Seite - 16 - in Water, Energy, and Environment - A Primer

thermalenergyassociatedwithanobject’s temperature.Energyis alsoaconservedquantity,as firstdiscussedbyLordKelvin inhis developmentof thermodynamics.Thelawofenergyconservation states that energy can be converted in form, but not created or destroyed. In addition, mass and energy are closely related, as expressed by the famous Einstein equation e=mc2. The importance of this mass–energy equivalence will be discussed in our discussionof nuclear energy (Chapter 7). 2.4 ENERGYTRENDS Historic trends in energy supply and demand – reflecting population growth in the 20th century (from1.8 billion in 1900 to more than 6 billion in 2000), increased average income and associated welfare, and increasing urbanization (from 13% in 1900 to48%in2000)– led toa rapid rise in electrificationanda dramatic increase in global energy demand, from 44 quads in 1900 to 406 quads in 2000. Transportation was the fastest- growing end-use sector, with petroleum supplying over 90%of itsenergyneeds.These trends are continuing in the21st century. Projections by the International Energy Agency (IEA), the Energy InformationAdministration (EIA) of theUSDepartment of Energy, and other major international energy organizations, all point to the same general conclusions: over the next few decades consumption of energy will increase, mostly in developing countries; fossil fuels will account for most of the increase and remain thedominant energy source; natural gas use will grow the fastest; nuclear power will grow, but slowly; and use of renewable energywill grow rapidly butwill not displace fossil fuelsas theprincipal energysource. To be specific, the EIA, in its ‘International EnergyOutlook 2017’ report (13), projects that under its ‘business as usual’ Reference case (which ‘considers current policies ‘as reflected in current laws, regulations’ and stated targets that are judged to reflect an actual policy commitment’) there will be an increase in global energy consumption from 575 quads in 2015 to 663 Water,Energy, andEnvironment–APrimer16