Energy Poverty-The Role of Sierra Leoneans in the Diaspora

“Access to energy is absolutely fundamental in the struggle against poverty,” said World Bank Vice President Rachel Kyte. “It is energy that lights the lamp that lets you do your homework that keeps the heat on in a hospital that lights the small businesses where most people work. Without energy, there is no economic growth, there is no dynamism, and there is no opportunity.”

Energy Poverty is a one of the major challenges we face in Sierra Leone. Energy poverty refers to the situation where large numbers of our people’s well-being is negatively affected by very low consumption of energy, use of dirty or polluting fuels, and excessive time spent collecting fuel to meet basic needs.

In other words 60% plus of our people reply on expensive and unsustainable alternatives such as kerosene, batteries and candles for their lightning needs. Until the grid expands, which will require of hundreds of million of investment, the majority of our people would have to adopt sustainable alternatives. Solar lanterns is one such alternative.
Burning money: In Sierra Leone, for example, poor families spend between 5-8 USD a month of kerosene, batteries and candles combined. This amounts to 96 USD a year! This is unacceptable when many people, 60% live on less than 2 dollars a day.

At the same time Sierra Leoneans in the Diaspora remit some 55 millions dollars every year back to their family and friends home. A large proportion of these remittances goes to household consumption. Very little is saved. As so many families are off grid, spending on kerosene, candles, batteries, diesel for lighting constitute a significant expenditure for many families. Given the alternative of solar, this is a real waste of money.
Unintentionally your remittances are contributing to Energy poverty and financing poor health. In addition, many of our children are not able to properly study because they reply on Kerosene lamp or candles.

Burning of fossil fuel like kerosene, oils, woods and coal are the biggest sources of indoor pollution. Indoor pollution causes half as many deaths as malaria, nearly as many casualties as TB, and half as many as HIV/Aids. Indoor pollution is leads to thoracic infections and lungs diseases. World-wide some 4 million people die every year from indoor pollution-the majority woman and children. Of the 4 million it is estimated 800,000 are children, majority in Africa and Asia.

Think about investing in a solar lantern for your relatives and friends back home. You can mitigate the effect of climate change by contributing to the use of more sustainable lighting alternatives.
The savings from not buying kerosene will free up funds for other household items or even schooling; reduction from the serious effects of indoor pollution; better light for studying purposes; safer home environment and more.

Visit DiasporaSolar.com to learn more. We have charts, diagrams and calculations showing the case study. For example, every year on average each Sierra Leone spends $97 on Kerosene, candles and batteries. A solar lantern costing $50, with a phone charger has no running cost and the battery can last from 3- 5 years. This means after year one you can potentially realize savings of $97 every year and you get better health!

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Forecasting aggregated wind power production of multiple wind farms using hybrid wavelet-PSO-NNs

SUMMARY

This paper describes the problem of short-term wind power production forecasting based on meteorological information. Aggregated wind power forecasts are produced for multiple wind farms using a hybrid intelligent algorithm that uses a data filtering technique based on wavelet transform (WT) and a soft computing model (SCM) based on neural network (NN), which is optimized by using particle swarm optimization (PSO) algorithm. To demonstrate the effectiveness of the proposed hybrid intelligent WT + NNPSO model, which takes into account the interactions of wind power, wind speed, wind direction, and temperature in the forecast process, the real data of wind farms located in the southern Alberta, Canada, are used to train and test the proposed model. The test results produced by the proposed hybrid WT + NNPSO model are compared with other SCMs as well as the benchmark persistence method. Simulation results demonstrate that the proposed technique is capable of performing effectively with the variability and intermittency of wind power generation series in order to produce accurate wind power forecasts. Copyright © 2014 John Wiley & Sons, Ltd.

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Stanford study could lead to paradigm shift in organic solar cell research

Organic solar cells have long been touted as lightweight, low-cost alternatives to rigid solar panels made of silicon. Dramatic improvements in the efficiency of organic photovoltaics have been made in recent years, yet the fundamental question of how these devices convert sunlight into electricity is still hotly debated.

Now a Stanford University research team is weighing in on the controversy. Their findings, published in the Nov. 17 issue of the journal Nature Materials, indicate that the predominant working theory is incorrect, and could steer future efforts to design materials that boost the performance of organic cells.

“We know that organic photovoltaics are very good,” said study coauthor Michael McGehee, a professor of materials science and engineering at Stanford. “The question is, why are they so good? The answer is controversial.”

A typical organic solar cell consists of two semiconducting layers made of plastic polymers and other flexible materials. The cell generates electricity by absorbing particles of light, or photons.

When the cell absorbs light, a photon knocks out an electron in a polymer atom, leaving behind an empty space, which scientists refer to as a hole. The electron and the hole immediately form a bonded pair called an exciton. The exciton splits, allowing the electron to move independently to a hole created by another absorbed photon. This continuous movement of electrons from hole to hole produces an electric current.

In the study, the Stanford team addressed a long-standing debate over what causes the exciton to split.

“To generate a current, you have to separate the electron and the hole,” said senior author Alberto Salleo, an associate professor of materials science and engineering at Stanford. “That requires two different semiconducting materials. If the electron is attracted to material B more than material A, it drops into material B. In theory, the electron should remain bound to the hole even after it drops.

“The fundamental question that’s been around a long time is, how does this bound state split?”

Some like it hot

One explanation widely accepted by scientists is known as the “hot exciton effect.” The idea is that the electron carries extra energy when it drops from material A to material B. That added energy gives the excited (“hot”) electron enough velocity to escape from the hole.

But that hypothesis did not stand up to experimental tests, according to the Stanford team.

“In our study, we found that the hot exciton effect does not exist,” Salleo said. “We measured optical emissions from the semiconducting materials and found that extra energy is not required to split an exciton.”

So what actually causes electron-hole pairs to separate?

“We haven’t really answered that question yet,” Salleo said. “We have a few hints. We think that the disordered arrangement of the plastic polymers in the semiconductor might help the electron get away.”

In a recent study, Salleo discovered that disorder at the molecular level actually improves the performance of semiconducting polymers in solar cells. By focusing on the inherent disorder of plastic polymers, researchers could design new materials that draw electrons away from the solar cell interface where the two semiconducting layers meet, he said.

“In organic solar cells, the interface is always more disordered than the area further away,” Salleo explained. “That creates a natural gradient that sucks the electron from the disordered regions into the ordered regions. ”

Improving energy efficiency

The solar cells used in the experiment have an energy-conversion efficiency of about 9 percent. The Stanford team hopes to improve that performance by designing semiconductors that take advantage of the interplay between order and disorder.

“To make a better organic solar cell, people have been looking for materials that would give you a stronger hot exciton effect,” Salleo said. “They should instead try to figure out how the electron gets away without it being hot. This idea is pretty controversial. It’s a fundamental shift in the way people think about photocurrent generation.”

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UC’s SmartLight More Than a Bright Idea, It’s a Revolution in Interior Lighting Ready to Shine

The innovative solar technology “would change the equation for energy,” according to UC researchers.

A pair of University of Cincinnati researchers has seen the light – a bright, powerful light – and it just might change the future of how building interiors are brightened.

In fact, that light comes directly from the sun. And with the help of tiny, electrofluidic cells and a series of open-air “ducts,” sunlight can naturally illuminate windowless work spaces deep inside office buildings and excess energy can be harnessed, stored and directed to other applications.

This new technology is called SmartLight, and it’s the result of an interdisciplinary research collaboration between UC’s Anton Harfmann and Jason Heikenfeld. Their research paper “Smart Light – Enhancing Fenestration to Improve Solar Distribution in Buildings” was recently presented at Italy’s CasaClimainternational energy forum.

The SmartLight technology would be groundbreaking. It would be game changing,” says Harfmann, an associate professor in UC’s School of Architecture and Interior Design. “This would change the equation for energy. It would change the way buildings are designed and renovated. It would change the way we would use energy and deal with the reality of the sun. It has all sorts of benefits and implications that I don’t think we’ve even begun to touch.”

MAJOR IMPROVEMENT THROUGH MINIMAL ADJUSTMENTS

There’s a simple question SmartLight addresses: Is there a smarter way to use sunlight? Every day the sun’s rays hit Earth with more than enough energy to meet many of society’s energy demands, but existing technologies designed to harness that energy, such as photovoltaic cells, aren’t very efficient. A typical photovoltaic array loses most of the sun’s energy when it gets converted into electricity. But with SmartLight, Harfmann says the sunlight channeled through the system stays, and is used, in its original form. This method is far more efficient than converting light into electricity then back into light and would be far more sustainable than generating electric light by burning fossil fuels or releasing nuclear energy.

The technology could be applied to any building – big or small, old or new, residential or commercial. But Harfmann and Heikenfeld believe it will have the greatest impact on large commercial buildings. The U.S. Department of Energy’s Energy Information Administration shows that 21 percent of commercial sector electricity consumption went toward lighting in 2011. Harfmann calls the energy demand for lighting in big, commercial buildings “the major energy hog,” and he says energy needed to occupy buildings accounts for close to 50 percent of the total energy consumed by humans.

 

Diagram of SmartLight on interior of building
This diagram shows how SmartLight can direct sunlight from the outside of a building (far right) …

 

Diagram of SmartLight on exterior of building
… to the inner part of a building and to a centralized harvesting- and energy-storage hub (far left).

SmartLight could help shift that energy imbalance. It works like this: A narrow grid of electrofluidic cells which is self-powered by embedded photovoltaics is applied near the top of a window. Each tiny cell ¬– only a few millimeters wide – contains fluid with optical properties as good or better than glass. The surface tension of the fluid can be rapidly manipulated into shapes such as lenses or prisms through minimal electrical stimulation – about 10,000 to 100,000 times less power than what’s needed to light a traditional incandescent bulb. In this way, sunlight passing through the cell can be controlled.

The grid might direct some light to reflect off the ceiling to provide ambient room lighting. Other light might get focused toward special fixtures for task lighting. Yet another portion of light might be transmitted across the empty, uppermost spaces in a room to an existing or newly installed transom window fitted with its own electrofluidic grid. From there, the process could be repeated to enable sunlight to reach the deepest, most “light-locked” areas of any building. And it’s all done without needing to install new wiring, ducts, tubes or cables.

“You’re using space that’s entirely available already. Even if I want to retrofit to existing architecture, I’ve got the space and the ability to do so,” says Heikenfeld, professor of electrical engineering and computer systems and creator of the Smart Light’s electrofluidic cells. “And you don’t need something mechanical and bulky, like a motor whirring in the corner of your office steering the light. It just looks like a piece of glass that all of a sudden switches.”

SMART APPROACH ALLOWS DYNAMIC RESPONSE

As for switching, Harfmann envisions a workplace where physical light switches join other anachronistic office equipment like mouse pads or bulky CRT monitors. Plans call for SmartLight to be controlled wirelessly via a mobile software application. So instead of manually flipping a switch on a wall, a user would indicate their lighting preferences through an app on their mobile device, and SmartLight would regulate the room’s brightness accordingly. SmartLight could even use geolocation data from the app to respond when a user enters or leaves a room or when they change seats within the room by manipulating Wi-Fi-enabled light fixtures.

SmartLight controls on a smartphone
A user could control SmartLight through a mobile app, as depicted in this rendering.

“SmartLight would be controlled wirelessly. There would be no wires to run. You wouldn’t have light switches in the room. You wouldn’t have electricity routed in the walls,” Harfmann says. “You would walk into a room and lights would switch on because your smartphone knows where you are and is communicating with the SmartLight system.”

But what happens at night or on cloudy days? That’s where SmartLight’s energy storage ability comes in. On a typical sunny day, sunlight strikes a facade at a rate that’s often hundreds of times greater than what is needed to light the entire building. SmartLight can funnel surplus light into a centralized harvesting- and energy-storing hub within the building. The stored energy could then be used to beam electrical lighting back through the building when natural light levels are low. The SmartLight’s grid is so responsive – each cell can switch by the second – it can react dynamically to varying light levels throughout the day, meaning office lighting levels would remain constant during bright mornings spent catching up on email, stormy lunch hours spent eating at your desk, and late nights spent reviewing the budget.

With such potential for energy storage, a building’s electrical network also could tap into the centralized hub and use the stockpiled energy to power other needs, such as heating and cooling. And if centralized collection of surplus sunlight isn’t possible inside some existing structures, the light could even be sent straight through a building to a neighboring collection facility.

PARTNERING FOR A BRIGHTER FUTURE

Heikenfeld says much of the science and technology required to make the Smart Light commercially viable already exists. He and Harfmann have begun evaluating materials and advanced manufacturing methods. The only thing missing at this point is enough funding to create a large-scale prototype which could call the attention of government or industry partners interested in bringing SmartLight to market.

“We’re going to look for some substantial funds to really put a meaningful program together,” Heikenfeld says. “We’ve already done a lot of the seed work. We’re at the point where it would be a big, commercially driven type of effort. The next step is the tough part. How do you translate that into commercial products?”

Harfmann and Heikenfeld originally began developing the idea for the Smart Light years ago. Harfmann was one of the leaders on UC’s team in the 2007 Solar Decathlon, a global competition to build the planet’s best solar house. Harfmann, an associate dean in UC’s College of Design, Architecture, Art, and Planning, collaborated with faculty from other disciplines, including the College of Engineering & Applied Science. That led to his relationship with Heikenfeld and eventually the first discussions of the SmartLight concept.

The cross-college efforts of Harfmann and Heikenfeld align with the university’s UC2019 Academic Master Plan goal of expanding collaborative engagement to advance the common good. Additionally, the SmartLight project exemplifies the UC2019 vision by transforming the world through research and creating a deliberate and responsible approach to our environment, resources and operations.

The innovation that results from similar collaborations taking place everywhere at UC, Heikenfeld says, is part of what helps make the university a leader in so many fields.

“A step beyond just working with someone in a multidisciplinary fashion, and where a lot of these partnerships go well, is when you take the time to learn enough about someone else’s discipline that you can then begin to inject innovation into it, but not independently,” Heikenfeld says. “It’s more than just bringing multidisciplinary folks together. You have to stretch yourself to the point where you begin to understand the drivers and some of the fundamentals of the other disciplines as well. One of UC’s greatest strengths is our diversity, this is in the classic sense of the term, but also in terms of academic thinking and expertise, which is a great melting pot for big, new ideas.

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Scientists develop heat-resistant materials that could vastly improve solar cell efficiency

Scientists have created a heat-resistant thermal emitter that could significantly improve the efficiency of solar cells. The novel component is designed to convert heat from the sun into infrared light, which can than be absorbed by solar cells to make electricity – a technology known as thermophotovoltaics. Unlike earlier prototypes that fell apart at temperatures below 2200 degrees Fahrenheit (1200 degrees Celsius), the new thermal emitter remains stable at temperatures as high as 2500 F (1400 C).

“This is a record performance in terms of thermal stability and a major advance for the field of thermophotovoltaics,” said Shanhui Fan, a professor of electrical engineering at Stanford University. Fan and his colleagues at the University of Illinois-Urbana Champaign (Illinois) and North Carolina State University collaborated on the project. Their results are published in the October 16 edition of the journal Nature Communications.

A typical solar cell has a silicon semiconductor that absorbs sunlight directly and converts it into electrical energy. But silicon semiconductors only respond to infrared light. Higher-energy light waves, including most of the visible light spectrum, are wasted as heat, while lower-energy waves simply pass through the solar panel.

“In theory, conventional single-junction solar cells can only achieve an efficiency level of about 34 percent, but in practice they don’t achieve that,” said study co-author Paul Braun, a professor of materials science at Illinois. “That’s because they throw away the majority of the sun’s energy.”

Thermophotovoltaic devices are designed to overcome that limitation. Instead of sending sunlight directly to the solar cell, thermophotovoltaic systems have an intermediate component that consists of two parts: an absorber that heats up when exposed to sunlight, and an emitter that converts the heat to infrared light, which is then beamed to the solar cell.

“Essentially, we tailor the light to shorter wavelengths that are ideal for driving a solar cell,” Fan said. “That raises the theoretical efficiency of the cell to 80 percent, which is quite remarkable.”

So far, thermophotovoltaic systems have only achieved an efficiency level of about 8 percent, Braun noted. The poor performance is largely due to problems with the intermediate component, which is typically made of tungsten – an abundant material also used in conventional light bulbs.

“Our thermal emitters have a complex, three-dimensional nanostructure that has to withstand temperatures above 1800 F (1000 C) to be practical,” Braun explained. “In fact, the hotter the better.”

In previous experiments, however, the 3D structure of the emitter was destroyed at temperatures of around 1800 F (1000 C). To address the problem, Braun and his Illinois colleagues coated tungsten emitters in a nanolayer of a ceramic material called hafnium dioxide.

The results were dramatic. When subjected to temperatures of 1800 F (1000 C), the ceramic-coated emitters retained their structural integrity for more than 12 hours. When heated to 2500 F (1400 C), the samples remained thermally stable for at least an hour.

The ceramic-coated emitters were sent to Fan and his colleagues at Stanford, who confirmed that devices were still capable of producing infrared light waves that are ideal for running solar cells.

“These results are unprecedented,” said former Illinois graduate student Kevin Arpin, lead author of the study. “We demonstrated for the first time that ceramics could help advance thermophotovoltaics as well other areas of research, including energy harvesting from waste heat, high-temperature catalysis and electrochemical energy storage.”

Braun and Fan plan to test other ceramic-type materials and determine if the experimental thermal emitters can deliver infrared light to a working solar cell.

“We’ve demonstrated that the tailoring of optical properties at high temperatures is possible,” Braun said. “Hafnium and tungsten are abundant, low-cost materials, and the process used to make these heat-resistant emitters is well established. Hopefully these results will motivate the thermophotovoltaics community to take another look at ceramics and other classes of materials that haven’t been considered.”

**

Other authors of the study are Nicholas Sergeant, Linxiao Zhu and Zongfu Yu of Stanford; Andrew Cloud, Hailong Ning, Justin Mallek, Berç Kalanyan, Gregory Girolami and John Abelson of Illinois; and Mark Losego and Gregory Parsons of North Carolina State University.

This article was written by Mark Shwartz, Precourt Institute for Energy at Stanford University.

Related information:

Fan Research Group http://www.stanford.edu/group/fan/

Braun Research Group http://braungroup.beckman.illinois.edu/

Global Climate and Energy Project http://gcep.stanford.edu/

 

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Optimization of hydrogen production from pretreated rice straw waste in a mesophilic up-flow anaerobic staged reactor

SUMMARY

This study was carried out to assess the efficiency of a mesophilic up-flow anaerobic staged reactor for continuous H2 production from pretreated rice straw waste. The reactor was operated at different hydraulic retention times (HRTs) of 20, 16, 12, 8 and 4 h. The organic loading rate and sludge residence time were kept constant at 30 g chemical oxygen demand (COD)/L/day, and 1.9 days, respectively. The results showed that increasing the HRT from 4 to 20 h increased the H2 production from 0.4 ± 0.1 to 3.6 ± 0.3 L H2/day, respectively. This corresponds to a H2 yield of 2.1 ± 0.2 mol H2/g CODremoved at an HRT of 20 h and 0.03 ± 0.002 mol H2/g CODremoved at an HRT of 4 h. Likewise, carbohydrate and COD removal efficiency was strongly dependant on HRT. The removal efficiency decreased from 76.5 ± 3.4% to 40 ± 2.2% for carbohydrate and from 77.7 ± 4.3% to 12.2 ± 2.1% for COD when the HRT is reduced from 20 to 4 h, respectively.

The addition of presettled sewage sludge to pretreated rice straw at a mixing ratio of 1:4 (v/v) increased the volumetric H2 production from 3.6 ± 0.3 to 8.2 ± 2.5 L/day and the H2 yield from 2.1 ± 0.2 to 2.8 ± 0.3 mol H2/g CODremoved. Moreover, the removal efficiency of COD, volatile solids and carbohydrate was significantly improved. Copyright © 2013 John Wiley & Sons, Ltd.

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Team uses a cellulosic biofuels byproduct to increase ethanol yield

CHAMPAIGN, Ill. — Scientists report in Nature Communications that they have engineered yeast to consume acetic acid, a previously unwanted byproduct of the process of converting plant leaves, stems and other tissues into biofuels. The innovation increases ethanol yield from lignocellulosic sources by about 10 percent.

Lignocellulose is the fibrous material that makes up the structural tissues of plants. It is one of the most abundant raw materials on the planet and, because it is rich in carbon it is an attractive source of renewable biomass for biofuels production.

The yeast Saccharomyces cerevisiae is good at fermenting simple sugars (such as those found in corn kernels and sugarcane) to produce ethanol. But coaxing the yeast to feast on plant stems and leaves is not so easy. Doing it on an industrial scale requires a number of costly steps, one of which involves breaking down hemicellulose, a key component of lignocellulose.

“If we decompose hemicellulose, we obtain xylose and acetic acid,” said University of Illinois food science and human nutrition professor Yong-Su Jin, who led the research with principal investigator Jamie Cate, of the University of California at Berkeley and the Lawrence Berkeley National Laboratory. Jin and Cate are affiliates of the Energy Biosciences Institute (EBI), which funded the research. Jin also is an affiliate of the Institute for Genomic Biology at Illinois.

“Xylose is a sugar; we can engineer yeast to ferment xylose,” Jin said. “However, acetic acid is a toxic compound that kills yeast. That is one of the biggest problems in cellulosic ethanol production.”

In an earlier study, graduate student Soo Rin Kim (now an EBI fellow) engineered S. cerevisiae to more efficiently consume xylose. This improved ethanol output, but the process generated an excess of NADH, an electron-transfer molecule that is part of the energy currency of all cells. The buildup of acetic acid also killed off much of the yeast.

After discussing the problem with Jin, Cate had an idea – perhaps the team could induce the yeast to consume acetic acid. It later occurred to Jin that that process might also use up the surplus NADH from xylose metabolism.

By reviewing earlier studies, postdoctoral researcher Na Wei found that another organism, a bacterium, could consume acetic acid. She identified the enzymes that catalyzed this process and saw that one of them not only converted acetic acid into ethanol, but also would use the surplus NADH from xylose metabolism.

The team was not ready to start putting the genes into their yeast, however. They first had to determine whether their efforts were likely to succeed.

“One challenge with yeast is it has evolved to do one thing really well,” Cate said. “When you start adding these new modules into what it’s already doing, it’s not obvious that it’s going to work up front.”

To get a better idea of the feasibility of the idea, graduate student Josh Quarterman used computer simulations to see how adding the new genes to the yeast’s metabolic repertoire would affect its ethanol output. His calculations indicated that the pathway Wei had identified would boost ethanol production.

The new advance will streamline the fermentation process and will simplify plant breeding and pretreatment of the cellulose, the researchers say. The new advance will streamline the fermentation process and will simplify plant breeding and pretreatment of the cellulose, the researchers say.

Next, Wei did the painstaking work of inserting the desirable genes into the yeast, a process that took several months. When she tested the yeast, she saw that it produced about 10 percent more ethanol than before, in line with Quarterman’s calculations. In further experiments, she demonstrated that the new yeast was in fact making some of the ethanol from acetate, a first for S. cerevisiae.

“We sort of rebuilt how yeast uses carbon,” Cate said.

The breakthrough also will help those who focus on other steps in the biofuels production process, Jin said. Plant geneticists and those involved in pretreatment can stop worrying about finding ways to eliminate acetic acid from lignocellulose, he said.

“Many people are curious about why we don’t have cellulosic biofuel right now,” Jin said. “But it’s not because of one limiting step. We have many limiting steps in growing the biomass, storing, moving, harvesting, decomposing the biomass to the sugar, fermentation and then separation (of the ethanol). The advance that we are reporting involves one of those steps – fermentation. But it also will make other steps in the process a little easier.”

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