Media coverage – and quite a lot of it.

From 2007-2011, Checks and Balances found these funded groups and their policy experts were mentioned at least 1,010 times in coverage of energy issues in America's 58 most-read newspapers, plus the Associated Press and Politico. That averages four mentions per week during on some of the most high-stakes clean energy and climate policy issues of our time.

These organizations also enjoyed heavier coverage in some of America's most influential newspapers. 31% of all coverage came in six outlets – the Associated Press, Politico, New York Times, Washington Post, USA Today, and Christian Science Monitor. (The Wall Street Journal was not included because its articles are not publicly searchable).

Unsurprisingly, a majority of their quotes supported fossil fuel sources while attacking clean energy or environmental support, often using similar messaging:

  • 43% attacked environmental or energy regulations
  • 18% attacked clean energy technologies
  • 17% promoted fossil fuels

Context is Key, Disclosure is Not

While this may not seem like an overwhelming amount of media mentions, a little context puts the situation into perspective. The National Renewable Energy Laboratory (NREL), a decades-old federally funded entity created to advance energy technology, was only mentioned 236 times in the same publications that mentioned the fossil-fuel interests 1,010 over the same period.

But the large amount of pro-fossil coverage wouldn't be unfair except for one major fact – the quoted spokespeople or media outlets only disclosed financial ties to fossil fuel interests 6% of the time. In more than half of all coverage (53%), media outlets only mentioned the organization by name, with another third of mentions only including vague ideology (conservative, 17%; free market, 8%; libertarian, 6%).

Difficult Problem, Simple Solution

Add it all up, and a sinister picture becomes clear: the fossil fuel industry provides direct funding to select policy analysts, who use similar messaging to promote fossil fuels while attacking clean energy, across the most influential newspapers in America, without disclosing funding sources that compel their positions.

And the worst part is, it's working. Credible estimates of federal fossil fuel subsidies approach $52 billion annually, while clean energy funding mechanisms like the Production Tax Credit are left to wither on the vine. Media coverage isn’t solely to blame — lobbying absolutely plays a role — but it’s a big aspect in how policymakers determine positions.

Fortunately, one simple solution to this problem exists – transparent disclosure of funding sources from spokespeople. Checks and Balances advocates media ask one question for quoted sources: "Do you get money, directly or indirectly, from interests that stand to benefit from what you are saying?"

That’s a question worth asking. But my money’s on these fossil-funded spokespeople avoiding the answer.

Show Me The (Fossil Fuel) Money was originally published on: CleanTechnica

Tesla Superchargers Set Up On East Coast

Posted: 29 Dec 2012 08:57 AM PST

Tesla has announced the locations of its first two supercharger electric vehicle charging stations on the US East Coast.

These charging stations allow Tesla Model S owners to charge for free, and in a relatively short 30-minute period.

The charging stations are located in Milford, Conneticut, and Wilmington, Delaware.

Tesla Motors eventually wants to set up a cross-country network of chargers that would enable Tesla Model S owners to drive from coast to coast, with some of them being solar-powered, too!

It is certainly cool that the nicest electric cars on the market come with this free service.

Source: Gas 2.0

Tesla Superchargers Set Up On East Coast was originally published on: CleanTechnica

MidAmerican Wind Completes 300 MW Of Wind Projects

Posted: 29 Dec 2012 08:21 AM PST

MidAmerican Wind has announced the completion of two large wind projects: Pinyon Pines Wind I, and Pinyon Pines Wind II.

This projects comprise 100 3MW Vestas wind turbines of the V90 model, and are located near Tehachapi, California.

"The completion of the Pinyon Pines Wind I and Pinyon Pines Wind II projects bring MidAmerican Wind's renewable energy portfolio to 381 megawatts," said Tom Budler, president of MidAmerican Wind. "We are pleased to have met our timeline for building the two projects and placing them in-service before year-end 2012."

Southern California Edison will purchase electricity from the two wind farms pursuant to the terms of the PPA (Power Purchase Agreement).

Source: Business Wire

MidAmerican Wind Completes 300 MW Of Wind Projects was originally published on: CleanTechnica

Measuring The Cost Of Energy, Drop By Drop

Posted: 29 Dec 2012 08:09 AM PST

As far as interrelated water and energy challenges go, the case of the natural gas drilling method known as fracking is a doozy. Natural gas has been touted as a relatively cheap, less-polluting replacement for coal and petroleum, and that's fine as far as global warming management goes. But on a local level, here in the U.S., evidence is steadily mounting that the vast quantities of chemical-laced water used in fracking can contaminate local water resources, put public health at risk, and disrupt communities that are already under economic distress.

Masdar Engage water and energy challenge

Fracking is about to get a public awareness boost from the new Matt Damon movie Promised Land, but that’s only part of the picture. Aside from the local impacts of both drilling and wastewater disposal, the fracking boom has already had a ripple effect on another water-energy nexus, involving coal.

Here in the U.S., coal mining has been a significant source of water contamination for generations. Researchers have also drawn a connection between long-term economic malaise and negative public health outcomes in coal mining regions.

One solution, of course, is to replace coal with less polluting forms of energy, and that is exactly what has been occurring in the U.S. as wind, solar, and other alternatives come on line. However, at least for the time being, natural gas has been chief among the alternative fuels replacing coal at U.S. power plants.

That has factored into an increase in pressure to export coal, with a consequent impact on local port communities and greenhouse gas emissions related to transportation.

The fracking boom in new areas like the Marcellus shale region has also set off an internal chain reaction, squeezing some older-gas producing states out of the domestic market. In consequence, legislators from those states have begun pressing for more natural gas exports.

Combine the coal, gas, and alternative energy trends together and ultimately you have a scenario under which the U.S. invests billions in developing safer, healthier domestic renewable energy resources, while fossil fuel production continues to put local communities and their water resources at increasing risk in order to supply overseas markets.

To add insult to injury, researchers are beginning to question whether or not natural gas really is a less-polluting fossil fuel than coal, due to methane leakage at drilling sites among other issues.

That brings us right up to the question for bloggers posed for the upcoming international conference, Abu Dhabi Sustainability Week 2013: "What steps can individuals, businesses or world leaders take to address the most pressing and often interrelated water and energy challenges?"

The answer is obvious to anyone who has undergone a 12-step program: admit that water and energy are bound at the hip (not just “often interrelated”), learn from past mistakes, adopt new behaviors, and help others who are trying to do the same.

That doesn’t mean it’s going to be easy, but a good place to start, here in the cradle of democracy, would be to ensure that local citizens have the regulatory framework, legislative support, and access to the information they need in order to make rational choices and reach collective decisions by vote and by compromise, working together to have a real say in determining their future.

Readers please note: this article has been entered in the “Masdar Engage” competition for Abu Dhabi Sustainability Week 2013. Follow the link and vote if you like.

Image (cropped): Water by mrsdkrebs

Follow me on Twitter: @TinaMCasey

Measuring The Cost Of Energy, Drop By Drop was originally published on: CleanTechnica

Negative European Power Prices Seen Sunday Through Thursday Due To Strong Wind Power Supply

Posted: 29 Dec 2012 03:02 AM PST

The European Energy Exchange has seen the price of electricity turn negative during certain hours of the day Sunday through Thursday of las week. This is largely due to a strong supply of wind power combined with relatively low electricity demand, which is partly triggered by warmer than average temperatures.

Negative prices are expected to return again Sunday through Tuesday.

We’ve reported on such occurrences before, but this is still something that I’m sure many people are unfamiliar with, so let’s run through a quick rehash:

On the wholesale electricity market, the lowest bidder looking to supply the grid with electricity wins. Since wind and solar power have fuel costs of $0, they can bid lower than coal, natural gas, nuclear, etc (which do have fuel costs) — naturally, this brings down the price of electricity on the wholesale market.

When the supply of solar and wind rises and electricity demand drops, the effect is strengthened.

Furthermore, with subsidies for wind and solar power production, wind and solar power producers can actually bid below $0 per unit of electricity and still make a profit. We’ve seen in happen in Germany due to high solar power production in the spring and summer, and we’ve seen it happen in Texas due to high wind power production, and it has happened many other places as well.

Wind, solar, and low demand aren’t the only causes of this phenomenon, however. Nuclear and hydro are also often implicated. Nuclear and hydro power plants can’t easily shut down or start up, so it may be more worth it to them to pay a little to put electricity on the grid for a short time than lose revenue from being shut down when it could be selling electricity for a profit.

Negative pricing isn’t that big of an issue, of course, but it’s an indicator of the rather noteworthy fact that wind and solar power drive down wholesale electricity prices. Unfortunately, that isn’t always passed on to retail electricity customers.

Negative European Power Prices Seen Sunday Through Thursday Due To Strong Wind Power Supply was originally published on: CleanTechnica

EPA Head Lisa Jackson To Leave Post In 2013

Posted: 29 Dec 2012 02:12 AM PST

Administrator for the Environmental Protection Agency Lisa P. Jackson has announced that she will step down after President Barack Obama’s State of the Union address in January.

Jackson, 50, has faced strong opposition from the GOP while heading the EPA, with continual threats of EPA defunding. She also had to accept Obama’s order to delay smog regulations prior to the 2012 election.

Some of the wins the EPA has had under Jackson include the push for higher fuel efficiency in vehicles, the launch of the Environmental Technologies Export initiative, and new CO2 emissions standards for new power plants.

During Jackson’s tenure, she made the rounds of TV, appearing on Comedy Central’s Daily Show, Real Time with Bill Maher, the Rachel Maddow Show, and plenty of other shows.

Jackson, a New Jersey native and trained chemist, said in her press release that she is ready for new challenges and time with her family.

There’s no word on who will be Obama’s next pick for EPA chief.

Source: The Guardian
Image: Lisa Jackson via Shutterstock 

EPA Head Lisa Jackson To Leave Post In 2013 was originally published on: CleanTechnica

Using Thermodynamics & 100-Year-Old Technology To Break The $20 Per MWh Barrier

Posted: 29 Dec 2012 02:05 AM PST

This is a guest post by one of our regular, cleantech-obsessed readers, David Fuchs. Clearly, David thinks he’s on to something big. Enjoy the article!

For years, the production of energy has fascinated me. Over the past 20 years, I have experimented with solar cells made via inkjet printer, a hydraulically coupled compressor and turbine based on Tesla's turbine, vertical wind turbines, high-temperature cracking of water, high COP heat pumps, all the different varieties of Stirling engines, and many other energy projects. Continuously going back to old projects to incrementally improve them and make them perfect has been fun, except perfect is the enemy of finished.

The week long power outage here in New Jersey, after hurricane Sandy, made me realize that we need simple, scalable, cheap, and locally produced power. Removing all distractions and giving an engineer of German lineage a week to think on a problem often gets the problem solved. After pulling out the 7-pocket expanding file with all my past Stirling designs, a couple notepads, my favorite gel pens, a dry erase board, and some reference books, I began designing. As with any engineering project, you need to describe what you want to accomplish, and your limiting factors. Due to cost constraints, engineering is always compromise.

What is the goal? An always-on (24 x 7 x 365) power supply that is inexpensive to produce, can be bulk produced with readily available materials, can be manufactured in any nation using 1950′s or earlier technology, and has a working lifespan greater than 20 years. (That sounds really simple, doesn't it?)

What are the design criteria?

  • Low Temperature Differential (LTD) Stirling based design.
  • All parts must be designed for high-speed manufacture and assembly.
  • All materials used must be inexpensive and readily available.
  • The Stirling design must have the least number of wear points possible.
  • It must use inexpensive solar thermal panels for gathering energy.
  • The solar panels must be easily produced in an automated fashion.
  • It must have inexpensive (dirt cheap) energy storage.
  • It must produce at least 3 kW of power continuously (24 x 7 x 365 x 20).
  • On a daily basis, it must be capable of gathering two to three times the energy required for a 24-hour period, on the least sunny day of the year. (NREL solar radiation manual)
  • It must be capable of storing the energy required for 3 to 5 days of continuous usage with no energy input.
  • Any person with basic mechanical skills should be able to install the system.
  • The total Levelized Cost of Energy (LCOE) must be under $20 per MWh.

The basic system layout.

Semi-Steampunk Energy Flow Diagram

This system layout image represents the individual pieces and the energy flows between the individual components. The flow controller controls the heat distribution between components.

The system consists of six main components:

  1. Solar thermal cells for gathering energy.
  2. An insulated thermal mass for storing the energy (dirt or water).
  3. A heat radiator for disposing of waste heat.
  4. An LTD Stirling engine for generating energy.
  5. A flow controller for for fluid flow, preventing energy loss from the system, and increasing efficiency.
  6. An inverter to connect to the grid and convert DC power from the generator to AC usable in your house and power grid.

Each component is designed to be as inexpensive, modular, easily replaceable, and mass producible  as possible.

Solar Thermal Panels absorb the sun’s energy in the form of heat. The price for solar thermal panels averages $150 per square meterExtrude plastic cased panels can reduce the cost to $33-$47 USD per square meter, with slightly lower efficiency.

Thermal Mass is a fancy engineering way of saying “insulated pile of dirt or bucket of water.” This is used to store the heat absorbed through the solar panels. The cost of this varies greatly. It can be dirt insulated all around with hay bales and covered with plastic (~$600 USD), four 2,500 gallon water tanks filled with water or sand (~$4,700 USD), a 9 x 20 shipping container insulated and filled with dirt or sand (~$1,100 USD), or an insulated hole in the ground (~$800 USD). This includes the cost of the aluminum tubing which runs from $1.50 to $2.00 per pound. There should be multiple thermal masses, or zones within a single thermal mass, each filled to thermal saturation in sequence.

Flow Controller is used to transfer liquid to and from each of the components. It is designed to keep as much heat in the system, and reuse the remaining heat as often as possible. When the system is energy saturated, or when there is no alternative, it will dump the energy out via the radiator. The multiple thermal masses or zones, at different temperatures, and external temperatures at different times of day, make waste heat reuse an efficient way to extract as much energy from the system as possible. This will run $150 to $300 USD.

Heat Radiator is used to radiate waste heat from the system, or as a heat sink when the system is saturated. This can be a standard aluminum fin radiator and fan, a cold body of water, a hole or trench in the ground with a pipe running into or through it, or any thing else at a lower temperature. The cost varies with type of radiator.

LTD Stirling is the key to this system. The design uses two separate heating and cooling chambers (upper and lower) with a shared piston. The volume is 9 cubic feet (68 gallons). It has 500 sq ft of radiator surface area (floor area of a large two car garage). It is 6.5 feet tall, 3.5 feet wide, and 3 feet deep. It can be vertically or rack mounted. And it is designed to produce up to 6 kW of power, but will be run at 3-4 kW for greater efficiency. The larger these units are, the greater the radiant surface area. The slower they run, the closer they can get to Carnot efficiencies. The full design specs are available here. These units can be daisy-chained together, one to the next. The cost of this device is between $180 and $350 USD.

Grid Synchronized Inverter allows you to attach to the power grid. These are now commodity items and the price for a UL Listed 5 kW unit is from $1,000 to $2,500 depending on manufacturer.

System Cost is based on the location and available kWh/m^2/day (kilowatt hours per meter squared per day) on the least sunny month of the year — for me, that is December. According to the NREL solar radiation manual for where I am, 50 miles south of New York City, that is 1.9 kWh/m^2/day. Over the period of a year, the power varies greatly from 1.9 – 6.2  kWh/m^2/day.

3 kW continuous output, over a 24-hour period, with 30% efficiency, requires we gather 240 kWh to produce the 72 kWh this system will produce over the period of a day. One of our design criteria is, we gather 2 – 3 times the power required for a given day. For safety, the further north you go, the higher the multiple should be. For where I am, it is ~2.5, for Texas 1.9 – 2, for Maine 3.0.

Panel Cost
600 kWh = 2.5 x 240 kWh
315.78 square meter = 600 kWh / 1.9 kWh/m^2/day
$10,428 = 315.78 sq meter * $33 per square meters

Other Costs
$1,100 – Thermal Mass (Shipping container or insulated hole in the ground)
$250 – Flow Controller
$200 – Heat Radiator
$250 – LTD Stirling
$1,500 – Grid Synchronized Inverter

$13,728 — Total Parts Cost

NOTE: None of these calculations take into account the reuse and recycling of the energy gathered, by cycling the energy into other zones or thermal masses at lower temperatures. (IE 90 C –> 60 C –> 30 C –> radiator, where "–>" is the LTD Stirling, and the temperatures are of different zones or thermal masses). Above are worst-case calculations.  

Designing the system based on the day-to-day data for Newark, New Jersey over the same time period, taking into account energy reuse and smart energy management, we can reduce our multiple to 2 and only require 288 kWh worth of panels, reducing the panel cost to $5002.10 USD and the system cost to $8302 USD. With economies of scale and alternate production techniques, increasing the thermal efficiency of the panels (1), further cost reductions are possible, reducing the system cost another ~$3,000 USD, making the system cost approximately $5500 USD. The cost would be lower in southern states like FL, TX, AZ, southern CA. 

Total Energy Output over the period of a day is 72 kWh of energy. With a lifespan a 25 years, the total power output is…

657,000 kWh = 25 year * 365 days * 24 hours * 3 kWh

657 MWh total energy produced over the lifespan of the Stirling.

Levelized Cost of Energy or LCOE is basically the the cost of the generating plant, fuel, and maintenance over its life span — minus subsidies — divided by the total energy generated over the period of a generators life span.

The LCOE for the first non-optimized design is $13,728 / 657 MWh or $20.89 USD per MWh. Optimizing just a little brings the LCOE to $8,302 / 657 MWh or $12.66 USD per MWh. Allowing for economies of scale, automation, home building techniques, reduced energy costs in manufacture, and other things this article didn't have room for, gets the LCOE to $5,500 / 657 MWh or $8.37 USD per MWh.


Comparing the current cost of energy at ~$100 USD per MWh to a system based on a redesign of a 100 – 200 year old technology shows that sub $20 USD per MWh energy is possible with technology available today. It also shows that renewable energy can be far cheaper than fossil fuels with a little creativity.

David Fuchs is a classically trained engineer and programmer. He is involved in open sourcing, software, and hardware. Current interests: 3d printing and nanotechnology, predicting the future of technology, and low-cost power production in developing nations using material at hand. You can check out his website for more of his writing, and you can contact David on Google +

Using Thermodynamics & 100-Year-Old Technology To Break The $20 Per MWh Barrier was originally published on: CleanTechnica