A fresh inch or two of snow had gently covered the city while we slept. As I tore open the shutter and threw up the sash, I couldn’t help but chuckle as I looked outside.

The snowfall, while always welcome, has some unforeseen consequences…

When I looked through the glass window onto our balcony, I saw the sight below, and thought to myself:

Hmm! No lights for us this evening!

Can you guess what this is?

It might help a bit if we zoom-out a little bit…or maybe not:

click to view larger image

What you’re looking at are the solar-powered fairy lights or solar-powered christmas lights that we have mounted on our balcony’s railing.

The way it works is pretty simple. During the day, sunlight shines onto the head of the device. Inside, two rechargable batteries are charged by the solar panel mounted on the head.

That little solar panel is just big enough to gather enough energy to power the lights from dusk until after we’ve gone to bed.

When the sun goes down and it gets dark, a light sensor in the device tells the batteries to stop charging and start putting-out.

So in the evenings, our balcony enjoys the cheerful twinkle of 25 little “Christmas” lights, all powered by the sun:

For about 15 bucks we were able to put the free and renewable energy of the sun to good use. We also avoided the hassle of having to hook the lights up to the electrical mains, and bother with turning them on and off each night.

The batteries inside the device appear to be about AA in size, but are obviously recharegable. For well over a year, they have peformed wonderfully, in all types of weather.

Seeing the pile of snow on the solar collector this morning made me think about what affects the brightness of our lights at night.

• Length of day: season
• Angle of sun: higher in summer, more direct light on the solar panel)
• Weather: cloud-cover, snow *cough*

 It is interesting to come home in the evening and observe the brightness of the lights. If you’ve had a hard day at work and didn’t bother to notice the conditions outside, you can guess what kind of day it was by the brightness of the lights.

On a cloudy day, they will generally be dimmer, although the shorter days in winter can give a similar effect. But since you are generally aware of the season, you start to notice the relative brightnesses from day to day. It sounds silly, but it is kind of fun to observe.

It seems a bit counterproductive that in summer, the nights are shorter but the lights burn a whole lot brighter. But in summer, we are more likely to be out on the balcony, enjoying the warmth of being outside. In the winter, the lights burn more dimly, but we spend much less time outdoors, and are likely to have the shades closed anyway.

At least there’s something for the neighbors to look at!

And they looked for an answer with a great data visualization that compares per-person, per-gallon efficiencies of various modes of transportation.

While the resulting poster is full of snazzy graphics and great information, there is a bit of debate about the validity of the comparisons it depicts. Yes, it seems to have fueled quite the controversy !

You see, an airplane burns through literally tons of fuel, but it also carries a lot of people, and travels a wide distance in a very short time. Meanwhile, you car’s engine is chugging along just to haul your single-butt across town, and depending on traffic, takes a while to get you there.

GOOD’s data visualization compares the fuel consumption of cruise ships, passenger trains, buses, SUVs, sedans, hybrid autos, motorcycles, bicycles and walking. And it factors in the number of passengers involved in each mode of transportation to give you an idea of how many gallons per passenger it takes to travel 350 miles.

Interestingly, since bicycling and walking don’t consume gas, they humorously made a calorie-equivalent comparison between petrol and cheeseburgers, proclaiming: we [humans]are efficient, we only need 2000 calories a day! Whereas a gallon of gasoline holds about 31,000 calories.

Here’s a preview, but you’ll want to see the full-sized graphic over at GOOD (just click the image)

click to see larger image at GOOD magazine, alternatively, click here

While the poster is eye-opening and thought-provoking, there is a bit of suspicion as to whether there is an agenda to make hybrid cars look much better than SUVs.

For cars, the red cans show the efficiency of single drivers and no passengers.

In the single-driver case, hybrids look pretty good compared to sedans and SUVs. But if you look at the legend below, you’ll see an explanation of the small solid, dashed and dotted lines above each row of cans:

When cars are full, then the difference in efficiences between SUVs, sedans and hybrids goes down quite a bit.

There is quite a bit of debate over this visualization. If you want to see how others are critiquing this info-graphic, have a read through the comments at FlowingData and in the GOOD magazine article itself.

This picture is a good start, if you’ll pardon the pun, but it would be nice to re-work the graphic showing the more typical cases of single-driver, or driver plus one passenger. If you know of anyone who’s done it already, let us know in the comments!

But different fuels and motor-technologies make this difficult. How do we make informed choices? How many Watt-hours-per-mile does your electro-car get? Is that better than 35 mpg? What’s it’s km/MJ efficiency?

Cars Are Getting Complicated

Most of us fill our vehicles with gasoline and diesel fuels.  Some even get around with compressed natural gas (CNG) in their fleet-vehicle or metro-bus. We compare efficiency in terms of miles-per-gallon or liters-per-100-km. Life is simple.

But it’s the future now. We’re worried about oil and CO2-emissions. We’re talking about hybrid motors, hydrogen fuel-cells and electric-powered (battery) automobiles. Comparisons just got a lot more complicated: How many Watt-hours-per-mile does your electro-car get? And is that better than my Toyota Prius?

What Are We Comparing?

Yes, there are more variables to compare, and more questions to ask. You, like me might wonder about issues like these:

• If I burn coal for electricity, and send the juice down the line to my battery-charger, is that cleaner and more efficient than delivering gasoline to the local station, filling up my car and burning it in my engine?
• If we’ve got a battery-powered car, we’ve got no liquid to measure in liters or gallons. So we can compare cost-per-mile or cost-per-km, but we’re not sure if lower cost means a cleaner world. We don’t foul the air for pedestrians when we drive by them, but the coal-fired electric plant has to burn a bit more to load our batteries. Cleaner air in my town might mean more acid rain for Canada.
• If we’ve got a hybrid car (battery and petrol), we can still talk about our liquid consumption per distance. But does the inclusion of both a battery and a motor in every vehicle add a drain on natural resources?
• With hydrogen fuel cells and CNG, we’ve got to wonder about the costs of safely transporting the fuels, and the energy involved in producing and compressing them. Are they dirtier overall than gas or diesel?

We need apples-to-apples comparisons. Some way to know that this car is cleaner than that one. Or that car A is more efficient than car B.

Well-to-wheel Efficiency to the Rescue?

Luckily smart people (and marketing departments) are working on this problem. They’ve come up with “life cycle assessments” that talk about how efficient a fuel-usage cycle is from extraction to consumption.

If you start Google-ing around, you’ll bump into phrases such as: well-to-station, station-to-wheel, well-to-tank, tank-to-wheel. These are all sub-stages of the entire well-to-wheel efficiency process. The “well” is the proverbial oil-well or fuel source, and the “wheel” is where your car puts it to use.

Recently, I found such information on the Tesla Motors web-site. Tesla markets completely-electric, high-performance autos (which are fast and look cool, by the way!), and have recently captured my attention.

Understanding the need for apples-to-apples comparisons, Tesla have come up with an interesting chart and matrix that compares efficiencies of cars that use different fuels and technologies.

The comparison includes an electric car (from Tesla), a hybrid gas/electric car, along with cars powered by gasoline, diesel, hydrogen fuel-cell, and natural gas.

The chart summarize well-to-station efficiency for various fuel types, compares vehicle efficiency in distance/energy, then the full well-to-wheel efficiency for each auto.

You can take a closer look at the details of Tesla’s Well-to-Wheel chart and matrix by clicking this image.

I’m not going to get into an analysis of this chart. And keep in mind that this is marketing material to some extent. But it is good to know that comparison models are being produced that will help us to make better decisions in the near future!

According to Energy Star, the average American household spends a whopping $1900 a year on energy.

Let’s take a look at where that energy flows by function.

Energy Star is a U.S. Environmental Protection Agency and U.S. Department of Energy program, which aims to help us save money and protect our environment through energy efficient products and practices.

I found an on-line brochure from Energy Star that detailed where the average American household’s energy gets used. They broke energy-use down into these categories: Dishwasher, Refrigerator, Clothes Washer & Dryer, Lighting, Water Heater, Electronics, Other, Heating and Cooling. A simple pie-chart illustrates the relative quantities, and makes it crystal clear that heating and cooling are our biggest expenditures, energy-wise.

Since energy is a flowing entity, I like to look at these kind of statistics using a Sankey Diagram. A Sankey diagram shows how flows break down into components.

Here is the Household Energy Use data from Energy Star, presented as a Sankey Diagram:

It’s pretty clear that the biggest targets for saving money and resources involve heating and cooling. Maybe we can buy a few cashmere sweaters with the money we save by turning the thermostat down!

If you like the way Sankey Diagrams present data, I recommend checking out: Sankey-Diagrams.com.  Phineas, who runs the site, is absolutely passionate about Sankey diagrams, and his enthusiasm can be infectious.

While looking for data on home energy use, I ran across some other interesting, odd and interactive data visualization that you might find interesting or at least entertaining:

As environmental causes gain momentum, we are encounter quantities, units, numbers, statistics and concepts that don’t always make sense to human beings.

We hope to bring this information down-to-earth with visuals that anybody can understand!