Useful chart comparing bang for the buck of various battery technologies

The other day, some other curious people and I ran numbers comparing the per-kWh price of the Tesla Powerwall & Powerpacks (the utility-scale battery options described on the bottom of this page) with top competitors on the market. Admittedly, that was too simplistic a comparison. The kWh rating provided for all of these products is simply the maximum amount of electricity they can store at one point in time. So, in the case of the Powerwall, 7 kWh means that the battery can hold up to 7 kWh of electricity at one time, similar to how a 5-gallon jug of water can hold up to 5 gallons of water.

You have to multiply that capacity rating by # of cycles (# of times the battery will be filled up and then emptied), depth of discharge (whether the battery can be fully emptied during each cycle or needs to be only 80% emptied, 70% emptied, etc), and efficiency (how much electricity is actually transmitted, not lost, in each cycle), and then divide by price to determine a per-kWh price for all of the kilowatt-hours your system is expected to produce… before degrading to 80% of its rated capacity, that is (at which point it’s actually still useful, but that’s apparently the global standard for “end of product life”).

As you can see, there are a number of assumptions you have to make to perform these calculations, and even if all of your assumptions are correct, it’s not like the products are completely dead at the end of the studied time period. This also leaves out operational costs (which we’ll assume to be $0 in the calculations below).

Anyhow, this is the best method I’ve found for comparing Tesla’s Powerwall and Powerpacks to top products on the market. More importantly, on the residential side, the numbers should help a consumer to evaluate the cost-effectiveness of getting a Powerwall (should you get commercial access to one) — that’s the main aim in the next section of this article. Note that I’ve actually left out “competing” lithium-ion and lead-acid batteries in the residential section. Basically, even at a glance, it’s clear that they don’t compete with the Powerwall, so I didn’t bother finding all of the specs and doing the calculations. If you want to do so for any particular battery, I’m happy to add the info in, but I’ll need links or company spec sheets indicating cycle life, expected DoD, efficiency, and price in order to do so.

With a ridiculous amount of help from three wonderful CleanTechnica readers, below are the assumptions and results, split into a “residential” section and a “utility-scale” section.
Residential Battery Storage — Tesla Powerwall x 4 vs Aquion Energy x 2 vs Iron Edison x 1

Subheading have you confused? I ran the numbers for 4 Powerwall purchase scenarios, 2 Aquion Energy products, and 1 Iron Edison product. Since the intro above was too long already, I’ll jump into the table first and list some of the takeaways and the assumptions underneath it:
http://cleantechnica.com/2015/05/09/tesla-powerwall-powerblocks-per-kwh-lifetime-prices-vs-aquion-energy-eos-energy-imergy/

The End Of The Lithium-Ion Era?

Lithium-ion technology is still the gold standard for energy storage as demonstrated by the popularity of the new Powerwall battery, Tesla Energy’s much-publicized foray into Li-ion energy storage for homes and businesses. However, some new technologies are sneaking up behind. In the latest development, lithium-sulfur batteries could benefit from a new “designer carbon” engineered by a team of researchers at Stanford University.


Li-S energy storage has important advantages over Li-ion in terms of cost, energy density, and toxicity, but until recently, some major drawbacks have stymied the development of Li-S batteries.

One solution crossed our radar back in 2013, when researchers at Oak Ridge National Laboratory developed a sulfur-enriched cathode (our sister site Gas2.org also took note).

In other developments, the University of Arizona has also been developing a method for converting waste sulfur to a lightweight plastic that could be used in EV batteries. Last December, researchers at Cambridge University came up with a graphene-based solution, and earlier this year, Drexel University announced that it has been leveraging its experience with MAX phase ceramics to push the Li-S envelope.

The new Stanford findings add more fuel to the energy storage findings. The team tested its new designer carbon material under real-world conditions in lithium-sulfur batteries and supercapacitors (supercapacitors are energy storage devices that charge and discharge rapidly).

For supercapacitors, the results were “dramatic,” with a threefold increase in conductivity compared to electrodes made with conventional activated carbon. Power delivery and stability also improved.

More to the point, the results showed a promising pathway to improving Li-S battery performance, as the designer carbon was able to trap lithium polysulfides, an undesirable byproduct from the interaction of lithium and sulfur.

The new material’s relatively low cost and easy fabrication method are added pluses. You can get all the details from the published study in ACS Central Science under the title “Ultrahigh Surface Area Three-Dimensional Porous Graphitic Carbon from Conjugated Polymeric Molecular Framework.”

You might not see much in the way of competition for Li-ion market share yet, but stay tuned.

Why Natural Is Not Better, Energy Storage Edition

The new designer carbon material could have a variety of applications, but the Stanford University team has zeroed in on the energy storage potential, particularly in respect to lithium-sulfur (Li-S) batteries.

The new material is actually a synthetic form of bio-based activated carbon. For those of you new to the topic, activated carbon is a common material that shows up in water filters and deodorizers, among many other things — but not energy storage devices, at least not yet.

Inexpensive forms of activated carbon are typically made from coconut shells, which involves a lot of high-temperature processing and chemical finishing. The result is a material rich in nanoscale pores, which gives it a high surface area ideal for storing electrical charges.

However, this “natural” form of activated carbon falls flat in terms of transporting a charge, partly because there is little connectivity between the pores. Here’s lead researcher Zhenan Bao describing the problem:

With activated carbon, there’s no way to control pore connectivity. Also, lots of impurities from the coconut shells and other raw starting materials get carried into the carbon. As a refrigerator deodorant, conventional activated carbon is fine, but it doesn’t provide high enough performance for electronic devices and energy-storage applications.

As a workaround, the Stanford team created its own synthetic sheets of carbon from a hydrogel polymer (hydrogel is fancyspeak for a class of super-absorbing “smart” materials). To activate the material, they added potassium hydroxide, which also increased its surface area.

The result is a carbon material with characteristics that can be controlled in two ways: by using different polymers and organic linkers, and by changing the temperature of the fabrication process.

Here are a couple of snippets from the new study:

For example, raising the processing temperature from 750 degrees Fahrenheit (400 degrees Celsius) to 1,650 F (900 C) resulted in a 10-fold increase in pore volume.

Subsequent processing produced carbon material with a record-high surface area of 4,073 square meters per gram – the equivalent of three American football fields packed into an ounce of carbon. The maximum surface area achieved with conventional activated carbon is about 3,000 square meters per gram.
The End Of The Lithium-Ion Era

Li-S energy storage has important advantages over Li-ion in terms of cost, energy density, and toxicity, but until recently, some major drawbacks have stymied the development of Li-S batteries.

One solution crossed our radar back in 2013, when researchers at Oak Ridge National Laboratory developed a sulfur-enriched cathode (our sister site Gas2.org also took note).

In other developments, the University of Arizona has also been developing a method for converting waste sulfur to a lightweight plastic that could be used in EV batteries. Last December, researchers at Cambridge University came up with a graphene-based solution, and earlier this year, Drexel University announced that it has been leveraging its experience with MAX phase ceramics to push the Li-S envelope.

The new Stanford findings add more fuel to the energy storage findings. The team tested its new designer carbon material under real-world conditions in lithium-sulfur batteries and supercapacitors (supercapacitors are energy storage devices that charge and discharge rapidly).

For supercapacitors, the results were “dramatic,” with a threefold increase in conductivity compared to electrodes made with conventional activated carbon. Power delivery and stability also improved.

More to the point, the results showed a promising pathway to improving Li-S battery performance, as the designer carbon was able to trap lithium polysulfides, an undesirable byproduct from the interaction of lithium and sulfur.

The new material’s relatively low cost and easy fabrication method are added pluses. You can get all the details from the published study in ACS Central Science under the title “Ultrahigh Surface Area Three-Dimensional Porous Graphitic Carbon from Conjugated Polymeric Molecular Framework.”

You might not see much in the way of competition for Li-ion market share yet, but stay tuned.

http://cleantechnica.com/2015/05/31/new-designer-energy-storage-breakthrough-packs-3-football-fields-1-ounce-carbon/

Highest efficiency in solar electric power generation with advanced Stirling!

Independent tests by IT Power in the UK confirm that a single Ripasso dish can generate 75 to 85 megawatt hours of electricity a year - enough to power 24 typical UK homes. To make the same amount of electricity by burning coal would mean releasing roughly 81 metric tonnes of CO2 into the atmosphere.

Paul Gauche, director of the Solar Thermal Energy Research Group at the University of Stellenbosch has visited the test site many times. “The technology looks good to me. I’ve seen it working and I believe it meets the efficiency goals. The technology is proven with years of performance in the navy.”

He points out that it will be crucial to keep costs low enough to compete with photovoltaics, a significant challenge as their price falls every year. The system is also limited in that it is only useful in areas with consistent bright sunshine.

The technology works by using the mirrors as giant lenses that focus the sun’s energy to a tiny hot point, which in turn drives a zero-emission Stirling engine.

The Stirling engine was developed by Reverend Robert Stirling in Edinburgh in 1816 as an alternative to the steam engine. It uses alternate heating and cooling of an enclosed gas to drive pistons, which turn a flywheel. Because of the material limitations at the time, the advanced stirling engine that Ripasso uses was not commercially developed until 1988, when Swedish defence contractor Kokums started making them for submarines.

http://www.theguardian.com/environment/2015/may/13/could-this-be-the-worlds-most-efficient-solar-electricity-system

Greenhouse gas can be absorbed in soil, with organic soil management

What if there were a risk-free way of helping to mitigate climate change while simultaneously addressing food and water security?

A new report from the Center for Food Safety's Cool Foods Campaign says that such an opportunity is possible, and it's right below our feet.

Soil & Carbon: Soil Solutions to Climate Problems outlines how it is possible to take atmospheric CO2, which is fueling climate change, and plug it into the soil. Far from moving the problem from one place to another, this shift can reduce ocean acidification because the oceans are no longer the sink for vast amounts of CO2, and can regenerate degraded soils by providing needed carbon.

The report lays out the problem in this way:

Humans are altering the chemistry of where carbon is stored, and climate change is a manifestation of that alteration.

Another way of looking at the problem is that too much of the carbon that was once in a solid phase in the soil is now a gas. As a result, there is too much carbon in the atmosphere, too much in the ocean, but not enough stable carbon where it once was, in the soil.

The report adds that "cultivated soils globally have lost 50-70 percent of their original carbon content." Multiple factors have contributed to the problem, the report states: paving over land; converting grasslands to cropland; and agricultural practices that involve tillage and chemical inputs, which not only deprive soil of organic matter and rob it of the ability to store carbon but also contribute to flooding and erosion.

Regenerative practices like this help build healthy soil. (Photo: London Permaculture/flickr/cc)Healthy soils, in contrast, fed through organic agriculture practices, like polycultures, cover crops, and compost, give soil microbes the ability to store more CO2. Not only that, the report states, healthy soil can better weather both drought and floods because its structure allows it to act like a sponge. And healthy soil means better crop yields.

Just how much CO2 can be stored in soils is unclear, with one estimate cited in the report being 75-100 parts per million of CO.

But the bottom line, the report states, is that healthy soils will help communities have resilience in the face of climate change impacts.

The report concludes: "Unlike geoengineering, rebuilding soil carbon is a zero-risk, low-cost proposition. It has universal application, and we already know how to do it. All that stands in our way is a greater awareness of the opportunity and the political will to make it happen."

This story was originally published on Common Dreams.

Another strategy is to incorporate terra preta, charcoal, that remains active in the soil for thousands of years, and has been discovered in brazil in the amazon area, after all that time it still is active, absorbing carbon into the soil, and adding fertility all that time!

Natural cooling explained with great examples from India, middle east

In fact, cultural acceptance of air conditioning varies widely. They’re very rare in French homes and not that common in Spanish ones either, says Lloyd Alter, an adjunct professor at Canada’s Ryerson University School of Interior Design. “In France, they think air conditioners make you sick,” he explains. “In Spain, their culture revolves around being outside and taking advantage of it: ‘We go out and eat our dinner at 10 o’clock at night, and we take it easy mid-day.’”

Looking to the Future
Zaelke sees a future in which governments play a stronger role in setting manufacturing standards, as the Japanese are with their Top Runner program; tax credits to stimulate innovative technology; and comprehensive labeling programs, somewhat like the LEED (Leadership in Energy and Environmental Design) ratings system developed by the U.S. Green Building Council, to address elements of air conditioning beyond the energy efficiency covered by federal Energy Star ratings. He also thinks part of the answer is returning to a design mindset that was prevalent before the advent of air conditioning. “Before cheap energy, we used to do a better job designing our buildings,” he says. “For example, we used to know how to situate a building so you had deciduous trees providing shade during the summer and evergreens providing shelter from the wind.”


The Torrent Research Centre of Ahmedabad, India, uses wind-catching intake towers to pull in air and cool it by diverting it through a fine mist. The cooled air descends through an open central corridor and is drawn into work spaces on each level. Exhaust towers around the perimeter of the complex vent hot air at night.
Abhikram

Pearce asserts that air conditioning has made architects lazy. “Air conditioning has allowed them to design buildings based on formal concepts without any response to the natural environment,” he says. “Architects should design buildings whose form is shaped by a scientific understanding of natural processes at the building’s location and not by some purely whimsical sculptural shape.”

LaRoche believes it’s imperative for people in his profession to pursue minimal environmental impacts when designing structures and strive to incorporate alternative ways to cool them. He says HEED (Home Energy Efficient Design)—free software developed at the University of California, Los Angeles—is a good example of a residential energy design tool that can be used by anybody.31 “Tools such as this one help any homeowner or designer produce low-energy buildings,” he says.

Ultimately, LaRoche says, architectural education is key to change: “If the new architects aren’t trained in the design of low-carbon, low-energy buildings, nothing will happen. New students must be trained with new software and tools that we did not have just a couple of years ago.” He adds, “Whenever we do passive cooling in a building instead of mechanical cooling, we’re helping our planet. It’s also good for our pockets, and our buildings are more culturally responsive to the environment around them.”

Alternatives to traditional air conditioning can reduce power demand

Calling on Traditional Technologies
Although air-conditioning use will certainly continue to increase globally with no serious regulatory frameworks in sight, some observers believe awareness of its environmental impact is beginning to change the ways in which architects and engineers, at least, are approaching the challenge of keeping people cool. In fact, many planned and existing buildings employ a variety of technologies—new and old—to achieve comfortable indoor temperatures without resorting to the use of air conditioners.

Pablo LaRoche, a professor of architecture at California State Polytechnic University Pomona who also practices in the Los Angeles firm HMC Architects, believes the true solution for temperature management is passive cooling systems. Such a system transfers heat from a building to any combination of exterior heat sinks—such as the air, water, and earth—through special design details in the building itself. By providing pathways to carry heat from the interior of the building to the outdoors, he explains, the building itself becomes the air conditioner, using little or no energy at all.19

LaRoche points out that different types of passive cooling systems work better in different climates. For example, he says evaporative cooling20 (which adds moisture to the air) works best when the air is dryer, whereas night flushing21 (using cold night air to ventilate a building and cool its thermal mass) is preferable for places where there is a greater temperature difference between daytime and nighttime temperatures.

Passive downdraft evaporative cooling (PDEC) employs the spraying of microscopic water droplets into the air, a concept borrowed from traditional architecture in Pakistan, Iran, Turkey, and Egypt, according to Kamal. These traditional buildings were topped by wind-catching hoods (malqafs) that pulled air down chimneys and cooled it by directing it across a source of moisture: a pool, a fountain, or porous pots that seeped water. Contemporary PDEC buildings also employ wind catchers but replace the water pots with wet cellulose pads or similar devices. Kamal cites the Torrent Research Centre in Ahmedabad, India, as an excellent example of contemporary use of PDEC. The center was completed in 1999 and has reportedly provided comfortable conditions for occupants while also recording extremely low energy consumption.22

Another example of a hot-climate structure using water and traditional design for cooling is Pearl Academy in Jaipur, India. The building includes a sunken courtyard pool, which architect Manit Rastogi explains functions similarly to a basement, staying cooler than the aboveground air in the summer and warmer in the winter; breezes flowing under the raised building create evaporative cooling currents that push air up through atria and open stairwells.

The building also features an exterior latticed screen ( jaali ) enveloping the building, a traditional feature of Rajasthani architecture that provides a thermal buffer for buildings (however, this is not considered true passive cooling, but rather a strategy to avoid overheating). Despite the fact that the building is located in a hot desert climate, Rastogi says it maintains interior temperatures of 80–85°F even when it’s 110°F outside, using minimal mechanical air conditioning just two months of the year.23

One of the most unusual and innovative examples of a structure utilizing traditional technology might be architect Mick Pearce’s Eastgate Centre, a shopping center in Harare, Zimbabwe, that was inspired by a 1992 BBC television program on termites, hosted by naturalist David Attenborough.24 Pearce was struck by the termites’ use of the thermal capacity of the ground and the mound, and their labyrinths of ventilation tunnels. “The termite mound which we see above ground is a breathing and air-conditioning system like the human lung,” he says.

Eastgate Centre relies on night flushing: Cool night air is driven through a multitude of air passages within the building’s heavy concrete and masonry structure, cooling the concrete vaulted ceiling, which absorbs heat during the day. The accumulated heat from each day is vented at night through these same passages, partly by fans and partly by convection forces in 48 huge stacks that run through the center of the building.

Pearce says it took about three years to optimize the timing of the daytime and nighttime fans to align with diurnal differences in temperature. “It was like tuning an organ built into a church, where the building resonance is important,” he says. “Another factor was the occupation of the building, where—like the termitary—the occupants’ heat [output] is crucial to the cycles.” According to Pearce, Eastgate uses 10% of the energy of comparably sized air-conditioned buildings in Harare.

Still another scheme for alternative cooling has been in place in Toronto for eight years: a “deep water source cooling” system in which cool water is pumped from a five-kilometer depth in Lake Ontario to participating office buildings and through metal coils.25 Fans blow the cool air from the coils into the buildings’ climate-control systems, reducing their energy demands. Although mostly used in cooler climates, it is also being explored in warmer areas. A project using this technology is about to break ground in Honolulu and will use seawater.26

Small-Scale Fixes
Apart from these large-scale demonstrations that mechanical air conditioning can be eliminated or reduced, experts say there are many smaller ways that workplaces and homes can be made comfortable during hot weather without air conditioning.
http://ehp.niehs.nih.gov/121-a18/

Low energy cooling with PDEC

Passive downdraft evaporative cooling (PDEC) employs the spraying of microscopic water droplets into the air, a concept borrowed from traditional architecture in Pakistan, Iran, Turkey, and Egypt, according to Kamal. These traditional buildings were topped by wind-catching hoods (malqafs) that pulled air down chimneys and cooled it by directing it across a source of moisture: a pool, a fountain, or porous pots that seeped water. Contemporary PDEC buildings also employ wind catchers but replace the water pots with wet cellulose pads or similar devices. Kamal cites the Torrent Research Centre in Ahmedabad, India, as an excellent example of contemporary use of PDEC. The center was completed in 1999 and has reportedly provided comfortable conditions for occupants while also recording extremely low energy consumption.
Another example of a hot-climate structure using water and traditional design for cooling is Pearl Academy in Jaipur, India. The building includes a sunken courtyard pool, which architect Manit Rastogi explains functions similarly to a basement, staying cooler than the aboveground air in the summer and warmer in the winter; breezes flowing under the raised building create evaporative cooling currents that push air up through atria and open stairwells.
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(7) Solar Energy - Quora
0 14 April, 2015 Source: quora.com
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