Okay, so you haven't seen this anywhere else and it isn't on Faux News or in the
. And, well, the Department of Energy isn't saying this. But, the
has a "draft" report that came to this conclusion. While the report (after the fold) was put out for comment, it seems to have disappeared from the DOE/NREL website. And, we must wonder whether it will ever see the light of day from the Cheney Fossil Fuel Administration.
Now, this report is not perfect and merits discussion, it is exciting. With just a little bit of leadership, could the US energy supply situation undergo massive change in the near term? What would that mean for Global Warming? For the economy? For the environment? And, this is supply. It does not discuss efficiency. Nor does it even question usage patterns. In any event, the full report as supplied to me is after the fold.
On January 16, 2006, the Energy Analysis Office (EAO) of the National Renewable Energy Laboratory (NREL) issued for the Office of Science a
analysis, for comment, of the technical potential for renewables. EAO's preliminary analysis included a summary table representing near-term and ultimate technical potential for renewable energy resources (economic and market considerations are not taken into account). The seven-page document is entitled
.
The representation for the near term potential is given in percentage of electric generation in the United States in 2020. Near-term potential is restricted by near-term challenges, such as infrastructure and reliability problems, electricity storage, and technological ability to use the resource. Nonetheless, the "near-term practical" potential of renewable resources as a percent of U.S. electricity generation in 2020 is estimated to be 99-124 percent, or - in terms of primary energy - as 47-55 quads/year (electricity only).
The ultimate technical potential is a compilation of previous estimates and calculations based on those estimates. While the analysis assumes some near-term challenges will be overcome, the ultimate potential does account for constraints on technologically insurmountable goals, such as generally accepted restrictions on offshore wind facility distance from shore (200 meters), and on drilling capability for enhanced geothermal systems (10 km of depth). The table suggests that the ultimate technical potential for renewable resources could be as much as 8,529 quads/year.
We must note that the resulting estimates offer rough estimates of the potential contributions from renewable resources, not economically or market-feasible projections. But, even if that "economic" (which would be changed massively with even the most reasonable of carbon taxes, critical to turn the corner / reach a positive tipping point re Global Warming) and market-feasible" would be just (just) 50%, that would mean that nuclear power and renewables would provide 70% of currently projected electricity. Add in easily achieved 15-25% efficiency, and that would mean a MASSIVE reduction in US green house gas emissions.
METHODOLOGY
Current Renewable Resource Use
Currently used renewable energy resources are drawn from a variety of
sources. The current installed nameplate capacity total is a summation of
verified, functioning electric-generation facilities (REPIS 2005).
Delivered electricity is based on 2004 electricity production (EIA 2005a).
For all the renewable electric technologies except biomass, primary
energy required to produce electricity is calculated based on an average
heat rate of 10,000 Btu/kWh for existing thermal power plants (EIA 2005b).
For biomass, a measured heat rate for power plants, 9,000 btu/kwh, is
used (EIA 2005b). For those renewable energy forms that also contribute
to heat and fuels markets, total primary energy shown is larger than the
thermal energy required to produce only electricity (EIA 2005a).
NEAR-TERM PRACTICAL POTENTIAL
The amount of electricity potentially produced by renewables is shown as a
percentage of the total projected U.S. generation in 2020: 5,085 billion
kWh (EIA 2005b).
BIOMASS
Biomass is the only renewable energy form cited that can be used as either
electricity or fuel. Because we cannot predict the distribution of
biomass use between electricity and fuel, we make two estimates. The
first assumes 100 percent of biomass is used for electricity, and the
second assumes that 100 percent is use for fuel. The baseline amount of
energy for these is the same, because it is limited by physical
availability of biomass. Perlack (2005) estimates 1.3 billion dry tons of
biomass is possible with the use of non-food cropland and forestland in
the long run. To determine the near-term potential the mid-range
scenarios from Perlack (2005) to identify a near-term range of 593 million
to 968 million dry tons. The biomass-to-energy conversion used is an
average of energy from biomass types of just more than 12 million btus per
ton (NREL 2005c). This range yielded a potential of between 8 and 13
quads of energy in the near term. To estimate the amount of electricity
that can be generated from the range, we assume a power plant heat rate of
9,000 Btu/kWh (EIA 2005b). The result is 17-28 percent of total U.S.
electric generation. Biomass as a fuel potential is expressed as a
percentage of projected 2020 petroleum demand: 26 million barrels per day
(EIA 2005b). Using 8-13 quads of available biomass energy, and a 49
percent fuel plant conversion efficiency, biomass could contribute 9-14
percent of the national petroleum demand in 2020.
GEOTHERMAL
Because of technology limitations, only hydrothermal energy is considered
in the short term. In 1979, the United States Geological Survey (USGS)
estimated that there were about 22 GW of discovered hydrothermal resources
(USGS 1979). While this estimate is dated, there has been no
authoritative study of the potential since that time. Using a 95 percent
capacity factor (NREL 2005c), 22 GWs represents 2 quads of energy (or 4
percent of U.S. electric generation) in 2020.
HYDROELECTRIC
Full hydroelectric potential is 140 GW (Hall et al 2003), which would
provide 9.4 percent of electric generation in 2020, assuming today's
national average capacity factor of 0.39 (NREL 2005c). Assuming a 10,000
Btu/kWh power plant heat rate conversion, this is equal to about 5.0 quads
of primary energy.
OCEAN
In the short term, the full potential of mechanical (wave, tidal, and
current) electrical generation is assumed. This resource is estimated to
have a full potential of 30 GW installed nameplate capacity. Assuming
constant power and a power plant conversion heat rate of 10,000 Btu/kWh,
this translates to 2.3 quads of primary energy (or 4.5 percent of the
electric generation) projected for 2020.
SOLAR
For the near-term technical photovoltaic potential, it is assumed that
there will be no storage for solar energy, and no PV generation will be
wasted. This implies that none of the nighttime loads can be met by
solar, and much of the load at dawn cannot be met (if PV capacity were
sufficient to meet such loads, PV output at midday would exceed loads,
wasting energy). These assumptions severely limit the impact of PV on the
electric system. The PV impact would be even more limited if one also
took into account the many conventional fossil and nuclear plants that
must run all the time. In this case, the PV capacity would have to be
even smaller to keep from wasting PV generation.
The near-term potential for concentrated solar power (CSP) is assumed to
be the minimum of the projected in-state electrical load and the actual
CSP resources in that state. In all cases, the projected state electrical
load is the minimum. Therefore, the near-term CSP potential is the
electric load of the state in which the CSP resource resides. In 2020,
the projected load for states for CSP potential is expected to be 12
percent of the total U.S. generation, creating an upper bound for CSP
electrical generation. Assuming a 10,000 Btu/kWh heat rate for power
plants, the estimated primary energy to create this electricity is 6
quads/year.
WIND
The short-term wind potential is limited by grid reliability/stability
concerns to be 20 percent of total generation [based on Wan and Parsons
(1993) estimate of between 4 percent and 50 percent]. Assuming a power
plant heat rate of 10,000 Btu/kWh, the primary energy equivalent is 10
quads.
ULTIMATE TECHNICAL POTENTIAL
Ultimate technical potential differs from the short-term potential by a
set of general assumptions for each resource type and one more general
assumption. The general assumption is that the electricity grid can
adjust to the diverse electricity fed into it by adding storage,
transmission, ancillary services, etc. Moreover, the ultimate assumptions
do not limit the amount of renewable electricity as a function of total
projected electricity demand. As with the short-term assumptions,
economic and market constraints are not accounted for in this long-term
technical potential.
BIOMASS
Biomass is the only renewable energy form cited that can be used as either
electricity or fuel. Because we cannot predict the distribution of
biomass use between electricity and fuel, we make no assumption regarding
the differences between the use of biomass for electricity and biomass for
fuel. The baseline amount of energy for these is the same, because it is
limited by physical availability of biomass. Perlack (2005) estimates 1.3
billion dry tons of biomass is possible with the use of non-food cropland
and forestland. The biomass-to-energy conversion used is an average of
energy from biomass types of just more than 13 million btus per ton (NREL
2005c). The total energy potential for biomass is 17 quads. To estimate
the amount of electricity that can be generated from 17 quads, we assume a
power plant heat rate of 9,000 BTU/kWh.
GEOTHERMAL
The hydrothermal estimate includes approximately 72-127 GW of as
yet-undiscovered resource (USGS 1979). The enhanced geothermal systems
estimate is based on an estimate of 42 TW, which includes the entire
potential heat source (Tester 1994).
HYDROELECTRIC
The ultimate potential is assumed to be the same as the near-term
potential.
OCEAN
The ultimate potential estimate or ocean-based power expands the near-term
potential to include power from ocean thermal energy of 0.11 TW (Sands
1980). The primary energy required for electricity generation, assuming a
heat rate of 10,000 Btu/kWh, is 9 quads.
SOLAR
Unlike the near-term potential, the ultimate potentials for both PV and
CSP are not assumed to be constrained by grid limitations, e.g., storage
is assumed, transmission is assumed available, etc. For PV, the total
resource potential (NREL 2003b) was restricted by excluding federal and
sensitive lands, assuming only 30 percent of land area can be covered with
PV, allowing only slopes that are less than 5 degrees, and requiring a
minimum resources of 6 kwh/m2/day. This results in an ultimate technical
potential of about 219 TW or 4,200 quads/year for PV systems, assuming a
22 percent capacity factor.
The CSP resource is restricted to areas with resource potential -- the
southwestern United States. The potential reduces that amount of land
that can be used for CSP by federal and sensitive lands, land with a slope
greater than a 5 percent gradient, major urban areas and features, and
parcels less than 5 km2 in area. The remaining area determined the
technical potential for CSP, assuming 50 MW/km2 (Price et al 2003).
WIND
The ultimate wind potential is not limited to 20 percent for intermittency
and grid stability reasons, as battery storage is assumed. Instead, wind
potential is limited by appropriate land selection (exclusions for federal
land, etc.) and technical feasibility. For onshore wind potential, using
estimated future capacity factors (NREL 2005b), and assuming complete use
of Class 3 winds and better, the result is 324 quads of primary energy
from wind. For offshore wind, Class 5 and better with a distance between
5 and 200 nautical miles (nm) were assumed. Between 5-20 nautical miles,
only one-third of wind energy in Class 5 and better is captured, between
20 and 50 nautical miles, two-thirds; and between 50 and 200 nautical
miles, the entirety. Assuming future capacity factors, the potential for
offshore wind primary energy is found to be 272 quads.
REFERENCES, DATA SOURCES, BACKGROUND MATERIAL
EIA 2005a - U.S. Department of Energy, Energy Information Administration.
Annual Energy Review 2004. DOE/EIA 0384-2004, Washington, DC: U.S.
Department of Energy
EIA 2005b - Assumptions to the Annual Energy Outlook 2005 with projections
for 2025. Washington DC: U.S. Department of Energy
EPRI/DOE. 1997. Renewable Energy Technology Characterizations, TR-109496.
Washington, D.C.: DOE
Hagerman, G., R. Bedard. 26-June-2005. "Ocean Kinetic Energy Resources in
the United States and Canada." EnergyOceans 2005, Washington, D.C.
Hall, D., R. Hunt, K. Reeves, G. Carroll. 2003. Estimation of Economic
Parameters of U.S. Hydropower Resources. Idaho National Engineering and
Environmental Laboratory
Land and Water Fund of the Rockies. 2002. Renewable Energy Atlas of the
West. The Hewlett Foundation and The Energy Foundation. Page 10.
http://energyatlas.org.
Morse, F. 2004. Presentations: The Concentrating Solar Power Global Market
Initiative (GMI) as a Result of Research and Development. Presented at
the Renewables 2004 Conference.
NREL 2003a - National Renewable Energy Laboratory. Assessing the Potential
for Renewable Energy on Public Lands. 95 pp.; NREL Report No.
TP-550-33530; DOE/GO-102003-1704. Golden, CO: NREL
NREL 2003b - National Solar Photovoltaics (PV) Data. U.S. Data
http://www.nrel.gov/...
NREL 2005a - Assessing the Potential for Renewable Energy on National
Forest Systems Lands. 123 pp; NREL Report No. BK-71036759. Golden, CO:
NREL
NREL 2005b - Potential Benefits of Federal energy Efficiency and Renewable
Energy Programs: FY 2006 Budget Request NREL-TP 620-37931. Golden, CO:
NREL
NREL 2005c - Power Technologies Energy Data Book. Golden, CO: NREL. URL:
http://www.nrel.gov/...
Perlack, R., Wright, L., Tuhollow, A., Graham, R., Biomass as Feedstock
for a Bioenergy and Bioproducts Industry: The Technical Feasibility of a
Billion-Ton Annual Supply, April 2005
Price, H.; Stafford, B.; Heimiller, D; Dahle, D. 2003. California Solar
Power Detailed Technical Report for Southern California Edison. 95 pp.;
NREL Report No. MP-710-35284
REPIS 2005 - Renewable Electric Plant Information System:
http://www.nrel.gov/...
Sands, D. 1980. "Ocean thermal energy conversion programmatic
environmental assessment." Proceedings of the 7th Ocean Energy
Conference, Volume 1, Paper 4.1., Washington, D.C.: U.S. Department of
Energy, Publication No. Conf-800633-Vol 1.
Tester, J.W., H.J. Herzog, Z. Chen, R.M. Potter, and M.G. Frank. 1994.
Prospects for Universal Geothermal Energy from Heat Mining. Science &
Global Security. Volume 5, pp.99-121
Thresher, R. (NREL). 2005. E-mail communication to Elizabeth Brown.
October 14, 2005
TroughNet. 2005. Troughnet CSP Projects Deployed Web page.
USGS (United States Geological Survey) 1979, "Assessment of Geothermal
Resources of the United States - 1978". Geological Survey Circular 790,
Edited by L.J.P. Muffler, United States Department of the Interior.
Wan Y. and Parsons, B. 1993. "Factors Relevant to Utility Integration of
Intermittent Renewable Technologies." NREL/TP-463-4953. National
Renewable Energy Laboratory: Golden, CO. Page 49
# # # # # # #
The DRAFT document had earlier been available for inspection at:
<http://www.nrel.gov/analysis/tech_potential/pdfs/tech_potential_table.pdf>
but now appears to have been withdrawn. Comments on the draft had been
requested to be sent to Elizabeth Brown in NREL's Energy Analysis Office
at elizabeth_brown@nrel.gov; 303-384-7489.