How Much Energy Do we Need?


(B) Our body needs to get from our meals 2,000 calories per day or the equivalent of a 100 watts light bulb. In our day-to-day life, every one of us needs 100 of those 100 watts light bulbs to meet our total energy needs for driving, in our homes, at work, and for producing the goods that we consume. In the US, the present total energy consumption per year is 1020joules (or 100 exajoules) and in the world 4.5 1020 joules (or 450 exajoules) with 80 to 90% of that energy derived from the combustion of fossils fuels.

Many parts of the world have still limited access to energy. As the developing nations such as China, India and soon South America are transitioning to stronger economic growths and higher living standards, the pressure on energy supply has already significantly increased and will increase much more in the soon future.

Now add to that equation – the worldwide population growth: according to the United-Nations, the world population is expected to grow by 40% from now to 2050 or from 6.6 billion in 2007 to 9.2 billion in 2050.

The bottom line – if you consider both the economic growth of the developing countries and the growth in worldwide population, we have to double the present production of worldwide energy in the next decade in order to satisfy a future worldwide consumption of 10 1020 joules (or one zettajoule) per year. So now imagine how much energy the world will need in 2050 when the standards of living of the developing world will have matched those of the present developed world and our already very crowded planet will count 9.2 billion human beings!

Worldwide economies have two essential challenges in order to maintain our “energy-hungry” way of living:

  1. How do we first double the worldwide supply of energy in the next decade?
  2. How can we meet this significant increase of demand in energy without damaging further the Earth’s climate and ecosystems

While the US has only 5% of the total worldwide population, it consumes 20% of the worldwide energy production. The US is definitely wasteful, consuming much more energy per capita than the rest of the world and could significantly benefit from “Save Baby Save” policies instead of “Drill Baby Drill” ones.

In the US, 95% of the fossil fuels are employed to generate energy, the remaining 5% is used to manufacture diverse materials such as plastics, fertilizers and various chemicals.

Following is the break-down of the US fossil fuel consumption:

  • 40% is used to generate electric power
  • 32% is used by the industry
  • 28% (mostly gasoline and jet fuel) is used for transportation
  • 20% (mostly natural gas and coal) is used for heating

And, the breakdown of the sources of energy for the US are:

  • 29% from imported oil
  • 11% from domestic oil
  • 24% from coal
  • 19% from natural gas
  • 8% from nuclear
  • And 8% from other sources (solar, hydro, wind, biomass, geothermal)

Three are three fundamental attributes of any energy source that are fundamental to consider in order to develop a sustainable energy policy:

  1. The potential damage of the energy source to the Earth’s environment (both from its production and its consumption)
  2. The efficiency of the energy source to produce “easy-to-use” energy
  3. The cost of producing that energy

Let’s examine how those three attributes differ among a few well-known alternatives:

For the same weight, gasoline delivers approximately:

  • 2 times the energy of coal
  • 2 times the energy of chocolate chip cookies
  • And 1.5 times the energy of ethanol

And, in energy per pound,

  • Natural gas (CH4) is 1.3 times better than gasoline
  • Uranium is 2 million times better than gasoline

Note how much energy food provides to the human body (that is the reason why it is so hard to lose weight without physical exercise and why we are desperate of eating chocolate when we fall in love!).

The cost of energy per kilowatt-hours is for (excluding production investment costs):

  • Coal: 0.4-0.8 cents ($40-80 per ton)
  • Natural gas: 3.4 cents ($10 per million cubic feet)
  • Gasoline: 11 cents ($3.70 per gallon)
  • Car battery: 21 cents (but $50 cost to replace).

In the US, coal is 21 times cheaper than gasoline. The cheap cost of producing coal and the abundance of coal are the obvious reasons why China and India are relying so much on it as their primary energy source today. China, India, the US, and Russia have huge coal reserves that could last for the next two centuries while the world might be running out of oil in the next few decades. Unfortunately, coal is primary by its nature carbon and so it generates more carbon dioxide (CO2) damaging the environment than oil or gas do.

We need to deliver to the world new sources of energy that are cost-effective (like oil), scalable and plentiful (like coal) to accommodate the growth in worldwide population and the economic development of China and India while at the same time, those sources of energy must be sustainable for the environment and preserving the remaining critical Earth ecosystems (not like oil and coal).

In the next few articles, soon to come on that blog, we will attempt to investigate the present sources of energy and which new sources of energy should we invest in for our future?

Note 1: This article is based on the talk “State of energy address? Are we are on the right track?” from Professor Gerritsen from Stanford University on July 23rd at the Cantor Museum of Art at Stanford University and from the talk “Physics for future presidents” from Professor Muller from UC Berkeley at Kepler’s bookstore in Menlo Park last summer.

Note 2: The picture above is a Citroen 2CV.

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Categories: Sustainability