IEEE Electrification Magazine - March 2015 - 20

an
y
m

2

er

2
/m
W
/m
0
W
0
25
11
n:
io
n:
rs
io
rs
ve
ve
on
on
C

ce

C

e
or
ef

2

/m

W

G

2

/m
W

e
or
ef
,B

B
n,
Su

2

Singapore

10

/m

W

2

/m

W

:5
e)

s)

0

:2

n
tio

p
ro

Fr
an

0

un
tS

ca

2

Eu

/m

Lo

rn

W

2

r
we
Po

ny

e
th

r
la
So

un
(S

or

.5

/m

Hong Kong

Algeria
China

Brazil

Sudan

India

W
2

la

ng
2

/m

W

sh

de

1

2

2

/m

/m

W

W
10

/m

Ba
0.

1

01

00

0.

0.

10

1

Energy Consumption Per Person (kWh/d/p)

00
1,

er

ks

(N

m
do
ng

g
tin
ra
nt

Ki

ce

ks

W

S. Korea
Uni Japan
ted
Kin
gdo
Portugal
m

Libya

es

d
te
ni

on

r
Pa

r
Pa

5
0.

:2

s:

p
ro

United States

Australia
Russia

D

U

C

PV

PV

r
we
Po

C

Qatar

Canada

100

r
la
So

r
la
So

y
rg

d
in
W

e
En

1,000

1,000
100
Population Density (People Per km2)

10,000

Figure 1. The power consumption per person versus the population density in 2005. The point size is proportional to the land area (except for
areas under 38,000 km2, which are shown by a fixed smallest point size to ensure visibility). Both axes are logarithms. (Figure courtesy of David
J.C. MacKay, www.withouthotair.com.)

Washington, D.C.) are well below the 10-W/m2 solar power
resource line, which means that local PV generation can meet
a significant portion of the total electricity demand. (Note that
a simple calculation using the National Renewable Energy
Laboratory's PV watts shows that PV power output ranges
from 10 to 30 W/m2, depending on geographic location, climate zone, module technology, and system configuration. For
the analysis in this article, we use 10 W/m2 to simply illustrate
its order of magnitude.) In rural areas, the energy consumption density is several times lower than the national average
and well below 0.1 W/m2; therefore, the local supply-anddemand picture looks much more favorable.
Countries and regions can be grouped into four categories with distinct energy consumption profiles: rural
developed, urban developed, rural developing, and urban
developing (Figure 3). Clearly, both rural-developed and
rural-developing regions can rely on local renewable
resources to meet the energy demand. The urban areas
will need more energy-dense local generation or will need
to import from other regions.

Local Grid Infrastructure
The traditional centralized ac power system is built and optimized for one-way power flow: generation, transmission,

20

I E E E E l e c t r i f i c ati o n M agaz ine / marCh 2015

distribution, and consumer. For future rural electrification,
this can be replaced by a local power delivery network (no
transmission or substation) that integrates an optimal
amount of energy storage, energy-efficient and flexible loads,
and uses operation management tools to self-balance the
local generation and demand. Communications, SCADA, and
information technologies will be critical parts of this new
system. The size of this model system can range from a few
kilowatts to several megawatts in size, representing an
individual home up to a small community of several thousands. This model system, essentially a microgrid, offers an
excellent solution for the future rural electrification because
it is 1) distributed and local, 2) clean and sustainable, 3) modular and scalable, 4) reliable and resilient, and 5) cost-effective. See Figure 4 for the rural electric model system and various microgrid configurations.
If the model system were built from scratch, it would
have been built from the bottom up, and from the edge to
the center, without centralized planning. It can start from a
single prosumer microgrid, in which rooftop PV, for example, will produce all of the energy needed for the household
consumption. An energy storage system will be needed for
nighttime use and for smoothing out the PV variability. A
home energy management system will monitor and
http://www.withouthotair.com
Table of Contents for the Digital Edition of IEEE Electrification Magazine - March 2015
