The Surprising Math of Getting The Whole World on Clean Energy
A super-explainer on the mechanics and hypothetical costs of going 100% green — as measured in “Shit-tons.”
Let’s start with the simple part. Pollution sucks. If we didn’t have to burn things to move cars around or make our light bulbs work, the world would be a whole lot nicer.
So what would it take to not have to do burn things in order to run the world and have the comforts we currently have?
How much would it cost? What would the technology actually look like?
What if we threw away all the marketing hype from companies with things to sell (green or not), and did the actual math of ENERGY THE WORLD NEEDS vs. COST AND PROCESS OF PRODUCING THAT MUCH ENERGY CLEANLY?
Before we dive into the answer, here’s a primer on how we measure energy:
A Btu is how much energy it takes to heat one pound (lb) of water by one degree Fahrenheit. The British made this one up because they are confusing.
A Joule is an international (metric) measure. It’s the amount of energy “dissipated as heat when an electric current of one ampere passes through a resistance of one ohm for one second.” Whatever that means. There are about 1,055 joules in a Btu. (1,055.05585 to be precise.)
A Watt is one joule per second. A Kilowatt is a thousand of those.
A Kilowatt-hour, or the amount of energy to expend a kilowatt for an hour, is 3.6 million joules (3.6 megajoules)
A Toe or “tonne of oil equivalent” is the energy released when you burn a metric ton of crude oil. It’s about 42 billion joules (or 42 gigajoules).
A Mtoe, which is the unit that engineers use when they talk about worldwide energy expenditure, is a million Toes.
For reference, 22 standard 60-watt light bulbs left on for a whole year would use a Toe’s worth of energy. A Ford Taurus can drive 7,590 miles on a Toe. (One gallon of gasoline is 33.7 Kwh.) A Toyota Prius can go 17,595 miles on a Toe. A 747 uses 39.47 Toe on a trip from New York to London. The Sun emits about 9 billion Mtoe every second, and the Earth receives 43 Mtoe of the Sun’s energy every second.
At last count, the U.S. Energy Information Administration reported that the average American used 313 million Btu of energy per year. The worldwide average energy usage per capita is 75 million Btu. (And this number is likely a bit low because the government can’t really track how much people in third world countries use campfire and wood stove style heat.)
This means that the 7.3 billion people living today collectively use 547 quadrillion (547,500,000,000,000,000) Btu per year. If everyone in the world lived like Americans, we’d need 2.28 quintillion (2,284,900,000,000,000,000) Btu of energy.
Including international air travel and everything else, the EIA estimates the world uses 8,979 Mtoe of energy each year.
Where I live, we call that a Shitton.
This is actually less than the Btus calculated based on the EIA’s per-capita counts. That would be ~13,000 Mtoe, or 1.55 Shittons. I don’t know why the EIA doesn’t agree with itself, but just so mankind never has to think about turning the lights or hairdryer off every again, let’s go with the higher number for our calculations.
That means we’d need to generate a little less than 6.5 Shittons of energy per year for the whole world to live like Americans do. (Americans use 4.17x more than the average human, and 1.44 Shittons times 4.17 is 6.0048.)
Right now, the energy we generate primarily gets used for two things: electricity and fuel. To truly clean up our act, we’d need to make all transportation and heat and manufacturing run on electricity. No more burning things. That possibility is imminent already with companies like Tesla now making batteries that can take a car hundreds of miles. Set’s assume that by the time we changed everything over to a new green system, technology would be good enough to power planes and tractors, too. And we can already make heat with electricity (although it can be more expensive; we’ll address that in a bit).
Okay. So the challenge at hand is to generate a heroic 6.5 Shittons of clean electricity.
How to make electricity
Electricity is basically a flow of excited electrons. There are a few common ways we can make those electrons flow:
Static: This happens when there’s an imbalance of electrons across a surface where they should be balanced. Electrons want to be balanced, so they try to go wherever there’s a deficiency.
Lightning is an extreme version of static electricity, where you have too many electrons on the bottom of a cloud that want to find balance with the ground, and what happens is sort of like Anakin Skywalker. He was supposed to bring balance to The Force, but then he screwed everything up.
Anyway…
Batteries (electrochemical): Batteries are kiiiind of like lightning in a can. You have chemicals in the battery that have an imbalance of electrons at either end (the positive and negative ends). When you connect the two ends of the battery with a circuit, electrons flow from the — to + end to balance themselves out, and whatever you’re powering with the battery can slurp up some of those electrons while they’re en route.
Batteries store potential energy. You have to put electrons into one end of your battery (charge it!), so the source of electricity generally comes from one of the next two methods:
Photovoltaics: This is a variation on the electrochemical method: basically, certain chemicals get excited when sunlight hits them. The Sun’s energy excites the electrons in the chemical, and they jump around. By capturing the jumping electrons, you get a flow of electricity. Which you then can put in a battery or send through wires to power something.
Electromagnets: If you spin a coil of copper wire in between the two poles of a magnet, it pulls electrons from one place to another, which turns out to be a super effective way to generate electricity.
This was discovered by a guy named Faraday, who may or may not have been reincarnated as the crazy dude from LOST:
Electromagnetic induction (Faraday’s method) is how 80 percent of the world’s electricity is generated.
An electric generator is the the thing that spins the coil (or magnet):
Basically, for the last century or so, we’ve run around looking for ways to get that coil magnet thing to spin A LOT. You could technically spin it by hand, or you can do what most power stations do and attach a turbine to it, and get something to turn the turbine:
Things that turn turbines include:
Wind:
Water situations:
(My man Alexander Hamilton built one of these in the once majestic Paterson, New Jersey, now the garbage hole of the Northeast. I lived here for 9 months one time and was friends with a homeless dude named Andrew. That’s a story for another day…)
Steam:
Steam is the way most of our turbines get turned, because so far it’s been the easiest to make ourselves. We usually make it by burning things to heat water, and that’s where our fossil fuel problem comes from.
Nuclear power plants are basically clever ways to boil water without spewing out a ton of carbon pollution into the air. When radioactive Uranium fuses or splits (fission), it gets really hot. So if you stick it in a giant tank of water, you can make a lot of steam:
Once you’ve made electricity, you have to put it somewhere or it will find a way to find balance, and usually that means going into the ground, no matter who gets in its way. So we have to either hold onto it in what we call “The Electric Grid” or store it in batteries. Until recently, batteries kind of sucked at holding large amounts of energy, so we built this giant Grid system to keep live electricity hanging around and ready to use:
(The electric grid works for us for the most part, but it has problems. Namely, a single point of failure along any of the pieces of the grid can cause a lot of people to lose power down the line. Also, whoever owns the electric lines basically has a monopoly and controls your electricity availability (and bill) if they want to.)
Transportation similarly is about getting things to turn: a combustion engine is all about turning a drive shaft; a jet engine is all about turning a jet turbine. You can use electricity to turn all those things, too, using an electric motor, which is basically the opposite of a generator:
For a long time, we’ve made our electricity using the burning/steam methods because it’s been the cheapest and easiest. (And we’ve made motors spin by burning things in a combustion engine for largely the same reason.) But as technology has gotten better, other methods have started catching up.
How much it would take to run the world on clean energy?
Here’s how much it costs to generate a megawatt-hour of electricity using each of the methods for which there exists enough potential energy to power the world:
(BTW: Critics like to point out that clean energy methods require construction, and that that construction requires energy and usually non-clean stuff to go in them. The above chart includes the capital cost of constructing the systems for each method. Fossil fuels, for example, are lower in capital (but higher in fuel and pollution), which solar and wind are higher in capital, but use zero fuel and don’t pollute. Clean energy can be used to manufacture the capital for more clean energy, but we indeed will need a ramp up of dirty construction to get us to clean, simply because we don’t have that much clean energy flowing yet.)
Here’s how that cost differential works out for the low-end estimate of one year of worldwide energy, assuming we were to produce it all from a single source:
There’s not enough energy in hydroelectric, geothermal, tidal, wave, biomass, or other clean energy sources combined to get us our 6.5 Shittons for the whole world to live the good life. There just isn’t. As such, I’d recommend that everyone working on those things think about career changes. I’d recommend the same for fossil fuel workers, as supplies are not only running out but (as we’ll see in a moment) they are soon going to be not worth continuing.
On the other hand, there’s enough potential energy by wind and sunlight hitting the Earth every year for us to generate what we need with either of them. Forever.
The waste factor of coal and gas is astounding, and many argue that this is worth the difference in cost between it and solar. Regardless, on the face of it, wind energy looks like a better economic deal right now anyway. Wind has downsides, of course (like the huge amount of space it takes up — e.g. offshore wind is twice as expensive but stays out of our way — how long it takes to set up, and the fact that it chops up birds and things). Also, we simply don’t have the physical gear to generate close to worldwide energy yet. However, despite its current price tag, solar is far and away most desirable energy source in the long run because of two things: portability, and the fact that it’s about to cost a lot less than everything else..
Why the Solar Option is the Best Option
The Earth absorbs 1,357 Shittons of energy from the Sun every day. We only need 6.5 of those in a year to power everything we need. The problem is converting that much energy in a way that’s cheaper than burning stuff.
Until now, we haven’t had the solar panel capacity to capture that much energy, nor the batteries to store it in an efficient way.
Here’s the exciting news, though: the cost of solar-generated electricity is going down like crazy. Here’s the cost of photovoltaic energy per watt over the last 40 years:
You’ll notice that two charts back we saw that the vast majority of solar energy’s cost was in its hardware. Said hardware is made of silicon — the stuff computer boards are made of — and photovoltaic silicon cells are increasing in capacity and decreasing in price in a similar manner to computers. Basically, Moore’s Law is at work when it comes to solar tech, too.
Solar cells right now are typically about 13–14% efficient. Laboratories, however, have already made 25% efficient cells, and 20% efficient cells have already been making their way to market, meaning we can expect the cost of solar energy to decrease by as much as 40% in the next couple of years. Some Chinese solar companies have reduced their cost per watt by 60% in the last three years, and analysts predict that to continue til at least 2017.
In fact, a new solar energy facility in Dubai, the Mohammed Rashid Al Maktoum Solar Park, has just this year started building a plant that will generate solar energy en masse at $58 per megawatt-hour, or $6 trillion per Shitton, which is cheaper than coal, natural gas, nuclear, and wind.
So in a couple of years, our energy chart will look like this:
Hot dang.
Most government studies I read about renewable energy forecast depressingly pessimistic rates of change. As in, “By 2050, ¼ of the world’s energy will be green.” That’s 35 years! This is like setting up a game of limbo with a six foot high bar.
To truly transition to a world of solar energy will take a lot of construction. And a lot of people and companies will slow things down. (Jobs will shift, oil-dependent economies will dig in their heels, cash cow-riding corporations will lobby, etc.) But the nice thing about solar is you can literally collect the energy anywhere. And for places like big cities with limited roof space per capita, we can still use our grid and just pump it with solar-sourced electricity.
On that note: How many solar panels would we in fact need to feed the world? A square meter of solar panel gets 5kwH of sunlight per day. (This will vary by where you are in the world and how much direct sunlight you get. The Sun hits Vermont and Arizona differently.) At 20% efficiency, that would be 1kwH per square meter, or 250 square meters of solar panel per person to feed an American energy lifestyle.
That would take up about this much total space:
We’d have to put solar panels all around the world in order to get the electricity locally, of course. (This guy here did an awesome calculation on how many solar panels we’d need a couple years back.)
Expensive spacecraft solar panels can get 40% efficiency. Assuming costs continue to decline and technology continues to improve, we could at some point only need 125 square meters of solar panel per person to get all the energy we could possibly need. So the map would look like this:
All that includes all the energy we collectively use for plane travel and construction and a zillion other things. Much of that energy could be created in solar farms that connect to the grid, while our personal household energy could be created for us individually with our own solar panels. The EIA says the average American household uses 909 kwH per month, which amounts to 30.3 square meters of solar panel per house.
That could fit on the roof of almost any house, hut, or Winnebago in the world. (If you put solar panels on the sides of the Winnebago, too.)
We now have battery technology that can store enough energy to keep your own mini-grid on your own premises. No more needing to be plugged into the rest of the neighborhood. I.e. no mass power outages. The new Powerwall, by Tesla, for example, is currently the world’s most baller battery. It attaches to a solar array on your roof and stores enough juice to get you through each day, night, and more.
Here’s what the new solar-powered grid would look like:
In undeveloped countries, cheap solar will likely leapfrog the whole grid part entirely, just like cell phones leapfrogged wired internet and computers in the third world.
How would a clean electricity-driven world need to change?
The switch to clean energy is inevitable. Tim Urban at WaitButWhy put it accurately with this timeline of mankind’s history:
By the time we build enough solar panels and batteries to generate 6.5 Shittons of electricity, the cost of solar could be cheaper than anything else. But there’s more to do than just generate the energy:
- We’d need to swap out all our combustion engine vehicles: cars, trucks, planes, construction vehicles, everything. This will take a while. Fortunately, if gas costs more than electric, this will eventually make financial sense to most vehicle owners.
- A lot of jobs would need to move from the burning industry to the solar industry. Training and education would need to change.
- We’d have to manufacture all these solar panels. That’s a lot of silicon.
All of that is doable, but it won’t happen overnight.
The best news of all is that the public wants solar more than any other type of energy.
Assuming the cost of solar falls as predicted, what the only thing that could really stop this from happening would be people and companies who profit from the burning industry cash cow trying to stop the switch from happening.
This is the nature of innovation. If you aren’t willing to reinvent yourself as technology changes, someone else will pass you with the hot new thing you could have built. If I were an oil company, I’d be thinking hard about how to shift to becoming a solar company now before someone like Elon Musk eats my lunch.
Shane Snow is a journalist/geek in New York City.
