Energy supplies and future engines for land, sea, and air

Figures & data

Table 1. Conversion factors ^a among different units to measure energy content and output (APS, 2012; BP, 2012; NRC, 2008)

	Multiply number of column 1 units to convert to:
Energy Unit	EJ	Quad	Btce	Btoe	Tcm NG	MW-hr	HP-hr
Exajoule (EJ = 10^18 J) ^b	1.000	0.948	0.033	0.022	0.025	3.6 × 10^−9	4.83 × 10^−6
Quadrillion British thermal units (Quad = 10^15 BTU)	1.055	1.000	0.035	0.023	0.027	3.41 × 10^−9	4.57× 10^−6
Billion metric tonnes coal equivalent (Btce) ^c	30.3	28.72	1.000	0.675	0.761	1.19 × 10^−10	1.59 × 10^−7
Billion metric tonnes oil equivalent (Btoe) ^d	44.9	42.559	1.482	1.000	1.128	8.02 × 10^−11	1.07 × 10^−7
Trillion cubic meters natural gas (Tcm NG) ^e	39.8	37.725	1.314	0.886	1.000	9.04 × 10^−11	1.21 × 10^−7
Megawatt-hour (MW-hr = 10^6 watt-hr)	2.78 × 10^8	2.93 × 10^8	8.42 × 10^9	1.25 × 10^10	1.11 × 10^10	1.00	8.41 × 10^9
Horsepower-hour (HP-hr)	2.07 × 10^5	2.19 × 10^5	6.28 × 10^6	9.31× 10^6	8.25 × 10^6	7.46 × 10^4	1.00
Notes: ^aThese factors follow the U.S. convention of high-heat values.
^bKilojoule (KJ = 10^3 J), megajoule (MJ = 10^6 J), gigajoule (GJ = 10^9 J), and terajoule (TJ = 10^12 J) are also in common use. One calorie (cal) equals 4.18 J.
^cChinese conversion factors for coal and other fuels are low-heat values. China typically converts energy statistics into “metric tons of standard coal equivalent” (tce); 1 tce equals 29.31 GJ (low heat), equivalent to 31.52 GJ per tce (high heat). Conversions to high heat have been made in this table. U.S. coal equivalents are often reported in “short tons” (ton). One metric tonne = 1.1023 tons.
^dOne barrel of oil (1 bbl = 42 U.S. gallons = 158.984 L). On metric tonne = 7.33 bbl. China uses a conversion factor for its oil of 41.87 GJ per metric ton (low heat), equivalent to 44.07 GJ t^−1 (high heat), assuming that low-heat values for oil are 95% of high-heat values.
^e1 m^3 NG = 35.3145 ft^3 NG. Standard conditions are 1 atm and 15.6°C. China uses a conversion factor for its natural gas of 38.98 GJ per thousand cubic meters (low heat), equivalent to 43.31 GJ tcm^−1 (high heat), assuming that low-heat values for natural gas are 90% of high-heat values.

Figure 1. U.S. Energy production by fuel, 1980–2035 (EIA, 2012). The major expansion of natural gas use is dependent on continued success with domestic shale sources and maintaining a low cost.

Table 2. North American fossil fuel reserves ^a (IER, 2011)

	Oil (10^9 toe ^b )			Natural Gas (10^12 m^3)			Coal (10^9 tce ^c )
Country	Disc ^d	Recov ^e	Proved ^f	Total	Recov	Proved	Total	Recov	Proved
United States	511	197	2.81	396	77.70	7.70	9344.10	440.90	235.87
Canada	246	43.6	23.9	881	21.46	1.76	320.24	8.71	6.62
Mexico	13.5	4.26	1.43		21.01	0.34		1.22	1.18
Total ^g	770	245	28.1	1277	120.18	9.80	9664.34	450.82	243.67
Notes: ^aConverted from original units using factors in Table 1.
^btoe: tonnes oil equivalent.
^ctce: tonnes coal equivalent.
^dDiscovered potential resources.
^ePotentially recoverable with current technology.
^fProven economically-recoverable reserves at current and projected prices and costs.
^gTotal North American reserves.

Table 3. Estimated cost of new electricity generation resources for CY 2017 (EIA, 2012)

		U.S. Average Levelized Costs (2010 U.S.$ per MW-hr) for Plants Entering Service in 2017
Plant Type	Capacity Factor (%)	Levelized Capital Cost	Fixed O&M	Variable O&M (including fuel)	Transmission Investment	Total System Levelized Cost
Dispatchable (available on demand) technologies
Conventional coal	85	65.8	4.0	28.6	1.2	99.6
Advanced coal	85	75.2	6.6	29.2	1.2	112.2
Advanced coal with carbon capture and storage (CCS)	85	93.3	9.3	36.8	1.2	140.7
Natural gas conventional combined cycle (CC)	87	17.5	1.9	48.0	1.2	68.6
Natural gas advanced CC	87	17.9	1.9	44.4	1.2	65.5
Natural gas advanced CC and CCS	87	34.9	4.0	52.7	1.2	92.8
Natural gas conventional combustion turbine	30	46.0	2.7	79.9	3.6	132.0
Natural gas advanced combustion turbine	30	31.7	2.6	67.5	3.6	105.3
Advanced nuclear	90	88.8	11.3	11.6	1.1	112.7
Geothermal	92	76.6	11.9	9.6	1.5	99.6
Biomass	83	56.8	13.8	48.3	1.3	120.2
Non-dispatchable (intermittent) technologies
Wind	34	83.3	9.7	0	3.7	96.8
Solar photovoltaic(PV) ^a	25	144.9	7.7	0	4.2	156.9
Solar thermal	20	204.7	40.1	0	6.2	251.0
Hydro ^b	53	77.9	4	6	2.1	89.9
Notes: These estimates do not include targeted tax credits such as the production or investment tax credit available for some technologies, which could significantly affect the levelized cost estimate. For example, new solar thermal and photovoltaic plants are eligible to receive a 30% investment tax credit on capital expenditures if placed in service before the end of 2016, and 10% thereafter. New wind, geothermal, biomass, hydroelectric, and landfill gas plants are eligible to receive either (1) a $22 per MW-hr ($11 per MW-hr for technologies other than wind, geothermal and closed-loop biomass) inflation-adjusted production tax credit over the plant's first ten years of service or (2) a 30% investment tax credit, if placed in service before the end of 2013, or 2012 for wind only.
^aCosts are expressed in terms of net AC power available to the grid for the installed capacity.
^bAs modeled, hydro is assumed to have seasonal storage so that it can be dispatched within a season, but overall operation is limited by resources available by site and season.

Table 4. Trends in light-duty vehicle (LDV) characteristics for seven model years (EPA, 2012)

	Calendar Year
Characteristic	1975	1987	2004	2008	2009	2010	2011
Advanced CO2 emissions (g mi^−1)	681	405	461	424	397	394	391
Adjusted fuel economy (miles per gallon [mpg])	13.1	22.0	19.3	21.0	22.4	22.6	22.8
Weight (lb)	4060	3221	4111	4085	3914	4002	4084
Horsepower	137	118	211	219	208	214	228
0-to-60 mph time (sec)	14.1	13.1	9.9	9.7	9.7	9.6	9.3
Truck production (%)	19	27	45	39	31	36	38
Four-cylinder engine (%)	20	55	28	38	51	50	47
Eight-cylinder engine (%)	62	15	24	17	12	14	16
Multivalve engine (%)	—	—	62	76	84	85	85
Variable valve timing (%)	—	—	39	58	72	84	94
Cylinder deactivation (%)	—	—		6.7	7.3	6.4	11.1
Gasoline direct injection (%)	—	—		2.3	4.2	8.3	13.7
Turbocharged or supercharged (%)			2.9	3.3	3.5	3.5	7.4
Manual transmission (%)	23	29.1	6.8	5.2	4.8	3.8	5.1
Continuously variable transmission (%)	—	—	1.2	7.9	9.4	10.9	10.8
6 Speed transmission (%)	—	—	3.0	19.4	24.5	38.1	52.4
7+-Speed transmission (%)	—	—	0.2	2.0	2.6	2.8	4.9
Hybrid (%)	—	—	0.5	2.5	2.3	3.8	4.0
Diesel (%)	0.2	0.3	0.1	0.1	0.5	0.7	0.6

Table 5. Potential GHG emission rate reductions from available technologies applied to internal combustion light-duty vehicles (Lutsey, 2010)

Vehicle system	Technology	Approximate GHG mile^−1 reduction *	Percent U.S. adoption (MY2008) ^a
Engine	Variable valve timing	2–8%	53%
	Cylinder deactivation	3–6%	6%
	Turbocharging	2–5%	2%
	Gasoline direct injection (stoich. and lean)	10–15%	4%
	Compression ignition diesel	15–40%	0.1%
	Digital valve actuation	5–10%	0%
	Homogeneous charge compression ignition	15–20%	0%
Transmission	5 speed	2–4%	32%
	6+ speed	3–5%	21%
	Continuously variable	4–6%	8%
	Automated manual, dual clutch	4–8%	1%
Overall vehicle	Lightweighting	10–20%	—
	Aerodynamics	5–8%	—
	Tire rolling resistance	2–8%	—
	Efficiency auxiliaries (steering, alternator, A/C)	2–10%	—
	Stop-start mild hybrid	5–7%	0.2%
	Hybrid electric system	20–50%	2.2%
Note: ^aFraction of vehicles sold in the 2008 model year having the specified technology.

Figure 2. Future projections for light-duty vehicle (LDV) CO₂ emission rates for different countries based on historical performance and proposed or enacted fuel efficiency standards (CARB, 2008; EC, 2009a; EC, 2009b; GCC, 2009; JAMA, 2010; NHTSA, 2011; NHTSA, 2012; NTC, 2012; NTCAS, 2012; Transport Canada, 2009; U.S. EPA, 2010). Solid symbols and lines represent historical performance, solid symbols and dashed lines represent enacted targets, solid symbols and dotted lines represent proposed targets, and hollow symbols and dotted lines represent targets under study. China's target reflects gasoline-powered vehicles only. The target may be lower after new energy vehicles are considered. U.S., Canada, and Mexico LDVs include light-commercial vehicles. NEDC, New European Drive Cycle (DieselNet, 2012b).

Figure 3. Technological evolution of LDV toward greater drivetrain electrification. Moving from left to right requires: (1) increased electrical complexity: battery size and electronic controls; (2) more frequent electric motor assist and electric-only propulsion; (3) increased capacity for regenerative power during braking; (4) increased accessory electrification (e.g., air conditioning, heating, power steering, lights, and audio); and (5) increased use of grid electricity or hydrogen/fuel cell with low life cycle GHG emissions.

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