Energy and the New Reality, Volume 1: Energy Efficiency and the Demand for Energy Services Chapter 2: Energy Basics L. D. Danny Harvey This material is intended for use in lectures, presentations and as handouts to students, and is provided in Powerpoint format so as to allow customization for the individual needs of course instructors. Permission of the author and publisher is required for any other usage. Please see for contact details. Publisher: Earthscan, UK Homepage:

Forms of energy Primary energy – as it is found in nature (coal, oil, natural gas in the ground) Secondary energy – energy that has been converted from primary energy to another form (electricity, refined petroleum products, processed natural gas) Tertiary energy – one more step in the chain – end-use energy (what we actually want: light, heat, cooling and mechanical power)

Conversions: Secondary energy = primary energy x conversion efficiency So, given an amount of secondary energy, divide by the conversion efficiency to get the amount of primary energy required to produce that amount of secondary energy

Figure 2.1 Primary to Secondary to End-Use Energy

Primary Energy Equivalent of Electricity from Hydropower or Nuclear Power: Electricity from hydro and nuclear could instead be produced by burning fossil fuels to generate electricity So, divide the amount of hydro or nuclear electricity by the efficiency in generating electricity from fossil fuels to get the primary energy equivalent of the hydro or nuclear electricity I use a standardized efficiency of 40% Thus, 1 MJ of hydro or nuclear (or wind or solar) electricity is treated here as the equivalent of 2.5 MJ of primary energy

Energy and Power Energy (the ability to do work) has units of joules (J) Power is the rate of supplying energy, and has units of watts (W), where 1 W = 1 J/s Thus, to convert power to energy used, we multiply by the length of time in seconds over which the power is supplied, whereas to convert the amount of energy used over a given time to the average power, we divide energy by time in seconds

Big Numbers It is convenient to represent global and regional annual energy use in units of exajoules, where 1 EJ = joules, and to represent world power demand in gigawatts or terawatts, where 1 GW = 10 9 watts and 1 TW = watts, so 1 TW=1000 GW Primary power (W) demand is given by annual energy use (J) divided by the number of seconds in one year Thus, total world primary energy use in 2005 of 483 EJ corresponds to an average rate of supply of primary energy (primary power) of 15.3 TW

Electrical Energy When it comes to the energy supplied by an electrical power plant, it is common to multiply the power times the number of hours in the time period during which the power is supplied Thus, from kW (kilowatts) we get kWh (kilowatt-hours) from GW (gigwatts) we get GWh (gigawatt-hours) from TW (terawatts) we get TWh (terawatt-hours) To convert energy in units of kWh, GWh or TWh into energy in units involving joules, multiply by the number of seconds in an hour (and divide by the appropriate factor of 10, depending on the desired final units)

Figure 2.2a Growth in the Use of Primary Energy

Figure 2.2b Growth in the use of primary energy

Figure 2.3 Variation in the price of crude oil,

Figure 2.4 Price of Oil, Natural Gas and Coal

Figure 2.5a Growth in Electricity Supply

Figure 2.5b Growth in Electricity Supply by Energy Source

Overview of Energy Supply and Use in 2005

Figure 2.6a World Primary Energy Sources in 2005

Figure 2.6b OECD Primary Energy Sources in 2005

Figure 2.6c Non-OECD Primary Energy Sources in 2005

Figure 2.7a Uses of Coal in 2005

Figure 2.7b Uses of Oil in 2005

Figure 2.7c Uses of Natural Gas in 2005

Figure 2.8 Direct Primary Energy Use in 2005

Figure 2.9 Electricity Use By Sector in 2005

Figure 2.10 Primary Energy Use by Sector in 2005 (after allocation of energy used to generate electricity to the sectors that use the electricity)

Figure 2.11 Annual Electricity Use per capita in 2005

Figure 2.12 Distribution of Global Electricity Generating Capacity in 2005

Figure 2.13 Distribution of Global Electricity Generated by Source in 2005 (IEA data)

Figure 2.14 Geographical Distribution of Electricity Generating Capacity in 2005

Energy Resource and Energy Reserves Energy Resource: in the case of non-renewable energy: how much is there in the ground and potentially extractable Energy Reserve: that portion of the resources that it is worthwhile extracting given current prices and technology As technology improves or prices increase, some of the energy in the resource base becomes part of the reserve

Figure 2.15 Hypothetical increase in the cost of natural gas in the US with increasing cumulative extraction Source: Rogner (1997, Annual Review of Energy and the Environment 22, 217–262)