The so-called green energy sector (i.e., alternative and renewable sources of energy) is one of the few areas that finds support from across the political spectrum. Liberals support green energy because it helps protect the environment and mitigates manmade climate change. Conservatives support green energy because they see it as path to energy security. Those in between support green energy for both reasons as well as economic reasons. If the global economy is going to continue to grow and millions of people are going to be brought out of poverty, then the supply of electrical power needs to grow as well. Most people in the developed world take for granted that they will have a reliable supply of electrical power; but as they continue to plug in more and more devices, they are beginning to realize that the information age increases electrical bills as well as connectivity. Consumer products are now the “fastest-growing source of power demand in the world” [“Plugged-In Age Feeds a Hunger for Electricity,” by Jad Mouawad and Kate Galbraith, New York Times, 19 September 2009]. Mouawad and Galbraith report:

“Electricity use from power-hungry gadgets is rising fast all over the world. The fancy new flat-panel televisions everyone has been buying in recent years have turned out to be bigger power hogs than some refrigerators. The proliferation of personal computers, iPods, cellphones, game consoles and all the rest amounts to the fastest-growing source of power demand in the world. Americans now have about 25 consumer electronic products in every household, compared with just three in 1980. Worldwide, consumer electronics now represent 15 percent of household power demand, and that is expected to triple over the next two decades, according to the International Energy Agency, making it more difficult to tackle the greenhouse gas emissions responsible for global warming. To satisfy the demand from gadgets will require building the equivalent of 560 coal-fired power plants, or 230 nuclear plants, according to the agency.”

Demand is quickly outstripping supply and there are only two ways to deal with that: increase supply or reduce demand. Most analysts believe that both strategies will be required to keep up. This series has dealt with the supply side of the energy business — specifically, the non-fossil fuel options for generating electricity. Alternative and renewable energy sources are not only important for the developed world, but for developing countries as well. Coal-fired and nuclear-powered electrical plants are expensive to build and require large, expensive electrical transmission grids to distribute power to customers. Many alternative and renewable power systems can be built closer to where the energy is used greatly reducing the challenges associated with transmission. In some cases, like solar panels and small wind turbines, systems can be connected to directly to homes and businesses eliminating the grid altogether. Cost and geography will determine what works best in various locations.

In this concluding post about alternative energy sources, I want to discuss activities and issues that didn’t fit neatly into any of the categories in the preceding posts. For example, most people think that green energy is always best for the environment; but that might not always be the case. In the post on solar power, I noted that some solar systems require enormous amounts of water and that can have environmental consequences since many of the solar systems are being built in deserts. Green energy systems can also have a negative impact on wildlife [“Renewable Energy’s Environmental Paradox,” by Juliet Eilperin and Stephen Mufson, Washington Post, 19 April 2009]. Eilperin and Mufson report:

“The SunZia transmission line that would link sun and wind power from central New Mexico with cities in Arizona is just the sort of energy project an environmentalist could love — or hate. And it is just the sort of line the Interior Department has been tasked with promoting — or guarding against. If built, the 460-mile line would carry about 3,000 megawatts of power, enough to avoid the need for a handful of coal-fired plants and to help utilities meet mandated targets for use of renewable fuel. … But the line would also cross grasslands, skirt two national wildlife refuges and traverse the Rio Grande, all habitat areas rich in wildlife. The graceful sandhill crane, for example, makes its winter home in the wetlands of New Mexico’s Bosque del Apache National Wildlife Refuge, right next to the path of the proposed power line. And much of the area falls under the protection of the Interior Department’s Bureau of Land Management (BLM). Renewable-energy development, which the Obama administration has made a priority, is posing conflicts between economic interests and environmental concerns, not entirely unlike the way offshore oil and gas development pits economics against environment. But because of concerns about climate, many environmentalists and government agencies could find themselves straddling both sides, especially in Western states where the federal government is a major landowner. … As the push for renewable-energy development intensifies across the United States, scientists and activists have begun to voice concern that policymakers have underestimated the environmental impact of projects that are otherwise ‘green.'”

They go on to point out that green energy projects often require more land than conventional power projects — with estimates ranging as high 300 times more land. For environmentalists, it’s not just the land required that is a worry but the structures that are built on the land. Some claim that whirling blades of wind turbines are a danger to birds while others worry that the structures will affect breeding habits of local creatures. Eilperin and Mufson explain:

“In some cases, scientists are just beginning to discover the unintended effect of projects such as wind turbines. Grassland birds such as the lesser prairie chicken and the greater sage grouse, both of which are candidates for listing under the Endangered Species Act, appear to avoid vertical structures such as wind turbines and transmission-line towers. This is proving to be a problem in states such as Kansas, an ideal site for wind power, because as more turbines are built, lesser prairie chickens will confine themselves to narrow ranges, fragmenting a population that must be connected to survive. ‘Nobody knows what’s in the bird’s head, but presumably there’s an inherited behavior that allows the birds to avoid avian predators who could perch overhead,’ said Michael Bean, wildlife director for the Environmental Defense Fund, an advocacy group.”

Such concerns are bound to create tensions between conservationists and developers. This is clearly a case, however, where both sides are willing to cooperate to find solutions since both sides believe that green energy is preferable to constructing plants that pollute. One of the issues that I raised early in this series is America’s inadequate grid. Everyone seems to agree that new transmissions lines are needed, but there is little agreement on who should pay for them [“Wiring America Up to Green Power,” by John Carey, BusinessWeek, 26 October 2009]. Carey asks: “Should the U.S. subsidize vast high-voltage lines to transport wind and solar electricity to the big cities?” The answer, he explains, is not an easy one.

“The wind howling over the Great Plains and the unrelenting Southwestern sun pack enough energy to power the entire U.S. with clean, renewable electricity. Trouble is, there’s no way to get that power from the Dakotas or Nevada to America’s big cities, many on the East Coast. As much as 300,000 megawatts worth of green power, enough to replace more than 300 coal-fired power plants, is being held on the shelf, as it were, because of the lack of transmission lines. This has sparked a movement to create “green power superhighways,” as supporters call them. ‘A high-voltage transmission system will cost a tiny fraction of the money we spent on the highways and do a ton more good,’ argues Joseph L. Welch, CEO of ITC Holdings, a Novi (Mich.) transmission line developer. The idea has powerful support in Washington. Senate Majority Leader Harry Reid (D-Nev.) sees an expanded power line system as key not only to tackling global warming but also to creating jobs in Nevada and the rest of the West. … But is subsidized transmission really a good idea? Naysayers such as Ralph Izzo, CEO of Newark (N.J.) utility PSEG, argue that such a system would undermine the development of renewable power. His company is putting solar panels on rooftops and planning to build hundreds of wind turbines in the waters off the New Jersey coast. Those projects would no longer be economically feasible if cheaper wind power from the Dakotas came flooding into the Northeast on the new power lines. Creating a transmission system that’s largely free to users, on the model of Interstate highways, ‘unfairly biases [people] against the construction of renewables in parts of the country closest to the load,’ Izzo complains.”

Carey goes on to note that transmission lines would cut through environmentally sensitive areas (as noted above) and even through coal-rich country where they would likely stir up more resentment than hope. In addition, since transmission lines are basically a common good, Carey notes that “any available cheap coal electricity would hop aboard for the trip to the Northeast. That would hurt local utilities—and increase carbon emissions.” He continues:

“Both sides in these debates acknowledge the status quo is not defensible. ‘Everyone pretty much agrees that the current transmission system is not built to do this job,’ says Jon Wellinghoff, chairman of the Federal Energy Regulatory Commission. It’s antiquated and inefficient, with 9% of all power generated getting lost in transmission (compared with 3.5% in other countries). Plus, mandates for renewable energy in most states and the coming carbon-emissions curbs mean the system must get greener and cleaner. As a result, billions of dollars of transmission upgrades must be made. The central question is who picks up the tab for new wires. At one extreme are those who argue that since everyone ultimately will benefit, all electricity users should pay a little extra in their bills, just as everyone pays gas taxes to support highways. … PSEG’s Izzo … wants wind developers in the Great Plains or solar plants in Arizona to pay for connecting to the grid. That would make it more expensive to bring that electricity to the East Coast, reducing the chances it will undercut his own renewable projects. … It’s a difficult debate to resolve. … What makes it even more challenging is that the U.S. can’t meet the goals of a low-carbon electricity system unless it does everything simultaneously: energy efficiency, small-scale ‘distributed power’ based on renewables, and big wind farms and solar plants. … Sierra Club transmission expert Carl Zichella says the problem could be solved with careful planning. The answer would include making better use of the existing grid and promoting small-scale renewable generation, while also building whatever new power lines the nation needs the most.”

Energy efficiency is becoming a bigger part of the energy security debate, which is why there is so much talk about smart grids. To learn more about the topic of smart grids, read my posts entitled GE, Google, and Grids, Building Up rather than Bailing Out, The Debate about Smart Grids Continues, and Smart Grids Take a Step Forward in the U.S. There are other efforts to improve energy efficiency underway as well and companies involved in those efforts are attracting investment capital [“Investment Dollars Flow to Green Energy Start-Ups,” by Russell Gold, Wall Street Journal, 3 February 2010]. Gold reports:

“Start-ups developing products aimed at wringing every last drop of efficiency from green technologies have become the standouts in the increasingly crowded field of renewable energy. These companies are gaining favor, in part because they don’t require a lot of cash to bootstrap, a big draw at a time when there’s not much financing available. Other winners in the investor sweepstakes are companies seeking to replace existing power grids to allow utilities to interact with home appliances, turning them on when power demand is low and electricity is cheaper. … In the third quarter of 2009, clean energy received 19% of venture capital investment in the U.S., second only to biotechnology, according to a report by PricewaterhouseCoopers and the National Venture Capital Association. … Using technology to reduce energy consumption is by far the hottest sector right now. A big reason is that the companies behind this approach promise a shorter path to profitability.”

The press for more energy efficiency is not only in developed countries like the United States, but in developing countries like China as well [“The Second Wave,” by Spencer Swartz, Wall Street Journal, 8 September 2009]. Swartz reports that “fast-growing emerging markets are making energy efficiency a high priority.” There are a number of new gadgets being marketed to help increase energy efficiency. For example, the Wattbox is aimed at teaching consumers better energy-use habits [“Wattbox: Habit-learning device to lower energy bills,” by Jeff Salton, Gizmag, 7 February 2010]. Salton reports:

“The adage ‘less is more’ rings true when discussing energy usage – as energy costs rise, using less saves you more money each year. And studies have shown that householders who know how much energy they use on a daily basis tend to use significantly less. A new device called the Wattbox – a smart control unit that learns householders’ energy habits relating to their central heating and hot water usage patterns and provides immediate feedback on consumption – could deliver home energy savings of up to 20 percent without compromising comfort, say UK researchers. A great feature of the Wattbox is that it is able to be retrofitted, meaning it’s suitable for all houses, not just new ones.”

Among the growing list of devices that consume electricity are power adapters for things like iPods, laptops, printers, etc. These devices slowly suck electrical power and have been called “vampires.” A new way of manufacturing power adapters promises to save billions of dollars in electrical charges [“Vampires on a diet,” The Economist, 3 December 2009]. According to the article, “about 5 billion such devices are in use worldwide” and more are on the way. It continues:

“Until recently the conversion was made using copper wire. Typically, half the power they drew from the wall, and sometimes as much as 80%, would be lost in conversion. As a result, electricity bills and carbon emissions were both higher than necessary. Making the conversion with integrated circuits is much more efficient, with as little as 20% of the power being lost. … Seven years ago the Natural Resources Defense Council and Ecos Consulting, an energy consultancy, got manufacturers, power utilities and the state and federal governments together to talk about shifting to integrated circuits. It took two years to get regulations in place in America. Once adopted in the world’s biggest market, integrated-circuit adaptors spread swiftly everywhere, because manufacturers cannot afford to make things that cannot be sold in America. For consumers the switch has meant lower power bills and smaller, lighter power adaptors. For the world as a whole it has meant a drop in global power consumption worth around $2 billion a year—saving 13m tons of CO₂ annually worldwide, the equivalent of closing down eight coal-fired power stations.”

One of the most efficient ways to reduce energy demand is to supply the energy yourself. With the world becoming more mobile, mobile devices, like cell phones, are becoming more ubiquitous. Finding ways to recharge them is becoming an issue. In a post entitled Portable Power, I discussed some innovative ways that researchers are trying to use human kinetic motion to generate electricity. For anyone who is a frequent flyer, you know how difficult it is to find a place at the airport to recharge your cellphone or laptop. An American designer has drawn up plans for a rocking chair that could allow you to relax and recharge (literally) at the same time [“Empower concept chair rocks!,” by Tannith Cattermole, Gizmag, 8 March 2010]. Cattermole reports:

“The Empower chair won second prize out of 18 shortlisted designs showcased at the Greener Gadgets 2010 Conference. The design, by Ryan Klinger of USA, comprises a flat-pack chair of tubes and a sling seat that folds out to a bench-style glider seat. The rocking mechanism is linked to a gearbox, DC generator, voltage controller and lithium battery. A red LED light shows that kinetic energy is stored, a blue LED light shows that power is being generated. The energy is converted by means of a DC/AC inverter and accessed by a USB or standard power outlet so it can be hooked up to a laptop, mobile, MP3 player or other gadget.”

Since human power is an unreliable source of energy for most activities, researchers continue to look for new ways of generating electricity. In closing, I’d like to mention four: carbon nanotubes, osmosis, geo-thermal, and wave power. For various reasons (as explained below), none of these technologies is likely to make a major dent in the near-term global energy picture. Let’s begin with carbon nanotubes [“Carbon nanotubes offer new way to produce electricity,” by Darren Quick, Gizmag, 8 March 2010]. Quick reports:

“Scientists have discovered that a moving pulse of heat traveling along the miniscule wires known as carbon nanotubes can cause powerful waves of energy. These ‘thermopower waves’ can drive electrons along like a collection of flotsam propelled along the surface of ocean waves, creating an electrical current. The previously unknown phenomenon opens up a new area of energy research and could lead to a new way of producing electricity. The team of scientists at MIT coated the electrically and thermally conduction carbon nanotubes with a layer of reactive fuel that can produce heat by decomposing. This fuel was then ignited at one end of the nanotube using either a laser beam or a high-voltage spark, and the result was a fast-moving thermal wave traveling along the length of the carbon nanotube like a flame speeding along the length of a lit fuse. Heat from the fuel goes into the nanotube, where it travels thousands of times faster than in the fuel itself. As the heat feeds back to the fuel coating, a thermal wave is created that is guided along the nanotube. With a temperature of 3,000 kelvins, this ring of heat speeds along the tube 10,000 times faster than the normal spread of this chemical reaction. It is the heating produced by that combustion that also pushes electrons along the tube, creating a substantial electrical current.”

Although that sounds interesting, it doesn’t sound either economical or practical. So what good is it? Quick continues:

“In the group’s initial experiments, [Michael Strano, MIT’s Charles and Hilda Roddey Associate Professor of Chemical Engineering,] says, when they wired up the carbon nanotubes with their fuel coating in order to study the reaction, ‘lo and behold, we were really surprised by the size of the resulting voltage peak’ that propagated along the wire. After further development, the system now puts out energy, in proportion to its weight, about 100 times greater than an equivalent weight of lithium-ion battery. The amount of power released, he says, is much greater than that predicted by thermoelectric calculations. … Because this is such a new discovery Strano says it is hard to predict exactly what the practical applications will be. But he suggests that one possible application would be in enabling new kinds of ultra-small electronic devices — for example, devices the size of grains of rice, perhaps with sensors or treatment devices that could be injected into the body. Or it could lead to ‘environmental sensors that could be scattered like dust in the air,’ he says. In theory, he says, such devices could maintain their power indefinitely until used, unlike batteries whose charges leak away gradually as they sit unused. And while the individual nanowires are tiny, Strano suggests that they could be made in large arrays to supply significant amounts of power for larger devices.”

The bottom line is that carbon nanotubes are not going to save the planet. What about osmosis? [“No pinch of salt,” The Economist, 3 December 2009]. The article reports on the world’s first osmotic power station recently opened in Norway.

“On November 24th [2009], when Princess Mette-Marit of Norway pressed the red button, pumps started to hum, pressing freshwater from a river and saltwater from the nearby Skagerrak through an array of white steel cylinders. Then a turbine began to run inside a small, redbrick hall at Tofte, a few kilometers south-west of Oslo, and electric current emerged. The power in question was generated by osmosis. This is the tendency for water to pass through a membrane separating a weak solution from a strong one. This causes a build-up of pressure on one side of the membrane. The Tofte experimental power station exploits this pressure. According to Statkraft, the company that owns the station, the pressure generated by water passing across the membrane from the fresh stream to the salty one is equivalent to a head of 120 meters of water—a sizeable hydroelectric plant. The membrane that can withstand such force is made of polyester, polysulfone and polyamide and is held within the white steel cylinders. Some of the resulting pressure is used to keep the pumps running. The rest turns a turbine.”

The article reports that “devising a suitable membrane—tough enough to withstand the pressure while remaining permeable to water but not to salt” was a difficult challenge that took nearly 10 years to accomplish. As great as that accomplishment is, however, it’s still not good enough. According to the article, the current membranes “put out one watt per square meter. For the technology to be commercially viable, that would have to be increased to five. According to Anja Car, the project’s manager at GKSS, that will be possible in the laboratory but not, yet, in applications the size of a power station.” Researchers are hoping that in another five years a commercially-viable power station can be built. The article continues:

“Since 2001 a Dutch company called KEMA has been working on an osmotic power plant that uses a different approach, reverse electrodialysis. In this case it is not water that passes through the membrane, but the sodium and chloride ions of which salt is composed. This actually requires two different sorts of membrane, one for each ion, which make the process more complicated than Statkraft’s. Nevertheless Kees van den Ende, the reverse-electrodialysis project manager at KEMA, thinks his process has some advantages over the Norwegian way (which is known, technically, as pressure-retarded osmosis). For one thing, it operates at lower pressure. For another, the actual passage of the ions (which are electrically charged atoms) creates the current, so no turbine is required. The disadvantage is that reverse electrodialysis produces direct current, whereas the world runs mostly on alternating current. Transforming one into the other wastes energy.”

KEMA has yet to build a working plant and the article sadly notes that, “at the moment the world’s first osmotic plant produces just enough power to make a cup of tea.” I’m not holding my breath that osmotic power plants are going to save the planet either. Before turning to geothermal and wave power alternatives, let’s return to the subject of biomass to biofuel production. Mark Scott calls biomass, geothermal, and wave power alternatives to alternative energy [“Now, an Alternative to Alternative Energy,” BusinessWeek, 18 February 2010]. The reason that Scott believes these three sectors offer an alternative to alternative energy is because “they don’t depend on favorable weather, a problem for wind and solar on calm or cloudy days.” Biomass was addressed earlier in this series and much of that discussion focused on research teams trying to find new enzymes that can efficiently break down organic material into sugars. A team from the University of Cincinnati are recruiting a tropical frog to help [“Tropical frog inspires new way to convert solar energy to biofuel,” by Tannith Cattermole, Gizmag, 18 March 2010]. Cattermole reports:

“Natural photosynthesis isn’t as efficient as we would like it to be, and incorporating solar energy of into useful products is the subject for much collective research. Engineering researchers from University of Cincinnati have found a way to artificially create a photosynthetic material from foam which uses plant, bacterial, frog and fungal enzymes to produce sugars from sunlight and carbon dioxide. … The advantage to this method is that all of the captured solar energy is converted to sugars, unlike natural organisms who must use a large proportion of the sun’s energy to maintain life functions. Additionally, the foam does not need soil to photosynthesize, unlike plants, and therefore does not require valuable space that could be used for food production. Furthermore, in natural plant systems, photosynthesis shuts down in the presence of highly-enriched carbon dioxide environments, but the foam is not limited by this due to its bacterial-based photo-capture strategy. The design was inspired by the foam nests of a semi-tropical frog called the Tungara frog, which creates long-lived foams for its developing tadpoles. Foam allows effective concentration of reactants, but also allows for good light and air penetration. While other methods that use sunlight to split water to oxygen and hydrogen are in development, this approach could prove more efficient and economical in harnessing the physiology of living systems, working with nature and not against it. ‘Specifically in this work it presents a new pathway of harvesting solar energy to produce either oil or food with efficiencies that exceed other biosolar production methodologies. More broadly it establishes a mechanism for incorporating the functionality found in living systems into systems that we engineer and build,’ says Dean Montemagno, Dean of College of Engineering and Applied Science whose Department of Biomedical Engineering lab provided the basis for the research. … The next stage for the team will be to look into other short carbon molecules they can make by altering the enzyme cocktail, and developing a strategy to extract both the lipid shell of the algae (used for biodiesel) and the cytoplasmic contents (the guts), and reusing these proteins in the foam. It’s hoped this will make the technology feasible for large-scale applications like carbon capture at coal-burning plants.”

One renewable energy source not discussed in this series was geothermal energy. Geothermal energy is highly dependent on geography and is raising some environmental concerns. To learn more about those issues, read my post entitled Concern Growing Over Energy, Water, and Hydraulic Fracturing. As I pointed out in that post, a company called GTherm has developed a system that does require hydraulic fracturing and can built with a footprint smaller than traditional power plants. Another renewable energy source not previously discussed in this series is wave power. Generating electricity using tidal currents is also highly dependent on geography. Nevertheless, Scott reports, “Market researcher Frost & Sullivan figures output from systems that harness ocean waves will go from almost nothing to more than 3,000 megawatts, equivalent to four coal power plants, by 2020.” If you don’t have an ocean nearby, a company called Bourne Energy has created a backpack sized hydraulic power plant for use in streams and rivers [“Backpack Power Plant offers hydroelectricity on the move,” by Tannith Cattermole, Gizmag, 16 March 2010]. To learn more about hydraulically-generated electricity, read my post entitled Generating Hydroelectricity without Dams.

A final area that was only tangentially mentioned during this series is hydrogen power. Most analysts believe that a hydrogen economy is a long way off (if ever) because it takes a lot of energy to break hydrogen atoms free from elements in which they are trapped. Like Honda’s solar-powered hydrogen fuel cell station mentioned in the post about solar power, a team at Emory University believes it has made a breakthrough that taps the power of the sun to produce hydrogen [“Breakthrough in quest for solar hydrogen production,” by Jeff Salton, Gizmag, 14 March 2010]. Salton reports:

“Scientists at Emory University, Atlanta, Georgia, have built on feats of Mother Nature to develop the most potent homogeneous catalyst known for water oxidation, which they hope will lead to producing clean hydrogen fuel using only water and sunlight. Could cars of the future be powered by just water and a solar collector on the roof? The water oxidation catalyst (WOC) research is a component of the Emory Bio-inspired Renewable Energy Center (EBREC), which aims to copy natural processes like photosynthesis to generate clean fuel. The next step involves incorporating the WOC into a solar-driven, water-splitting system. The long-term goal is to use sunlight to split water into oxygen and hydrogen. While hydrogen becomes the fuel, its combustion produces water – which would then flow back into a clean, green, renewable cycle. ‘The fastest, carbon-free molecular WOC to date has really upped the standard from the other known homogeneous WOCs,’ said Emory inorganic chemist Craig Hill, whose lab led the effort. ‘It’s like a home run compared to a base hit.’ The new WOC is based on the cheap and abundant element cobalt, adding to its potential to help solar energy go mainstream.

Salton reports that the new process is not without challenges. He explains:

“The lab developed a stable, carbon-free WOC prototype two years ago, but this was based was ruthenium, a relatively rare and expensive element. Three main technical challenges face the team. They are developing a light collector, a catalyst to oxidize water to oxygen and a catalyst to reduce water to hydrogen. Hill says all three components need improvement, but a viable WOC may be the most difficult scientific challenge.”

A research team from the University of Wisconsin-Madison believes it can produce hydrogen using sound as fuel [“Generating hydrogen fuel from waste energy,” by Darren Quick, Gizmag, 15 March 2010]. Quick writes:

“Scientists have found a way to use ambient noise to turn water into usable hydrogen fuel. The process harvests small amounts of otherwise-wasted energy such as noise or stray vibrations from the environment to break the chemical bonds in water and produce oxygen and hydrogen gas. Materials scientists at the University of Wisconsin-Madison grew nanocrystals of two common crystals, zinc oxide and barium titanate, and placed them in water. When pulsed with ultrasonic vibrations, the nanofibers flexed and catalyzed a chemical reaction to split the water molecules into hydrogen and oxygen. When the fibers bend, asymmetries in their crystal structures generate positive and negative charges and create an electrical potential. This phenomenon, called the piezoelectric effect, has been well known in certain crystals for more than a century and is the driving force behind quartz clocks and other applications. The researchers applied the same idea to the nanocrystal fibers. ‘The bulk materials are brittle, but at the nanoscale they are flexible,’ says UW-Madison geologist and crystal specialist Huifang Xu. He likened them to the difference between fiberglass and a pane of glass. Smaller fibers bend more easily than larger crystals and therefore also produce electric charges easily. So far, the researchers have achieved an 18 percent efficiency with the nanocrystals, higher than most experimental energy sources. In addition, Xu says, ‘because we can tune the fiber and plate sizes, we can use even small amounts of [mechanical] noise – like a vibration or water flowing – to bend the fibers and plates. With this kind of technology, we can scavenge energy waste and convert it into useful chemical energy.’ Rather than harvest this electrical energy directly, the scientists took a novel approach and used the energy to break the chemical bonds in water and produce oxygen and hydrogen gas. The chemical energy of hydrogen fuel is more stable than the electric charge, Xu explains. It is relatively easy to store and will not lose potency over time. With the right technology, Xu envisions this method being useful for generating small amounts of power from a multitude of small sources – for example, walking could charge a cell phone or music player, and breezes could power streetlights. ‘We have limited areas to collect large energy differences, like a waterfall or a big dam,” he says. “But we have lots of places with small energies. If we can harvest that energy, it would be tremendous.'”

I won’t be holding my breath for a near-term hydrogen breakthrough that speeds the world towards a hydrogen-based economy any time soon. As this lengthy series has probably convinced you, there are no technological marvels just over the horizon that will solve the world’s energy needs safely, reliably, and affordably. Fossil-fueled power plants (especially coal-fired plants) are going to be around for a long time. As more and better ways of producing electricity are found, however, utility companies and communities will find a wider array options available to them to satisfy their energy needs.