Calculating DG Energy Savings
This section provides a summary description of DG energy savings. (If
you would like to calculate DG savings before you review this page, click
on Your Site Savings)
Topics include:
Overview
Potential energy bill savings available with a DG system at your site are
determined with a detailed mathematical/engineering optimization process
which considers each of the following factors:
-
Technology characteristics of alternative DG systems
-
Your site's electric and thermal hourly loads for each of the 8,760 hours
in the year
-
Energy rate structures
-
Alternative operating strategies
-
Other considerations including emissions and noise constraints
More information on each of these factors and their application in DG Marketplace
analysis is provided below.
Limited User Inputs
We know that you are busy, so we've developed a process that requires as
little or as much information as you would like to provide on your site.
Rerun your analysis with more information later.
Technology Characteristics
Each DG technology is described by the following characteristics:
-
size (kW)
-
electric generation efficiency
-
waste heat characteristics (BTU/kWh)
-
equipment & installation costs
-
operating & maintenance costs
-
other operating/cost characteristics
8760 Hourly Loads
Your site's 8,760 hourly energy use characteristics are one of the most
important determinants of DG system economics. Hourly load (i.e., hourly
kW use for each hour in the year) detail is developed in a proprietary on-line
hourly load profiling process which makes use of information that you provide
on your site or which is developed for "typical customers" in detailed market
segments. 8,760 load series are developed for
-
Total site electric use
-
Electric space heating, air conditioning, water heating and process heating
and cooling
-
Fossil-fuel fired or district energy supplied space heating, air conditioning
water heating and process heating and cooling
Energy Rate
Structures and Operating Strategies
For all but the smallest customers (i.e., for all but residential and small
commercial and small industrial), electricity bills typically include an
energy charge for all kWh used in the month and a demand charge for the maximum
kW used in within the month. It is economically advantageous to run a DG
system when cost savings of the system (reduced electric and reduced fossil
fuel bills) minus the cost of operating the DG system (fossil fuel for generation
and O&M costs) are greater than the cost of purchasing electricity from
the utility. The optimal DG operating design and operating strategy is
determined from an hour-by-hour analysis of the system throughout the year.
DG Marketplace evaluates peak clipping, intermediate and baseload applications
of each technology in electric generation-only and combined heat and power
(CHP) applications. CHP applications which apply waste heat to space heating,
air conditioning and water heating are especially important in determining
potential energy bill savings at each site for intermediate and baseload
applications.
Other Issues
Other technology and site-specific constraints such as emissions requirements
and noise restrictions also impact DG economics and technology choices and
must be considered in individual site applications.
Analysis Methodology
The DG analysis process in DG Marketplace effectively "tries out" each available
technology at your site in various applications and operating strategies
to determine which system best meets the economic criterion you have specified
in the session.
Note
on How DG Marketplace Develops 8760 Hourly Loads for Your Site
The analysis process described above illustrates the important role played
by DG Marketplace's online 8760 hourly loads profiler. By using information
provided for each user along with an extensive database of 8760 hourly loads
for approximately one million utility customers, DG marketplace is able to
apply an engineering/statistical process to determine the unique hour-by-hour
electric and fossil fuel energy use characteristics of your site.
The initial forms in a DG Marketplace session ask a series of questions
describing the potential DG site. Business type, size, and location (zip
code) are required for all sites; some additional energy use information
is required for manufacturing sites. Optional site information includes items
such as operating hours, heating and air conditioning fuel use and available
billing data.
From this customer site information DG Marketplace develops detailed hourly
loads for each hour of the year for the entire site and for individual fuels
and end uses (e.g., space heating, etc) mentioned above. This 8760 hourly
load development is accomplished with a proprietary customer load profiling
system developed by Jackson Associates and widely used by utilities, retail
energy providers, ESCOS, DG equipment manufacturers, DG integrators and other
energy-related organizations.
The load profiling methodology applies an engineering/statistical process
which integrates actual site-data with 8760 hourly loads data from the
MAISY (Market Analysis and Information
System) Utility Customer Hourly Loads Databases which consist of approximately
1 million individual utility customer 8760 hourly load records.
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