PRIMARY ENERGY AND CO2 OF US, NE AND VERMONT ELECTRICITY SYSTEMS

Primary Energy Sources Requiring Combustion

 

Source energy is the energy taken from the earth, such as from a well, a mine, a forest. The energy for exploration, extraction, processing and transport is used to convert the source energy to primary energy for the US economy. The US electrical system uses about 40% of all primary energy.

 

- Source energy is the energy taken from coalmines, oil and gas wells, and forests for conversion (by means of combustion) to electricity and heat.

- Primary energy = source energy - energy used for exploration, extraction, processing and transport of fuels (coal, oil, gas, biofuels, wastes, etc.) to fuel users, such as electricity generating plants, process plants, buildings and vehicles, etc.

- Consumed energy by users = electricity fed to grid + electricity imports fed to grid + fuel to process plants, buildings and vehicles, etc.

- Gross electricity generation = primary energy (fuel to power plants) x conversion efficiency.

- Net electricity generation = gross electricity generation - plant self-use = electricity fed to grid.

- Plant efficiency = energy out/energy in = electricity fed to grid/gross electricity generation

- Electricity at user meters = electricity fed to grid - transmission & distribution losses.

 

For exploration and extraction mostly diesel and electricity are used.

For processing mostly diesel, natural gas and electricity are used.

For transport mostly diesel is used.

 

Primary Energy Sources Not Requiring Combustion

 

Examples of such primary energy sources are nuclear, hydro, geothermal, solar and wind. Their primary energy factors are set at 1.0, according to the Direct Equivalent Method used by the UN.

 

Other entities, such as the EIA, BP, World Bank, etc., use other methods, which assign artificial factors to those energy sources, but they are not part of this article.

 

Primary Energy of US Grid

 

The PE factors are shown in table 1 for the US grid. They were obtained from this website. Google the title and the article displays as a PDF.

“Primary Energy Demand of Renewable Energy Carriers”. See page 12, left column in table.

 

The CO2 is only the combustion CO2, i.e., upstream is not included. See URLs.

The combustion CO2 of hydro; geo; solar and wind were set at zero.

The combustion CO2 of muni refuse; solid biomass (such as wood/pellets); biogas (such as landfill methane) & bio-liquids (such as ethanol) were not counted, per international agreement.

 

NOTE: Hydro, geo, solar and wind have upstream CO2 emissions. That CO2 is counted as part of A to Z, lifecycle, cradle to grave analyses.

 

NOTE: In case of ethanol from corn, the upstream CO2/gallon is actually greater than the combustion CO2/gallon. That CO2 is counted as part of A to Z, lifecycle, cradle to grave analyses.

 

NOTE:

1 quad = 10^15 Btu

1 quad = 293.071070 TWh

 

https://en.wikipedia.org/wiki/Energy_in_the_United_States

https://upload.wikimedia.org/wikipedia/commons/f/fd/Energy_Flow_US_...

https://www.eia.gov/environment/emissions/co2_vol_mass.php

CO2 Emissions of an EV: Almost all EV owners do not have a wall meter dedicated to measure the kWh charged into an EV. They use the vehicle meter to calculate their electricity consumption.

 

Vehicle meter = 12000 miles/y x 0.300 = 3600 kWh/y

Vehicle meter, CO emissions = 3600 x 520 = 1.872 million gram/y. See table 1.

Wall meter = 12000 miles/y x 1.125 x 0.300 = 4050 kWh/y purchased from utility.

Wall meter, CO2 emissions = 4050 x 463 = 1.872 million gram/y. See table 1.   

 

Direct Equivalent Method	Factor	PE	PE	To grid	CO2	To grid	To meters	In EV batteries
Table 1/US Grid/2017					Combustion	Combustion	Combustion	Combustion
							T&D 6.5%	Charge 12.5%
		quad	TWh	TWh	million mt	g/kWh	g/kWh	g/kWh
Coal	0.3245	12.700	3722.00	1207.90	1207.1	999
Oil	0.3427	0.210	61.54	21.09	30.5	1446
Gas	0.4603	9.540	2795.90	1287.02	506.4	393
Total Fossil	0.3824	22.450	6579.45	2516.02	1744.0	693	738	830
Nuclear	1.0000	2.747	804.95	804.95
Hydro	1.0000	1.024	300.05	300.05
Geo	1.0000	0.055	15.98	15.98
Solar	1.0000	0.181	52.96	52.96
Wind	1.0000	0.868	254.25	254.25
Muni Refuse	0.1770
Biomass, solid	0.2860	0.520	185.38	53.02
Biogas & bio-liquids	0.2620
Total RE	1.0000	2.648	687.29	687.29
Imports	1.0000	0.060	17.58	17.58
Total		27.905	8178.15	4014.80	1744.0	434	463	520

 

Primary Energy of NE Grid

 

The below table 2 is for the NE grid. Generation and CO2 data were obtained from the URLs.

 

https://www.iso-ne.com/about/key-stats/resource-mix/

https://www.iso-ne.com/static-assets/documents/2018/01/2016_emissio...

 

The NE grid is significantly “cleaner “, has much less g CO2/kWh, than the US grid. That is largely due to the high percentages of gas, nuclear and hydro, which contribute about 90% of all electricity generated in NE.

The CO2/kWh is 454 g/lb x 36389000 US ton x 2000 lb/US ton/(102532 GWh x 1000000 kWh/GWh) = 322 g. See table 2.

 

ISO-NE estimates NE generation with CO2 at 59% and without CO2 at 41%.

 

NOTE:

Combustion CO2 was 37.468 million US ton in 2016. Generation was 105572 GWh.

Combustion CO2 for 2017 was estimated a 37.468 million US ton x 102532/105572 = 36.389 million US ton.

 

CO2 Emissions of an EV: Almost all EV owners do not have a wall meter dedicated to measure the kWh charged into an EV. They use the vehicle meter to calculate their electricity consumption.

 

Vehicle meter = 12000 miles/y x 0.300 = 3600 kWh/y

Vehicle meter, CO emissions = 3600 x 327 = 1.1772 million gram/y. See table 2.

Wall meter = 12000 miles/y x 1.125 x 0.300 = 4050 kWh/y purchased from utility.

Wall meter, CO2 emissions = 4050 x 291 = 1.1772 million gram/y. See table 2.  

 

Direct Equivalent Method	Factor	PE	To Grid	CO2	To grid	To meters	In EV batteries
Table 2/NE Grid/2017				Combustion	Combustion	Combustion	Combustion
					2016	T&D 6.5%	Charging 12.5%
		GWh	GWh	million US ton	g/kWh	g/kWh	g/kWh
Coal	0.3245	5190	1684
Oil	0.3427	2031	696
Gas	0.4603	106882	49198
Total fossil	0.4520	114103	51578
Nuclear	1.0000	31538	31538
Hydro	1.0000	8572	8572
- Geo	1.0000	0	0
- Solar	1.0000	880	880
- Wind	1.0000	3280	3280
- Muni Refuse	0.1770	17881	3165
- Biomass, solid	0.2860	10538	3014
- Biogas & bio-liquids	0.2620	1874	491
- Steam	1.0000	0	0
Total RE	0.3143	34454	10830
Other	1.0000	14	14
Total Generation	0.5434	188681	102532	36.389	322	343	386
Net Flow over External Ties	1.0000	20243	20243
- Québec	1.0000	14401	14401
- New Brunswick	1.0000	4306	4306
- New York	1.0000	1536	1536
Pumping Load	1.0000	-1716	-1716
Net Energy for Load	0.5842	207208	121059	36.389	273	291	327

 

Primary Energy of Vermont Grid

 

The below table 3 is for the VT grid. Generation and CO2 data were obtained from the Energy Action Network.

 

The Vermont grid is significantly “cleaner “, has much less g CO2/kWh, than the US and NE grid. That is largely due to the high percentages of VT-generated RE, purchased nuclear, purchased H-Q hydro (via a connection that is not monitored by ISO-NE), which contribute about 72% of the total supply to the VT grid.

Fossil CO2 = 322 x 1618775 x 1000/1000000 = 521246 metric ton, as allocated to VT by ISO-NE.

 

ISO-NE estimates NE generation with CO2 at 59% and without CO2 at 41%

VT estimates its electricity supply with CO2 at 40.6% and without CO2 at 59.6%

 

CO2 Emissions of an EV: Almost all EV owners do not have a wall meter dedicated to measure the kWh charged into an EV. They use the vehicle meter to calculate their electricity consumption.

 

Vehicle meter = 12000 miles/y x 0.300 = 3600 kWh/y

Vehicle meter, CO emissions = 3600 x 104, table 3 = 0.3744 million gram/y. See table 2.

Wall meter = 12000 miles/y x 1.125 x 0.300 = 4050 kWh/y purchased from utility.

Wall meter, CO2 emissions = 4050 x 92, table 2 = 0.3744 million gram/y

 

Direct Equivalent Method
Table 3/VT Grid/2016
Energy Action Network					To grid	To meters	In EV batteries
Vermont 2016 Electricity Sources					Combustion	Combustion	Combustion
2018 update	Factor	PE	PE	To Grid	2016	T&D 6.5%	Charge 12.5%
	%	million Btu	MWh	MWh	g/kWh	g/kWh	g/kWh
Oil/Distillate	0.3189	77987	22857	7288
Gas	0.4319	140350	41134	17766
ISO-NE Non-RE	0.4319	12590386	3690031	1593721
Total fossil	0.4312	12808723	3754022	1618775	322	343	386
Nuclear	0.3281	8046529	2358303	773705
H-Q system mix*	0.9600	4790000	1403869	1347714
Hydro*	1.0000	2457967	720389	720389
Solar*	1.0000	876318	256834	256834
Wind*	1.0000	1628658	477332	477332
Landfill methane/Muni Refuse*	1.0000	327327	95934	95934
Biomass, solid (wood)*	0.2275	6982047	2046321	465470
Farm Biogas & bio-liquids*	1.0000	77364	22674	22674
ISO-NE RE*	1.0000	855945	250863	250863
Net Energy for Load	0.5295	38850878	11386541	6029690	86	92	104
Total RE*	0.6794	17995626	5274216	3583301	59.4%
Total Non-RE	0.4002	20855252	6112325	2446389	40.5%

NOTE:

- Landfill methane/Muni refuse should be 0.1770, instead of 1.0000

- Biomass, solid (wood) of 0.2860 used by “Primary Energy Demand of Renewable Energy Carriers” (See page 12, left column in table), is for very efficient biomass plants, but should be 0.2275 in case of Vermont’s very old McNeil and Ryegate plants.

 - Farm biogas & bio-liquids should be 0.2620, instead of 1.0000