Thursday, October 13, 2011

You Do The Math - Desktop PC vs Smart Phone

Did you know that almost every dollar you spend in the US ends up paying for fossil fuels? How can this be? Firstly, imagine the retail outlet where you buy your products. Their costs are labor, energy, rent, supplies and finally the products they buy at wholesale prices to put on their shelves. Obviously their utility bill goes to energy, even the water bill, because we use energy to move water and clean the water. But what about rent?

Rent goes to pay for construction of the building and the asphalt parking lot. Asphalt is literally made from crude oil products mixed with an aggregate (fancy way of saying sand and gravel). And it's spread using diesel powered machines and steam rollers. It's even delivered in a diesel powered dump truck. But, what about the building?

The steel and aluminum structure (I beams, sheet metal, tubing, flashing, angled pieces) are delivered by trucks, assembled with cranes, welded or riveted or bolted together with electrically powered tools, or gasoline powered pneumatic tools, like Ignersol-Rand sells for construction purposes. Before delivery, the steel and aluminum parts were created by melting metal and using gargantuan machinery in absolutely huge factories.

Melting the steel and aluminum is by far the most energy intensive part of the project, because various formulations of steel melt between 2300 and 2700 degrees Fahrenheit. Aluminum melts at only 1200 degrees, but requires huge amounts of electricity to break the aluminum-oxide molecule apart. This is probably why aluminum pays 10 times more than steel at the recycler. Thankfully, moving and forming requires fractions of this energy. (Think of the 4500 watt furnace in your home, which uses maybe a 200 watt fan to move the heated air, but that heat accounted for the other 4300 watts.) The fancy assembly lines use machinery that run on electric motors or engines using diesel or gasoline or natural gas.

These foundries either use electricity to make heat, or have coal delivered to them so they can create their own heat more efficiently. This coal is delivered by diesel powered trains half a mile long (made of steel). Coal mines use electricity, gasoline or diesel powered machines. Machines made of steel and aluminum.

Then, keep in mind that the steel and aluminum came from melting rock, aka ore. Ore melts at these extremely high temperatures as well. But, only a small fraction of the ore is actually metal. There's a huge waste of energy there, heating all that rock. (That's why recycling aluminum saves over 90% of the costs of production, which is good for the economy and the environment.) And remember that all this ore must be blasted from a mountain with explosives, lifted by huge bucket loaders, carried by house-sized dump trucks, loaded onto trains, and delivered to the foundry. These machines are diesel powered.

Keep in mind that roads are made of steel-reinforced concrete with a layer of asphalt on top. The steel and asphalt are bad enough, what about concrete? Concrete is delivered by diesel powered cement trucks, after being mixed at electrically powered factories, whose materials were delivered by diesel truck or train. Moreover, concrete is made from cement, which is made by heating limestone for hours at extremely high temperatures, similar to melting iron ore or aluminum ore. Also, this limestone and cement's other ingredients must be mined and transported with explosives, diesel powered trucks and trains, and electrically powered equipment. Concrete is made from cement mixed with aggregate, which was also mined and transported.

And that's just the metals in the retail outlet. There's lots more. Similar manufacturing stories describe glass windows, linoleum floors, tile floors, concrete floors, carpeting, drywall, paint, copper or PVC plumbing, copper wiring coated in plastic, lights (glass and metal), light fixtures, counters, shelving, signage, cash registers, UPC scanners etc, etc. All are made from materials that need to be mined, transported, heated, formed, machined, and transported again. Many of these products are made from petroleum, such as all the plastics (officially known as thermosets and thermoplastics - note the word thermo, which means heat). Copper melts at around 1000 degrees and glass melts between 2300 and 2700. These are made from copper ore, sand and many other ingredients that melt at temperatures in the same range, around 1000 to over 2000.

At this point you might be saying that all these electrically powered machines don't necessarily get their power from fossil fuels. Sure, if they're run in France (mostly nuclear) or Sweden (mostly hydro power). But this is America, where our electricity is mostly made by burning coal, natural gas (coming from crude oil wells), or petroleum (crude oil) products, from the thicker fuel oils and diesel, to the more "liquid" gasoline, octane, heptane, and hexane, to the more gaseous methane, butane, propane and LPG, aka liquified petroleum gas.

The 2007 stats from the Department of Energy show that 8.21% of the US's total energy use is from nuclear, while only 6.84% is from renewable resources. All other sources are coal (22.51%), natural gas (22.43%), and petroleum (39.76%). Since 2007, solar power has more than doubled, which is probably a modest increase of a few percentage points. But, the US population keeps going up, as does our fossil fuel use. I highly doubt renewables are making a significantly bigger dent now than before.

So, what's left at this retail outlet besides rent, supplies and products? That would be labor. But what happens after the employee finishes his shift? He drives home in a 4000 pound car, 6000 pound van or SUV, or a 7000 pound pickup or Hummer. These are made from steel, glass, aluminum, plastic, rubber, etc. Then he stops at the gas station to buy gasoline or diesel, fill up his propane tank for a cookout later, and grabs a little butane lighter. Then he stops at the grocery store for food, then goes home. His home has the same manufacturing story as his work place, no need to repeat it. But what about groceries?

Fertilizers and pesticides are made from crude oil. Tractors that plant the crops are diesel powered. Combines and harvesting machines are run on diesel or gasoline. Delivery trucks and trains use diesel. Boats that ship bananas from Costs Rica or pineapple from Hawaii use diesel. Then the price of food goes up when it's placed in a grocery store, aka retail outlet. And we all know by now how much energy goes into making, furnishing and operating one of those places.

As it turns out, every dollar this employee earns is spent on one of two things: goods or srvices. Even if he dies, his money gets spent. And anything he buys has the same manufacturing or agricultural story... rape of the land by using fossil fuels. And when he spends his money on services, that money goes to equipment costs, energy costs, transportation costs, and finally labor costs. And all those costs end up spent on energy as well.

In the end, every penny you spend ends up spent on energy, and 85% of that goes to fossil fuels. This brings us back to the title of this story, "Desktop PC vs. Smartphone". Which uses more energy?

Assuming you always had and always will have a desktop PC, what energy savings can you expect by using a smartphone to do your computing needs? Obviously, buying a smartphone without a cell service contract will cost as much as a laptop. Last time I checked prices at a whatehouse club, the small (useless) smart phones were around $250 while the larger designs (useful) quickly went up in price to $450, $650 and $850. Since all of this money goes to energy, you could have simply not bought the smartphone, and spent your money on energy to power the desktop. At the national average of 11 cents per kilowatt-hour, and a fast, modern, high-speed desktop using 300 watts, the $850 will last 25,757 hours. This is about 2.8 hours a day for 25 years!

If your electricity costs 21 cents per Kw-hr, then the $850 only lasts 13 years. However, if you use the desktop only 1 hour a day, the $850 will last 70 years. But, buying the cheaper models makes a huge difference. For instance, an iPodTouch can be had for under $200, it nearly replaces a desktop as well, and that $200 would power that desktop only 5.9 years.

However, these smartphones use energy, too. The original iPhone used 2 watts when charging. And because the USB 2.0 port puts out a maximum of 5 volts at half an amp, the most any USB 2.0 powered device can use is 5 times 0.5, or 2.5 watts. Let's assume you charge your $200 iPodTouch 20 minutes a day at 2 watts. This lets you use it an hour a day for a combination of low speed and high speed internet needs and wants, like watching video and checking email. This saves you from using the desktop until the end of the week when you have to print something out, upload photos from a camera, create a spreadsheet or other document, etc.

So the iPodTouch eliminates 6 hours of desktop usage a week. If your desktop uses 300 watts, then the iPodTouch saves 6 hours times 300 watts, or 1800 watt-hours. But, the iPodTouch used 6 times 1/3 hour times 2 watts, or 4 watt-hours. This is a savings of 1796 watt-hours a week. At 11 cents per 1000 watt hours, it would take 1012.35 weeks to save $200. That's almost 19.5 years!

Obviously, a $400 iPodTouch (the one with 64 gigs of memory), will require twice as long to pay off, 39 years. Same 39 years if your desktop only uses 150 watts (typical single processor, 1.5 giga-hertz era system). Worst case scenario is when you buy an $850 Android to augment your 150 watt desktop. It will take 165.75 years to pay off.

Going to the other extreme, let's say you do 3 hours of high speed internet video a day on your 300 watt desktop. Supplanting that with 3 hours a day on a $200 iPodTouch, 7 days a week, which may require an hour of charging at 2 watts per day. The desktop would use 21 hours times 300 watts, or 6.3 kilowatt hours. The iPod uses 7 hours times 2 watts, or 14 watt hours. Each week there's a savings of 6.286 kilowatt hours. At the extreme of 21 cents per kilowatt hour, it will take only 151.5 weeks for the iPodTouch to pay off. This is 2.9 years, just in time to upgrade to the next generation of iPodTouch (Apple stopped supporting your older model two years after you bought it, anyway, so you might as well upgrade).

BTW, I just wasted a 3 hours writing this blog on my iPodTouch, thus saving 5 cents by not doing it on my 150 watt desktop. Or, one could say, I wasted 1 watt hour writing this blog, or about 1/1000th of a kilowatt hour, which comes out to 11/1000th of a penny, or 0.00011 dollars. Darn it.

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