Most greenhouse gasses come from combustion engines used for transportation. Cars and trucks usually take most of the heat for this pollution, but did you know marine vessels are also major emitters?

In fact, marine gasoline and diesel engines are among the greatest contributors of hydrocarbons (HC) and oxides of nitrogen (NOx) pollution in the United States. So while cruising around the lake may feel better than sitting in traffic, it's actually having a similar negative impact on the planet.

Traditional boat owners can take steps to minimize their vessel's polluting ways, like eliminating unnecessary idling and avoiding carburetor equipped engines. Or they can simply buy a boat that doesn't have a pollution-emitting engine, like this sweet all-electric motorboat from Hammacher Schlemmer.

Forget about costly gas and dangerous tail-pipe emissions--this 5-foot craft is perfect for lounging on the water in eco-friendly style. Outfitted with a 12-volt electric motor that drives a two-bladed propeller, it's true that this compact watercraft isn't going to break boating speed records anytime soon, but its perfect for taking 4 mph cruises around the pond or small lake without disturbing everyone in a five-mile radius (including the fish!). On a full charge, the batteries will provide up to 6 hours of continuous use.

Featuring advanced fiberglass construction technology, the Hammacher Schlemmer limited edition is trimmed with mahogany, chromed moldings, and stainless steel drink holders, cradling riders in twin foam-padded recumbent seats upholstered in marine-grand vinyl. It also includes a waterproof 120-watt audio system with two 5" speakers that play music from a connected iPod and a built-in cooler that holds up to 24 bottles or cans...of soda, right? No drinking and boating allowed.

Best of all, it's made in the USA, and unlike many all-electric alternatives, is pretty cost-competitive. Sail away with it for only $4,000.

Let's face it: we're obsessed with mobile technology. Smart phones give us access to the internet while on a road trip, and tablets make it possible to watch our favorite basketball team while suffering through an airport layover.

Although the price of these technologies is dropping every day, it still isn't cheap, especially if you're toting the latest and greatest Apple product. So protection from drops, spills, and scratches is essential.

Being the green geeks that we are, it was important to find protective cases and covers that were kind to the environment as well as our mobile devices. We've done the homework so you don't have to, and our top 5 choices are below! (If you think we missed one, please share it in the comments!)

1. AQUA TEK S (pictured above)

Being based in Colorado, we spend a fair share of our time enjoying the great outdoors. Hiking, camping, kayaking, mountain biking--these are all great ways to relax and burn some calories--but they're not exactly an appropriate place for a delicate piece of mobile technology. If you're tired of leaving your phone (and all its GPS capabilities) in the car, the AQUA TEK S is the case for you. Brought to life by overwhelming support on Kickstarter, this case is the first ever battery powered, solar charged, rugged under water iPhone 4/4S case made with technology enthusiast and adrenaline junkies in mind. The built-in solar panel gives your battery a boost when you're far from an outlet,  it's waterproof up to 20 feet, and the outer shell is made from tough Poly-carbonate materials with rubber grips for added protection.

2. E-Pouch & Ecoskin

OK, so maybe you're not an "adrenaline junkie." Maybe you're just looking for something that will keep your smart phone safe from keys, water bottles, and all the other stuff that's jangling around in your purse or backpack. The complete, low-key line of eco-friendly protective accessories from Anokimobi might be right up your alley. The e-pouch style (pictured above) is constructed from a combination of organic and naturally biodegradable materials; the vibrant fabric dyes are GOTS regulated and all the print designs use water-based, biodegradable inks. All packaging is made from 100% recycled paper. If you prefer a sleeker, healthier look, the Ecoskin line is the only recycled/recyclable mobile phone skin to be impregnated with silver ions to reduce harmful bacteria levels on the phone

3. Spark Solar Tablet Case

The iPad is one of the most popular gadget in the world. It's also one of the most power hungry, and we know that batteries always choose to fail at the moment when you need them most. Thanks to the new Spark Solar tablet case from Voltaic Systems, however, you can have power, video, and access to the interwebs no matter where you go. The four solar panels built into this protective carrying case are capable of cranking out up to 8 watts of power, enough to provide one hour of video playback on an iPad for every hour the case spends in direct sunlight. In addition to the iPad, the Spark Solar Tablet Case is also capable of charging other tablets such as the Samsung Galaxy Tablet, the Blackberry Playbook and the T-Mobile G-Slate.

There's no denying that a case that both protects and charges your tablet is super cool. But lots of people buy the iPad because of it's minimalist look and feel, and carrying around a small solar power plant is going to add a lot of weight and bulk. If you're fine with being tethered to an outlet as long as your screen stays free of dings and smudges, this handmade sleeve from Grove. Constructed in from thick premium wool felt imported from Germany the sleeve also features a natural, hand-oiled bamboo veneer for added protection.

5. RE-Case

So far we've talked about protective cases made from lots of sustainable things: biodegradable materials, non-toxic ink, bamboo, wool...but it's hard to argue with the eco-friendliness of a product that's literally made from trash. The case is made out of an architectural grade plastic called POLLI-BER, that the company developed. Polli-ber is a trash composite made with processed organic rice husk and post-consumer thermoplastics from used car bumpers, CD containers, bottle caps, etc. As Becky Striepe of greenUPGRADER reports, "The case fit my phone nicely, though I wish that it also protected the phone's face...and there's room in the case to insert your refillable transit card, though I guess if you have one of those tap and spend credit cards, you could use that, too."

Thanks to a recent upgrade, the "World's Most Famous Office Building" will be a showcase for the world’s most advanced LED lighting system.

The Empire State Building is one of the most iconic members of the New York City skyline. It's always fun to see the massive building lit up with colorful lights celebrating key national milestones, social causes, and holidays. What most of us didn't realize is that it takes a team of workers seven hours to change the light fixtures every time the building needs to display a new combination of colors.

Thanks to a new, custom LED system created by Philips Color Kinetics, however, the façade and mast of the Empire State Building will now be able to change lighting scenes in real-time, without wasting a ton of energy.

The building's owners are working with Philips to replace the existing 400+ traditional light fixtures--old fashioned high intensity discharge bulbs—with over 1,200 state-of-the-art LED fixtures, uniquely designed for the building. Not only is the new system computerized, allowing ESB staff to customize lightings from a palette of over 16 million colors (right now, it has 10), the staff will be able to do program updates to the lights almost instantaneously.

The new lighting upgrade is part of the building's renovation and modernization initiatives and is estimated to use just ¼ of the energy that the previous lighting systems did—reducing the energy consumption by approximately 73 percent.

Humanity has developed an unhealthy relationship with Apple products. Is our i-obsession polluting our world?

Grown adults camp on the sidewalk for days to pay ridiculous prices for a slightly different version of the device in their pocket. People who are otherwise very intelligent act as if their life would end if they had to send an email on a PC. But I digress...

Did you know Apple has sold 55 million iPad's since they were introduced in 2010? Yes, your tablet might help you organize your life, but what's it doing to your world? The infographic below shows some of the green (and not so green) aspects of your iPad.

Created by Sortable

Top Image via yto/Flickr

Capitalizing on the fact that LEDs offer more opportunity to reinterpret how light is embodied and delivered, a new design imagines LEDs of an entirely new shape

There's no question that LEDs are the energy-efficient lighting solution of the future. In fact some experts predict that by 2015, 5- percent of all residential homes will completely lit by LEDs. There have been some issues with price and versatility, but as cost of LEDs continues to fall, while selection goes up, we think this is a pretty realistic prediction.

For the most part, LED designs cling pretty tightly to our deep rooted notions of what a light bulb is supposed to look like. But a new design from Artemide shows that it's time to let this uber efficient light source out from under that lampshade.

Sisifo, Scott Wilson's new hybrid luminaire for Artemide, challenges conventional light bulb design with a new typology of light that blends task lamp with table lamp and leverages LEDs qualities to create a new icon in lighting. The design's large diffused disk of light seems to float in air and easily rotates 360 degrees to direct a soft, powerful source of illumination.

"With its spherical central articulation, Sisifo guarantees maximum freedom in directing light with minimum encumbrance at the base, allowing use on both larger tables and smaller bedside surfaces," writes Wilson on Behance. "The lamp head and light source utilize micro lenticular surface details to amplify the light output. Sisifo’s generous adjustable diffuser eliminates unwanted harsh shadows and provides a soothing familiar feeling."

No longer will you have to deal with the harsh glare of a light bulb peeking out from your desk lamp, creating a blinding spot on the page or wall. Instead, the Sisifo provides bright, ambient light with a tiny carbon footprint.

Image via Scott Wilson/Behance

It's Monday, and most of us wish we were still enjoying the Earth Day weekend. This afternoon, you might be tempted to kill some time chuckling at LOLCats or browsing pictures on Facebook. But all that needless surfing has serious consequences for the planet.

What's the least eco-friendly thing you do? C'mon...be honest, we won't tell... Do you drive your car to the store around the corner? Leave your TV on when you're in the other room? Crank the air conditioning in the summer time?

None of us are perfect, and Earth Day is a good time to reevaluate our daily habits, making changes for the future. But did you know that your biggest contribution to global climate change might be all the time you spend in front of a computer?

Six billion people log on to the internet at least once a day. All that Twittering and emailing requires millions of data centers that have to be up and running, all day every day. These massive server warehouses require tons of energy to keep the websites you love available 24/7, and that means a lot of carbon emissions. But there’s an upside! The Internet has some positive effects on the planet too.

Read on to find out how the internet is killing the planet, and what you can do about it.

Thanks to WordStream.com for letting us use this graphic.

Top Image via Sarah G../Flickr

New to the area? Trying to get outdoors more, but tired of the same old trails? A new app from the Sierra Club does your hiking homework for you.

Aptly named "Trail Explorer" this app uses the built-in GPS capabilities of your iPhone, iPad or iPod Touch to discover new places to enjoy the outdoors without spending years planning a trip.

With a database of over 40,000 trails across the United States (thanks to AllTrails.com) the app allows you to search by name, activity, length, and location. Users can also track routes, view live stats, and take geo-tagged photos using the iPhone GPS, or traick and add new trails along with personal and photos.

A word of warning though, especially for greenhorns who may think this app can replace back country experience: it's a very new app and as such, isn't infallible. Several early user reviews claim that directions to trail heads are incomplete (or just plain wrong) and that often the trail itself isn't shown on the map, just a pin in the general area where the trail head should be.

We highly recommend giving the web based version a whirl before buying.