WRSC Renewable Energy Solutions For Utility-Scale Applications

1
WRSC Renewable Energy SolutionsFor Utility-Scale
Applications
Images Cleantechia.com, biocomicfuel.com
2
METHODOLOGY

• METRICS
• For each Renewable Option, the following factors
  were compiled and analyzed
• The factors highlighted in grey are evaluated in
  the following report.

Capacity Reliability Technology Risk Legal/Regulatory Available Incentives
Carbon Footprint Environmental Impact Payback Period Marginal Cost Ease of Implementation
All sources listed on accompanying spreadsheet
3
RENEWABLE ENERGY SOLUTIONS
Concentrating solar power (CSP) technologies use
mirrors to reflect and concentrate sunlight onto
receivers that collect the solar energy and
convert it to heat. This thermal energy can then
be used to produce electricity via a steam
turbine or heat engine driving a generator. The
following four technologies are forms of CSP
Solution Overview
Parabolic Trough (CSP) Trough technology is a type of solar thermal energy collector and is constructed as a long parabolic mirror. Sunlight is reflected by the mirror and concentrated on a central tube. It uses one-axis (usually North to South) tracking and achieves a maximum temperature of about 400C. This relatively low operating temperature makes it very difficult to provide the amount of heat storage (in a cost-effective manner) that is required for around-the-clock availability.
Power Tower (CSP) Tower receiver technology uses two-axis tracking and achieves a maximum temperature of about 650C. The higher operating temperature of tower technology reduces susceptibility of these systems to efficiency losses, especially when dry cooling is used.
Dish Sterling/Dish Engine (CSP) Dish Engine systems convert solar thermal energy into mechanical energy and then to electrical energy in much the same way that conventional power plants convert thermal energy from combustion of a fossil fuel to electricity. They use a mirror array to reflect and concentrate incoming sunlight onto a receiver. Dish Engine systems have the inherent hybrid capability to operate on either solar energy or a fossil fuel, or both, making them an attractive option.
Linear Fresnel Reflector (CSP) Linear Fresnel reflector technology uses one-axis tracking and achieves a maximum temperature of about 400C. The reduced efficiency (15 to 25) compared to troughs is expected to be offset by substantially lower capital costs.
4
RENEWABLE ENERGY SOLUTIONS
Solar PV Large Scale Solar PV Installations generate electrical power by converting solar radiation into direct current electricity using semiconductor panels. Rapid advancements in PV technology are making it an increasingly cost-effective option for utilities who require it in their energy portfolio.
Big Wind Large wind farms, thanks to increased investment and policy, are very prevalent across the US. With a very low marginal cost (0.01-0.02/kWh) and several mechanisms in place to expedite their development in California, utility use of wind power continues to grow. Storage issues, however, limit the availability of energy needed to match peak loads, making new transmission infrastructure a critical factor in their development.
Biomass/Biogas Biomass includes agricultural residues, forest resources, perennial grasses, woody energy, crops, wastes (municipal solid waste, urban wood waste, and food waste), and algae. It is unique among renewable energy resources in that it can be converted to carbon-based fuels and chemicals, in addition to power.
Geothermal Utility-scale geothermal power production employs three main technologies. These are known as dry steam, flash steam and binary cycle systems. The technology employed depends on the temperature and pressure of the geothermal reservoir. Unlike solar, wind, and hydro-based renewable power, geothermal power plant operation is independent of fluctuations in daily and seasonal weather.
5
CAPACITY
To measure the productivity of a renewable
energy option, we use its Capacity Factor (CF),
which is the amount of energy a power station
generates over time (usually a year) compared to
what it could have produced if it had been
running at full power for the whole period.
Capacity Factor is important not only because it
reflects the performance of a power station, but
also because a higher capacity factor represents
a more stable power grid.
Capacity Factor
Renewable Energy Options
6
CAPACITY INSIGHTS
Renewable Energy Option Capacity Factor
Geothermal .85
Biomass/Biogas .70
Parabolic Reflector Technologies Parabolic Trough Linear Fresnel .56 .54
Nuclear .95 - .98 Coal .65 - .75

Geothermal Energys high capacity factor is due
to the nature of its source, the Earths heat,
which is independent of daily and seasonal
weather fluctuations, allowing it to run at full
power most of the time. Its ability to match
peak loads, makes it a promising option to
replace dirty coal in the energy mix. Similarly,
with a steady supply, Biomass/gas plants can run
at full power around the clock. Of the four CSP
based Solutions, Parabolic Reflector Technologies
- Linear Fresnel and Parabolic Trough have
significantly greater productivity and grid
stability than the other two options. It should
be noted, however, that Power Tower technologies,
have a projected Capacity Factor of .73. Although
development is less advanced than Parabolic
Reflector based systems, they offer higher
efficiency and better energy storage capability,
which is required for around-the-clock
dispatchability (NREL).
7
RELIABILITY

• An Availability Factor (AF) is used to determine
  how reliable or constant an energy source is,
  especially during peak loads. Note, this is
  different from capacity factor which measures
  what percentage of the time the plant is able to
  run at full capacity. When looking at the AF it
  is important not only to compare across renewable
  sources but also to conventional fossil fuel
  based sources.

Availability Factor 1 (Low) - 5 (High)
Renewable Energy Options
8
RELIABILITY INSIGHTS
Renewable Energy Option Availability Factor
Geothermal .80
Concentrated Solar Technologies .70
Wind Biomass/Biogas .30 .80

Coal .65 - .90 Nuclear .70 - .90
(depending on how new the plant is)
Geothermal is considered the most reliable source
due to its ability to generate a steady stream of
energy 24/7.
Although Solar is an intermittent resource,
concentrated solar energy can be stored at high
temperatures using molten salts. Salts are an
effective storage medium because they are
low-cost, have a high specific heat capacity and
can deliver heat at temperatures compatible with
conventional power systems.
Wind and Biomass/Biogas are less reliable since
their energy source is more variable.
9
INSIGHTS CONT
Wood comprises the majority of the energy source.
Therefore, logging regulations and transportation
costs vary greatly depending on the location of
the plant.
Wind, also an intermittent source, cannot
guarantee constant availability. And without
storage, must be used as soon as it is produced,
or immediately transported to where it can be
used, through transmission lines. Improved
reliability is possible with a widely
geographically dispersed set of wind farms,
raising its availability factor to .85.
Image http//www.dasgelbeforum.de.org/
10
TECHNOLOGY RISK
Technology Risk is the degree of uncertainty
associated with technology performing according
to its planned or desired functionality. It is
important when considering renewable energy
options because performance in lab or pilot
studies can vary greatly from installed
operational performance.
Technology Risk Ratings 1 (High Risk) - 5 (Low
Risk)
Renewable Energy Options
11
TECHNOLOGY RISK INSIGHTS
Renewable Energy Option Rating
Parabolic Trough Solar PV Wind Biomass/Biogas 5 (Low)
Linear Fresnel Geothermal 4 3 (Moderate)
Power Tower Dish Sterling (Dish Engine) 2 (High)

• Trough technology is further advanced than
  tower, fresnel and dish technology, with 354 MW
  of commercial generation in operation in US. It
  is fully mature and there is low technical and
  financial risk in developing near-term plants.
• Solar PV, Wind Biomass/gas are all well
  established technologies with proven operational
  performance.

• Linear Fresnel, while the oldest CSP technology,
  suffers from a lack of reference plants already
  built, as well as up and running.
• Geothermal energy provided 16,010 GWh of
  electricity in 2005. However, larger scale use is
  limited unless permeability can be increased. The
  DOE has determined that the most critical
  near-term goal is the successful demonstration of
  Enhanced Geothermal Systems (EGS) and has
  identified 2015 as the key decision point for
  determining if it is technically feasible.

• Tower technology has been successfully
  demonstrated with a conceptual and pilot plants
  (Solar One and Solar Two) but has not been proven
  in a large commercial application.
• Dish Engine systems face high technology
  development risk. The DOE is currently working
  with companies to design, develop, install, and
  test pre-production prototype 25-kilowatt
  systems.

12
ENVIRONMENTAL RISK

• Environmental Risks associated with
  utility-scale Renewable Energy Installations can
  be very high and vary greatly on a site-by-site
  basis. Mitigating these risks can delay projects
  for years and cost millions in legal fees.
  Additionally, over the life of a plant the laws
  and regulations governing the environmental
  impacts are likely to change.

Environmental Risk Ratings 1 (High Risk) - 5 (Low
Risk)
Renewable Energy Options
13
ENVIRONMENTAL RISK INSIGHTS
Renewable Energy Option Rating
Wind Linear Fresnel Reflector Solar PV Biogas Geothermal 5 (Low)
Power Tower Parabolic Trough Dish Engine 3 (Moderate)
Biomass 2 (High)

• Wind carries low environmental risk because land
  is minimally effected and can still be used for
  agriculture/livestock. Additionally, it is well
  established and environmental risk assessments
  are easily carried out.
• Linear Fresnel installations use less than 4
  acres/MW, making the land requirement less than
  trough plants because more surface area can be
  covered with mirrors.
• Solar PV installations use 4 acres/MW, and have
  minor panel disposal issues.
• Biogas generation typically improves air
  quality, since methane from landfills is used as
  an energy source instead of being released into
  the atmosphere.
• Geothermal energy has low environmental risk and
  impact. When used with a closed-loop binary
  power plant, geothermal systems emit zero
  greenhouse gas emissions and have a near zero
  environmental risk or impact.

Typically parabolic trough power plants use about
8-10 acres/MW, Tower and Dish Engine use 10-15
acres/MW. Installations are usually are in remote
desert areas, however unique plants and animals
have to be protected costing time and money.
Biomass power raises the most environmental
issues.. Combustion of biomass and
biomass-derived fuels produces air pollution
beyond this, there are concerns about the impacts
of using land to grow energy crops that could be
used for food.
14
MARGINAL COST ESTIMATES

• One of the most important factors in evaluating
  how competitive renewable energy options are with
  traditional fossil fuels is the Levelized Cost of
  Energy (LCOE), or constant price per unit of
  energy that causes the utility companys
  investment to break even. The LCOE equation
  evaluates the life-cycle energy cost and
  production of a power plant, allowing alternative
  renewable energy options to be compared.

.30 - .40
Marginal Cost (/kWh)
.06 - .10
.08 - .10
.07
.05 - .08
.04 - .06
.06
.01 - .02
Renewable Energy Options
15
MARGINAL COST INSIGHTS
Renewable Energy Option Levelized Energy Cost (/kWh)
Wind Power Tower 0.01 - 0.02 0.04 - 0.06
Geothermal Biomass/Biogas Dish Sterling/Dish Engine Linear Fresnel Parabolic Trough 0.08 - 0.10 0.05 - 0.08 0.06 0.07 0.06 - 0.10
Solar PV 0.30 - 0.40

• Even with wind generations high upfront costs,
  low maintenance and low operational costs drive
  the LCOE down.
• With advances in technology, Power Towers are
  expected to be the most economical solar energy
  technology with estimates of less than 4
  cents/kWh.

• The other 3 CSP technologies range between 0.06
  - 0.10/kWh. Prices are expected to drop as more
  plants become operational and efficiencies are
  gained from new technologies.
• Biomass prices depend on the price of its
  source, which can vary widely at times.

Utility-Scale Solar PV installation have the
highest LCOE, which is greatly influenced by the
plants capacity factor. By raising the capacity
factor, the LCOE can decrease substantially, even
up to four times lower.
16
AVAILABLE INCENTIVES
Federal/State policy and tax incentives greatly
influence utility investment in renewables and
can help them offset high initial costs. The
availability and degree of incentives for
renewable energy options varies across industries
and states.
Incentives Rating 1 (Low) - 5 (High)
Renewable Energy Options
17
INCENTIVES INSIGHTS
Renewable Energy Option Rating
Wind Solar PV 5 (High)
Power Tower Parabolic Trough Dish Engine Linear Fresnel Reflector Biomass/Biogas 3 (Moderate)
Geothermal 2 (Low)
Wind and Solar PV receive a high degree of tax
and policy incentives. Large Federal tax
incentives and new state policies that expedite
permitting, environmental reviews and approval
processes for new Wind Farms and Solar PV
installations have enabled both industries to
flourish. c

• Concentrated Solar Technology is also receiving
  a relatively high degree of support. The same
  federal tax incentives are available to utilities
  looking to utilize these renewable energy
  supplies and, in California, efforts are being
  made to streamline the approval processes for new
  CSP plants as well.
• New National and DOE incentives are aimed at
  expanding the scope of Biomass/Biogas to include
  the development of other advanced biofuels that
  will contribute to the requirements of the
  Renewable Fuels Standard (RFS).

The largest problem facing the geothermal
industry is the lack of a Federal policy
promoting geothermal development. The economic
viability of most geothermal electricity
production projects continues to be dependent on
the financial support created by state energy
policy.
18
CASE STUDIES
Utility-Scale Case Studies (OSTI, NREL)
http//www.osti.gov/accomplishments/NRELprofiles.h
tml