Energy for Dummies

Note: This post is an add-on to the post “Why is My Laptop On?” for those who want to become someone who understands energy better than pretty well but still not really well.

In 2014, we’re constantly hearing words like clean energy, solar power, fossil fuels, carbon emissions, the price of oil, and fracking. And if you’re like me, you know what some of those words mean but you’re hazy on others.

So here’s a little overview of the major types of energy in today’s world and a little bit about each.

Let’s start with what’s almost definitely not powering whatever device you’re reading this on (or using to charge its battery)—

Renewable Energy

Renewable Energy, sometimes called Green Energy or Clean Energy, is warm and fuzzy and everyone likes to hold hands and sing songs about it. This is because A) it uses resources that are essentially infinite, like water, wind, or sunlight, or those that can be replenished on a human time scale, like wood, and B) it does very little harm to the environment, relatively speaking.

Unfortunately, renewable energy is a minor part of the energy equation and looks to continue being that way for a long time—the problem is that compared to other energy sources, renewables are expensive or inefficient to implement, and countries aren’t really that into hurting their current productivity and global competitiveness for long term reasons, especially if the other countries aren’t doing it alongside them (we’ve tried to all agree to do it together—and it hasn’t worked). The end result is that renewable energies make up only 19% of the world’s energy, and the cleanest, greenest types that you hear about most make up just about 1% of the world’s energy consumption:


Let’s take a closer look at the main renewable energies we use—


Biomass energy is created by burning living or recently-living organisms or manufacturing them into fuel—common examples include burning wood or converting corn into ethanol fuel.

When people talk about clean energy, you don’t often hear the words biomass or biofuel. This is because it’s both less renewable and less clean than the other clean energies. But if you’re going to include biomass in the renewable category, it makes up most of world’s renewable energy.

The bad news is that, unlike the other types of renewable energy, bio-related energy does add to carbon dioxide emissions, often requires a great deal of soil, and its resources aren’t infinite like the sun, wind, or water are.


Hydropower is the other relatively prominent renewable energy, representing almost 4% of the world’s energy and over 8% of the electricity in the US.1 It works by harnessing the power of gravity by placing a dam in front of water that’s falling or rushing downstream. When the water forces its way through the dam, it spins a turbine (a big propellor) which rotates coils of copper wire between magnets—this generates electricity, which shoots out into wires and into the electrical grid.

This process of spinning a turbine to generate electricity is at the heart of most power plants and the origin of nearly all the electricity you’ll ever encounter.


Wind energy—which is used entirely to generate electricity—makes up about .5%, or 1/200th of the world’s energy consumption. A super-clean and harmless type of energy, wind power is fast growing and already pretty big in some places (Denmark generates over a quarter of their electricity from wind).


You hear a lot about solar power, but right now, solar covers only about .3%, or 1/300th or the world’s energy consumption (sometimes as electricity, sometimes as heat). A ton of research and innovation is going into solar technology, and it’s the fastest growing renewable energy in the world.2

It’s also amazing how little of the Earth’s surface you’d need to cover with solar panels to power the entire world. Here’s how little (courtesy of LAGI)3:

Solar Panels to Power the Whole World


Georthermal power plants use the force of natural steam emerging from the hot inner Earth to spin turbines and generate electricity (and like solar, geothermal is often used for heating as well). Right now, geothermal power covers only about .2%, or 1/500th of the world’s energy consumption.
Alright, enough of the soft shit. Moving up in intensity now to what might be powering whatever you’re reading this on (but probably isn’t)—

Nuclear Energy

Nuclear energy harnesses the immense power of nuclear fission—the process of splitting heavy atoms, which releases energy—to generate electricity.

Nuclear energy is controversial. Some feel positive about it,4 often going so far as to lump it into the renewable energy category, and argue that it’s both sustainable and good for the environment because it reduces harmful emissions. Others think those people are stupid,5 and that between catastrophic accidents, harmful waste disposal, high costs, and the increased risks of nuclear proliferation and terrorism, the effects of nuclear power should be considered as bad or worse than those of fossil fuel energy.

The pessimists’ case was strengthened in 2011 when a tsunami smashed into Japan and caused the Fukushima nuclear power plant to meltdown, resulting in the most harmful nuclear disaster since the hideous Chernobyl meltdown in 1986. After the Fukushima disaster, a number of countries decided to cut down or ban nuclear power all together (Germany and Italy are two).

And while these horrible disasters take a huge toll and fully expose nuclear energy’s downsides, over time, nuclear energy has caused fewer fatalities per unit of energy generated than any other major source of energy (coal, petroleum, natural gas, or hydroelectric), and since 1kg of uranium-235 can generate 2-3 million times as much energy as 1kg of coal or oil, without adding to our CO2 problem, there seems to be compelling reason to further explore nuclear energy.

As of 2011, nuclear energy represented 2.8% of the world’s energy consumption, but over 8% of energy in the US (all in the form of electricity).

And now, onto the bad boys—

Fossil Fuels

Undoubtedly the most dickish of energy sources, the burning of fossil fuels (coal, oil, and natural gas) make up 78% of the world’s energy consumption (82% in the US), and they’re probably responsible for powering whatever device you’re using to read this post.

Fossil fuels can be credited for enabling the Industrial Revolution, raising the quality of life for the masses by growing the middle class, and thrusting the world into modernity. They can likewise be credited for about 90 environmental catastrophes, including global warming, acid rain, water contamination, oil spills, increased lung cancer, pollution and smog, and that polar bear in the video being extra sad because his ice is melting.

The question, “How bad are the effects of burning fossil fuels, what does it mean for the future, and what should we do about it?” is an entire post in itself, and one for another time. For today, let’s pleasantly ignore all that and just try to understand what fossil fuels are and where they come from.

The basic idea behind fossil fuels is that coal, oil and natural gas are all the remains of ancient organisms (mostly plants and mostly those from the Carboniferous Period 300-360 million years ago) who died and whose energy was partially preserved before they decomposed. After many millions of years of being squashed under the intense heat and pressure of the inner Earth, these organisms and their stored chemical energy have been converted to fossil fuels—and they’re still underground. We can now mine them up to land and burn them, which releases their stored energy (and emits lots of CO2 in the process). Most of the electricity and gas we use and nearly all of the energy our cars and planes run on comes from the burning of fossil fuels. People in the year 2300 will look upon this time as the Fossil Fuel Era of human history.

Let’s check out the big three fossil fuels:


Coal, a black sedimentary rock that’s found in underground layers called coal beds, is used almost entirely for making electricity, and is the most prolific material at doing so. Because coal is plentiful and relatively cheap, the world goes through a ton of it—but it’s also the worst culprit for CO2 emissions, releasing about 30% more CO2 than the burning of oil and almost double that of natural gas when generating an equivalent amount of heat.6

The US is to coal as Saudi Arabia is to oil, possessing 22% of the world’s coal and the most of any nation. China, though, has become by far the world’s largest consumer of coal—over half of the coal burned in the world in 2011 was burned in China.7


When you hear people talk about oil, they’re talking about crude oil, also called petroleum—a gooey black liquid normally found in deep underground reservoirs. When crude oil is extracted, it heads to the refinery, where it’s separated, using different boiling points, into a number of distinct fuels and gases—the most prominent being gasoline (about 45% of every barrel), but including everything from jet and diesel fuel to motor oil to the propane you use for your grill to candle wax. In most parts of the world, oil’s purpose is transportation fuel, not for generating electricity.

The United States is by far the biggest consumer of oil in the world, consuming over 20% of the world’s oil and about double the next biggest consumer. The US is also one of the three biggest oil producers in the world, alongside Saudi Arabia and Russia, who all produce roughly the same amount. But the US hardly has the most oil reserves—that’s all in the Middle East:

Who has the oil?

Looking at this map,8 three things become clear:

1) Why Saudi princes have such fancy palaces
2) Why Saddam Hussein wanted to steal Kuwait so badly
3) Why Dubai has things like an indoor ski resort, a few hundred man-made islands, and the world’s tallest building

All in all, the Middle East has over 60% of the world’s remaining oil reserves.

One other interesting thing—when I looked at an image9 of the actual oil fields, it struck me how small a part of the land they were. For example, Iran is almost entirely barren of oil, but that little sprinkling of reserves on the far west side of the country is enough to make it the second-richest oil nation in the world:

Oil Spots

We’ve been talking about conventional oil, but there are also great reserves of “oil sands”—rocks or sludge that contain oil—in Canada and Venezuela. It’s expensive and inconvenient to extract this oil, but if/when normal oil begins to run dry, the world will likely tap into these extra reserves.

Natural Gas

Natural gas is essentially gaseous methane found in pockets underground, or sometimes embedded inside shale rock. This is the gas that fires up your stove or heats your apartment (if those aren’t electricity-powered), and also one of the major sources of electricity (it makes up about 20% of electricity in the US). Natural gas is on the rise and now makes up almost a quarter of the world’s energy.

One of the reasons it’s on the rise is that scientists have found a new way of extracting natural gas from the Earth called hydraulic fracturing, or “fracking,” which uses a mixture of water, sand, and chemicals to create cracks in natural gas-rich shale and force out the gas. This method has been hugely effective, but it’s also controversial because of some serious environmental concerns—this video explains it well.

Fossil fuels contain the Earth’s entire history of buried organism remains, and unlike renewable energy sources, once they’re gone, they’re gone forever (newly generated fossil fuels happen so slowly that they’re not considered a “renewable” resource).

So how much is left?

According to the US Energy Information Administration, here are the remaining proven reserves of the three fossil fuels10:

  • Coal: 905 billion metric tons – which equals 4,416 billion barrels (702.1 km3) of oil equivalent
  • Oil: 3,740 billion barrels (595 km3) – this figure includes all the extra oil in Canadian and Venezuelan oil sands
  • Natural Gas: 181 trillion cubic meters – which equals 1,161 billion barrels (184.6 km3) of oil equivalent

Adding this all together, the volume of oil and oil equivalent that represents the total that remains of all three fossil fuels is 1,481 km3. That would make a cube with a side of 11.3 km, or 7 miles—it would cover most of Brooklyn, and contain all fossil fuels left on Earth. Using the same “oil equivalent” method, each year, the world’s fossil fuel consumption amounts to a cube with a side of about 2.4 km, or 1.5 miles—this would fit nicely on top of downtown Manhattan.

At some point soon, I’ll get more into the concept of our remaining fossil fuels and how much of them we have left. But the key point is that that 7 mile cube of our remaining fossil fuels will last us just about 80 years, if we use the same amount each year moving forward as we’re using today. Spicy.

Finally, here’s a great visual11 laying out all the energy sources we just discussed and their usage in the US in 2012 (a “quad” is a quadrillion BTU—the US’s 95.1 annual quads of energy consumption represents a little under a fifth of the world total). Interesting to see how much produced energy ends up going to waste:

How US energy is used


1. US Energy Information Administration
2. Renewables 2010 Global Status Report, p. 15.
3. Land Art Generator Initiative
4. James J. MacKenzie. Review of The Nuclear Power Controversy by Arthur W. Murphy The Quarterly Review of Biology, Vol. 52, No. 4, pp. 467-468.
5. Sturgis, Sue. “Investigation: Revelations about Three Mile Island disaster raise doubts over nuclear plant safety”
6. “Natural Gas and the Environment”
7. World Energy Council – Survey of Energy Resources 2010
8. BP Statistical Review Year-End 2004
10. World Proved Reserves of Oil and Natural Gas, Most Recent Estimates
11. Lawrence Livermore National Laboratory – Flowcharts

  • Hennessy

    This is phenomenal. A great pairing to the Laptop post. I’m struggling to decide which one I like better. Perhaps I should kidnap an 8 year old and have him decide for me.

  • wobster109

    Whew! That’s a lot of information. This is excellent and totally deserves to be on the main page.

  • wobster109

    Ok, so a bit under 5 Manhattan-diameters per Brooklyn, so about 100 years of fossil fuels remaining. Less if we expect usage to increase. That’s pretty worrisome, actually.

  • Brett

    There is enough wind energy, with current technology, to meet the world’s energy demands 6 time over! But it’s going slow because fossil fuels cost 2-3 cents per kwh versus wind costing 6 cents per kwh. So we are burning our future to save 3 cents.

    • Brian

      Actually, that’s misleading, since a kilowatt-hour is a relatively small unit of measure. More accurately, wind power costs 2-3 times more than fossil fuels for the same amount of energy.

      Which means, if you live in the cold(ish) northeast of the US, and you pay $800 per year to heat your home for the winter, switching to wind power entirely would instead cost you $1,600-2,400 per year. As much as I’d like to, I can’t blame people for not switching, because I sure can’t afford that difference.

      • jaime_arg

        Would you say that you spend $60-135 on unnecessary or “luxurious” items a month?
        If so, you could probably do without those and switch to wind power.
        If not you, at least many other unitedstatesians probably could.
        Also, I imagine that if most of us were able to use renewable energies there would be a lot more money invested into it and its efficiency would increase, this way you would have to make the effort for a few years and then the technology would have advanced enough to eliminate the difference.

      • Mark Monnin

        You’re right, but one thing we can do it buy offsets which allows for more clean energy to be produced because you are increasing demand. The offsets allow you to be indirectly powered by clean energy.

  • Bob

    Your chart of “who has the oil” is incredibly dated and inaccurate because it doesn’t include oilsands or oil that can be recovered using fracking or other current technologies.

    Also it is a well known and established fact that the US has enough coal and natural gas to power the country for over 200 years; the question is if we have the political will to use our resources.

    • Tony

      @ Bob. Political Will? It has nothing to do with political will and everything to do with pollution caused by these “resources”. If they were really clean, I’m sure “political will”
      would NOT be an issue.

    • Damphoose

      Did you miss the part about China using 50% of the world’s coal? Where do you think that’s coming from? If we’re selling off our coal how do you except it to last 200 years.

  • Idan

    I think the picture would be even clearer if you show the production price per kW, in direct cost and indirect social & enviromental costs.

    • Mark Monnin

      I’d love to see a post about the indirect costs! Renewable energy is so cheap!

  • Joyanne

    Really enjoyed the post. Being from Canada I couldn’t let the technical inaccuracy on Canadian oil sands pass by – Oil has been extracted from these oils sands for quite some time.

  • Tommy

    If I’m reading this right, it’s insane how inefficient gas powered automobiles are. I mean, only 5.6 out of 26.7 quads is used as “energy services”, or 21% efficiency?

    Then again, generating electricity is also pretty inefficient – only 12.4 out of 38.1 quads or 33% efficiency.

    I’m sure it’s been researched to death, but you’d think that there has to be a way to make these processes work more efficiently.

    • Chris

      It should be noted that this is probably the wrong way to look at it. Thermodynamic efficiency ( is limited by the minimum and maximum temperature of your system. This represents the largest possible efficiency you can reach in a perfect world. For most process you might get lucky with 60% thermodynamic effiency. This is the limit to how efficient energy generation processes can ever be with unlimited perfect technology (essentially a physical limit on an ideal system). If we even come within 10 percentage points of this in real life, its an engineering marvel, and some of our highly efficient power plants get surprisingly close at great investment. This percentage displayed above is probably the % of the total energy available vs. what we actually extract vs. what is lost to the environment to heat, friction, ect. This is a very poor number to use, as even a perfect, ideal thermodynamic system will allow a great deal of energy to be lost. It would be better to show energy efficiency for a heat engine like this:

      (Actual Theromo. Effeciency %)/(Ideal Carnot Effeciency)*100 = Process Efficiency.

      You’ll end up with a much higher, and much more accurate, number for some things. Automobile engines will still be awful though, especially compared to a modern power plant.

  • Sally

    Hi, great post — thanks!

    However, I just want to point out that wind energy is not quite the wonderful clean green thing people think it is. For one, I have read that the carbon footprint involved in creating the turbines is massive, and it takes something like 15 or 20 years of wind power generation to offset that (apologies, I don’t have time right now to check up on the references for that, but they can’t be too hard to find). Also, they cause a lot of problems for birds and bats, sadly. I know of one area of wind turbines in the US that had to be shut down because many raptors were being killed on the turbines.

    I understand, also, that the materials involved in creating solar power plants have to be mined from all over the place and that process may also cause further environmental problems… haven’t read up about that one, but was told it by a geologist who knows a lot about mining!

    It seems there are no simple or straightforward solutions to our energy hunger, sadly…

    • Jason


      Good point about the lack of “straightforward solutions to our energy hunger”. It is complicated and anyone who tells you otherwise (there are plenty who do) isn’t taking the whole picture into account. Often, these people use just one single point of view in their argument: Economics, physics, the environment, whatever.

      One way researchers do take many things into account is called Life Cycle Assessment, or “LCA”. Using LCA, they look at the entire lifecycle of an energy source from cradle to grave. That includes extraction (digging coal, pumping oil), transporting the fuel (rail, trucks, pipelines), the manufacturing of stuff needed to convert the fuel to energy (smoke stacks, turbines, solar panels), the infrastructure needed to transport the energy to where we use it (trucking, pipelines), and measure the environmental effects of all this. Then they give these sources a series of numbers so that you can compare them, apples to apples. It’s not perfect, but it helps.

      When you look at the whole lifecycle of an energy source, from cradle to grave, you’ll find that renewable sources like Solar & Wind end up being far better than any of the fossil fuels and far less risky than nuclear.

      It’s also really important to note that the traditional, easy-to-get fossil fuels are quickly going away and only the hard-to-get sources will soon be left. Already, this is true in the US and many other places. When you compare renewables to those hard-to-get sources like fracking and tar-sands extraction, then renewables come out looking even better.

      • Sally

        Thanks Jason,

        That’s very interesting, and good to know. I have to say, I think the only real solution is to reduce the ultimate cause of the problems associated with energy production — our energy hunger. That is a whole different discussion, though!

    • Mark Monnin

      I just want to point out that the bird/bat issue is a bit overblown. There may be localized issues, as you’ve stated, but wind energy kills far fewer birds and bats per kWh than fossil fuels.

  • EH

    Just have to point out one thing here – “proven reserves” and “left on earth” are very different quantities! Proven Reserves specifically refers to the amount of resources that is extractable at today’s market price. As that number goes up, it becomes economically rational to extract more of the resource, and proven reserves increases.

    There is much more than 80 years worth of fossil resource left on earth.

    • Mark Monnin

      And I wish there were only about 5 years left :/ (retroactive so as to avoid sudden economic crisis).

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  • I have been checking out many of your posts and it’s nice stuff. I will definitely bookmark your website.

  • Thanks for your helpful post. Over time, I have come to understand that the particular symptoms of mesothelioma cancer are caused by the particular build up of fluid between lining of your lung and the chest muscles cavity. The ailment may start in the chest vicinity and propagate to other body parts. Other symptoms of pleural mesothelioma include fat loss, severe breathing in trouble, fever, difficulty ingesting, and puffiness of the neck and face areas. It must be noted that some people having the disease tend not to experience just about any serious signs or symptoms at all.

  • Kilgore Trout

    Regarding the biomass adding to carbon dioxide emissions: Wasn’t that CO2 captured from the atmosphere to store the energy to begin with? So, if you are using renewable biomass resources, it should be a zero-sum game over time (disregarding CO2 emissions from equipment used in the the process of cutting down and transporting the trees etc). Or have I not understood this correctly?

    • Mark Monnin

      Maybe there’s some sort of pollution (smog, particulates) that is produced by burning biomass but isn’t produced (or relatively negligible) from other renewable energy sources.

  • madflower

    Alternative energy, is common, but “clean” energy can also refers to natural gas, or sometimes shale.

    • Mark Monnin

      I’d argue that the CO2 generated from burning natural gas disqualifies it from being considered clean. Cleaner than coal, but not clean.

      • madflower

        I agree with you. I actually don’t consider it “clean” energy. It is just marketing hype from the NG industry who was trying to keep momentum from consumers for their product. Trying to keep you from ignoring the fact they have to frack for it or otherwise they would be out of NG.

  • Roland Deschain

    Hi. I think this is an older post since everyone else’s comments are from months ago, but I’m just now reading it so it’s new to me! Anyway, enjoyed both this and the Laptop post. Would like to see the follow up you suggested about how much fossil fuel we have left and what sort of changes will take place when we run out. 80 years isn’t that far away, I’ll be dead by then I guess, but interesting nonetheless.

    Also thought it would be interesting to see a similar explanation of how oil becomes gasoline and (more interesting, IMHO) how that market works. Now that gas is down around $2.00 a gallon after it was over $4.00 last summer, I’d like to know what accounts for such drastic shifts. You hear all sorts of amorphous things about the Saudis artificially driving down costs to try and drive domestic manufacturers out of business but I have no idea if that is true or not. Who sets the prices, who communicates those prices to gas stations, who makes what percentage of the $2.00/gallon? You always hear that the gas stations themselves make very low margins on gas but, again, no idea if that’s true. I’m sure I could figure this all out myself, but I just bought a coffee mug from your store, so I kinda feel like you guys should be the ones to do it. Quid pro quo, and so forth.

    Love the site, thanks!

  • Eric Wolff

    Would have been fun if, in the section on hydropower, you’d pointed out that it’s solar energy (heat energy on the atmosphere) that “lifts” water, in rain or snow form, “up” to where it can flow “down” to the dam and then the gravitational fall to the turbine.

    • Samuela Rasa

      Everything is solar energy

  • korakys

    Bah, I’m in Wellington right now so about 99% of the electricity powering my computer is renewable*. I think your “almost definitely” phrasing is too strong. Nice post otherwise though.

    *Mostly hydro, with wind and geothermal playing a supporting role.

  • PHN

    I was interested to find some quantification on the loss of life involved in electricity generation. Forbes threw out these figures in fatalities per trillion kilowatt-hour.

    Coal – global average __________170,000
    Coal – China _________________280,000
    Coal – U.S. ___________________15,000
    Oil __________________________36,000
    Natural Gas ___________________4,000
    Biofuel/Biomass _______________24,000
    Solar (rooftop) ___________________440
    Wind ___________________________150
    Hydro – global average ___________1,400
    Nuclear – global average ____________90 (17% global electricity w/Chern&Fukush)


  • Sam

    BUSH DID 9/11

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