Earth and Industry » Energy

Can Solar Energy Lower the Cost of Carbon Capture?

Timothy Hurst — Fri, 27 Jan 2012 11:20:51 +0000

Researchers at the Masdar Institute in Abu Dhabi chart a promising course toward cheaper carbon capture

Looming above a test plot full of mirrors like some kind of Transformer-inspired arachnid, the tower at the center of Masdar City's concentrating solar power plant is almost menacing at first glimpse.

Although still only one year into the R&D phase, the 100 kW Beam-Down Solar Thermal Concentrator at Masdar City, the emerging renewable energy research hub located 15 miles from downtown Abu Dhabi, has the potential to generate 75-85 megawatt-hours of renewable energy annually.

But as Masdar City Director Alan Frost tells a small group of journalists as we approach the plant on a recent January afternoon, "the Beam Down project is a different kind of concentrating solar plant."

Whereas most concentrating solar power (CSP) plants employing tower technology gather sunlight aimed at them from the mirror arrays below, the CSP tower at Masdar City goes one step further and directs the solar rays back downward and onto a receiver at the base of the tower, thereby eliminating the need for energy to pump the fluid up the tower.

Masdar City's Frost says the pilot project is "quite experimental," but he is also quick to point out that it is "the kind of thing we should certainly do."

The Beam Down at Masdar City is only a pilot project, but Dr. Matteo Chiesa, the head of the Laboratory of Energy and Nano Sciences (LENS) at the Masdar Institute of Science and Technology, says that substantially greater efficiencies could be found if the project was scaled up.

"The possibility of employing a multi-towers concept we have proposed (due to the fact of a simpler tower structure) can provide a way to optimize the overall energy outcome of the solar field," Chiesa said in an email.

By directing certain heliostats to different towers during the day, says Chiesa, "We have shown that one can reduce the energy losses due to cosine effect."

Solar-assisted carbon capture

But an even more important discovery made by Dr. Chiesa and his team of graduate students, though "not directly and exclusively related to the beam down," is the viability of a hybrid carbon capture process that uses solar thermal energy to assist the capture of carbon dioxide from power plant flue gases.

"Solvent-based Post-combustion Carbon Capture (PCC) is one of the promising technologies for reducing CO2 emissions from existing fossil-fuel power plants due to ease of retrofitting," writes one of Dr. Chiesa's students, Masdar Institute's Marwan Mokhtar, the lead author in a forthcoming paper published in the journal Applied Energy (available online Sept., 2011).

While experts agree that the most promising PCC processes in development around the world use absorption (pdf), these technologies are still incredibly expensive because of the energy intensive CO2 separation process.

According to the research team at Masdar, however, solvent regeneration requires thermal energy of lower quality, which can be provided cost-effectively by a solar thermal plant, leaving the higher quality for use in electricity generation at the plant.
To test their hypothesis, Mokhtar, et al modeled the performance of the process on a 300MWe pulverized coal power plant in New South Wales, Australia, using actual weather and wholesale electricity price data from the area. The New South Wales location was chosen because sunny regions with long summers, substantial air-conditioning demand and a reliance on coal-fired power plants would be the most promising candidates for the implementation of this solar-assisted carbon capture technology. Given those conditions, the results of the test were favorable.

"It is shown that the proposed technology can be economically viable for solar collector costs of US$100/m2 at current retail electricity prices and optimal Solar load-Fraction of 22%," the authors write (Solar load-Fraction is the portion of solvent regeneration energy provided by solar energy).

Furthermore, the authors write, reducing the need for heat energy during the daytime coincides with peaks in wholesale electricity prices "thus increasing the revenue stream for a solar-assisted PCC plant."

And though a solar-assisted PCC plant has yet to be built, the economics are likely to become even more favorable as electricity prices continue to climb and solar collector prices decrease.

(Check out this short video of how the Beam Down's heliostats can move to track the movements of the sun and optimize efficiency.)

Disclosure: Tim Hurst's travel to Abu Dhabi was covered by Masdar.
All photos: CC licensed by Tim Hurst

Energy Efficient Data Centers: Why They’re Important [INFOGRAPHIC]

Becky Striepe — Fri, 30 Dec 2011 01:20:48 +0000

If you're not a techie person, something like a data center probably feels like it doesn't affect you, but you probably interact with data centers all the time without even realizing it. Any time load a website on your computer, you're relying on a data center. Basically, a data center is a huge building full of computers.

Large companies like Apple, IBM, and Amazon have huge data centers that they use to do everything from keeping inventory to processing orders, and all of those computers in all of those buildings add up to a huge environmental impact. We need to hold companies accountable when they're not doing everything possible to make their data centers energy efficient.

This infographic from Peer 1 Hosting takes a look at efficient data centers, what makes them that way, and how companies can improve.

Image Credits:
Data Center. Creative Commons photo by The Planet
Infographic via Peer 1 Hosting

One Plug to Rule Them All: Unifying Electric Car Fast Charge Systems

LiveOAK Staff — Wed, 02 Nov 2011 10:48:08 +0000

by Olan Dantes

The dream of gasoline freedom is becoming a reality as electric cars are slowly filling showrooms and attracting a lot of customers. The Nissan Leaf, for example, has its sales reaching 10,000 as of August this year. Other manufactures like Mitsubishi, Porsche and Audi are poised to join in. Greener cars are indeed hitting the mainstream with one thing dragging their progress: a standard charger plug.

The problem with the older charging systems of electric cars was the amount of time needed to charge one. The Level 1 Charging, as it is called, plugs the car into a 120 volt power. Hybrid cars can use it for overnight charging but for a pure electric car like the Nissan Leaf, it would take 20 hours to fully charge its battery. A second level has been made using a 240 volt power supply which can fill up a Leaf within eight hours.

Users though are still are not satisfied with an eight-hour wait on charging. This was addressed with the direct current fast charging system developed by Japanese car manufacturers and Tokyo Electric Power Company (TEPCO). The system which is named CHAdeMO can deliver 62.5 kilowatts of high-voltage direct current and can refill a Nissan Leaf to 80 percent of its capacity in only half an hour. Interestingly, CHAdeMO is a pun for a Japanese term that means “How about some tea while charging?”

Level 1 and Level 2 charging systems has the connectors standard SAE J1772 but none has been named for the CHAdeMO. Instead it uses a separate connector and is not compatible with older levels. It is incorrectly called a Level 3 charging system as Magne Charge claimed that title years ago but was discontinued because of its inefficiency being an inductive charger.

The CHAdeMO is poised to become a global standard for DC Fast Charging Systems. 532 charging systems have been installed in Japan and 17 are available in the U.S. Something is coming though that may alter its fate.

Daimler made a statement last October 11 of this year that they will be showcasing a prototype combination plug and port that will be used by hybrid cars and pure electric vehicles. The system is a joint effort by other car manufacturing giants such as Audi, BMW, Porsche, and Volkswagen. This has been the clearest indication that European automakers are not favoring the CHAdeMO. Instead they are considering the standard proposed by SAE International.

China’s Clean Tech Efforts Tarnished by Solar Panel Factory Protests

The Guardian — Tue, 20 Sep 2011 04:01:17 +0000

This article titled "Solar panel factory protests tarnish China's clean-tech efforts" was written by Jonathan Watts, Asia environment correspondent, for The Guardian on Sunday 18th September 2011 18.05 UTC

China's ambition to build a harmonious clean-tech economy lost some of its sheen on Sunday after a violent confrontation over pollution from a solar panel factory.

Riot police broke up a four-day protest by several hundred villagers in Haining, Zhejiang province, who overturned cars and stormed the compound of a photovoltaic manufacturer that is accused of releasing toxins into a local river.

The demonstrators complained of police brutality and efforts to silence their voices in the latest in a rash of rallies and protests over environmental concerns in China.

The target on this occasion was Jinko Solar Holding, a fast-growing company listed on the New York stock exchange that produces ingots, wafers, cells and modules.

Although solar is seen as clean energy in terms of carbon emissions, the production of many components is energy intensive and polluting. Toxic discharges from the factory killed large numbers of fish and regulators have previously ordered the company to suspend operations, according to the domestic media.

Chen Hongming, deputy head of Haining's environmental protection bureau, told the Xinhua news agency that the plant has failed to meet pollution standards since April despite official warnings.

Locals are frustrated their complaints have not been heard. On Thursday, 500 people burst into the factory compound. They were dispersed, but continued their protests by camping outside.

Photographs and video of the demonstrations have spread across the internet. One banner – shown on the website of the National Business Daily newspaper – reads: "Return our lives to us, stay away from Jinko."

Video images on the municipal website showed smashed factory windows. Eight company vehicles were overturned on Thursday and four police vehicles were damaged on the following days, according to official accounts.

Riot police dispersed the gathering on Sunday and sealed off the site. Witnesses complained to reporters that the security forces had used heavy-handed tactics.

"Some people were beaten up during the protests," a protester with the surname Cao told Reuters. "Why can't we just tell the truth about this pollution? Now people talking to reporters are also being detained: what justice is there? We are being silenced."

Villagers said they wanted the factory to move because they were worried about the impact of its discharges into the river and air on the health of their children.

The clash highlights the difficulty that China faces as it tries to clean up its environment, reduce its reliance on coal and secure "clean tech" export business. The country is the world's biggest manufacturer of solar panels with about 70% of the global market, but overseas rivals say this dominant position has been achieved through unfair subsidies, low wages and lax environmental regulation.

Increasingly, however, Chinese citizens are uneasy about the consequences of pollution in all industries. As incomes levels and environmental awareness rise, there is a growing reluctance to accept dirty growth. Last month, the Dalian city government promised to halt a planned paraxylene (PX) plant after a rally by tens of thousands of people. In recent years, there have also been several violent demonstrations against battery factories and smelting facilities that are blamed for unhealthy levels of lead in the blood of children in some area. Many other smaller protests in the countryside go largely unreported.

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Solar Car Race in Australia Drives Solar, Cleantech Innovation

Zachary Shahan — Mon, 29 Aug 2011 13:28:36 +0000

Solar power is evolving every day, and a solar car race across Australia is part of that.

There are dedicated scientists and businesses working to advance solar power technology and electric vehicle technology every day. In recent years, we have heard of all sorts of innovative solar technologies that are in development or have already hit market -- solar shingles, solar paint, printable solar cells, and increasingly efficient and cheap solar cells are a few things that come to mind.

Solar power technology has evolved a ton in the past few decades and it's projected that solar power will be cheaper than fossil fuels in a few years (not even taking externalities into account, such as the effects fossil-fuel-based electricity has on our health, environment, and economy).

Yes, most of these scientific advancements happen in labs away from the public eye and the whole testing and development process may be boring to most of us. However, there are some truly fun events connected with solar technology advancement that turn the process into something more like a sporting event and help to drive innovation at the same time.

World Solar Challenge in Australia

One such event is the World Solar Challenge in Australia. In the annual World Solar Challenge, the first of which was way back in 1987, people race solar-powered vehicles 1,864 miles across Australia, from Darwin to Adelaide. These vehicles use innovative technologies created by university and business researchers around the world, and a lot of these technologies actually end up making it into future cars and solar power systems to make them more efficient.

“To design and build a car capable of crossing Australia on the silent power of nature comprehends the most innovative research and development trends in alternative transport technologies,” the World Solar Challenge website states.

“The World Solar Challenge is one the most prestigious events of its kind and attracts the world’s best Technical Universities and Colleges.” Here's a little more on the history of the event:

This year's World Solar Challenge is going to be October 16-23. I'm looking forward to it, as are hundreds of journalists and who knows how many solar, clean energy, and racing fans? If you want to make sure not to miss it and keep up with updates leading to the event, you can register for email updates on the World Solar Challenge website.

This Year's Solar Challenge Winner?

One team worth keeping an eye on is the team pictured at the top of this page from Tokai University. This is the team's second time competing. It won in its first year, but it was using Sharp compound solar cells used in space satellites at that time and won't be able to this time around due to regulations changes. This year, though, the team is excited to be using Panasonic’s HIT (heterojunction with intrinsic thin layer) solar cells and is hopeful it can win again.

"The silicone-based HIT solar cells, which demonstrate a high rate of conversion efficiency, are to be used for the first time in a race car," Charis Michelsen of CleanTechnica writes.

These solar cells "use a hybrid system; both sides of the crystal silicon substrate are coated with an amorphous thin film silicon formation. Since an amorphous formation is used, the HIT solar cells avoid the pitfall of most silicone-based products – a loss of conversion efficiency as temperatures rise."

Looks like a useful technology. Will Tokai University win again this year? We'll have to wait and see. (Or maybe a psychic octopus can tell us ahead of time.)

Image via CleanTechnica/Eco Japan

Mitsubishi, Nissan and Toyota Cars to Provide Home Back-Up Power

Timothy Hurst — Tue, 16 Aug 2011 11:33:33 +0000

Still reeling from the March earthquake, tsunami and nuclear disasters, Japan has not only been forced to deal with energy shortages, the island nation has been forced to rethink the security and capacity of its electric grid, as well as the policies necessary to make any substantive changes in it. But boosting capacity from any energy source takes time, no matter how urgently it is needed. One untapped distributed energy source that could provide up to two days of electricity for the average Japanese household and that requires relatively little investment is just sitting in 10,000 driveways and garages across Japan.

More than 6,000 Nissan LEAF electric vehicles and more than 4,000 Mitsubishi i-MiEVs have been sold in Japan and the batteries in these electric cars could be used to provide back-up power for households — as long as that electricity is converted from the direct current (DC) used in the car battery to alternating current (AC) used in households.

While Nissan said last week it hopes to have a commercial version of the LEAF-to-Home system ready for sale in Japan next year, the Mitsubishi system was unveiled earlier this summer. But the problem up until this week, at least, was that a Nissan would not be able to hook up to a Mitsubishi system and vice versa. But this past weekend, Mitsubishi and Nissan announced a plan to address that problem and standardize such a device, The Daily Yomiuri reports.

According to Nissan officials, the LEAFs 24 kilowatt hour (kwh) battery can store enough juice to power the average Japanese household for two days.

Nissan said that home power systems for LEAF owners in other countries including the U.S. are also possible, but the timeline is longer. And because the average home uses substantially more electricity in the U.S. than in Japan, the back-up power provided would not last as long. At least not with the current generation of vehicle batteries.

Toyota, which has been a little late to the EV game as the company focused on developing its hybrid vehicle line, has announced a different kind of solution, making available AC outlets for the 2012 Prius Hybrid. The big difference between the hybrid home power model offered by Toyota and the EV home power model offered by Mitsubishi and Nissan, however, is that the Toyota hybrids can continue to provide electricity as long as there is gas in the tank, essentially turning the vehicle into a generator.

Toyota's absence from the electric car market will end next year as the Japanese powerhouse automaker will begin selling three plug-in electric vehicles beginning in 2012.

Fungus May Be the Key to Cheaper, More Efficient Biofuel

Allison Leahy — Tue, 02 Aug 2011 06:35:20 +0000

Biofuel may soon be produced quickly, efficiently, and at a cost comparable to gasoline thanks to a discovery from researchers at the Great Lakes Bioenergy Research Center. The research team has identified several genes that improve yeast's ability to digest the natural sugar xylose. This means that it will soon be possible to efficiently produce bio-ethanol from cellulosic biomass--waste matter such as the stalks, leaves, and husks of plants, wood chips, sawdust, and dead trees--as opposed to land-intensive crops like corn. The unlikely source of the genes: fungus living symbiotically with bark beetles.

Cellulosic materials cost about half as much as corn per ton, but are historically more difficult than corn to convert to ethanol. Current strains of yeast used industrially for the purpose of converting cellulosic biomass to ethanol have difficulty fermenting the plant sugar xylose, and can do so only after all glucose is exhausted. As xylose makes up nearly half of all available plant sugars, this marks a great loss in ethanol yield.

The team chose bark beetles on account of their woody, xylose-rich habitat. By comparing the sequencing of two xylose-fermenting fungi that live alongside the beetles--Spathaspora passalidarum and Candida tenuis--the researchers was able to identify several genes that effectively increase fermentation of the sugar.

Ethanol can be used as a fuel for cars, but is usually used as a gasoline additive to increase octane and improve vehicle emissions. Production of corn-based ethanol in the United States is just over thirteen billion gallons per year. While biodiesel offers a fossil energy ratio of 5.54 to 1, there is still apprehension about its production and use. These concerns are linked to increased food prices because of the large amount of arable land required for crops as well as the energy-intensive production process (especially corn-based fuels). With available US cropland diminishing, the ability to convert woodier waste will be an important factor in keeping bio-ethanol part of the alternative fuels discussion.

As bark beetles and their related fungi are devastating forests from the northern Rockie s to the Czech Republic, it's nice to know they may provide some great ecological benefit alongside the destruction.

Image Credits: ja.fotopedia, Forest Service - Northern Region

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