Nuclear plants produce power by grabbing the energy released from the nucleus of an atom via nuclear fission, a process that splits atoms into at least two nuclei and creates byproducs of heat and gamma radiation (radiation made out of high-energy photons). Fission is triggered by the absorption of a neutron by a fissile atomic nucleus like uranium or plutonium. At the most basic level, the heat generated from this nuclear reactor is used to boil water, which turns a turbine and creates energy.

What makes nuclear power appealing is its lack of emissions and relatively abundant fuel source. There is little shortage of fuel resources for nuclear energy—according to some estimates, for example, there is up to five billion years’ worth of uranium-238, a fuel used in fast breeder reactors. And there is up to four times as much thorium—another fuel used in certain fast breeder reactors—as there is uranium worldwide.

But fuel availability is hardly the biggest problem for nuclear power plants. There's also the issue of safety. Barring Homer Simpson-like accidents, there are a number of things that can go wrong, including meltdowns, fires, and potential terrorist attacks. The potential damage that radiation can cause has been observed the world over through pictures and video of accident sites like Chernobyl and Three Mile Island.

And then there's the issue of where to store spent fuel. After radioactive materials have been used in a power plant for a while, they can't sustain a nuclear reaction any longer and have to be replaced. However, they're still dangerous and radioactive; so storing them safely and securely is a challenge. The U.S. government proposed using Yucca Mountain, a Nevada mountain near nuclear test sites, as a nuclear waste repository. The plan was scrapped in 2010, and as a result, the country has no long-term plan for nuclear waste storage. Instead, waste is stored on-site at nuclear plants; currently, 70,000 tons of radioactive waste are stored at more than 100 nuclear sites across the United States—a potential safety issue for surrounding communities.

Nuclear power plants aren't cheap, either. Reactors cost billions of dollars to build, which is why there are only 104 operating in the entire country and why they're all old—all of these plants began construction in 1974 or earlier. Ground was broken on a South Carolina reactor in 2010, and Obama promised loan guarantees for two new reactors at Georgia Power's Vogtle LLP plant the same year, but construction has not yet started.

None of this sounds encouraging for the future of nuclear fuel. But there is hope coming from unlikely corners. A startup called TerraPower recently teamed up with Toshiba to develop hot tub-sized reactors that can use depleted uranium as fuel and go up to a century without needing to be refueled. The pair still are searching for building materials that can withstand 100 years worth of radiation. And the Defense Advanced Research Projects Agency is currently soliciting design ideas for reactors that use human waste in addition to radioactive material, which would have the benefit of easily accessible and limitless supplies of fuel.

These advances are far-off, however, and few research initiatives look promising in the near-term. Until we can solve problems of cost, waste storage, and safety, nuclear will remain an enticing but unrealistic option.

Illustration by Sara Saedi

Imagine: You're driving down the highway while drinking coffee and reading the newspaper—but you're not putting any of your fellow drivers in danger. Instead, you're letting the car itself take the wheel as it guides you safely down the road, all the while saving fuel. It's not a pipe dream—it's the vision of vehicle manufacturers working on the next generation of autonomous cars.

Autonomous vehicles, or vehicles that drive themselves, have actually been around for decades. The EUREKA Prometheus Project, launched in 1987 by Daimler-Benz AG, exhausted nearly $1 billion building robotic cars. In 1994, the project successfully sent two robot vehicles more than 600 miles on a Paris highway in standard traffic conditions (with drivers in each vehicle in case of emergency, natch).

Eureka ran out of funding, but autonomous car research has been going on continuously since then, albeit under the radar. And the autonomous vehicle craze never really caught on until recently. In the past months, we've seen companies like GM, Volvo, and even Google getting serious about autonomous vehicle research projects.

Perhaps the most well-known autonomous vehicle project of late is GM's EN-V, a pod-like autonomous car that features vehicle-to-vehicle communications, distance-sensing, and GPS. According to GM, the all-electric, lithium-ion battery powered vehicle can travel 25 miles on a charge. The vehicle could be on roads as soon as 2015.

Google's foray into autonomous vehicles was revealed last October when the company announced that its fleet of self-driving Toyota Priuses has been in testing for years—and they have already logged 140,000 miles driving across California with help from cameras, lasers, and radar. The reasoning behind the project, according to Google, is that "self-driving cars will transform car sharing, significantly reducing car usage, as well as help create the new 'highway trains of tomorrow.'"

We're not sure how self-driving vehicles could reduce car usage, but they certainly have the potential to revolutionize car sharing. Consider that a new service in San Francisco, dubbed Spride Share, allows members to rent out their vehicles, a la Zipcar, to strangers. If members had self-driving vehicle, they could be assured that renters wouldn't get into fender-benders. In other words, members might be more comfortable renting out their vehicles, and similar car-sharing services could grow dramatically as a result.

And as for those "highway trains of tomorrow?" Look no further than Volvo, which this week announced that it successfully completed testing of vehicle platooning technology at the Volvo Proving Ground near Gothenberg, Sweden. Vehicle platoons consist of a lead vehicle with a driver and several autonomous "slave" vehicles trailing close behind. The slave vehicles keep track of speed, distance, and direction, and can leave the road train at any time.

The technology is perfect for relieving drivers of stress while stuck in traffic jams—and Volvo claims that it cuts down on fuel consumption by up to 20 percent. This is because vehicle platooning cuts down on the drag of each vehicle. At the same time, platooning increases the amount of cars that can safely fit on a highway (cars maintain a close but safe distance), decreasing traffic and cutting down on fuel wasted by constantly switching between the brake and gas pedal.

Will autonomous vehicle technology allow us to move more quickly off oil and onto cleaner sources of energy? No, but it can provide us with safer and more fuel-efficient vehicles in the interim. And if companies like GM get their way, the electric vehicles of the future may even integrate autonomous driving capabilities, to boot.

A number of materials are piezoelectric, including topaz, quartz, cane sugar, and tourmaline. That means a charge begins accumulating inside these materials when pressure is applied. Piezoelectrics are already commonly used in a number of applications. Quartz clocks, for example, rely on piezoelectricity for power, as do many sensors, lighters, and actuators. But these are the old uses for piezoelectricity. Scientists today have much more interesting piezoelectric plans in mind.

One of the most popular uses for piezoelectricity in the past few years relies on roads and sidewalks. It all started in 2008 with Club Watt, a dance spot in the Netherlands dubbed the world's first sustainable dance club. The club installed piezoelectric materials in its dance floor to turn patrons' moves into electricity that is used to change the color of the floor's surface.

After Club Watt, the piezoelectric floors kept coming. A Tokyo railway station installed a piezoelectric floor that uses kinetic energy to generate 1,400 kW of energy per day—enough to power ticket gates and displays. Toulouse, France, recently became the first city to put pressure-sensitive piezoelectric modules on the sidewalk, generating enough energy to power streetlamps. And the United Kingdom plans to install power-generating tiles on London streets to light up bus stops and pedestrian crossings.

Piezoelectrics are also increasingly becoming common on roads. In 2009, a British supermarket installed kinetic road plates that collect energy from customers driving over road bumps in the store parking lot. The road plates are pushed down by vehicle weight, which creates a rocking motion that turns generators. The system is used to power the supermarket's checkout lines.

In Israel, a company called Innowattech is installing strips of asphalt embedded with piezoelectric materials. According to the company, the generators could produce 1 MWh of electricity from a four lane highway, or enough to power 2,500 homes.

The technology just keeps getting better, too. Last year, Princeton University researchers combined silicone and nanoribbons of lead zirconate titanate to create PZT, an ultra-efficient piezoelectric material that can convert up to 80 percent of mechanical energy into electricity. PZT is 100 times more efficient than quartz. It's so efficient, in fact, that the material could be used to harness energy from the minute vibrations found in items like shoes and clothing. That means a piezoelectric-equipped shirt could potentially charge up your cell phone after a day of  activity.

Piezoelectric sidewalks, roads, and clothing items haven't taken off in a big way quite yet, but they probably will soon. As we become more reliant on having fully-charged gadgets with us at all times, a shirt or pair of shoes that can prevent a device from dying will be incredibly valuable.

Fuel cells come in a number of different varieties, but all feature three main components: an anode, an electrolyte, and a cathode. Chemical reactions at the interface between the three components consume a fuel that a user inputs, creating steam or carbon dioxide (depending on the fuel being used), and generating an electric current. It's like having a small power plant at your fingertips. Unlike batteries, fuel cells don't store energy; they're always running. While batteries are recharged, fuel cells are simply refuelled.

Perhaps the most talked about fuel cell device in recent years is Bloom Energy's Bloom Box Energy Server, a $700,000 machine that is made out of solid oxide fuel cells (in this case, a stack of ceramic disks coated with green and black inks separated by metal alloy plates). When a fuel is added, the disks heat up to extreme temperatures and produce electricity. The box can run on a number of fuels, including natural gas, biomass gas, landfill gas, and ethanol.

EBay recently installed five natural gas-powered Bloom Boxes, which now generate 15 percent of all power at the company's San Jose, California, campus. They're efficient, too—the company claims that its Bloom system generates five times more energy over the course of a year than its 3,246 solar panels since they can still generate power during adverse weather conditions. And unlike the company's dispersed solar panels, a single Bloom Box fits in the size of a standard parking space.

In the next decade, Bloom plans on bringing its technology to the home market, so environmentally-minded consumers can quickly relieve themselves of monthly power bills from their local utility.

But fuel cells can do a lot more than power our homes and workplaces. Just this week, Apple scored a patent for an internal fuel cell component. Apple was first rumored to be using fuel cells to juice up its PowerBooks in 2003, but now it looks like the rumors may finally be coming to fruition. Could the next iPhone be powered by fuel cells?

There are already a number of companies working on personal pocket-sized fuel cell chargers. Hydrogen Fuel Cell Technologies is, for example, showcasing its MiniPak fuel cell at this week's Consumer Electronics Show. The device, which currently retails for $99, comes with two solid state hydrogen cartridges that can reportedly provide as much power as 1,000 AA alkaline batteries—the advantage over traditional batteries being the ability to carry around large amounts of electricity in your pocket. In the near future, Hydrogen Fuel Cell Technologies plans on selling the HydroFILL, a small recharge for the catridges that requires just water and power from either a wall socket or solar panel.

Of course, just because enterprising companies are rapidly churning out fuel cells doesn't mean that the devices will catch on. The Bloom Box is still an expensive purchase—power from the box reportedly costs $12.50 per watt when upfront costs and fuel are taken into account (federal and state subsidies in California bring that cost down to $6.25 per watt). Microturbines, in comparison, cost less than $1 per watt to run, though they produce far less energy per square inch.

And there are still issues to resolve before fuel cells become common in small electronic devices. Currently, they produce too much heat to become integrated into, say, a laptop computer, and they're generally too large to fit into smaller mobile gadgets. But smaller, cheaper fuel cells are coming—they may just take a little while to arrive.

First, a bit of history. Incandescent bulbs (Thomas Edison's bulb) generate light by heating a metal filament wire to a high temperature until the bulb glows. The problem is that there is a low ratio of visible light produced versus heat loss when compared to efficient alternatives like CFLs and LEDs. And in a world that is increasingly concerned with saving energy, that inefficiency won't do. Brazil, Venezuela, the European Union, and Australia are all in the midst of phasing out incandescent bulbs; Argentina, Russia, Canada, Malaysia, and the United States all plan to phase out the bulbs in the next few years.

The CFL bulb, as you likely know, is a fluorescent lamp that gives off the same amount of visible light as an incandescent but uses less power and has a longer life. The bulbs are cheap, to boot, with some costing under $2. But there are a few disadvantages to CFLs—they contain mercury, which makes their disposal difficult, and they have a different (some would go so far as to say unpleasant) light spectrum than their predecessors.

The next most popular option is LED lighting, a semiconductor light source that recombines electrons with electron holes when the light is turned on, triggering the release of photons in the form of energy. The light's color corresponds to the energy of the photon. Like CFLs, LED bulbs have a longer lifetime and decreased energy consumption compared to incandescents. They also have a much wider range of colors than CFLs, and don't contain mercury.

Sounds perfect. But the technology is still in its infancy. Just last May, Philips released what it calls the first LED replacement for the common 60-watt household bulb—a 12-watt LED dubbed the Endura. Philips's bulb is a direct swap-in for a 60-watt incandescent, and it has a lifespan of 25,000 hours. Pricing has not yet been announced, but a 16-watt Endura bulb retails for $65.95 on Amazon.

The first dimmable swap-in LED was also recently announced by Lemnis Lighting, which last October released the 6W Pharox60 bulb, a light source that is 90 percent more energy efficient and 25 times longer-lasting than a 60-watt incandescent. Once again, though, the price isn't quite there yet; the bulb retails for $60 $30. That's cheap when the bulb's lifespan is taken into account, but that kind of reasoning isn't usually employed in the aisles of a drug store.

There are other options. A company called Vu1 recently debuted its ESL light bulb, a dimmable, low-energy bulb that retails for $20 and that features less harsh lighting than CFLs, and lasts for 10,000 hours. (An ESL bulb uses accelerated electrons to light up a phosphor coating on the inside of a bulb). The first units, which are designed to replace 65-watt incandescents, will be released in 2011 and 2012. But ESL technology simply doesn't have the muscle of major lighting companies behind it.

In the long term, LEDs will probably win out—as soon as companies like Philips can lower the price to a point where purchasing them doesn't have to be a major household decision.

Perhaps you've noticed the glut of hybrid and electric vehicles set to enter the market in the next few months—the Nissan Leaf, Chevrolet Volt, and Ford Focus Electric are just some the EVs coming down the pipeline. Electric vehicles get the majority of the attention from car companies looking to build next-generation vehicles. It makes sense; major automakers have been working on hybrids, all-electric vehicles, and charging stations for years. But there's a dark horse in the race to switch to alternative fuels—a fuel that allows drivers to fill up in a matter of minutes for the same price as gasoline: hydrogen power. Does it stand a chance?

Hydrogen fuel cell-powered vehicles use a fuel cell (an electrochemical cell that turns a fuel—hydrogen, in this case—into an electric current) to power an electric drive train. Fuel cells convert hydrogen and oxygen into water, producing electricity in the process. Batteries also turn energy produced by a chemical reaction into electric power—but fuel cells don't lose their charge as long as hydrogen is available.

Hybrid fuel cell vehicles come with both a fuel cell and a battery or a fuel cell and an ultracapacitor.

Hydrogen can be produced in a number of ways, including water electrolysis, coal gasification, and steam reforming from hydrocarbon (a process that forces fossil fuels and steam to react at high temperatures). The gas can also be produced using solar and wind power.

A number of car companies have worked on fuel cell vehicles over the years, starting with GM's Electrovan Fuel Cell vehicle, which debuted in 1966, and continuing to the present day with cars like the Mercedes Benz F-Cell Roadster and the Kia Borrego FCEV-Fuel Cell. Toyota has concrete plans to produce a $50,000 hydrogen sedan by 2015, and GM hopes to get a hydrogen-powered vehicle on the road by the same year. While Ford originally planned to cancel its fuel cell program in 2008, the company's test fleet proved so robust that the company extended the program through 2011 (26 out of 30 original cars produced in 2005 are still running). The company acknowledges, however, that large-scale commercialization is at least a decade away.

But even if every major automaker releases a fuel cell model in 2015, the industry can't get going without a fueling infrastructure. Electric vehicles have major players like GE working on building out EV charge spots in major cities and highways around the world. And the U.S. Department of Energy's EV Project will see 15,000 EV charging stations built in 16 cities throughout the United States. Plans for a hydrogen vehicle infrastructure are considerably smaller.

There are projects popping up, to be sure. Germany has a vague plan to develop a countrywide hydrogen fueling network by 2015, the Hawaiian island of Oahu is set to receive 20 to 25 hydrogen stations by the same year, and a company called SunHydro is building a privately funded network of nine hydrogen fueling stations spanning from Maine to Florida. But so far, hydrogen just isn't getting as much funding as EVs.

So why bother at all? Well, hydrogen fuel cell vehicles do have a number of advantages compared to EVs. SunHydro claims, for example, that drivers can fill up on hydrogen in a fueling station in just three minutes. The process is much like filling up a tank of gasoline—drivers simply attach a hydrogen-filled nozzle to the vehicle's fuel receptacle.

EVs, on the other hand, take hours to charge. That makes hydrogen-powered vehicles better suited to long distance trips where drivers don't have time to stop for long periods of time (Better Place gets around the issue by offering "switch stations" where EV drivers can quickly swap out batteries). Fuel cell vehicles also don't strain the power grid like EVs, which can potentially overload utilities if they aren't prepared to meet the increased demand for electricity.

Still, it will be surprising if hydrogen fuel cell vehicles take off in the coming years. There just isn't enough money—or time—to build out fueling infrastructures for both hydrogen and EVs before petroleum supplies become even more depleted. And at the moment, most of the auto industry's efforts are aimed squarely at EVs.

Smartphones are energy hogs. Just think about how much longer the battery in your cell phone from five years ago lasted as compared to your Android or iPhone's battery now. But while smartphones quickly suck up battery power, they can make up for it in other ways—namely, by helping you save energy in other parts of your life. Welcome to the world of the energy app.

At the moment, energy-saving apps are mostly geared towards high-end home energy management systems. The Control4 Mobile Navigator, for example, works with Control4's home control systems, which can automate everything from lighting and shades to thermostats and sprinkler systems. Forgot to turn your lights off? You can do it from the office. Control4's app simply extends the functionality of the brand's touch screens, keypads, and remote controls by allowing home control from anywhere. Similar apps are available for Wiser Home Control and eQ-3 branded energy management systems.

Do you have a rooftop solar array? SunPower’s Solar Electric Home Energy Management System lets you keep track of energy generated by SunPower-branded solar systems in real time. The app also offers information on the lifetime energy production of the panels, daily production, daily usage, and net energy use.

If you're lucky enough to have a smart meter installed in your home or apartment, the app options expand even more. Tendril Vantage Mobile allows select utility customers to monitor home energy use in real time, monitor dynamic price changes, and control smart meter-connected thermostats and appliances remotely. Utilities are getting in on the act, too—Irish utility company Bord Gáis Energy plans to release an iPhone app that offers detailed information about energy consumption and costs. Utility companies in other countries won't be far behind.

Don't have a home energy management system, a solar system, or a smart energy meter? There are other energy-saving app options. Consider downloading the MeterRead iPhone app ($2.99), which allows you to read your old-fashioned energy meter using your phone. The app calculates energy usage to the millisecond, predicts 30-day usage based on history, and stores data for hundreds of meter readings. It can even tell you how much energy a single appliance is using—just read the meter with the device plugged in and then check it again when the appliance is unplugged. It's a clunky way to track appliance usage, to be sure, but it's nearly free.

And this is just the beginning. App makers have barely scratched the surface of what handsets can do. That's not surprising—a recent Pike Research study revealed that only 13 percent of consumers can imagine controlling household appliances via smartphone in the future.

But that could quickly change. Pike also predicts that 28.1 million people will use home energy management systems worldwide by 2015. At the same time, the number of people with smart meter installations will also shoot up. And since smartphones probably aren't going anywhere, it's a safe bet to say that the future of home energy management lies at least partially in our cell phones.

Electric cars are all the rage these days, but another alternative means of powering vehicles has been around for years, and it's still hovering in the background, despite the excitement over the latest plug-in hybrids.

Biofuels, or fuels derived from biomass, are great in theory. Sure, so-called "first generation" biofuels (think corn-based ethanol) are somewhat inefficient and often suck up land that could be used for food crops, but as a whole, biofuels are a handy alternative to traditional petroleum-based fuels, right? Not quite yet.

Part of the trouble is that we haven't yet weaned ourselves off of land-intensive biofuels. Consider: the European Union has an ambitious biofuels target requiring 20 percent of liquid transport fuels to come from renewable sources by 2020. As a result, European companies are snapping up arable land in Africa to produce biofuels; currently, a third of all land sold or acquired on the continent is designated for fuel crops like jatropha, oil palm, cassava, and sugar cane, according to a report (PDF) from Friends of the Earth. Countries hit hardest by these land grabs—Mozambique, Benin, Sierra Leone, to name a few—have to deal with problems like water depletion, soil degradation, and increased food prices.

Cellulosic ethanol, which is produced from wood, grasses, and the non-edible parts of plants, is more promising—since it is produced from non-food and waste products, it doesn't use up large swaths of arable land like first generation biofuels.

Cellulosic waste can also be used for drop-in biofuels, or biofuels that can be implemented within today's fuel distribution infrastructure. These fuels can be substituted for aviation or diesel fuel; traditional biofuels cannot.

But cellulosic biofuel production is lagging. A recent estimate from the U.S. Energy Information Administration projects cellulosic biofuel production to be 3.94 million gallons in 2011. That's just a tiny fraction of the 250 million gallon requirement given to oil companies by the Environmental Protection Agency. The problem? Producers can't get the capital necessary to rev up commercial-scale production.

And what about algae fuel, once thought of as the holy grail of biofuel production? Approximately 100 companies in the United States are working towards developing algae-based biofuels, and for good reason—algae can generate up to 300 times more oil per acre than conventional crops, it has a quick harvest cycle (as little as one day), and it can flourish in everything from seawater to wastewater.

The technology, however, is still far from maturity. According to a report from Berkeley’s Energy Biofuel Institute, the algae fuel development process could take up to a decade. Even though some companies have managed to successfully produce algae fuel in lab conditions, the report claims that the ability to generate fuel "under outdoor conditions, while achieving both high productivities and oil content, is still to be developed."

Does this mean we should give up on biofuels entirely? Of course not. We need all of the alternative fueling mechanisms we can get, and the corporate world knows it; just this week, CoolPlanet Biofuels, a startup that turns cellulosic waste into biofuel, got $8 million in funding. And as a recent Economist article points out, many vehicles may soon rely on electricity for power, but widespread electric air travel is still far off.  That means airlines will increasingly lean on drop-in biofuels as oil prices rise in the coming years.

But the next time you come across a biofuel start-up touting its product as the Fuel That Will Change the World, just remember: It won't happen tomorrow.

Illustrations by Junyi Wu

Have you noticed that plug-in electric vehicles are slowly trickling into the mainstream? If you haven't, you certainly will soon—major automakers like Nissan, Chevrolet, and Toyota all have plug-in electric or hybrid electric offerings set to roll off production lines in the next few years. But there's a catch: As it stands, the electrical grid can't handle the onslaught of electric vehicles that will all start charging at, say, 7 p.m. every evening when commuters get home from work. If everyone in your city or town started driving (and subsequently charging) EVs today, the grid would probably fail. So what can be done?

As I explained in a previous column, some automakers with EVs in the pipeline are already working on the issue. Ford, for example, recently joined up with Microsoft Hohm for an in-vehicle charging system in the  2011 electric Ford Focus. The system will allow drivers to schedule vehicle charging during off-peak hours, or times when the grid has capacity to spare.

Microsoft and Ford aren't the only companies working on EV charging software. Google is also working on a platform that will use something called a vehicle dispatch algorithm to smooth out the electricity load on the grid. And the U.S. Department of Energy's Pacific Northwest National Laboratory is developing a Smart Charger Controller to automatically juice up vehicles when electricity is cheapest and the demand for power is lowest.

Further down the line, we'll see two-way EV-to-grid communications networks—charge points that can both feed electricity to vehicles and send power from EV batteries back to the grid during times of peak demand. But that technology is still in the experimental stages; one-way grid-to-vehicle connections will almost certainly become prevalent in the short term.

Utilities are also toughening up the electrical grid in anticipation of EVs, which will dramatically increase power consumption in most homes. A study from the Electric Power Research Institute estimates that the upcoming Chevy Volt will increase the energy consumption of the average U.S. home by 13 percent, while the all-electric Nissan Leaf will hike up energy use by 19 percent (they'll both save you a lot on gas, though).

SoCal Edison, one of the most well-prepared utilities in the United States, is surveying its customers to find out which ones plan on buying EVs early. The zip codes with the most early adopters will probably receive wiring and circuitry that can handle excess pressure on the grid. The utility is still trying to figure out how to incentivize drivers to charge during off-peak hours.

Less prepared utilities also have the option of turning to companies like IBM, which offers a readiness assessment service that identifies smart grid weak spots. Even IBM can't help with everything, however—only time will tell if the majority of drivers opt to update their garages for EV charging or juice up vehicles at public charge spots. It's the kind of thing that's hard to predict in advance—and it's why utilities, automakers, and electronics manufacturers need to have all their bases covered when preparing the EV infrastructure.

So you want to supplement—or perhaps even replace—your electrical grid power consumption with rooftop solar panels, but you don't want to pay thousands of dollars for a solar panel kit. There are, fortunately, a number of cheaper solar power options available—if you know where to look.

One popular solar purchasing model that has sprung up in recent years is the group purchase, which operates on the idea that everything is cheaper when bought in bulk. San Francisco-based startup One Block Off the Grid offers city-based collective purchasing for solar panels. The startup vets solar installers and negotiates for the lowest prices it can get based on how many people in a city join a particular solar purchasing campaign (each campaign only goes on for a limited amount of time). One Block Off the Grid also helps homeowners navigate city and state solar rebates, making the purchasing process significantly less headache-inducing.

Perhaps the most enticing solar model comes from companies like SunRun, Sungevity, and SolarCity, which lease rooftop solar arrays with a small upfront fee (sometimes) combined with monthly payments. This model is easiest for customers who suffer sticker shock from the high cost of solar panels—and don't want to commit to purchasing an array.

Sungevity's system is simple—customers request an "iQuote," Sungevity's team of solar designers estimates your financing options and potential monthly savings, and you choose whether to buy a system or get a solar lease. Sungevity has no upfront fee, instead relying entirely on small monthly payments. The company claims that the combined cost of the payments plus the cost of a monthly electricity bill augmented by a solar installation is probably lower than your current electricity bill. Sungevity takes care of all maintenance, too.

SunRun (the leading home solar company in the United States) and SolarCity offer equally simple leasing plans. Choosing between the three is easy enough—do a little investigating to find out which offers the best deal for your home.

Don't want to go through a third party for your solar installation? It's still possible to save plenty of cash. The U.S. Department of Energy provides a handy database of state incentives for renewable energy and energy efficiency. The site yields city-specific information—telling us, for example, that Boulder, Colorado, offers a 15 percent rebate on photovoltaic and solar water heating installation, and that the city's ClimateSmart Solar Grant Program gives grants for solar power on affordable housing units.

In a perfect world, rooftop solar panels would be cheap enough that customers wouldn't have to navigate through rebate deals and third-party leasing offers. That might not happen in the near future, but researchers are working on solar cells that could literally be painted onto rooftops using nanoparticle "inks." Once that happens, solar cell costs could be slashed to a tenth of their current price—making the dream of affordable solar power for all a reality. Until then, if you're interested in solar power, you still have options.

The smart grid has the potential to revolutionize the way we consume electricity. But there's a catch—networking digital electrical meters into what is essentially an internet for electricity makes the smart grid vulnerable to hackers. And according to some smart grid experts, an educated hacker with $500 worth of materials and equipment could gain control of thousands—or even millions—of meters. Once a hacker has access to the grid, mass blackouts (and chaos) could ensue.

There are, unfortunately, a number of different ways that hackers could shut down the grid, like intercepting codes from a smart meter's two-way radio chip; reverse-engineering smart meter hardware, or using a software radio to interact with wireless communications. And those are just a few of the ways that hackers could access smart meter codes and programming. Once someone has access to this information, they can communicate with all meters of the same brand on a network. In one simulation, the computer security firm IOActive showed that self-replicating malware could turn off power for 15,000 homes in just 24 hours.

The potential for hackers to cause havoc isn't lost on utilities and smart grid companies. According to a recent report from Pike Research, $21 billion will be invested in smart grid security over the next five years. But what does smart grid security look like?

One important factor in securing the grid will be ensuring that it is "future-proof"—that is, making sure that smart meters and other pieces of equipment can be upgraded without swapping them out entirely. Wireless technology company SmartSynch has developed a Universal Communications Module—a device containing wireless networks, fiber optic cables, and power line carriers—with individual components that can be upgraded when new technologies become available. That means security holes can be quickly patched up without having to replace the entire module.

Companies with experience in internet security are also advertising their wares to concerned utilities. Cisco, for example, believes that traditional IT security technologies like firewalls, protection from denial of service, and intrusion detection and prevention should be leveraged to keep the smart grid running. The grid will have to use internet networks for that to work—a solution that Cisco is heavily promoting.

The smart grid's vulnerability goes beyond just shutting down our electricity. Curious hackers (and marketers) could learn volumes about our daily habits if they have access to smart meters. At a recent conference, Siemens admitted that it has the technology to record energy consumption up to the microsecond. It's a capability that allows the company to infer when you get up in the morning, how many people live in the house, whether you have pets, if anyone in the house works from home, and more.

The potential for widespread access to this this kind of information has triggered the Electronic Frontier Foundation to propose a set of rules that would better inform California customers about what kind of information can be collected from their meters and how that information may be shared. The EFF's rules also propose that law enforcement be required to collect a warrant before accessing energy use information.

It's fitting that the EFF is pushing for smart grid privacy rules; the smart grid is undoubtedly on the electronic frontier. Before it moves beyond the frontier and into the mainstream, we need to ensure that it is prepared to meet a slew of security challenges—and fast.

Illustration by Junyi Wu

This is your house on the smart grid. What the future of home appliances will look like when we're managing our electricity better.

Smart energy management is becoming common among utilities across the United States. But the smart grid—a catch-all term for an upgraded electrical grid that leverages two-way digital meters to monitor power use, keep track of home electricity costs, and integrate renewable energy sources—is still a nascent technology. That will change quickly, though. In the next five years, smart meters, electric vehicles, and smart appliances are all going to grow in popularity, and when they do, the smart grid will take off.

Take a look at your electrical meter. Does it have a digital read-out? If so, it might be a smart meter, or a two-way electrical meter that constantly sends information about energy use to your local utility. Many utilities are rolling out smart meters as fast as possible, and for good reason. Smart meters make it easy for utilities to adjust electricity pricing to account for the unpredictability of renewable energy sources, which are quickly becoming part of the energy mix. Electricity prices may rise, for example, when solar power is unavailable. In theory, this should reduce pressure on the grid during times when there isn't as much electricity available.

A handful of smart meter-equipped homeowners currently have access to energy use and pricing information via energy monitoring tools like Google PowerMeter and Microsoft Hohm. But a slew of upcoming smart grid-connected appliances will make it easy to schedule energy-sucking devices to run only when prices are low.

GE is getting ready to roll out a range of smart appliances, including microwaves, oven ranges, hot water heaters, and dryers. Some of the appliances go into lowpower mode when overall grid energy consumption is up, and others feature on-board displays that signal when electricity is cheap. All of the appliances can be scheduled to run when electricity prices are lowest.

The appliances, many of which will become commercially available later this year, won't be cheap—smart water heaters (available now) cost up to $1,500 compared to $500 for a standard water heater today—but they pay for themselves in energy savings within 10 years.

Appliances may be the biggest energy vampires in today's homes, but plug-in hybrid and electric vehicles are set to emerge as a major source of electricity consumption in the near future. If everyone on your street decides to charge up their EVs at the same time, the grid could quickly be overloaded. That's why new companies are quickly popping up to manage EV charging. Juice, a startup backed by consumer electronics giant Belkin, is working on a smart EV charging system that uses software to charge up car batteries when electricity is cheapest.

Automakers are also taking an interest in the issue—Ford recently teamed up with Microsoft Hohm to optimize vehicle charging for the 2011 electric Ford Focus. Ford imagines that an in-vehicle Hohm system could eventually do everything from scheduling a washing machine to run at off-peak electricity times to letting drivers see if a house has the correct wiring to accommodate an EV. 

Perhaps the best example of how the smart grid will transform our daily lives comes from Japan, where Toyota is testing its Smart Center, an all-in-one system that connects homes, vehicles, and utilities into a home-based energy management hub. The Smart Center syncs with Toyota plug-in hybrids for charge monitoring and scheduling via a smartphone and allows remote energy monitoring and coordination (taking into account power consumption, solar panel electricity production, and electric heat pump hot water volume, among other things).

This is the energy efficient home of the future—a house with an array of appliances, devices, and vehicles that communicate with utilities to keep the renewable energy-reliant electrical grid running smoothly. And it's coming soon to a city near you.

On August 14, 2003, the Northeastern and Midwestern United States were hit by the biggest blackout in the nation's history. In total, approximately 55 million people lost power—all because of an overloaded power line in Ohio (it was a hot day) that made contact with some overgrown trees and shut down, creating a domino effect that ultimately shut down 100 power plants across neighboring regions. California faced similarly widespread blackouts in 2000 and 2001, triggered in part by an energy supply shortage.

Flash-forward to July 6, 2010. New York City turned into a veritable pressure cooker as temperatures rose to a record 103 degrees Fahrenheit. But, for the most part, the lights stayed on in spite of the heavy strain on the electrical grid created by millions of air conditioners on full blast. The reason? Utilities across the country are rapidly replacing the old, "dumb" power grid, with smart grids that use two-way digital technology to keep track of power use, help customers monitor electricity costs, and integrate renewable sources into the energy mix. While many utilities are still in the early stages of rolling out smart meters (electrical meters with real-time sensors), the smart grid is already beginning to affect the way utilities handle events like last week's heat wave.

It wasn't easy for New York City's utility Con Edison to prevent brownouts and blackouts as the heat wave mounted. The utility went so far as to call individual customers, pleading with them to turn off nonessential appliances.

But Con Ed had a backup weapon in its fight against blackouts: an initiative that lets the utility reprogram thermostats in 20,000 homes and businesses outfitted with central air-conditioning systems. When the heat wave began, Con Ed sent radio signals to the thermostats, triggering them to cycle on and off every half hour. The initiative saved 25 megawatts of energy during peak demand last week—enough to at least partially prevent the grid from collapsing.

This type of program isn't unique to Con Edison. Depending on where you live, there are several similar programs of which you could take advantage. PG&E's voluntary (and free) Smart AC program, for example, allows the utility to send signals to customers' air-conditioners to use less power than normal on hot days. So far, 120,000 customers have signed up, giving PG&E the flexibility to cut 63 megawatts of power use from the grid when necessary.

As utilities roll out smart meters, demand-response programs will become even more common. Just last week, energy management startup EcoFactor partnered with Texas utility Oncor in a bid to shave three megawatts of power off the utility's load during times of peak electricity usage. EcoFactor manufactures software that turns thermostats into two-way programmable devices that can be controlled by an internet connection. The startup's software also keeps track of customer temperature preferences, adjusting thermostats based on past use, seasonal changes, and real-time weather conditions. EcoFactor's commercial deployment is limited to Texas for now, but rest assured that similar programs will pop up in other regions as utilities search for new ways to micro-manage the grid.

All of the smart energy solutions mentioned thus far don't require smart meters. But the lucky few who already have the new meters installed have access to an array of energy-saving solutions. Smart meter-equipped customers of select utilities in the United States and Europe have automatic access to Google's PowerMeter software, which helps users track energy use over time and predict annual energy bills. And select Duke Energy customers in North Carolina and Ohio will have access later this summer to Cisco's sleek Home Energy Controller, a virtual command center for home energy management that allows users to automate energy consumption based on the time of day, participate in utility pricing incentive programs, and monitor energy use of all networked devices in the home. As these test cases see results, smart meters should be more widely available. Keep your ears open.