The principal driver of energy consumption and demand growth in the United
States is increased population. The nations population is growing at a rate
of approximately 1 percent per year, as are total energy consumption and electric
consumption.,, If the current trend continues, the U.S. population
will be more than 460 million by 2050 and more than 750 million by 2100. If
current electricity consumption and demand trends continue, electric generating
capacity would be required to grow by nearly 60 percent by 2050 and by nearly
160 percent by 2100. While projecting the past into the future hardly represents
strategic planning, it can fit Einsteins definition of insanity: Continuing
to do the same things and expecting different results.
In order to do different things to gain diverse results, we must explore:
- What electric generation technologies will be used to meet future demand
for electricity in the U.S. and to replace the components of the current,
aging U.S. generating fleet?
- Where will new and replacement generation capacity be located?
- Who will build, own and operate the generating fleet?
This set of decisions will most likely be affected by political and environmental
considerations, as well as by technology and economics. For example, the growing
interest and concern regarding emissions from electric generation facilities
includes: criteria pollutants (sulfur oxides, nitrogen oxides, particulates,
mercury and radioactive gases, which are already regulated) and gases not currently
classified as pollutants, such as carbon dioxide. Federal limitations (or caps)
on carbon dioxide emissions, particularly if established on an absolute rather
than a per-capita basis, would be the most daunting political and environmental
challenge. It would also have the greatest impact on the electric generation
technologies employed to meet the future energy needs of the U.S.
As an illustration, consider Senate Bill 139, the Climate Stewardship Act of
2003. This bill would have required the reduction of total absolute carbon dioxide
emissions in the U.S. to 1990 levels by 2016 and would have capped them at that
level in the future. The door is left open for further reductions and reduced
caps on future carbon dioxide emissions beyond those required by the Kyoto Accords.
This initial reduction and compliance schedule is four years longer than that
established by the Kyoto Accords, which stipulated absolute emissions reductions
to 7 percent below 1990 levels by 2012 in the U.S. While some analysts have
characterized achieving these reductions and maintaining these caps as achievable
and realistic (even in the face of a growing population), others seriously question
both the need to reduce carbon dioxide emissions and the economic consequences
of doing so to this degree and on this schedule.
The X Factors
While the United States Congress is considering energy legislation and environmentalists
are advocating carbon dioxide emissions reductions, energy consumption and demand
continue to grow. Therefore, assuming no change in current population trends
or in per-capita energy consumption trends, the 60 percent increase by 2050
in U.S. energy consumption and U.S. electric consumption and demand would require
the construction of approximately 400 gW of incremental generation capacity,
as well as the replacement of most of the 680 gW of existing generating capacity
serving the U.S. market by 2050. If carbon dioxide emissions were capped at
1990 levels, this cumulative generation capacity would be required to have an
average carbon dioxide emission level per gW of capacity 50 percent below the
carbon dioxide emissions rate of the current U.S. generation fleet. This reduction
in carbon dioxide emissions would require a combination of dramatically more
efficient power plants, a significant shift in the mix of generation technologies
serving the U.S. market and the application of new technology for the capture
and permanent fixation of a significant portion of the carbon dioxide that would
otherwise be released.
A second factor that will also have a significant effect on what power plant
technology will be used and where it will be located is the availability of
water resources. Potable water for personal consumption and agricultural irrigation
is already under significant pressure in many parts of the United States. Some
states are restricting the use of water for power plant cooling, requiring the
use of dry cooling towers on new power plants. (The availability of power in
parts of Europe during the summer of 2003 was limited by the unavailability
of adequate cooling water for the full-capacity operation of nuclear power plants
in France.) The projected growth in U.S. population will put further pressure
on potable water supplies, yet current critical infrastructure planning in electricity
does not take this constraint into account.
The need for additional potable water produced by the desalination of seawater
and brackish water may have an even more significant impact on the technology
selection and location of power-generation capacity. While current desalination
plants typically use the reverse osmosis process, this process is electricity-intensive.
The heat rejected by steam-cycle power plants can also be used to desalinate
seawater or brackish water, increasing the overall thermal energy efficiency
of the power plants as well. However, this joint application would require that
the power plants be located relatively close to large sources of nonpotable
water along or near coastal areas.
A third factor is the potential demand for hydrogen as a motor vehicle fuel.
Hydrogen can be produced using either electrochemical or thermochemical processes;
however, the thermochemical process can also use the thermal energy released
in nuclear steam-cycle power plants, thus increasing the overall thermal energy
efficiency of the power plants. Hydrogen can also be produced by reforming natural
gas with steam, but this process releases carbon dioxide, and its application
to hydrogen production will ultimately be limited by competing demands for natural
gas and by federal and state restrictions on natural gas exploration and production.
A Mighty Wind?
The growing pressure to increase the role of renewable energy in power generation
would place new generation resources in very different locations from fossil
fuel or nuclear capacity requiring cooling water, or using process heat for
water desalination or hydrogen production. Increased solar and wind generation
would also require significantly improved electricity storage equipment. A significant
increase in wind-powered generation would add an additional complication. According
to the wind power industry, equivalent wind generation capacity must be installed
at eight to 10 selected sites to assure reliable availability of 8,760 hours
per year, since wind availability at any specific location is inconsistent.
Alternatively, larger-capacity facilities could be installed at a limited number
of sites, in combination with significantly improved electricity storage equipment,
to compensate for the intermittent nature of wind itself. Transmission capacity
would have to be available to move power at peak capacity from each of these
multiple sites to the load centers served by the generation. Regardless, it
is clear that both solar and wind generation must transition from their current
role as sources of opportunity to reliable sources of power if they are to
provide a significantly greater share of U.S. electricity generation.
Significant increases in large-scale hydroelectric generation in the U.S. are
unlikely because of environmental concerns and the limited availability of potential
additional sites. Significant increases in biomass generation face the same
carbon dioxide emissions and cooling water availability issues as coal-fueled
Perhaps the wild card in renewable-source generation of electric power is geothermal
production from dry, hot rock, which is estimated to have the potential capacity
to meet all of our electric generation needs in perpetuity. However, the
technology required to drill into this resource is not currently available.
A Modest Proposal
The challenges associated with the development of incremental and replacement-generating
capacity could be offset somewhat by a variety of factors, including:
- Increased appliance and equipment efficiency;
- Active retail and wholesale demand response, and market-based retail pricing;
- Increased electric load factors, resulting from both active and passive
demand management by electricity users; and
- The increased use of onsite or near-site power systems for peak shaving,
load sharing or combined heat and power systems.
Controlling the rate of population growth is another potential approach, although
it is fraught with political and ethical difficulties.
No single generation technology is likely to supply all of the new and replacement
generation capacity required over the next 50 to 100 years. The total capacity
requirement of approximately 1,700 gW would require approximately: 1,000 to
1,500 large nuclear power plants or Integrated- Gasifier Combined-Cycle (IGCC)
coal-fueled power plants with carbon dioxide fixation technology; 10,000 to
12,000 Combined-Cycle Turbine (CCT) natural gas-fueled power plants; 3,500,000
5mW wind turbines; or roughly 7,500 square miles of flat plate solar photovoltaic
collectors, with the associated storage and inverters. Serving this total capacity
with either coal or natural gas-fueled plants would exhaust the known reserves
of these fuels within the expected lives of the generators. These estimates
ignore the energy required for water desalination and hydrogen generation. While
much of this energy could be recovered from nuclear power plants, additional
generation would be required in the coal-fueled IGCC, natural gas CCT, wind
and solar cases, since adequate reject heat of sufficient quality would not
be available. NIMBY (not in my back yard) and BANANA (build absolutely nothing
anywhere near anyone) concerns will significantly increase the costs of developing
these new-generation resources.
The construction of new nuclear power plants presents an additional series
of very difficult issues. The nations nuclear-generation industry has been
plagued by high investment costs, the perceived risk of a nuclear accident,
delays in construction schedules resulting from regulatory re-evaluation of
plant design and construction requirements, the federal governments failure
to meet its obligations regarding longterm waste storage, and issues regarding
evacuation plans. Concerns regarding nuclear plant vulnerability to terrorist
attack have recently been added to the mix. It is highly unlikely that any new
nuclear generating plant construction will occur in the U.S. until regulatory
process issues are resolved. Plant developers can be reasonably sure that plants
can proceed through the siting, design, construction and commissioning process
without protracted delays.
A Road Map
Assuring that the solutions adopted today to solve current problems are sufficiently
flexible and adaptive to solve tomorrows problems is a very difficult challenge.
This test is especially difficult because the acceptable parameters for tomorrows
solutions, while they can be discussed, have not been defined in law and regulation.
This means they cannot be known with reasonable certainty. In many cases, they
are also not defined technically, particularly in commercially available hardware,
especially hardware that can be tested and characterized, much less deployed.
However, identifying, analyzing and discussing these issues are crucial to ensuring
that they are taken into account in current planning. In the immortal words
of that great American philosopher Yogi Berra: Youve got to be careful if
you dont know where youre going, because you might end up somewhere else.
- U.S. Census estimates. www.censusgov/popest/states/tables/NSTEST2004- 03.xls
- U.S. Department of Energys Energy Information Administration energy overview
- U.S. Department of Energys Energy Information Administration electricity
overview 1949-2003. www.eia.doe.gov/emeu/aer/txt/stb0801.xls
- The Status and Future of Geothermal Electric Power, Charles F. Kutscher,