Last week I was stretched out on a dock near Woods Hole, MA watching the sky at four in the morning. A few hours before I was in a great discussion and, walking back to my cottage, I noticed the sky was dark. Much darker than I'm used to these days. The Milky Way was wonderful and the night was only a bit on the chilly side. It seemed a shame to waste the experience so I watched the sky until dawn.
The last time I had been around a dark sky in the East was during the aftermath of Superstorm Sandy. I was able to spend several hours watching, but it was cold outside and inside as our area was without power. There are times when I'm upset at all of the artificial lighting that ruins a good view of the night sky, but not during this period.
On the dock I started to think about the dramatic change brought on by the Industrial Revolution as well as a few current changes. Laying there my body was ticking away at something around 90 watts - less than my daily average of about 110 watts.1 During my rowing sessions I'm up to about 700 watts for about an hour and a half, but that is all I can manage.2
A really interesting question to ask is how much power am I using beyond just keeping my body running? I drive a car, have a house, fly every now and again, eat food raised by someone, buy things and so on. I've done some calculations for my own use as well as the average per capita use for a few nationalities.
It turns out Americans are something over 13,000 watts. To put that in perspective a hair dryer is about 1,500 watts. You can come up with your own number by adding up your personal energy use, but you have to include the energy cost of the inefficiency of power generation, how much was used to make and move your stuff and what it takes to run all of the elements of the economy you use. For example - per capita power used by the Department of Defense is a bit less than 100 watts - about the same as the average person. The post office is a couple of watts - about the same as a small night light.
Danes use about half of what we do and the Swiss even less. There are huge inefficiencies that we can address. But how has this changed over time?
In 1800, near the beginning of the Industrial Revolution, worldwide per capita power usage was about 600 watts - only six times higher than a modern person's power requirements. Now it is about 2,500 watts - there are a lot of people living in the third world as well as those who are much more efficient than Americans.
Not quite a factor of five, but going from a global per capita energy use that wasn't that different from pre-industrial living - most of the energy used probably went into farming, heating and cooking - to what we have today brought dramatic change. Change for better and worse, but mostly better to date. Losing power during Sandy makes me appreciate why people were willing to spend substantial fractions of their income to have electric lighting installed in their homes as soon as electricity was available and why the buildout of the electricity infrastructure was such a massive and politically important thing.
At the same time electricity was reshaping our lives, petroleum and the internal combustion engine made the automobile practical. That, combined with the road infrastructure that came about in a few decades radially altered so much about how we live. It also dramatically increased our usage of energy forms with consequences we have only started to realize in the past few decades.
About seventy years ago people in my own community worked on harnessing much greater energy densities and the ability to supply mind numbing amounts of power - the energy density of 235U is a few million times higher than that of oil and sadly, under the right conditions, it can be released in a short amount of time.
It is a remarkable testament to humanity that only two devices have been used against people in the Summer of 1945 and nothing has happened since. Many in the physics community became pacifists as they reflected on the scale and nature of the change. The notion that it had become possible to destroy much or even most of humanity was potent enough to prevent disaster. I was thinking of offering Robert Oppenheimer's famous quote from the Bhagavad Gita, but watching him is more powerful
Huge changes that few would have predicted... genies that, for good, bad or evil, can't be forced back into the bottle. We tend to be surprised by the changes and react with varying degrees of clue. Maybe we can learn from our past encounters... at least I hope we can.
The discussion going on just before my pleasant re-acquaintance with the Milky Way centered on society and computer security issues. The meeting had been scheduled for some time, but the NSA revelations from Edward Snowden increased the sense of urgency. People are not equipped to think about and compare risks and our social interactions are such that our views of privacy don't map onto what has developed. The scale of social media, sales and marketing, and other areas like government surveillance are all out of proportion and we need to find our way. We are being forced to think about fundamental changes to things we have just assumed and the ride promises to be rough.3
1 Colleen and I found it was much easier for most people to understand power rather than energy. The average person requires about 2,000 nutritional calories of energy from food every day. That works out to something close to 2,400 watt-hrs. (there are any number of units you can use to express energy in - watt-hrs, calories, BTUs, therms and so on - they are just energy, so you pick what is convenient) Power is just the rate energy is used and you can easily find average power over a period by dividing by the length of time of the period. Here the average power over the course of a day is 100 watts. Remarkably lightbulbish. When you sleep it is less, when you are exercising or doing manual labor it is more.
I like to use watts and watt-hrs as it is convenient to compare many forms of energy and power we use. For quick back of the envelopes a nutritional calories is about 1.16 watt-hours - rounding to 1.2 should be good enough for many estimates. So a 4 calorie M&M would provide near 5 watt-hours of energy. If you could easily convert most of that chemical energy to electricity, you'd have the basis for a great battery - technically a fuel cell - for your smartphone.
2 I can deliver about 150 watts of power to the rowing machine for long (at least to me) periods, but am only about 25% efficient at turning food energy into work. So my muscles require about 600 watts from my metabolism. Light exercise doesn't allow you to eat much, heavy exercise does.
3 I have quite a bit to say about the NSA and other programs as well as corporate surveillance, but this is not the place and I'm sure in five or ten years it would seem ridiculously naive anyway. Feel free to chat if you want some of my views and I'd be interested in those of others.
A friend lives in Cameroon. I've been trying to learn some of her dishes (at least those without meat) and find this one a winner. I don't know what it is properly called
Mashed Sweet Potatoes from Cameroon
° 1 large sweet potato
° 1 head of garlic (she loves garlic and uses two, but start with one!)
° 1 tsp cooking oil (I used a cooking grade olive oil - canola would be fine too)
° 1 very ripe avocado
° 1/3 cup sliced onion
° juice from 1/2 lime (I only had a lemon on hand and substituted it)
° sea salt and freshly ground pepper
° fresh parsley or some other herb you like
Technique (modified for American kitchens)
° preheat your oven to 400°F
° Skin and dry the sweet potato, poke holes into it and nuke in a microwave for about four minutes
° cut the top third or so off the head of garlic and make sure every clove is exposed.
° put the garlic on foil, drizzle with some oil and wrap leaving the tops exposed
° roast the sweet potato for about 20 minutes in the oven until it is soft. At the same time roast the garlic, but leave it in for a total of about 30 minutes or until golden brown and soft.
° let the garlic cool and squeeze the cloves out
° mash the sweet potato and garlic and season with salt and pepper to taste
° peel the avocado and mash adding the citrus juice. combine with the sweet potato
° serve and top with the onions and parsley. You can be a hedonist and fry or roast the onions... I won't tell