Option C Energy

C.1: Energy sources State essential features of a useful energy source. Cheap Plentiful Easily accessible Contains a large quantity of potential energy Reasonably high specific energy Reasonably high energy density Release/convert energy at a reasonable rate Produce minimal pollution/unwanted products Suggest examples of energy sources that violate above characteristics.

Energy quality Define energy. What are its units? What are some ways that “quality of energy” may be defined? Cost per unit energy (energy companies) Efficiency of conversion Write a formula to define efficiency of energy transfer (not “free”)

Energy conversions http://www.ems.psu.edu/~radovic/Chapter4.pdf

Specific energy (formula “free” in Data Booklet) Wood is essentially composed of cellulose, hemicelluloses, and lignin. Different types of wood have different calorific values but the average specific energy of wood is about 15 000 kJ kg-1. Good quality anthracite contains about 95% carbon and 3% hydrogen by mass. The standard enthalpies of combustion of carbon and hydrogen are -394 and -286 kJ mol-1 respectively. (a) Calculate the specific energy of good quality anthracite in kJ kg-1  (assuming that only the carbon and hydrogen content of the anthracite undergoes combustion). (b) Compare and contrast anthracite and wood as energy sources.

Specific energy (formula “free” in Data Booklet) Deduce the value of specific energy for methanol in kJ/g from the information in the figure to the right. How many grams of methanol must be used to generate 60 Watts for 1 hour?

Efficiency of energy transfer  A 60 W incandescent light bulb emits 800 lumens of light. One lumen represents 1/683 W of energy at a wavelength of 555 nm (i.e. the middle of the visible region of the spectrum). (a) Calculate the energy efficiency of the transfer of energy from the energy used to power the light v. the light energy emitted by the bulb. (b) For an incandescent light bulb to be illuminated it requires a prime energy source producing 188 J s-1. Calculate the overall energy efficiency.

Energy transfer If the prime energy source for the previous question comes from a coal-fired power plant list five separate stages during the energy transfer process that account for the low energy efficiency just calculated. Any five from: Mining and processing of coal Transportation of coal to power station Heat transfer from combustion of coal to produce steam Generation of mechanical energy to drive turbine Transfer of mechanical energy to electrical energy in generator Transfer of electricity through grid to the home Transfer of electrical energy to light energy in light bulb.

Energy conversion efficiencies—use table to rank (generalize) the most  least efficient sources http://www.ems.psu.edu/~radovic/Chapter4.pdf

Discuss the use of different sources of renewable and non-renewable energy. List 5 renewable or “green” energy resources. Solar Energy Wind Energy Biomass Hydropower Geothermal Ocean Icons taken from http://energy4me.org/all-about-energy/what-is-energy/energy-sources/

Discuss the use of different sources of renewable and non-renewable energy. Discuss pros and cons of Geothermal Energy. One of the most widely used commercial forms of renewable energy. Efficiency ~23%, but overall cost-effectiveness is attractive. Table taken from http://energy4me.org/all-about-energy/what-is-energy/energy-sources/ Pros Cons Minimal environmental impact Efficient {???} Power plants have low emissions Low cost after the initial investment Geothermal fields found in few areas around the world Expensive start-up costs Wells could eventually be depleted

Discuss the use of different sources of renewable and non-renewable energy. Discuss pros and cons of Solar Energy. Taken from http://energy4me.org/all-about-energy/what-is-energy/energy-sources/ Pros Cons Non-polluting Most abundant energy source available Systems last 15-30 years High initial investment Dependent on sunny weather Supplemental energy may be needed in low sunlight areas Requires large physical space for PV cell panels Limited availability of polysilicon for panels

C.2: Fossil fuels store energy from photosynthesis Many fossil fuels contain saturated alkanes. Explain how how this changed from carbon sources present in decaying organisms. ~C.1: State the equation for the combustion of glucose. C.4: State the equation for photosynthesis.

Crude oil fractions and their uses Label the following diagram (skip 3) 1 What happens to crude oil here? 2 Top = “Bottled gas” 4 = Gasoline/petrol 5 = Naphtha = used to make chemicals 6 = Kerosene; aircraft fuel 7 = Diesel fuel (cars & trucks…& also trains) 8 = Fuel oil (for ships & power stations) 9 = Residue/bitumen (surfacing roads/roofs) See https://www.youtube.com/watch?v=JZdvsQzOKuk

Explain how the fractionating process works—what happens inside the column?