I'm a well known pessimist about the potential of wind and solar power
to to plug the coming energy gap. In defense of my concerns, here is
some analysis of the energy we will need to replace over the next few
decades and the potential for wind power to address that shortfall.
: As with the
previous articles in this series, the
analysis is intended
solely to clarify future trends based purely on the
situation as it now exists and the directions it shows obvious signs of
taking. The model does not include any effects of the various
large-scale changes in direction that have been proposed to cope
with declining oil supplies or rising levels of greenhouse gases.
or nuclear power "Manhattan Project" style efforts, for example,
are not considered. Treat this scenario as a cautionary
tale: Given projected trends in
energy supplies, energy efficiency and population levels, this is a
probable outcome if we just
continue business as usual.
Supply vs. Demand
First we need to decide how much energy is the world
going to need over the next few decades. We can find out how much we've
used in the past from the BP Statistical Review of World Energy 2007
that source we find that over the last 20 years global primary energy
consumption has grown by an average of about 2% per year.
The world demand in the future is harder to predict, because we're
heading into a time of recession (at the very least). Given the coming
uncertainties and the possibility for a global
conservation effort, for this scenario I cut the growth estimate of 2%
in half, for a conservative average
growth of 1% per year. That gives the following demand curve (MTOE
stands for Millions of Tonnes of Oil Equivalent):
Now we need to decide what the energy supply will look like over that
period. I did a fairly careful analysis of that question last
year, and published it in this
. The following curve uses the data from that analysis, and
aggregates the expected supply of oil, natural gas, coal, hydro and
Looking at those two graphs, it is obvious that there will be a growing
gap between energy supply and demand:
Wind Power Potential
Here is a well-known chart from the World Wind Energy Association
showing world wind capacity, installed and planned out to 2010:
We can extract the annual increase in installed capacity from that
chart to give us the next graph. It shows the annual capacity
addition out to 2050. It uses the data from the above chart out
to 2010 and a mathematical projection from 2010 to 2050. It shows
an estimate of the amount of wind capacity we will be able to add each
does that added capacity compare to the requirement created by the gap
we saw opening
In order to answer that question I translated that gap into annual wind
requirements as follows:
- I determined the amount of new energy
required each year by subtracting the total demand in the previous year
from the total demand in the current year.
- I converted MTOE to TWh
by multiplying by 4.42, the same conversion factor BP uses in their
- I converted the TWh figure into GW of capacity
by first multiplying first by 8.76 to convert TWh of energy required per year to GW of power, then
multiplying by 4 to account for an average capacity factor of 0.25.
I then plotted the resulting curve on the same graph as the actual
installation curve shown just above. The result looks like this:
projected growth in actual wind installations is a second-order
polynomial projection, and that may turn out to be excessively
conservative. Nevertheless, As you can see, a remarkable disconnect
begins to develop in the coming decade. With the current increase in
installed wind capacity the situation looks increasingly difficult as
the decades roll by. I'm not saying it's impossible to plug the gap,
but it looks to me as though there will be a massive energy shortfall
unless something truly remarkable happens.
A small point of clarification is required about the above graph.
As long as the curve of actual additions stays below the curve
of required additions, the shortfall in cumulative capacity will
continue to grow. Only once the installation curve rises to meet the
requirement curve does the gap stop increasing. Then, mathematically
speaking, installations would need to consistently exceed requirements
to reduce the supply-demand shortfall. In the scenario above, it looks
as though the gap would stop growing in about 2060 or so.
When I first published this article I received a number of objections
to the assumptions and methodology. Each of those objections is
addressed below. You may decide for yourself if my rebuttals are
correct or sufficient.
You Shortchange the Role of Conservation
One question that comes up in response to any analysis like this is
whether conservation can play enough of a role to soften the blow of
energy decline. Might we be able to conserve our way out of the
My answer is, "What amount of annual global energy reduction through
do you think is possible, probable and realistic?"
Our economic system is built on an intrinsic assumption of permanent
growth, and has shown no sign at all of changing that cornerstone
principle. If that
continues to be the case, then conservation and efficiency improvements
have to be modeled as an improvement in the energy intensity of the
global GDP (I previously discussed energy intensity in this
As high-return energy sources like oil and gas are used up
and gradually replaced by lower-return sources like biofuels and wind
turbines, is such an improvement even possible? Some analysts (and I am
argue that it's not possible, that the reduction in the EROEI
(Energy Return on Energy Invested) of the world's aggregate energy
supply will cancel out most efficiency and conservation
improvements. As a result I do not feel that the realistically
expected levels of conservation will be enough over the time we have
You Didn't Mention Solar, Tidal or Fusion Power
isn't enough history of large-scale solar or tidal installations yet to
project a realistic growth curve for either. Certainly solar
have a bright future
but it's still too early to tell. Current global installed solar
only 5% of wind. I used wind as a proxy for all renewables, because it
has a very healthy growth curve, and one that can be extrapolated with
some degree of confidence. I prefer to base my projections on a
reasonable amount of historical data.
The same need for evidence mandates my exclusion of fusion -- let's get
a couple of fusion reactors up and running first, and then see where
The Capacity Factor You Used is Too Low
Wind turbines typically put out a lot less power than their nameplate
rating might suggest. While a turbine can theoretically put out
any amount from 0 to 100% of its nameplate rating, the accepted
'average" range is 25% to 30% of nameplate capacity. However,
some turbines in operation are putting out 35% of their rated
capacity. Perhaps my assumption of 25% was too low?
For a global analysis like this I assume that since we'll be putting up
wind around the world,
the amount required will necessarily force us to build wind farms in
less-than-ideal locations (say in Africa or much of South Asia). As a
result, I based the analysis on the lower number -- coming in on the
low end of the first standard deviation for
the global picture seems reasonable.
In fact, according to installed capacity figures for 2004 and
2005 from the American
Wind Energy Association,
and wind generation figures for
2005 from the Energy
, the actual wind generation capacity
the USA for 2005 was just a bit over 25%. The assumption appears
What About High Efficiency Electric Transportation?
This argument insists that much of the additional electricity will be
used for transportation. Since electric cars are much more
efficient than gasoline powered automobiles, it will require less
electrical energy to replace the transportation needs not being filled
While this argument is true, it doesn't tell the whole story.
A bit less than 70% of oil is used for
transportation. Natural gas (which contributes to the total energy gap)
is a very minor player in that application: it's used mainly for
electricity, process heat and petrochemicals. As a result the overall
impact of the higher efficiency of Electric Vehicles vs. Internal
Combustion vehicles is diluted.
the conversion factor of 4.42 TWh of electricity per MTOE used by by BP
significantly lower than the thermal energy of oil (11.63 TWh of
thermal energy per MTOE as given in standard
. As a result, the conversion the conversion
factor already takes into account the higher
efficiency of electricity, and certainly much of the improved
efficiency of electric cars.
One last point is that
some of the energy gap is due to the decommissioning of older nuclear
reactors at their end-of-life, with insufficient construction to
them. Any energy lost from that source has to be directly replaced by
electricity from another source, with no source-related efficiency
You're Ignoring the Price Elasticity of Gasoline Demand
This argument maintains that as gasoline prices rise due to shortages
that gasoline use will fall off to compensate.
elasticity of demand
for transportation fuel is actually quite low
(i.e. demand is very price inelastic). Typical
for gasoline in developed nations are around
-0.1. That means that a 10% increase in fuel
prices would result in only a 1% drop in demand. Even that figure seems
too high in the short term given the fact that North American driving
habits really haven't changed appreciably as gasoline prices have risen
over the last couple of years. Part of that may be due to the lack of
available substitutes like electric cars, but that's the picture at the
The reason I think the elasticity picture is unlikely to change much in
term is that fuel costs are still a small part of family budgets.
That means that gasoline prices would need to rise a lot before most
people saw much economic sense in investing in a new type of vehicle. I
don't expect such a shift to be widespread before the next vehicle
replacement cycle is over in 15 years.
I do not think that wind power
(or any combination of wind, solar or other renewables) is likely to
plug the energy gap that will be opening up over the next couple of
decades. We should all be preparing ourselves for a world in
which energy is becoming increasingly scarce and expensive.
In the light of all I've described here, do you think my pessimism is