# Bite-Sized, Big Picture Data: 180 Lightbulbs

The trouble with big issues is that… well, they’re big. Big issues have many facets, which generate many different (and often contradictory) points of view among those who care. This creates problems when people use data to think about big issues. I want to focus on two:

1. Confirmation Bias — big issues have many facets, which makes it easy for people to cherry-pick evidence to support their opinions. There are tons of examples of this; we will continue to see anecdotal statistics about politicians thrown around this election season. Unfortunately, these bits of information fail to provide any useful overall context for thinking through which candidates actually make good politicians. We should avoid focusing too narrowly on the facets of big issues, and instead focus on understanding the issues as wholes. Big issues call for big-picture data.
2. Scope Confusion — big issues usually involve very big numbers and unfamiliar units, which we are bad at understanding intuitively. It’s easy to get lost in large numbers. I recently saw a sign on a hand-dryer advertising that the machine saves several thousands of pounds of CO2 compared to using paper towels. That sounds great — except that I have no intuitive concept for what a ton of CO2 means, the impact that that amount of CO2 has on the environment, how much CO2 that is relative to other activities like driving, etc.  Big issues call for intuitive, bite-sized data.

Looking at big-picture, bite-sized data goes a long way towards actually understanding big issues.

## Energy Consumption

Take energy for example. Many of us are concerned with the impact that our energy choices have on the planet, the timeframe for and implications of running out of fossil fuels, and the national security risks associated with relying on other countries for oil. If we want to form educated opinions about energy issues in the US, it would be nice to have a big picture, bite-sized reference point.

The good people at Lawrence Livermore National Laboratory made this graph, showing how energy is produced and consumed in the US (in units of Quads, or Quadrillion BTUs):

This is definitely big picture — it shows the contribution of all the major sources of energy in the US (solar, wind, nuclear, coal, etc.), as well as the various ways energy is consumed (residential, industrial, commercial, transportation). It isn’t all that intuitive or bite-sized, however. First, there is simply too much information to digest all at once; it’s a good reference, but I’m certainly not going to remember how many quadrillion British Thermal Units of energy are produced by nuclear plants per year. More problematic — I have no intuitive understanding of what a British Thermal Unit of energy means, let alone how to deal with 100 Quadrillion of them.

We can put this information on a more tangible scale by considering the power (rate of energy usage) per person in America. Dividing 100 Quadrillion BTUs per year by the number of people in America, and converting to Watts, gives a per-person power consumption of:

$100 \times 10^{15} \frac{\rm ~BTU}{\rm year} \times \frac{1 {\rm ~year}}{24 \times 365 {\rm ~hours}} \times \frac{1 {\rm ~Watt ~hour}}{3.412 {\rm ~BTU}} \times \frac1{300 \times 10^6 {\rm ~people}} \sim 10,800 {\rm~ Watts / person}$

On average, each person in America uses about 11,000 Watts of power. We can go one step further by considering this number in terms of how much energy a typical (60W) incandescent light bulb uses:

$10,800 {\rm ~Watts} \times \frac{1 {\rm ~ lightbulb}}{60 {\rm ~Watts}} \sim 180 {\rm ~lightbulbs}$
180 Lightbulbs per person. The energy it takes to run America is equivalent to running 180 lightbulbs, per person, 24 hours a day. That is a number most people understand:

America's energy usage is equivalent to running 180 lightbulbs per person

For fun, we can go a few steps further to divide up these lightbulbs by how the energy is produced and consumed:

The fraction of renewable and non-renewable energy in the US, in lightbulbs per person

How energy is consumed in the US, in lightbulbs per person. The black lightbulbs represent how much energy is lost when converting other forms of energy (natural gas, solar, coal, etc) into electricity

It is much easier to avoid scope confusion when we think of energy in these units. In his great, free book on sustainable energy, David MacKay points out that, despite good intentions, we waste a lot of effort trying to make a greener planet by focusing on solutions that are simply too small. For example, high-efficiency light bulbs can be up to 90% more efficient than incandescent bulbs. Switching to these efficient bulbs certainly saves energy. But how much of a difference does that really make if we are concerned with reducing our dependence on non-renewable energy? Most people probably only have 10 or fewer such bulbs to replace, and these are only on for a few hours a day. At best, then, this choice “turns off” 1 or 2 lightbulbs out of 180. It’s not that switching to high-efficiency light bulbs is a bad idea. It’s just not a good enough idea, and we shouldn’t be fooled into thinking that changes like this will solve our problems.

Given that 150/180 bulbs are currently powered by non-renewable resources, then, a truly green planet demands changes on a much larger scale. Indeed, it’s hard to imagine making individual decisions that turn off 150 bulbs — we don’t even have direct access to most of the light switches, since they are controlled by the people who make, transport, and sell us stuff we use. As MacKay argues, when our non-renewable resources start to run out (perhaps in the next 100 years, say some), we will need to make some very big changes. Our options are:

1. Cut back on how much energy we use by a factor of ~6 (i.e. turn off 150 light bulbs)
2. Decrease the world population to decrease energy consumption
3. Increase the infrastructure for renewable energy by a factor of ~6 (figuring out how to do nuclear fusion, and convincing people that it’s not evil, would satisfy our energy needs for a long time)

There is, of course, much more to be said about energy, which is a very big issue. There are many facets that the 180 bulbs-per-person figure doesn’t address (the economic and environmental costs of different energy sources, how energy consumption varies throughout the world, how population growth affects things, etc.). But we should always hold on to big picture, bite-sized bits of data like this — they do so much to keep the debates about the nuances in check.