Cost of Power

Primary Batteries

Energy from non-rechargeable batteries is most expensive in terms of cost per kilowatt-hours (kWh). Primary batteries are used for low-power applications such as wristwatches, remote controls, electric keys and children’s toys. Military in combat, light beacons and remote repeater stations also use primaries because charging is not practical. Table 1 estimates the storage capability and cost per kWh of primary batteries.

 

AAA Cell

AA Cell

C Cell

D Cell

9 Volt

Capacity (alkaline)

1,100mAh

2,500mAh

7,000mAh

14,000mAh

600mAh

Energy (single cell)

1.4Wh

3Wh

9Wh

18Wh

4.2Wh

Cost per cell (US$)

$1.25

$1.00

$1.60

$1.60

$3.10

Cost per kWh (US$)

$890

$330

$180

$90

$730

Table1: Energy and cost comparison of primary alkaline cells. Energy from primary batteries is most expensive; cost increases with smaller battery sizes.

Secondary Batteries

Improved runtimes, lower unit price and the convenience of recharging have shifted many portable applications previously reserved for primary batteries to rechargeable batteries. Table 2 compares the cost of power with rechargeable batteries. The cost is based on battery price and the number of possible discharge/charge cycles. The analysis does not include electricity for charging or the cost of purchasing and maintaining charging equipment. The table compares commercial battery packs used for communications, computing or medical devices.

 

Lead Acid

NiCd

NiMH

Li‑ion

Capacity

2,000mAh

600mAh

1,000mAh

1,200mAh

Battery voltage

12V

7.2V

7.2V

7.2V

Energy per cycle

24Wh

4.5Wh

7.5Wh

8.6Wh

Number of cycles

250

1,000*

500

500

Battery cost (est.)

$50

$50

$70

$100

Cost per kWh ($US)

$8.50

$11.00

$18.50

$24.00

Table 2: Energy and cost comparison using rechargeable batteries. Older technologies have lower cost/kWh than newer systems; larger cells are most cost-effective. The costs are commercial packs at estimated over-the-counter prices.

*   Cycle life is based on battery receiving maintenance.

Power from Other Sources

With dwindling fossil fuel supply, governments and the private sector are studying alternate energies. Table 3 compares the cost to generate 1kW of power by taking into account the initial investment, adding the consumption of fuel and including the eventual replacement of the system. Power from the electrical utility grid is most cost-effective; consumers in industrialized countries pay between $0.05 and $0.25US per kWh. (The typical daily energy consumption per household is 25kW.) Gasoline (and equivalent) is the most economical portable fuel.

Fuel type

Equipment
to generate 1kW

Life span

Cost of fuel
per kWh

Total cost
per kWh

Li-ion
for vehicular use

$1,000/kW
(based on 10kW battery at $10,000)

2,500h (replacement cost $0.40/kW)

$0.10
 

$0.50
(replacement and $0,10/kWh)

Gasoline engine
for vehicular use

$30/kW
(based on IC engine
at $3,000/100kW)

4,000h
(replacement cost $0.01/kW)

$0.33

$0.34
 

Fuel cell
- portable use
- mobile use
- stationary use

$3,000 – 7,500


2,000h
4,000h
40,000h

$0.35
        ->
        ->
        ->


$1.85 – 4.10
$1.10 – 2.25
$0.45 – 0.55

Electricity
electric grid

All inclusive

All inclusive

$0.10

$0.10

Table 3: Cost of generating 1kW of energy
The table includes the initial investment, fuel consumption, maintenance and eventual replacement of the equipment. The figures are estimates at the time of writing.

The fuel cell is most effective in converting fuel to electricity, but high equipment cost makes this power source expensive in terms of cost per kWh. In virtually all applications, power from the fuel cell is considerably more expensive than from conventional methods.

We now look at the energy that our bodies consume. An active man requires 3,500 calories per day to stay fit, which relates to roughly 4,000 watts in a 24-hour day (1 food calorie = 1.16 watt-hour). Traveling on foot covers about 40km (25 miles) per day and a bicycle increases the distance by a factor of four to 160km (100 miles). Eating two potatoes and a sausage for lunch can propel a bicyclist for the entire afternoon, covering 40km (25 miles), as I have experienced myself. The human body is amazingly efficient in converting food to energy.

Table 4 compares the energy per passenger/kilometer for a loaded Boeing 747, the retired Queen Mary ocean liner, a gas-guzzling SUV, a fit person on a bicycle, and a person walking on foot. The figures are estimated.

 Function

Boeing 747
jumbo jet

Ocean liner Queen Marry

SUV
or large car

Bicycle

On foot

Weight (loaded)

369 tons
 

81,000 tons

2.5 tons

100kg (220lb)

80kg 
(176 lb)

Cruising speed

900km/h
(560 mph)

52km/h
(32mph)

100km/h
(62mph)

20km/h
(12.5mph)

5km/h
(3.1mph)

Maximum power

77,000kW
(100,000hp)

120,000kW
(160,000hp)

200kW
(275hp)

2,000W
(2.7hp)

2,000W
(2.7hp)

Power at cruising

65,000kW
(87,000hp)

90,000 kW
(120,000hp)

130 kW
(174hp)

80 W
(0.1hp)

280 W
(0.38 hp)

Passenger

450

3000

4

1

1

Power per passenger

140kW

40kW

50kW

80W

280W

Energy per passenger

580 kilojoules*

2,800 kilojoules*

1,800 kilojoules*

14.4 kilojoules*

200 kilojoules*

Table 4: Power needs of different transportation modes. In terms of high-speed transportation, air travel consumes theleast amount of energy per passenger-km. The boat is efficient for slow and heavy freight. The absolute lowest energy consumption is the bicycle.

*  1 joule is the energy of 1A at 1V for 1 second, or 1 watt/s, or 0.238 calorie/s; 4.186 joules raise the temperature of 1g of water by 1°Celsius; 1,000 joules are 0.277Wh.

Bicycles are by far the most effective form of transportation. Comparing the energy consumption of a bicycle to that of a car, a cyclist would consume only 0.4 liter of fuel per 100km (630mpg). Walking is also efficient; it uses about one liter per 100km (228mpg). The problem with self-powered propulsion is the limited travel range before fatigue sets in.

In terms of energy usage, cars are one of the least efficient modes of transportation. The internal combustion engine utilizes only 25 percent of the net calorific value from the fuel for propulsion. The calculation looks even worse when taking into account the weight of the vehicle with a single passenger, the driver. The ratio of machine to man is typically ten-to-one. When accelerating a 1.5-ton vehicle, less than two percent of the energy moves the 75kg (165lb) driver, his briefcase and the lunch bag; 98 percent goes to heat and friction. Even a modern jet plane has better fuel efficiency than a car. A fully occupied Airbus 340 gets 3.4l/100km (70mpg), cruising at 950km/h (594mph).

Trains are one of the most efficient modes of transportation. The 36km Yamanote circle line connecting major urban centers in Tokyo carries 3.5 million passengers per day. During rush hour, the 11-car train runs every 150 seconds. Such a passenger volume would be unthinkable by private cars on city streets. Trains are also economical to move freight. Transporting one ton of freight consumes only 0.65 liters of fuel per 100km (362mpg).

Affluent societies want personal transportation, but with a large critical mass driving vehicles on government-funded highways with minimal contribution by the drivers and without mandated limits, this free-roaming lifestyle is taking a toll on our energy resources. Developing countries also desire personal transportation. As car become affordable to them, they will begin consuming fossil fuel too and this will increase the need for hydrocarbons further. According to the US Department of Energy, 71 percent of the oil consumed in the USA is for transportation. Out of this, 51 percent goes to passenger cars and light trucks. Smaller vehicles and the development of efficient rail systems could cut the energy for transportation in half. Read more about Hooked on Cheap Energy.

Comments

On July 7, 2011 at 4:44am
david turner wrote:

‘Energy per passenger’ would be better changed to ‘..per passenger.mile’ .
Do the human powered modes allow for the fuel used just to keep the power source alive?

On April 20, 2012 at 5:02am
charles agbeke wrote:

Please I want to know how to know the size of a battery from the numbers written on them. In my part of the country batteries are rekonned in the number of ‘plates’ But how do I know how many plates has a battery if the model is MF160G51, MF135F51, MF57220, MF105D3 1R, MF105D3 1L AND SO ON AND SO FORTH?
Thank you very much and I hope to quickly from you soon.

On July 11, 2012 at 10:58pm
Imran Ahmed Arain for dear Charles agbeke wrote:

Dear Charles as u ask i m giving u some information In Battery language the G51 code is showing N150 Family mean in this battery box a battery company can be insert the matarial who can be stored 150Ah +/- 10%
like this F51 box show the box for 135Ah capacity battery etc.
One other way read care fully the name of product
MF160G51 here MF for Maintenance Free
160 for Capacity
G51 for Box Family I hope that now u can understand a battery numbers easily

On July 4, 2013 at 6:02am
P sheel venkatesh wrote:

suggest battery for streetlight 6volt and 4.5 to 5 for inbuilt operation with backup for
solar street light. 
thanks
sheel

 

 

 

 

 

On July 27, 2013 at 11:50am
angela wrote:

hi,
just wondering, lead-acid is known for its low specific capacity and low energy density, thus usually insufficient power for many electrical devices, correct?
but according to your table 2, lead-acid batteries seem to have highest capacity, and power?
i am quite confused.

On August 31, 2013 at 10:59am
Tony klodd wrote:

These charts would be of great help in my thesis on the hydrogen economy, but I must be misunderstanding something, because the cost per kWh for Lithium Ion batteries in table 2 is way lower than I expected.  ($24/kWh instead of a few hundred).  Here are the values that I found in different sources:

$500/kWh
http://en.wikipedia.org/wiki/Electric_vehicle_battery

$600/kWh
http://www.mckinsey.com/insights/energy_resources_materials/battery_technology_charges_ahead

$400/kWh
http://green.autoblog.com/2012/04/06/lithium-ion-battery-costs-will-still-be-about-400-kwh-by-2020/

How do you explain this discrepancy in price?  Could you tell me where you got this information?  This is a surprisingly difficult statistic to nail down, considering Lithium Ion batteries are so popular.

Also, unrelated: This article conflates power and energy a lot.  Power is measured in kW.  Energy is measured in kWh.

On September 5, 2013 at 9:52pm
Ken wrote:

Hi,
Interesting stuff.  I would like to add to the comment you make where you say the internal combustion engine is 25%, 3rd para under heading Table 4.  As a traction motor the story is very much worse than you suggest.  An IC engine will manage about 30% at one RPM and one torque setting of the throttle.  For any other conditions the conversion is less than 30% and it includes 0% when providing no propulsion power at all.  Using the time weighted or distance traveled weighted conversion the figure can be less than 5%.  The main advantage that a hybrid transmission provides is that it avoids asking the IC machine to prove mechanical conversion in the range the engine does badly. Very approximately the efficiency ranges from 0% to 30% as the throttle goes from maximum throttle to wide open throttle and very approximately the efficiency is not dependent on the RPM.  So the good range is full throttle from the lowest workable RPM to the highest RPM and that turn-down ratio is too small for the task of a traction motor in a car.  Third paragraph under heading Table 3 the units should read 4000 Wh not 4000 watt. In SI units (watt, ampere etc) the singular and the plural are both covered with the same name always without adding the s. i.e. 1 watt 4 watt.

On September 30, 2013 at 7:25pm
alejandro wrote:

Hi i was hoping someone could clarify a few questions. I am a business mayor and I dont consider myself a battery expert.
according to Tesla’s website, The Tesla Model S uses lithium ion cells, 40 % of the worlds cylindrical battery production is used in this producing the model s.
I was wondering:
if this batteries are useful for grid energy storage?
if some grid energy storage batteries like the ones used in solar farms are compatible to fit the role of an electric car?
what batteries are the best for grid energy storage?
what batteries are the best for electric cars?
any considerable innovation in any of these markets?

On February 12, 2014 at 3:32pm
JJ wrote:

Nice try BUT half the numbers on this post are wrong, or don’t make sense - at least by an order of magnitude. This ‘university’ is wrong. Table 2 - Cost per Wh (not kWh!). Bike - max power 2000W (1/2mv^2)= 1.5kJ, all dissipated in ~1s is 1.5kW BUT? Really try to light up your house on your bike - good luck, human can power continuously a LOT less, more like 100W actual power. Just in your ocean liner example, 90MW/3000 passengers is 30kW/passenger… Check your math, assumptions, equations and logic. I don’t even believe I bother trying to comment - waste of time.

On March 19, 2014 at 11:02pm
judy moore wrote:

Looking for suppliers of batteries for solar panels, wind and generators