Energywise iconEnergywise

Mud-Fueled Smart Sensors for the Bottom of the Ocean

If you put tiny electrodes in the mud on the ocean floor, you can harvest enough energy to power a tiny sensor platform that can monitor what’s going on at those depths.

So say researchers from the University of Michigan at Ann Arbor, in a recent issue of IEEE Transactions on Circuits and Systems I. Together with collaborators from Korea and California, they have designed a self-sustaining sensor platform for oceanic sensing applications that is powered entirely by small-scale benthic microbial fuel cells.

“We wanted a platform that could run off very small harvesting sources,” Michigan electrical engineering professor and IEEE Fellow David Blaauw tells IEEE Spectrum. “If you can get power consumption down enough, there are all sorts of things you can use. Even plants produce little bits of voltage,” he says.

When benthic bacteria are in an anaerobic environment, their metabolism produces electric current. “It’s been well studied,” says Blaauw, “but in the past, people have struggled to get enough current to run something.”

 According to Blaauw, laboratory experiments confirmed that if a microbial fuel cell sits in the sediment, with the cathode floating in a water column where it is exposed to oxygen, it can deliver enough energy to run the platform perpetually.

Though using electrodes with larger surface areas generates more power, the researchers say that it is more challenging to maintain the anaerobic environment with larger electrodes. “If the anode pops out, the whole thing stops working,” Blaauw says, adding that large-size microbial fuel cells also require human divers and sophisticated deployment equipment in order to be properly installed in the ocean floor.

But his team’s setup has very little in the way of complications. “We have much lower power requirements. Just shoot a small dart into the mud, wait a couple of days for the oxygen deprived environment to establish itself, and then you get current.”

Blaauw explains that the sensor platform features a microprocessor, a radio, and few kilobytes of memory. Its power management unit helps keep the draw from its battery to a minuscule 2 nanowatts.

“When the system is in standby mode, it retains data, but consumes little power,” he says. “Very low power timers allow it to wake up occasionally, take readings, then check, store, or transfer data. Low power consumption enables us to work with obscure, small harvesting sources. We can now deploy sensors in the oceanic floor easily and cheaply, and we don’t have to provide batteries that will run forever.”

Blaauw told Spectrum that the prototype system was designed to track changes in temperature, but that it’s easy to imagine it measuring other things such as changes in coral reefs suffering from decay due to pollution.

He explains that this platform is part of a broader portfolio of work focused on powering electronic systems with low energy sources. “These platforms could be used inside the human body, by oil companies investigating fissures in the ground, or by security systems where you need something unobtrusive that fits into the surrounding décor,” he says. “We’ve had interest from a university that wants to study snails, and another that is studying bees. Make a platform really small, and it opens up all sorts of new avenues.”

Renewable Minigrids Should Be the End Goal for Rural Poor

Distributed energy solutions, such as rooftop solar, should be the electrification solution for the 1.1 billion people who are not plugged into a national power grid, not just a stopgap measure. That is the message from a new global industry group, Power for All, launched in New York City this week amidst the latest gathering of the United Nations’ universal energy access program. 

Power For All brings together businesses and not-for-profit organizations that distribute off-grid solutions, including solar-LED lights and home power systems. Founding members include San Francisco-based d.light; Arusha, Tanzania-based Off Grid Electric; and London-based NGO SolarAid—owner of solar-LED light global market leader SunnyMoney, which sold 650,000 lights last year. 

Their message is that bottom-up distributed energy solutions should be the preferred solution for assuring universal access to electricity because they are faster, cleaner, and cheaper than extending power grids to rugged or sparsely-populated regions.

Figures released this week by the joint UN-World Bank energy access program—Sustainable Energy for All—lend credence to Power for All’s argument. SE4ALL’s report on energy access trends compares progress during the 2010-2012 period with energy access trends of the previous two decades. From 2010 to 2012 some 222 million people—more than the population of Brazil—gained grid access for the first time. The growth outpaced global population growth almost 2 to 1, thus trimming the number not yet connected from 1.2 billion to 1.1 billion.

Those figures make electrification a bright spot. Little progress was detected in access to cleaner cooking fuels. Some 2.9 billion people were still cooking with biomass fuels such as wood and dung in 2012. 

Even the progress in electrification was problematic. It was uneven, and, according to SE4ALL’s trend trackers, likely overstated. 

Grid access expanded mainly in urban areas, and fully one-quarter of the growth was in India. In Sub-Saharan Africa — the region with the highest energy access deficits — electrification just barely outpaced population growth; electrification trailed demographic growth in half of the world’s 20 least electrified countries [see graph].  

The problem is that building grid extensions is simply too costly according to Charlie Miller, Head of Policy & Programme Funding at SolarAid. “In places like Zimbabwe and the Democratic Republic of Congo there’s no business case or government or consumer willingness to pay for the grid.” Bottom line according to Miller: “Policies that are grid-focused will not meet the needs of the worst off.” 

In contrast, he says, the organizations behind Power for All are building businesses that are enjoying strong customer demand. “We’re advocating a subsidy-free energy solution that is aligned with people’s willingness to pay,” says Miller. 

Solar-LED lighting is selling because a $10 solar light pays for itself in 10 weeks thanks to avoided kerosene and candles and, according to Miller, it will save its owner $200-340 over its 3-5 year lifetime. He says a solar light that also charges cell phones—a $25 investment—pays off in both dollars saved and by expanding its owner’s access to market opportunities and phone-based banking. 

Miller says much of the commercial investment to Power for All’s segment is going to firms like Off Grid Electric that sell solar as a service, charging something like $15 up front and $2 a week. “You pay indefinitely, just like a utility bill,” says Miller. He says Off Grid Electric is scaling up rapidly in Tanzania, and cites competitors in Kenya, Uganda, and Rwanda who are growing fast using the same model.

Technology improvements and better management means that equipment is cheaper and lasts longer. The sector has come a long way from even a decade ago, when well-meaning programs with under-engineered products and minimal customer service came up short (such as the village lighting program in the Bolivian Andes that IEEE Spectrum featured in 2004).  

Various efforts are underway today to backstop quality, including a quality assurance program for isolated mini-grids operated by the Global Lighting and Energy Access Partnership (Global LEAP), a global energy access initiative hosted by the U.S. Department of Energy.

At the same time ultra-efficient devices such as USB-powered televisions are squeezing more value out of every watt that remote solar panels deliver. Global LEAP issued a study last week asserting that high-efficiency appliances running on direct-current (DC) can cut the total cost of providing off-grid energy services in half.

SE4ALL’s report adds that grid access is not all that it’s cut out to be. In the developing world brownouts and blackouts can be a daily affair. As its U.N.-World Bank authors put it: “The presence of an electricity connection is a prerequisite for receiving electricity supply, but does not guarantee it.” 

The report makes this case through a recent study of electricity access in Kinshasa. Close to 90 percent of residents in the DRC’s capitol have access to electricity through grid connections. But in practice extensive limitations in hours of service, unscheduled blackouts and voltage fluctuations degrade access. “The reality is that the streets of Kinshasa are dark on most nights and that few households can actually use the electrical appliances they own,” according to the report.

This year SE4ALL is launching a new global survey of electrification based on a multi-tier measurement to replace the currently binary “yes/no” grid access surveys. Under the tiered scheme Kinshasa’s electrification rating drops from 90 to 30.

Might that emperor of electricity, the power grid, have no clothes? 

Holography Makes 3-D On-Chip Batteries

By employing the principles used to make holograms, scientists have developed microscopic high-energy, high-power 3-D lithium-ion batteries that they can fabricate directly on microchips.

Existing thin-film microbatteries can deliver high levels of power, but when sized to store a reasonable amounts of energy they take up too much of a chip’s area. To reduce the battery’s footprint and improve microbattery performance inventors have sought to expand into the third dimension with complex 3-D structures that increase the amount of surface area available for electricity-generating chemical reactions. However, it has proven challenging.

Now scientists at the University of Illinois at Urbana-Champaign are using the same principles employed to make holograms to help create advanced 3-D microbatteries. Holography uses patterns of laser beams that interfere with each other in precise ways to encode holograms. Holographic lithography systems fire laser beams at a photosensitive material, and the way these beams interfere with each other can make complex 3-D structures harden into existence in that material in just seconds. The researchers noted that 3-D holographic lithography is highly scalable and compatible with existing microfabrication techniques.

Read More

Nepal’s Hydropower Battered but not Beaten by the Quake

The Kathmandu-based República online news service reported last week that over a dozen hydropower facilities were significantly damaged by last month's earthquake and were not operating. The affected plants’ combined capacity of roughly 150 megawatts (MW) represents about one-fifth of Nepal’s total power supply—which is 93 percent hydropower—but the damage may not be long-lasting according to state utility Nepal Electricity Authority (NEA).

NEA told República that Nepal's remaining hydropower plants and about 210 MW of imported power from India was enabling it to distribute about 564 MW total.  And its 144-megawatt Kaligandaki hydroelectric power station—Nepal’s largest—is not on the list of damaged projects. A 27 April report from industry news source Hydroworld had initially raised concerns about Kaligandaki, citing local news sources.

Sher Singh Bhat, NEA’s deputy managing director, told República that some of the most severe damage from the Magnitude 7.8 quake was at NEA’s 10 MW Sunkoshi Hydropower Project, where “severe leakage” was observed. At the same time, some damaged plants could keep running, such as NEA’s 60 MW Kulekhani project was operating in spite of cracks that opened at the top of its dam. 

Bhat noted that other damaged projects could be fixed “within weeks” -- once workers and heavy equipment operators became available. These include the 24 MW Trishuli plant, where cracks opened in the “crest” of a reservoir and landslides destroyed the workers’ quarters; another 14 MW plant downstream at Devighat can only run after Trishuli restarts. 

More serious damage was wrought upstream of the Trishuli plant at the construction works of the 60 MW Upper Trishuli 3A project. A landslide killed four employees at the site and caused “severe” damage to tunnels and a suspension bridge. 

Nepal’s biggest independent hydropower project—the 45 MW Upper Bhotekoshi plant—was immediately shut down after being struck by boulders wrought loose from overlying cliffs. Narendra Prajapati, CEO of Bhotekoshi Power Company, told República that the penstock pipe that feeds water to Upper Bhotekoshi’s turbines was damaged and they assume that its generators had been flooded as a result. 

While Nepal’s 150 MW of idled capacity sounds small by the standards of developed industrial economies, the impact of any loss in power supply is massive for Nepal because the country is already vastly underpowered. Power outages are a daily reality, even in Kathmandu. 

NEA’s latest Load Shedding schedule is one of the standard links atop every page at MyRepú, telling readers how electricity supplies will shape their day much like a daily weather report. On Saturday 25 April NEA expected to shut off power in Kathmandu from 6-8 am, and then again for another four hours in the afternoon. The schedule warns, however, that load shedding could shift forward or back by one hour depending on conditions. 

In recent years Nepal has been accelerating hydropower developments. At least one of which has been set back by the earthquake: the 111-MW Rasuwagadhi hydropower dam under construction by Chinese hydropower giant Three Gorges Corporation. Two Chinese workers were killed in the earthquake, and the dam was “severly damaged” according to Three Gorges. Chinese military helicopters rescued 280 Chinese workers from the site within days of the quake, while the New Yorker reported that Three Gorges’ 350 Nepali workers were “left to walk” out of the remote region

Much more hydropower investment is slated for Nepal. Three Gorges has contracts to build two other projects in Nepal, including the comparatively massive $1.6-billion, 750-MW West Seti project approved by Kathmandu less than two weeks before the April earthquake. And Indian-financed megaprojects in the development pipeline —including a pair approved last year worth $2.4 billion—would add another 1,800 MW to Nepal’s power generating capacity. 

It is important to note that these Himalayan heavyweights are financing Nepalese projects primarily as a source of power for their own economies. Such projects’ benefit to Nepal is more financial than electrical. For example, all but 12 percent of the 900 MW to be generated by the Indian-financed Upper Karnali project is to be exported. 

The New Yorker raised another potential caveat to the hydropower-filled future Nepal has been developing: the risk that hydropower megaprojects could induce future earthquakes. Human-induced seismicity is a real liability associated with a growing number of energy projects, including oil and gas production, geothermal energy, and—in some cases—hydropower projects. 

However, for hydropower, it is the shifting weight of water stored in reservoirs that has been linked to earthquakes such as 7.9 Sichuan quake that devastated central China in 2008. Many of the Nepalese projects rely on a run-of-river design that exploits its rivers’ strong, steady currents rather than storing lots of water behind big dams.

A real and longer-term threat is the melting of Himalayan glaciers, which threatens to increase flooding and landslides and in the longterm could reduce Nepal’s raging rivers to trickles. Nepal lost over a quarter of its glacier mass between 1980 and 2010, according to a 2014 report from the Kathmandu-based International Centre for Integrated Mountain Development

How future melting will play out for river flows is, however, unclear. The same research center reported in 2013 that glacial melting in the Himalayas could peak by 2070, thus preserving river flows in key watersheds. 

Hawaii Votes to Go 100% Renewable

Hawaii’s legislature voted yesterday to stake the state’s future on renewable energy. According to House Bill 623, the archipelago’s power grids must deliver 100 percent renewable electricity by the end of 2045. If the compromise bill is signed by the governor as expected, Hawaii will become the first U.S. state to set a date for the total decarbonization of its power supply. 

Renewable energy has been booming since 2008 when the state set a goal of making renewables 40 percent of its power mix by 2030, and government and utility incentives ignited wind power and solar installations. By the end of 2013, renewable energy had jumped from 7.5 percent to 18 percent of the state’s capacity. HB623 seeks to extend and turbo-boost that trend, calling for 30 percent renewables in 2020 and 70 percent by 2030 en route to the final leap to 100 percent.

That last jump could be difficult, says Peter Crouch, a power grid simulation expert and dean of engineering at the University of Hawaii’s flagship Manoa campus. “Today I don’t know whether we can do it,” he says.

Read More

Electricity Use Could Soar as Global Middle Class Embraces Air Conditioning

Energy use in U.S. and European homes is predicted to flatten, for the most part. But it will soar in developing and middle-income countries. The main culprit, according to new research from the University of California, Berkley, is air conditioning.

In China, sales of air conditioners have nearly doubled in the last five years, with more than 60 million units sold in 2013 alone.

Using data from Mexico, researchers at UC Berkley’s Haas School of Business built a model that took into account the relation between climate, income, and air conditioning.

When accounting for increases in incomes and expected higher temperatures, they found the number of homes with air conditionings would rise from 13 percent today to more than 70 percent at the end of the century.

Read More

U.S. Hydropower Fleet has Upside Power and Storage Potential

Hydropower has a dowdy, low tech image that conjures visions of concrete and degraded ecosystems. It is mostly shut out of the incentives driving solar, wind and other newer forms of renewable energy. InsideClimate News just dubbed it the “Unloved Renewable.” How wrong this image is according to a first-of-its-kind comprehensive study of the U.S. hydropower industry released by the Department of Energy’s Oak Ridge National Laboratory (ORNL) in Tennessee. 

ORNL researchers found that U.S. hydropower grew by 1.5 gigawatts to 79.6 GW over the past decade, thus holding on to its seven percent share of U.S. power supply. In so doing it is offsetting roughly 200 million metric tons of carbon emissions per year, equivalent to taking more than 42 million cars off the road.

Read More

Micromotors to Boost Hydrogen Fuel Cells

Hydrogen fuel cells promise vehicles whose only emission is water. But their appearance, at least as a one-to-one replacement for internal combustion engines, has been stymied by the challenges of storing hydrogen gas. Now researchers say micromotors could help vehicles generate hydrogen gas on board in order to power hydrogen fuel cells.

Hydrogen fuel cells work by combining hydrogen with oxygen from the air to generate electricity and water vapor. Instead of storing hydrogen gas in bulky pressurized tanks, scientists have suggested storing the fuel in the form of liquids loaded with hydrogen-containing salts such as sodium borohydride, which release hydrogen gas when exposed to a metal catalyst.

Most catalysts that are used to release hydrogen from sodium borohydride have come in the form of either nanoparticles or thin films. But the speed and efficiency with which these systems release hydrogen is limited by deactivation of the catalysts by poor mixing of the fuel or accumulation of the catalytic reactions’ byproducts.

Now scientists at the University of California, San Diego, suggest they have solved these problems by using 20-micron-wide particles that act like self-propelled micromotors. These so-called "Janus particles" have two different faces, just like the Roman god Janus; one side is made of a very fine catalytically active platinum powder, while the other is coated with titanium. They detailed their findings online in the 23 April edition of the journal Angewandte Chemie.

Read More

First X-ray Views Inside Overheating Lithium-ion Batteries

For the first time, scientists have looked inside a lithium-ion battery as it failed due to overheating. The researchers suggest learning more about such "thermal runaways" can help improve the design and safety of these batteries.

When a lithium-ion battery overheats, it can burn through pockets, burst into flames, or even explode. Although such thermal runaways are rare, they do happen regularly enough to lead some engineers to explore the creation of lithium-ion batteries with their own fire alarms or search for signal processing tricks that can predict fires.

To learn more about how thermal runaway happens—and perhaps how to prevent it—scientists at University College London and their colleagues scanned overheating lithium-ion batteries at the European Synchrotron Radiation Facility in Grenoble, France. The image resolution from the X-rays generated at this particle accelerator is far greater than that of conventional X-ray machines. They detailed their findings online in the 28 April edition of the journal Nature Communications.

Read More

Newsletter Sign Up

Sign up for the EnergyWise newsletter and get biweekly news on the power & energy industry, green technology, and conservation delivered directly to your inbox.

Load More