<s>
The	O
environmental	O
effects	O
of	O
Bitcoin	B-Protocol
are	O
considerable	O
.	O
</s>
<s>
This	O
is	O
because	O
bitcoins	B-Protocol
are	O
made	O
using	O
electricity	O
partially	O
generated	O
by	O
gas	O
and	O
coal-fired	O
power	O
plants	O
.	O
</s>
<s>
,	O
such	O
bitcoin	B-Protocol
mining	O
is	O
estimated	O
to	O
be	O
responsible	O
for	O
0.1	O
%	O
of	O
world	O
greenhouse	O
gas	O
emissions	O
.	O
</s>
<s>
A	O
second	O
environmental	O
effect	O
is	O
the	O
air	O
pollution	O
caused	O
by	O
coal-fired	O
electricity	O
generation	O
,	O
and	O
a	O
third	O
is	O
the	O
e-waste	O
due	O
to	O
the	O
short	O
life	O
expectancy	O
of	O
bitcoin-mining	O
equipment	O
.	O
</s>
<s>
Bitcoin	B-Protocol
is	O
a	O
cryptocurrency	O
made	O
by	O
proof-of-work	O
,	O
while	O
some	O
other	O
cryptocurrencies	O
,	O
such	O
as	O
Ethereum	B-Application
,	O
are	O
made	O
by	O
proof-of-stake	B-Protocol
,	O
which	O
consumes	O
less	O
electricity	O
.	O
</s>
<s>
,	O
the	O
Cambridge	O
Centre	O
for	O
Alternative	O
Finance	O
(	O
CCAF	O
)	O
estimates	O
that	O
Bitcoin	B-Protocol
consumes	O
around	O
annually	O
,	O
and	O
says	O
bitcoin	B-Protocol
mining	O
uses	O
about	O
as	O
much	O
electricity	O
as	O
Egypt	O
.	O
</s>
<s>
But	O
it	O
is	O
difficult	O
to	O
find	O
out	O
how	O
the	O
electricity	O
used	O
for	O
mining	O
was	O
generated	O
,	O
and	O
thus	O
Bitcoin	B-Protocol
's	O
carbon	O
footprint	O
.	O
</s>
<s>
One	O
study	O
found	O
that	O
from	O
2016	O
to	O
2021	O
,	O
each	O
US	O
dollar	O
worth	O
of	O
bitcoin	B-Protocol
mined	O
caused	O
35	O
cents	O
worth	O
of	O
climate	O
damage	O
,	O
comparable	O
to	O
the	O
beef	O
industry	O
and	O
the	O
gasoline	O
industry	O
.	O
</s>
<s>
As	O
of	O
2021	O
,	O
Bitcoin	B-Protocol
's	O
annual	O
e-waste	O
is	O
estimated	O
to	O
be	O
over	O
30,000	O
tonnes	O
,	O
which	O
is	O
comparable	O
to	O
the	O
small	O
IT	O
equipment	O
waste	O
produced	O
by	O
the	O
Netherlands	O
.	O
</s>
<s>
Creating	O
one	O
bitcoin	B-Protocol
generates	O
of	O
e-waste	O
.	O
</s>
<s>
The	O
average	O
lifespan	O
of	O
bitcoin-mining	O
devices	O
is	O
estimated	O
to	O
be	O
about	O
1.3	O
years	O
.	O
</s>
<s>
Unlike	O
most	O
computing	O
hardware	O
,	O
the	O
used	O
application-specific	O
integrated	O
circuits	O
have	O
no	O
alternative	O
use	O
beyond	O
bitcoin	B-Protocol
mining	O
.	O
</s>
<s>
Reducing	O
Bitcoin	B-Protocol
's	O
environmental	O
effects	O
is	O
difficult	O
;	O
possible	O
remedies	O
include	O
making	O
bitcoin	B-Protocol
only	O
where	O
or	O
when	O
there	O
is	O
excess	O
clean	O
electricity	O
.	O
</s>
<s>
Some	O
policymakers	O
have	O
called	O
for	O
further	O
restrictions	O
or	O
bans	B-Architecture
on	I-Architecture
bitcoin	I-Architecture
mining	I-Architecture
.	O
</s>
<s>
,	O
the	O
Cambridge	O
Centre	O
for	O
Alternative	O
Finance	O
(	O
CCAF	O
)	O
estimates	O
that	O
Bitcoin	B-Protocol
consumes	O
annually	O
,	O
representing	O
0.29	O
%	O
of	O
the	O
world	O
's	O
energy	O
production	O
and	O
0.59	O
%	O
of	O
the	O
world	O
's	O
electricity	O
production	O
,	O
ranking	O
Bitcoin	B-Protocol
mining	O
between	O
Ukraine	O
and	O
Egypt	O
in	O
terms	O
of	O
electricity	O
consumption	O
.	O
</s>
<s>
George	O
Kamiya	O
,	O
writing	O
for	O
the	O
International	O
Energy	O
Agency	O
,	O
said	O
that	O
"	O
predictions	O
about	O
Bitcoin	B-Protocol
consuming	O
the	O
entire	O
world	O
's	O
electricity	O
"	O
were	O
sensational	O
,	O
but	O
that	O
the	O
area	O
"	O
requires	O
careful	O
monitoring	O
and	O
rigorous	O
analysis	O
"	O
.	O
</s>
<s>
One	O
study	O
in	O
2021	O
by	O
cryptocurrency	O
investment	O
firm	O
Galaxy	O
Digital	O
claimed	O
that	O
Bitcoin	B-Protocol
mining	O
used	O
less	O
energy	O
than	O
the	O
banking	O
system	O
,	O
with	O
Galaxy	O
Digital	O
later	O
clarifying	O
that	O
bitcoin	B-Protocol
mining	O
's	O
energy	O
usage	O
is	O
not	O
correlated	O
with	O
its	O
"	O
transactional	O
volume	O
or	O
throughput	O
"	O
as	O
it	O
is	O
in	O
banking	O
.	O
</s>
<s>
Until	O
2021	O
,	O
according	O
to	O
the	O
CCAF	O
,	O
much	O
of	O
the	O
mining	O
for	O
Bitcoin	B-Protocol
was	O
done	O
in	O
China	O
.	O
</s>
<s>
In	O
June	O
2021	O
China	O
banned	O
bitcoin	B-Protocol
mining	O
and	O
the	O
miners	O
moved	O
to	O
other	O
countries	O
.	O
</s>
<s>
It	O
switched	O
entirely	O
to	O
bitcoin	B-Protocol
mining	O
in	O
2019	O
.	O
</s>
<s>
As	O
of	O
September	O
2021	O
,	O
according	O
to	O
the	O
New	O
York	O
Times	O
,	O
Bitcoin	B-Protocol
's	O
use	O
of	O
renewables	O
ranged	O
from	O
40%	O
to	O
75%	O
.	O
</s>
<s>
Concerns	O
about	O
Bitcoin	B-Protocol
's	O
environmental	O
effects	O
relate	O
the	O
network	O
's	O
energy	O
consumption	O
to	O
carbon	O
emissions	O
.	O
</s>
<s>
The	O
difficulty	O
of	O
translating	O
energy	O
consumption	O
into	O
carbon	O
emissions	O
is	O
due	O
to	O
the	O
way	O
bitcoin	B-Protocol
mining	O
is	O
distributed	O
,	O
making	O
it	O
difficult	O
for	O
researchers	O
to	O
identify	O
miner	O
's	O
location	O
and	O
electricity	O
use	O
.	O
</s>
<s>
The	O
results	O
of	O
studies	O
into	O
Bitcoin	B-Protocol
's	O
carbon	O
footprint	O
vary	O
.	O
</s>
<s>
Per	O
a	O
study	O
published	O
in	O
Finance	O
Research	O
Letters	O
in	O
2021	O
,	O
the	O
differences	O
in	O
underlying	O
assumptions	O
and	O
variation	O
in	O
the	O
coverage	O
of	O
time	O
periods	O
and	O
forecast	O
horizons	O
have	O
led	O
to	O
Bitcoin	B-Protocol
carbon	O
footprint	O
estimates	O
spanning	O
from	O
1.25.2Mt	O
to	O
130.50Mt	O
per	O
year	O
.	O
</s>
<s>
According	O
to	O
studies	O
published	O
in	O
Joule	O
and	O
American	O
Chemical	O
Society	O
in	O
2019	O
,	O
Bitcoin	B-Protocol
's	O
annual	O
energy	O
consumption	O
results	O
in	O
annual	O
carbon	O
emission	O
ranging	O
from	O
17	O
to	O
22.9Mt	O
which	O
is	O
comparable	O
to	O
the	O
level	O
of	O
emissions	O
of	O
countries	O
as	O
Jordan	O
and	O
Sri	O
Lanka	O
.	O
</s>
<s>
In	O
September	O
2022	O
,	O
a	O
report	O
in	O
the	O
journal	O
Scientific	O
Reports	O
found	O
that	O
from	O
2016	O
to	O
2021	O
,	O
each	O
US	O
dollar	O
worth	O
of	O
mined	O
bitcoin	B-Protocol
market	O
value	O
also	O
caused	O
35	O
cents	O
worth	O
of	O
climate	O
damage	O
.	O
</s>
<s>
Compared	O
to	O
gold	O
mining	O
,	O
"	O
Bitcoin	B-Protocol
's	O
climate	O
damage	O
share	O
is	O
nearly	O
an	O
order	O
of	O
magnitude	O
higher	O
"	O
according	O
to	O
study	O
co-author	O
economist	O
Andrew	O
Goodkind	O
.	O
</s>
<s>
Bitcoins	B-Protocol
annual	O
e-waste	O
is	O
estimated	O
to	O
be	O
over	O
30,000	O
tonnes	O
as	O
of	O
May	O
2021	O
,	O
which	O
is	O
comparable	O
to	O
the	O
small	O
IT	O
equipment	O
waste	O
produced	O
by	O
the	O
Netherlands	O
.	O
</s>
<s>
One	O
bitcoin	B-Protocol
generates	O
of	O
e-waste	O
per	O
transaction	O
.	O
</s>
<s>
Due	O
to	O
the	O
consistent	O
increase	O
of	O
the	O
Bitcoin	B-Protocol
network	O
's	O
hashrate	O
,	O
mining	O
devices	O
are	O
estimated	O
to	O
have	O
an	O
average	O
lifespan	O
of	O
1.29	O
years	O
until	O
they	O
become	O
unprofitable	O
and	O
need	O
to	O
be	O
replaced	O
.	O
</s>
<s>
Other	O
estimates	O
assume	O
that	O
a	O
Bitcoin	B-Protocol
transaction	O
generates	O
about	O
of	O
e-waste	O
,	O
equivalent	O
of	O
2.35	O
iPhones	O
.	O
</s>
<s>
Unlike	O
most	O
computing	O
hardware	O
the	O
used	O
application-specific	O
integrated	O
circuits	O
have	O
no	O
alternative	O
use	O
beyond	O
bitcoin	B-Protocol
mining	O
.	O
</s>
<s>
Several	O
papers	O
concluded	O
that	O
these	O
renewable	O
power	O
stations	O
could	O
use	O
the	O
surplus	O
energy	O
to	O
mine	O
Bitcoin	B-Protocol
and	O
thereby	O
reduce	O
curtailment	O
,	O
hedge	O
electricity	O
price	O
risk	O
,	O
stabilize	O
the	O
grid	O
,	O
increase	O
the	O
profitability	O
of	O
renewable	O
energy	O
infrastructure	O
,	O
and	O
therefore	O
accelerate	O
transition	O
to	O
sustainable	O
energy	O
and	O
decrease	O
Bitcoin	B-Protocol
's	O
carbon	O
footprint	O
.	O
</s>
<s>
A	O
survey	O
on	O
technologies	O
approached	O
cryptocurrencies	O
 '	O
technological	O
and	O
environmental	O
issues	O
from	O
many	O
perspectives	O
and	O
noted	O
the	O
plans	O
of	O
using	O
the	O
methods	O
of	O
unconventional	B-Device
computing	I-Device
and	O
grid	B-Architecture
computing	I-Architecture
to	O
make	O
Bitcoin	B-Protocol
both	O
greener	O
and	O
more	O
justified	O
.	O
</s>
<s>
Per	O
a	O
2021	O
study	O
in	O
Finance	O
Research	O
Letters	O
,	O
"	O
climate-related	O
criticism	O
of	O
Bitcoin	B-Protocol
is	O
primarily	O
based	O
on	O
the	O
network	O
's	O
absolute	O
carbon	O
emissions	O
,	O
without	O
considering	O
its	O
market	O
value.	O
"	O
</s>
<s>
It	O
argues	O
that	O
the	O
inclusion	O
of	O
Bitcoin	B-Protocol
in	O
an	O
equity	O
portfolio	O
reduces	O
that	O
portfolio	O
's	O
"	O
aggregate	O
carbon	O
emissions	O
"	O
.	O
</s>
<s>
Policy	O
to	O
move	O
from	O
proof	O
of	O
work	O
to	O
proof	B-Protocol
of	I-Protocol
stake	I-Protocol
has	O
been	O
compared	O
to	O
policy	O
to	O
move	O
from	O
fossil-fueled	O
to	O
electric	O
cars	O
,	O
with	O
some	O
calling	O
for	O
a	O
ban	O
on	O
PoW	O
.	O
</s>
<s>
Bitcoin	B-Protocol
developers	O
are	O
working	O
on	O
the	O
Lightning	B-Protocol
Network	I-Protocol
.	O
</s>
