Introduction
Let’s start with the good news. The technology to produce energy without carbon emissions already exists. There is as much solar energy beaming down from the sky onto the Earth every hour that humanity consumes in a year. Energy blows on the wind, boils out of the ground, and literally grows on trees. There is thousands of times more non-fossil fuel energy available than even our hungry consumer mouths are swallowing. And we have the means to gather it up and put it to useful work.

The challenge is not just constructing the wind turbines, solar farms, geothermal plants, tidal stations, biofuels and other alternative energy devices, the big elephant in the room is giving up the most convenient, versatile source of energy that has driven civilization since the Industrial Revolution and turned humans into a super-species. Black gold.

Fossil fuels are incredible. They pack an amazing amount of energy into a very small space. Gasoline has one hundred times the energy density of lithium-ion batteries, and the batteries are about fifty times heavier. Fossil fuels are easy to carry around, can remain in storage without losing energy until we need them, and, besides providing the power to keep trains, planes, and automobiles on the move, can be broken down into many useful products, from plastics to synthetic fabrics, fertilizer, even coffee whitener. No wonder they’re so popular.

Too bad that the way we burn them is changing the climate.

Alternatives to fossil fuel energy are everywhere, but clean sources such as solar and wind are spread over large areas, so it takes large technology covering a lot of land to gather it up and concentrate it into useful forms. Fossil fuels come out of the ground already densely packed with energy, which is why they have been the fuel of choice for centuries. And why we burn a lot of it.

Our thirst for oil is insatiable. Worldwide, we consume around 100 million barrels of it every day. That’s 4 billion gallons, 15 billion litres, or enough to keep Niagara Falls running for two hours. That’s just one day of quenching our thirst for oil. And that consumption continues to rise as both our population and the popularity of new energy-consuming devices grow. Of all the fossil fuels consumed since the beginning of the Industrial Revolution about 150 years ago, more than half has been used in the last 50 years. All we had to do was dig this black gold out of the ground and light a match to reap its many benefits.

Look around you. Everything that powers up, gets warm, or moves is using energy. From the alarm clock that wakes you in the morning to the lights in your home, the heat to cook meals, and the vehicles to transport you. And we assume all that energy will always be there. Flip a switch and lights come on. Plug in a device and it automatically charges up. Turn up the thermostat and your home becomes warmer. Press the accelerator pedal and your vehicle moves. And for the most part, that energy is invisible. We don’t see the electricity that came from a generating station and into the wires of your home, the gas in the pipelines that feed a furnace, or the combustion inside an engine that turns the wheels.

We also don’t see where that energy comes from, whether from burning coal, oil, or natural gas in generating stations, water falling through the penstocks of a dam, or the nuclei of atoms smashing into one another in a nuclear reactor. All these forms of energy are simply there when we need them, and they have become so entrenched in our lifestyles that we can’t live without them. The only time we get a sense of how much we consume is when the monthly bills come in and it hits us in the pocketbook. But trying to quantify just how much energy all of humanity consumes is as difficult as trying to count the stars in the universe. The numbers are incredible.

According to the International Energy Agency (IEA), our global energy demand from all sources is about 120 million tons of oil equivalent, known as Mtoe, every year. That’s a lot (a gross understatement). We use it in such quantities because oil contains a huge amount of energy. One 45-gallon drum, seen being used by the military or shined up and played as an instrument in a Jamaican steel band, is a standard barrel, or 159 litres. To measure the energy in a barrel, another unit is used, the metric joule, which is how much work that energy can do. One joule is the energy used to lift 1 kilogram up 1 metre. So pick up a small bag of oranges from the floor and your muscles are burning one joule of energy.

A single barrel of oil holds 6 billion joules. That’s right, 6 billion. So how much work could that oil do?

Think about the great pyramids of Egypt, the largest manmade monuments on the planet. Based on the mass of all the stones that make up the pyramids and the height to which those stones were lifted during construction, in pure energy terms, it has been calculated that it took about 2.4 trillion joules to build those ancient structures. Don’t tell that to the slaves who dragged those stones around—they would say they put out that many gallons of sweat. Translated into oil, the pyramids could be built with about 400 barrels. That’s not a lot of oil. A typical oil well can pump that amount in one day. That is less than one second of world oil production. So when we look at our total global energy consumption from all sources—fossil fuels, hydro, geothermal, wind, solar, nuclear—as 120 million tons of oil equivalent, it works out to more than two million pyramids every year!

It took the Ancient Egyptians twenty years to build them once.

Our energy consumption goes beyond keeping ourselves warm, well lit, and moving from place to place. Vast amounts are consumed mining minerals out of the ground and heating blast furnaces to smelt ore into metals. We literally move mountains and change the course of rivers to cover the land in concrete and asphalt, then build towers of glass and steel above them. We manufacture products and ship them around the globe. Northern countries are supplied with fresh fruit and vegetables during winter months thanks to a huge transportation network that brings food up from the tropics. Everywhere we look, energy is being used in one form or another. Just a few city blocks of downtown Manhattan consume a pyramid’s worth of energy every day. If the world population continues to grow to nine billion, and fossil fuel use maintains business as usual, we will not reach the target of limiting climate increase to 1.5 C.

These are staggering numbers, and the only reason we have been able to become such energy hogs is because fossil fuels are abundant, and we have become very good at digging them out of the ground and shipping them around the globe. That, and the fact that they carry so much energy in such a small portable space, giving them that pyramid-building potential, means they still dominate the energy we consume.

Is it any wonder that fossil fuels powered the Industrial Revolution? Think about the convenience of a lump of coal. It is a rock that burns. Just dig it up, light a match, and boom, instant heat. Use it to boil water and you have steam power to run factories and drive locomotives. So much punch in such a small package. Oil has even more punch, and it is fairly easy to handle. Fuels can be stowed in storage tanks, coal bunkers, or underground reservoirs. If we need instant energy, or want to go somewhere in a hurry, just shovel coal into the firebox or pour liquid fuel into a gas tank, and we can cross the country. And when we need more, there is always a refuelling station close at hand. Yes, fossil fuels and the network that supplies them are amazing.

Unfortunately, throughout most of the history of burning, no one thought about the products of combustion that were spewing out of smokestacks and tailpipes. They simply blew away on the wind, out of sight, out of mind. Now we know that those gases behave like the glass of a greenhouse, and are warming the climate.

But the fossil fuels themselves are not the problem. It is the inefficient ways we have been burning them that is changing the chemistry of the atmosphere. The internal combustion engines that have been powering vehicles for more than a century are around 20 percent efficient. (Efficiency varies depending on the size of a vehicle, type of engine, and body shape. A big, heavy, four-wheel-drive truck with a large engine and boxy shape is less efficient than a small lightweight vehicle with a smooth aerodynamic shape.) Efficiency is converting energy from one form to another, and if the amount of chemical energy put into a system—say, the energy in gasoline—is the same as the amount of mechanical energy coming out—such as the turning of the wheels in a car—then the system is 100 percent efficient. But no energy conversion is that good. There is always energy lost along the way. Even if you drive a small car that you think gets great mileage, only 20 percent of the energy in the gasoline ends up driving the wheels. The rest of the energy is lost as heat thrown out the tailpipe or carried away by the radiator. Then there are losses due to friction from all the moving parts within the engine, rolling resistance on the highway, and pushing the wind out of the way, although all vehicles have to deal with the last two. In other words, a combustion engine is 80 percent inefficient. But thanks to that supreme energy density of gasoline, we can afford to throw most of it away and still have enough to drive a full- sized vehicle at high speed down the highway for hundreds of kilometres. We accept that as good mileage. But think of it this way: If you spend $50 filling up your car, only $10 is used to move it. You are essentially throwing away $40.

Imagine going to a filling station, pumping gas into the fuel tank but stopping at $10. Then remove the nozzle from the car and spray $40 of gas into the air. You would probably be arrested for polluting, and it would look like you are wasting gas. But when you burn gas in the engine, most of the products of that burning are indeed thrown into the air. Waste heat, of course, but also combustion products such as carbon dioxide and carbon monoxide that remain in the atmosphere. An average vehicle will produce more than its own weight in carbon every year. Such is the hard reality of heat engines and technologies that burn fossil fuels directly.

Improving efficiency would go a long way towards reducing our impact on the climate and, while we’re at it, finding other ways to get energy out of fossil fuels without all those nasty by-products. New research is looking into cleaner, more efficient ways to get energy out of oil, such as extracting hydrogen, which is then run through a fuel cell to make electricity and drive an electric car. That is just one way the oil industry can remain viable.

Fossil fuels have transformed humans into a superspecies, enabling us to spread over the entire planet, including places humans don’t normally belong, such as flying high through the air or diving to the bottom of the ocean. We have extended our lifespans through better food and health care, built a globe-circling communications network, sent robots to every planet in the solar system, with humans soon to follow. The Earth has seen many giant species come and go over time, but there has never been anything like Homo sapiens. We have eliminated our natural enemies and taken over the habitats of millions of other species in what is now called the Holocene, the age of humans. We are also responsible for the sixth mass extinction event, where species are disappearing at a rate that hasn’t been seen since the dinosaurs bid farewell to the planet.