# Source code for temoa_rules

"""
Tools for Energy Model Optimization and Analysis (Temoa):
An open source framework for energy systems optimization modeling

Copyright (C) 2015,  NC State University

This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

A complete copy of the GNU General Public License v2 (GPLv2) is available
in LICENSE.txt.  Users uncompressing this from an archive may not have
"""

# Import below required in Python 2.7 to avoid integer division
# (e.g., 1/2 = 0 instead of 0.5)
from __future__ import division

from temoa_initialize import *

##############################################################################
# Begin *_rule definitions

[docs]def TotalCost_rule ( M ):
r"""
Using the :code:Activity and :code:Capacity variables, the Temoa objective
function calculates the cost of energy supply, under the assumption that capital
costs are paid through loans. This implementation sums up all the costs incurred,
and is defined as :math:C_{tot} = C_{loans} + C_{fixed} + C_{variable}. Each
term on the right-hand side represents the cost incurred over the model
time horizon and discounted to the initial year in the horizon (:math:{P}_0).
The calculation of each term is given below.

.. math::
:label: obj_loan

C_{loans} = \sum_{t, v \in \Theta_{IC}} \left (
\left [
IC_{t, v}
\cdot LA_{t, v}
\cdot \frac{(1 + GDR)^{P_0 - v +1} \cdot (1 - (1 + GDR)^{-{LLN}_{t, v}})}{GDR}
\cdot \frac{ 1-(1+GDR)^{-LPA_{t,v}} }{ 1-(1+GDR)^{-LP_{t,v}} }
\right ]
\cdot \textbf{CAP}_{t, v}
\right )

Note that capital costs (:math:{IC}_{t,v}) are handled in several steps. First, each capital cost
is amortized using the loan rate (i.e., technology-specific discount rate) and loan
period. Second, the annual stream of payments is converted into a lump sum using
the global discount rate and loan period. Third, the new lump sum is amortized
at the global discount rate and technology lifetime. Fourth, loan payments beyond
the model time horizon are removed and the lump sum recalculated. The terms used
in Steps 3-4 are :math:\frac{ GDR }{ 1-(1+GDR)^{-LP_{t,v} } }\cdot
\frac{ 1-(1+GDR)^{-LPA_{t,v}} }{ GDR }. The product simplifies to
:math:\frac{ 1-(1+GDR)^{-LPA_{t,v}} }{ 1-(1+GDR)^{-LP_{t,v}} }, where
:math:LPA_{t,v} represents the active lifetime of a process :math:(t,v)
before the end of the model horizon, and :math:LP_{t,v} represents the full
lifetime of a process :math:(t,v). Fifth, the lump sum is discounted back to the
beginning of the horizon (:math:P_0) using the global discount rate. While an
explicit salvage term is not included, this approach properly captures the capital
costs incurred within the model time horizon, accounting for technology-specific
loan rates and periods.

.. math::
:label: obj_fixed

C_{fixed} = \sum_{p, t, v \in \Theta_{FC}} \left (
\left [
FC_{p, t, v}
\cdot \frac{(1 + GDR)^{P_0 - p +1} \cdot (1 - (1 + GDR)^{-{MPL}_{t, v}})}{GDR}
\right ]
\cdot \textbf{CAP}_{t, v}
\right )

.. math::
:label: obj_variable

C_{variable} = \sum_{p, t, v \in \Theta_{VC}} \left (
MC_{p, t, v}
\cdot
\frac{
(1 + GDR)^{P_0 - p + 1} \cdot (1 - (1 + GDR)^{-{MPL}_{p,t, v}})
}{
GDR
}
\cdot \textbf{ACT}_{t, v}
\right )

"""
return sum( PeriodCost_rule(M, p) for p in M.time_optimize )

def PeriodCost_rule ( M, p ):
P_0 = min( M.time_optimize )
P_e = M.time_future.last() # End point of modeled horizon
GDR = value( M.GlobalDiscountRate )
MLL = M.ModelLoanLife
MPL = M.ModelProcessLife
x   = 1 + GDR    # convenience variable, nothing more.

loan_costs = sum(
M.V_Capacity[S_t, S_v]
* (
value( M.CostInvest[S_t, S_v] )
* value( M.LoanAnnualize[S_t, S_v] )
* ( value( M.LifetimeLoanProcess[S_t, S_v] ) if not GDR else
(x **(P_0 - S_v + 1) * (1 - x **(-value( M.LifetimeLoanProcess[S_t, S_v] ))) / GDR)
)
)
* (
(
1 -  x**( -min( value(M.LifetimeProcess[S_t, S_v]), P_e - S_v ) )
)
/(
1 -  x**( -value( M.LifetimeProcess[S_t, S_v] ) )
)
)

for S_t, S_v in M.CostInvest.sparse_iterkeys()
if S_v == p
)

fixed_costs = sum(
M.V_Capacity[S_t, S_v]
* (
value( M.CostFixed[p, S_t, S_v] )
* ( value( MPL[p, S_t, S_v] ) if not GDR else
(x **(P_0 - p + 1) * (1 - x **(-value( MPL[p, S_t, S_v] ))) / GDR)
)
)

for S_p, S_t, S_v in M.CostFixed.sparse_iterkeys()
if S_p == p
)

variable_costs = sum(
M.V_ActivityByPeriodAndProcess[p, S_t, S_v]
* (
value( M.CostVariable[p, S_t, S_v] )
* ( value( MPL[p, S_t, S_v] ) if not GDR else
(x **(P_0 - p + 1) * (1 - x **(-value( MPL[p, S_t, S_v] ))) / GDR)
)
)

for S_p, S_t, S_v in M.CostVariable.sparse_iterkeys()
if S_p == p
)

period_costs = (loan_costs + fixed_costs + variable_costs)
return period_costs

##############################################################################
#   Initializaton rules

def ParamModelLoanLife_rule ( M, t, v ):
loan_length = value( M.LifetimeLoanProcess[t, v] )
mll = min( loan_length, max(M.time_future) - v )

return mll

def ParamModelProcessLife_rule ( M, p, t, v ):
life_length = value( M.LifetimeProcess[t, v] )
tpl = min( v + life_length - p, value(M.PeriodLength[ p ]) )

return tpl

def ParamPeriodLength ( M, p ):
# This specifically does not use time_optimize because this function is
# called /over/ time_optimize.
periods = sorted( M.time_future )

i = periods.index( p )

# The +1 won't fail, because this rule is called over time_optimize, which
# lacks the last period in time_future.
length = periods[i +1] - periods[ i ]

return length

def ParamPeriodRate ( M, p ):
"""\
The "Period Rate" is a multiplier against the costs incurred within a period to
bring the time-value back to the base year.  The parameter PeriodRate is not
directly specified by the modeler, but is a convenience calculation based on the
GlobalDiscountRate and the length of each period.  One may refer to this
(pseudo) parameter via M.PeriodRate[ a_period ]
"""
rate_multiplier = sum(
(1 + M.GlobalDiscountRate) ** (M.time_optimize.first() - p - y)

for y in range(0, M.PeriodLength[ p ])
)

return value(rate_multiplier)

def ParamProcessLifeFraction_rule ( M, p, t, v ):
"""\

Calculate the fraction of period p that process <t, v> operates.

For most processes and periods, this will likely be one, but for any process
that will cease operation (rust out, be decommissioned, etc.) between periods,
calculate the fraction of the period that the technology is able to
create useful output.
"""
eol_year = v + value( M.LifetimeProcess[t, v] )
frac  = eol_year - p
period_length = value( M.PeriodLength[ p ] )
if frac >= period_length:
# try to avoid floating point round-off errors for the common case.
return 1

# number of years into final period loan is complete

frac /= float( period_length )
return frac

def ParamLoanAnnualize_rule ( M, t, v ):
dr = value( M.DiscountRate[t, v] )
lln = value( M.LifetimeLoanProcess[t, v] )
if not dr:
return 1.0 / lln
annualized_rate = ( dr / (1.0 - (1.0 + dr)**(-lln) ))

return annualized_rate

# End initialization rules
##############################################################################

##############################################################################
#   Constraint rules

[docs]def BaseloadDiurnal_Constraint ( M, p, s, d, t, v ):
r"""
There exists within the electric sector a class of technologies whose
thermodynamic properties are impossible to change over a short period of time
(e.g.  hourly or daily).  These include coal and nuclear power plants, which
take weeks to bring to an operational state, and similarly require weeks to
fully shut down.  Temoa models this behavior by forcing technologies in the
:code:tech_baseload set to maintain a constant output for all daily slices.
Note that this allows the model to (not) use a baseload process in a season, and
only applies over the :code:time_of_day set.

Ideally, this constraint would not be necessary, and baseload processes would
simply not have a :math:d index.  However, implementing the more efficient
functionality is currently on the Temoa TODO list.

.. math::

SEG_{s, D_0}
\cdot \textbf{ACT}_{p, s, d, t, v}
=
SEG_{s, d}
\cdot \textbf{ACT}_{p, s, D_0, t, v}

\\
\forall \{p, s, d, t, v\} \in \Theta_{\text{baseload}}
"""
# Question: How to set the different times of day equal to each other?

# Step 1: Acquire a "canonical" representation of the times of day
l_times = sorted( M.time_of_day )  # i.e. a sorted Python list.
# This is the commonality between invocations of this method.

index = l_times.index( d )
if 0 == index:
# When index is 0, it means that we've reached the beginning of the array
# For the algorithm, this is a terminating condition: do not create
# an effectively useless constraint
return Constraint.Skip

# Step 2: Set the rest of the times of day equal in output to the first.
# i.e. create a set of constraints that look something like:
# tod[ 2 ] == tod[ 1 ]
# tod[ 3 ] == tod[ 1 ]
# tod[ 4 ] == tod[ 1 ]
# and so on ...
d_0 = l_times[ 0 ]

# Step 3: the actual expression.  For baseload, must compute the /average/
# activity over the segment.  By definition, average is
#     (segment activity) / (segment length)
# So:   (ActA / SegA) == (ActB / SegB)
#   computationally, however, multiplication is cheaper than division, so:
#       (ActA * SegB) == (ActB * SegA)
expr = (
M.V_Activity[p, s, d, t, v]   * M.SegFrac[s, d_0]
==
M.V_Activity[p, s, d_0, t, v] * M.SegFrac[s, d]
)
return expr

[docs]def EmissionLimit_Constraint ( M, p, e ):
r"""

A modeler can track emissions through use of the :code:commodity_emissions
set and :code:EmissionActivity parameter.  The :math:EAC parameter is
analogous to the efficiency table, tying emissions to a unit of activity.  The
EmissionLimit constraint allows the modeler to assign an upper bound per period
to each emission commodity.

.. math::
:label: EmissionLimit

\sum_{I,T,V,O|{e,i,t,v,o} \in EAC_{ind}} \left (
EAC_{e, i, t, v, o} \cdot \textbf{FO}_{p, s, d, i, t, v, o}
\right )
\le
ELM_{p, e}

\\
\forall \{p, e\} \in ELM_{ind}
"""
emission_limit = M.EmissionLimit[p, e]

actual_emissions = sum(
M.V_FlowOut[p, S_s, S_d, S_i, S_t, S_v, S_o]
* M.EmissionActivity[e, S_i, S_t, S_v, S_o]

for tmp_e, S_i, S_t, S_v, S_o in M.EmissionActivity.sparse_iterkeys()
if tmp_e == e
if M.ValidActivity( p, S_t, S_v )
for S_s in M.time_season
for S_d in M.time_of_day
)

if int is type( actual_emissions ):
msg = ("Warning: No technology produces emission '%s', though limit was "
'specified as %s.\n')
SE.write( msg % (e, emission_limit) )
return Constraint.Skip

expr = (actual_emissions <= emission_limit)
return expr

[docs]def MinCapacity_Constraint ( M, p, t ):
r""" See MaxCapacity_Constraint """

min_cap = value( M.MinCapacity[p, t] )
expr = (M.V_CapacityAvailableByPeriodAndTech[p, t] >= min_cap)
return expr

[docs]def MaxCapacity_Constraint ( M, p, t ):
r"""

The MinCapacity and MaxCapacity constraints set limits on the what the model is
allowed to (not) have available of a certain technology.  Note that the indices
for these constraints are period and tech_all, not tech and vintage.

.. math::
:label: MinCapacityCapacityAvailableByPeriodAndTech

\textbf{CAPAVL}_{p, t} \ge MIN_{p, t}

\forall \{p, t\} \in \Theta_{\text{MinCapacity parameter}}

.. math::
:label: MaxCapacity

\textbf{CAPAVL}_{p, t} \le MAX_{p, t}

\forall \{p, t\} \in \Theta_{\text{MaxCapacity parameter}}
"""
max_cap = value( M.MaxCapacity[p, t] )
expr = (M.V_CapacityAvailableByPeriodAndTech[p, t] <= max_cap)
return expr

def MinCapacitySet_Constraint ( M, p ):
r""" See MinCapacity_Constraint """
min_cap = value( M.MinCapacitySum[p] )
aggcap = sum ( M.V_CapacityAvailableByPeriodAndTech[p, t]
for t in M.tech_capacity_min
)
expr = (aggcap >= min_cap)
return expr

def MaxCapacitySet_Constraint ( M, p ):
r""" See MaxCapacity_Constraint """
max_cap = value( M.MaxCapacitySum[p] )
aggcap = sum ( M.V_CapacityAvailableByPeriodAndTech[p, t]
for t in M.tech_capacity_max
)
expr = (aggcap <= max_cap)
return expr

def MaxActivity_Constraint ( M, p, t ):
r"""

The MaxActivity sets an upper bound on the activity from a specific technology.  Note that the indices
for these constraints are period and tech_all, not tech and vintage.

"""

activity_pt = sum( M.V_Activity[p, S_s, S_d, t, S_v]

for S_s in M.time_season
for S_d in M.time_of_day
for S_v in M.ProcessVintages( p, t )
)
max_act = value( M.MaxActivity[p, t] )
expr = (activity_pt <= max_act)
return expr

def MinActivity_Constraint ( M, p, t ):
r"""

The MinActivity sets a lower bound on the activity from a specific technology.  Note that the indices
for these constraints are period and tech_all, not tech and vintage.

"""

activity_pt = sum( M.V_Activity[p, S_s, S_d, t, S_v]

for S_s in M.time_season
for S_d in M.time_of_day
for S_v in M.ProcessVintages( p, t )
)
min_act = value( M.MinActivity[p, t] )
expr = (activity_pt >= min_act)
return expr

def MinActivityGroup_Constraint ( M, p , g ):

g_techs=set()
for i in M.GroupOfTechnologies.value:
if i==g:
activity_p = sum( M.V_Activity[p, S_s, S_d, t, S_v]

for  t  in g_techs
for S_s in M.time_season
for S_d in M.time_of_day
for S_v in M.ProcessVintages( p, t )
)
min_act = value( M.MinGenGroupOfTechnologies_Data[p,g] )
expr = (activity_p >= min_act)
return expr

[docs]def Storage_Constraint ( M, p, s, i, t, v, o ):
r"""

Temoa's algorithm for storage is to ensure that the amount of energy entering
and leaving a storage technology is balanced over the course of a day,
accounting for the conversion efficiency of the storage process.  This

constraint relies on the assumption that the total amount of storage-related
energy is small compared to the amount of energy required by the system over a
season.  If it were not, the algorithm would have to account for
season-to-season transitions, which would require an ordering of seasons within
the model. Currently, each slice is completely independent of other slices.

.. math::
:label: Storage

\sum_{D} \left (
EFF_{i, t, v, o}
\cdot \textbf{FI}_{p, s, d, i, t, v, o}
-     \textbf{FO}_{p, s, d, i, t, v, o}
\right )
= 0

\forall \{p, s, i, t, v, o\} \in \Theta_{\text{storage}}
"""
total_out_in = sum(
M.Efficiency[i, t, v, o]
* M.V_FlowIn[p, s, S_d, i, t, v, o]
- M.V_FlowOut[p, s, S_d, i, t, v, o]

for S_d in M.time_of_day
)

expr = ( total_out_in == 0 )
return expr

def HourlyStorage_Constraint ( M, p, s, d, t ):

InitialStorage = 0.0	# Batteries are assumed delivered uncharged

# This is the sum of all input=i sent TO storage tech t of vintage v with
# output=o in P,S,D, (in PJ)
charge = sum( M.V_FlowIn[p, s, d, S_i, t, S_v, S_o] * M.Efficiency[S_i, t, S_v, S_o]
for S_v in M.ProcessVintages( p, t )
for S_i in M.ProcessInputs( p, t, S_v )
for S_o in M.ProcessOutputsByInput( p, t, S_v, S_i )
)

# This is the sum of all output=o withdrawn FROM storage tech t of vintage v
# with input=i P,S,D, (in PJ)
discharge = sum( M.V_FlowOut[p, s, d, S_i, t, S_v, S_o]
for S_v in M.ProcessVintages( p, t )
for S_o in M.ProcessOutputs( p, t, S_v )
for S_i in M.ProcessInputsByOutput( p, t, S_v, S_o )
)

stored_energy = charge - discharge

# This hourly storage formulation allows stored energy to carry over through
# time of day and seasons, but must be zeroed out at the end of each period

# Last time slice of the last season (aka end of period), must zero out
if d == M.time_of_day.last() and s == M.time_season.last():
d_prev = M.time_of_day.prev(d)
expr = ( M.V_HourlyStorage[p, s, d_prev, t] + stored_energy == 0 )

# First time slice of the first season (aka start of period), starts at zero
elif d == M.time_of_day.first() and s == M.time_season.first():
expr = ( M.V_HourlyStorage[p,s,d,t] == stored_energy )

# First time slice of any season that is NOT the first season
elif d == M.time_of_day.first():
d_last = M.time_of_day.last()
s_prev = M.time_season.prev(s)
expr = (
M.V_HourlyStorage[p,s,d,t]
== M.V_HourlyStorage[p,s_prev,d_last,t] + stored_energy
)

# So this is any time slice that is NOT covered above (so not the period end
# time slice; not the period beginning time slice; and not the first time
# slice of any season)
else:
d_prev = M.time_of_day.prev(d)
expr = (
M.V_HourlyStorage[p,s,d,t]
== M.V_HourlyStorage[p,s,d_prev,t] + stored_energy
)

return expr

def HourlyStorage_UpperBound ( M, p, s, d, t ):
# V_HourlyStorage is in terms of PJ; so in any single time slice, amount of
# cumulative stored energy cannot exceed capacity (GW) * 8 (hours) = GWh
# need to convert GWh capacity to PJ (3600/10^6)

energy_capacity = M.V_CapacityAvailableByPeriodAndTech[p,t] * 8 * 3600 / 10**6
expr = ( M.V_HourlyStorage[p,s,d,t] <= energy_capacity )

return expr

def HourlyStorage_LowerBound ( M, p, s, d, t ):
# V_HourlyStorage is in terms of PJ; so in any single time slice, amount of
# cumulative stored energy cannot dip below some minimum value (zero)
# need to convert GWh capacity to PJ (3600/10^6)

expr = (M.V_HourlyStorage[p,s,d,t] >= 0)   #no minimum charge, can achieve 100% DOD

return expr

def HourlyStorageCharge_UpperBound ( M, p, s, d, t ):
# This must limit the rate that energy (PJ) can flow into the battery
# - limited by the battery size (capacity in GW).
# The battery capacity is defined by GW (GJ/s). Convert GJ/s to PJ/h, and
# this is the maximum that can flow into the battery in 1 hour

# Calculate energy charge in each time slice in PJ
slice_charge = sum( M.V_FlowIn[p, s, d, S_i, t, S_v, S_o] * M.Efficiency[S_i, t, S_v, S_o]
for S_v in M.ProcessVintages( p, t )
for S_i in M.ProcessInputs( p, t, S_v )
for S_o in M.ProcessOutputsByInput( p, t, S_v, S_i )
)

# Maximum energy charge in each time slice in PJ
max_charge = (
M.V_CapacityAvailableByPeriodAndTech[p, t]
*M.CapacityToActivity[t]
*M.SegFrac[s, d]
)

# Energy charge cannot exceed the capacity of the battery (in PJ)
expr = ( slice_charge <= max_charge )

return expr

def HourlyStorageCharge_LowerBound ( M, p, s, d, t ):
# This must limit the rate that energy (PJ) can flow out of the battery
# - limited by the battery size (capacity in GW).
# The battery capacity is defined by GW (GJ/s). Convert GJ/s to PJ/h, and
# this is the maximum that can flow out of the battery in 1 hour

# Calculate energy discharge in each time slice in PJ
slice_discharge = sum( M.V_FlowOut[p, s, d, S_i, t, S_v, S_o]
for S_v in M.ProcessVintages( p, t )
for S_o in M.ProcessOutputs( p, t, S_v )
for S_i in M.ProcessInputsByOutput( p, t, S_v, S_o )
)

# Maximum energy discharge in each time slice in PJ
max_discharge = (
M.V_CapacityAvailableByPeriodAndTech[p, t]
*M.CapacityToActivity[t]
*M.SegFrac[s, d]
)

# Energy discharge cannot exceed the capacity of the battery (in PJ)
expr = ( slice_discharge <= max_discharge )

return expr

def HourlyStorageThroughput_Constraint ( M, p, s, d, t ):
# It is not enough to limit charge and discharge rate only, since a battery
# cannot both charge and discharge at the maximum rate at the same time, and
# we should limit the throughtput of a battery during each time slice.

discharge = sum( M.V_FlowOut[p, s, d, S_i, t, S_v, S_o]
for S_v in M.ProcessVintages( p, t )
for S_o in M.ProcessOutputs( p, t, S_v )
for S_i in M.ProcessInputsByOutput( p, t, S_v, S_o )
)

charge = sum( M.V_FlowIn[p, s, d, S_i, t, S_v, S_o] * M.Efficiency[S_i, t, S_v, S_o]
for S_v in M.ProcessVintages( p, t )
for S_i in M.ProcessInputs( p, t, S_v )
for S_o in M.ProcessOutputsByInput( p, t, S_v, S_i )
)

throughput = charge + discharge
max_throughput = (
M.V_CapacityAvailableByPeriodAndTech[p, t]
*M.CapacityToActivity[t]
*M.SegFrac[s, d]
)
expr = ( throughput <= max_throughput )
return expr

[docs]def TechInputSplit_Constraint ( M, p, s, i, t, v ):
r"""

Allows users to specify fixed or minimum shares of commodity inputs to a process
producing a single output. These shares can vary by model time period. See
TechOutputSplit_Constraint for an analogous explanation.
"""
inp = sum( M.V_FlowIn[p, s, d, i, t, v, S_o]
for S_o in M.ProcessOutputsByInput( p, t, v, i )
for d in M.time_of_day

)

total_inp = sum( M.V_FlowIn[p, s, d, S_i, t, v, S_o]
for S_i in M.ProcessInputs( p, t, v )
for S_o in M.ProcessOutputsByInput( p, t, v, i )
for d in M.time_of_day
)

expr = ( inp >= M.TechInputSplit[p, i, t] * total_inp )
return expr

[docs]def TechOutputSplit_Constraint ( M, p, s, d, t, v, o ):
r"""

Some processes take a single input and make multiple outputs, and the user would like to
specify either a constant or time-varying ratio of outputs per unit input.  The most
canonical example is an oil refinery.  Crude oil is used to produce many different refined
products. In many cases, the modeler would like to specify a minimum share of each refined
product produced by the refinery.

For example, a hypothetical (and highly simplified) refinery might have a crude oil input
that produces 4 parts diesel, 3 parts gasoline, and 2 parts kerosene.  The relative
ratios to the output then are:

.. math::

d = \tfrac{4}{9} \cdot \text{total output}, \qquad
g = \tfrac{3}{9} \cdot \text{total output}, \qquad
k = \tfrac{2}{9} \cdot \text{total output}

Note that it is possible to specify output shares that sum to less than unity. In such
cases, the model optimizes the remaining share. In addition, it is possible to change the
specified shares by model time period. The constraint is formulated as follows:

.. math::
:label: TechOutputSplit

\sum_{I} \textbf{FO}_{p, s, d, i, t, v, o}
\geq
SPL_{p, t, o} \cdot \textbf{ACT}_{p, s, d, t, v}

\forall \{p, s, d, t, v, o\} \in \Theta_{\text{split output}}
"""
out = sum( M.V_FlowOut[p, s, d, S_i, t, v, o]
for S_i in M.ProcessInputsByOutput( p, t, v, o ) )

expr = ( out >= M.TechOutputSplit[p, t, o] * M.V_Activity[p, s, d, t, v] )
return expr

[docs]def Activity_Constraint ( M, p, s, d, t, v ):
r"""
The Activity constraint defines the Activity convenience variable.  The Activity
variable is mainly used in the objective function to calculate the cost
associated with use of a technology.  In English, this constraint states that
"the activity of a process is the sum of its outputs."

There is one caveat to keep in mind in regards to the Activity variable: if
there is more than one output, there is currently no attempt by Temoa to convert
to a common unit of measurement.  For example, common measurements for heat
include mass of steam at a given temperature, or total BTUs, while electricity
is generally measured in a variant of watt-hours.  Reconciling these units of
measurement, as for example with a cogeneration plant, is currently left as an
accounting exercise for the modeler.

.. math::
:label: Activity

\textbf{ACT}_{p, s, d, t, v} = \sum_{I, O} \textbf{FO}_{p,s,d,i,t,v,o}

\\
\forall \{p, s, d, t, v\} \in \Theta_{\text{activity}}
"""
activity = sum(
M.V_FlowOut[p, s, d, S_i, t, v, S_o]

for S_i in M.ProcessInputs( p, t, v )
for S_o in M.ProcessOutputsByInput( p, t, v, S_i )
)

expr = ( M.V_Activity[p, s, d, t, v] == activity )
return expr

[docs]def Capacity_Constraint ( M, p, s, d, t, v ):
r"""

Temoa's definition of a process' capacity is the total size of installation
required to meet all of that process' demands.  The Activity convenience
variable represents exactly that, so the calculation on the left hand side of
the inequality is the maximum amount of energy a process can produce in the time
slice <s,\ d>.

.. math::
:label: Capacity

\left (
\text{CFP}_{t, v}
\cdot \text{C2A}_{t}
\cdot \text{SEG}_{s, d}
\cdot \text{TLF}_{p, t, v}
\right )
\cdot \textbf{CAP}_{t, v}
\ge
\textbf{ACT}_{p, s, d, t, v}

\\
\forall \{p, s, d, t, v\} \in \Theta_{\text{activity}}
"""

if t in M.tech_hourlystorage:
return Constraint.Skip

produceable = (
(   value( M.CapacityFactorProcess[s, d, t, v] )
* value( M.CapacityToActivity[ t ] )
* value( M.SegFrac[s, d]) )
* value( M.ProcessLifeFrac[p, t, v] )
* M.V_Capacity[t, v]
)

expr = (produceable >= M.V_Activity[p, s, d, t, v])
return expr

[docs]def ExistingCapacity_Constraint ( M, t, v ):
r"""

Temoa treats residual capacity from before the model's optimization horizon as
regular processes, that require the same parameter specification in the data
file as do new vintage technologies (e.g. entries in the efficiency table),
except the :code:CostInvest parameter.  This constraint sets the capacity of
processes for model periods that exist prior to the optimization horizon to
user-specified values.

.. math::
:label: ExistingCapacity

\textbf{CAP}_{t, v} = ECAP_{t, v}

\forall \{t, v\} \in \Theta_{\text{existing}}
"""
expr = ( M.V_Capacity[t, v] == M.ExistingCapacity[t, v] )
return expr

[docs]def ResourceExtraction_Constraint ( M, p, r ):
r"""

The ResourceExtraction constraint allows a modeler to specify an annual limit on
the amount of a particular resource Temoa may use in a period.

.. math::
:label: ResourceExtraction

\sum_{S, D, I, t \in T^r, V} \textbf{FO}_{p, s, d, i, t, v, c} \le RSC_{p, c}

\forall \{p, c\} \in \Theta_{\text{resource bound parameter}}
"""
collected = sum(
M.V_FlowOut[p, S_s, S_d, S_i, S_t, S_v, r]

for S_t, S_v in M.ProcessesByPeriodAndOutput( p, r )
if S_t in M.tech_resource
for S_i in M.ProcessInputsByOutput( p, S_t, S_v, r )
for S_s in M.time_season
for S_d in M.time_of_day
)

expr = (collected <= M.ResourceBound[p, r])
return expr

[docs]def CommodityBalance_Constraint ( M, p, s, d, c ):
r"""

Where the Demand constraint :eq:Demand ensures that end-use demands are met,
the CommodityBalance constraint ensures that the internal system demands are
met.  That is, this is the constraint that ties the output of one process to the
input of another.  At the same time, this constraint also conserves energy
between process.  (But it does not account for transmission loss.)  In this
manner, it is a corollary to both the ProcessBalance :eq:ProcessBalance and
Demand :eq:Demand constraints.

.. math::
:label: CommodityBalance

\sum_{I, T, V} \textbf{FO}_{p, s, d, i, t, v, c}
=
\sum_{T, V, O} \textbf{FI}_{p, s, d, c, t, v, o}

\\
\forall \{p, s, d, c\} \in \Theta_{\text{commodity balance}}
"""
if c in M.commodity_demand:
return Constraint.Skip

vflow_in = sum(
M.V_FlowIn[p, s, d, c, S_t, S_v, S_o]

for S_t, S_v in M.helper_commodityDStreamProcess[p, c]
for S_o in M.helper_ProcessOutputsByInput[ p, S_t, S_v, c ]
)

vflow_out = sum(
M.V_FlowOut[p, s, d, S_i, S_t, S_v, c]

for S_t, S_v in M.helper_commodityUStreamProcess[p, c]
for S_i in M.helper_ProcessInputsByOutput[ (p, S_t, S_v, c) ]
)

CommodityBalanceConstraintErrorCheck( vflow_out, vflow_in, p, s, d, c )

expr = (vflow_out == vflow_in)
return expr

[docs]def ProcessBalance_Constraint ( M, p, s, d, i, t, v, o ):
r"""

The ProcessBalance constraint is one of the most fundamental constraints in the
Temoa model.  It defines the basic relationship between the energy entering a
process (:math:\textbf{FI}) and the energy leaving a processing
(:math:\textbf{FO}). This constraint sets the :code:FlowOut variable, upon
which all other constraints rely.

Conceptually, this constraint treats every process as a "black box," caring only
about the process efficiency. In other words, the amount of energy leaving a
process cannot exceed the amount coming in.

Note that this constraint is an inequality -- not a strict equality.  In most
sane cases, the optimal solution should make this constraint and supply should
exactly meet demand.  If this constraint is not binding, it is likely a clue
that the model under inspection could be more tightly specified and has at least
one input data anomaly.

.. math::
:label: ProcessBalance

\textbf{FO}_{p, s, d, i, t, v, o}
\le
EFF_{i, t, v, o}
\cdot \textbf{FI}_{p, s, d, i, t, v, o}

\\
\forall \{p, s, d, i, t, v, o\} \in \Theta_{\text{valid process flows}}
"""
expr = (
M.V_FlowOut[p, s, d, i, t, v, o]
==
M.V_FlowIn[p, s, d, i, t, v, o]
* value( M.Efficiency[i, t, v, o] )
)

return expr

[docs]def DemandActivity_Constraint ( M, p, s, d, t, v, dem, s_0, d_0 ):
r"""

For end-use demands, it is unreasonable to let the optimizer only allow use in a
single time slice.  For instance, if household A buys a natural gas furnace
while household B buys an electric furnace, then both units should be used
throughout the year.  Without this constraint, the model might choose to only
use the electric furnace during the day, and the natural gas furnace during the
night.

This constraint ensures that the ratio of a process activity to demand is
constant for all time slices.  Note that if a demand is not specified in a given
time slice, or is zero, then this constraint will not be considered for that
slice and demand.  This is transparently handled by the :math:\Theta superset.

.. math::
:label: DemandActivity

DEM_{p, s, d, dem} \cdot \sum_{I} \textbf{FO}_{p, s_0, d_0, i, t, v, dem}
=
DEM_{p, s_0, d_0, dem} \cdot \sum_{I} \textbf{FO}_{p, s, d, i, t, v, dem}

\\
\forall \{p, s, d, t, v, dem, s_0, d_0\} \in \Theta_{\text{demand activity}}
"""

DSD = M.DemandSpecificDistribution   # lazy programmer
act_a = sum(
M.V_FlowOut[p, s_0, d_0, S_i, t, v, dem]

for S_i in M.ProcessInputsByOutput( p, t, v, dem )
)
act_b = sum(
M.V_FlowOut[p, s, d, S_i, t, v, dem]

for S_i in M.ProcessInputsByOutput( p, t, v, dem )
)

expr = (
act_a * DSD[s, d, dem]
==
act_b * DSD[s_0, d_0, dem]
)
return expr

[docs]def Demand_Constraint ( M, p, s, d, dem ):
r"""

The Demand constraint drives the model.  This constraint ensures that supply at
least meets the demand specified by the Demand parameter in all periods and
slices, by ensuring that the sum of all the demand output commodity (:math:c)
generated by :math:\textbf{FO} must meet the modeler-specified demand, in
each time slice.

.. math::
:label: Demand

\sum_{I, T, V} \textbf{FO}_{p, s, d, i, t, v, dem}
\ge
{DEM}_{p, dem} \cdot {DSD}_{s, d, dem}

\\
\forall \{p, s, d, dem\} \in \Theta_{\text{demand}}

Note that the validity of this constraint relies on the fact that the
:math:C^d set is distinct from both :math:C^e and :math:C^p. In other
words, an end-use demand must only be an end-use demand.  Note that if an output
could satisfy both an end-use and internal system demand, then the output from
:math:\textbf{FO} would be double counted.

Note also that this constraint is an inequality, not a strict equality.  "Supply
must meet or exceed demand."  Like with the ProcessBalance constraint, if this
constraint is not binding, it may be a clue that the model under inspection
could be more tightly specified and could have at least one input data anomaly.

"""
supply = sum(
M.V_FlowOut[p, s, d, S_i, S_t, S_v, dem]

for S_t, S_v in M.helper_commodityUStreamProcess[ p, dem ]
for S_i in M.helper_ProcessInputsByOutput[ p, S_t, S_v, dem ]
)

DemandConstraintErrorCheck( supply, p, s, d, dem )

expr = (supply >= M.Demand[p, dem] * M.DemandSpecificDistribution[s, d, dem])

return expr

def GrowthRateConstraint_rule ( M, p, t ):
GRS = value( M.GrowthRateSeed[ t ] )
GRM = value( M.GrowthRateMax[ t ] )
CapPT = M.V_CapacityAvailableByPeriodAndTech

periods = sorted(set(p_ for p_, t_ in CapPT if t_ == t) )

if p not in periods:
return Constraint.Skip

if p == periods:
expr = ( CapPT[p, t] <= GRS )

else:
p_prev = periods.index( p )
p_prev = periods[ p_prev -1]

expr = ( CapPT[p, t] <= GRM * CapPT[p_prev, t] + GRS )

return expr

##############################################################################
# Additional and derived (informational) variable constraints

def ActivityByPeriodAndProcess_Constraint ( M, p, t, v ):
if p < v or v not in M.ProcessVintages( p, t ):
return Constraint.Skip

activity = sum(
M.V_Activity[p, S_s, S_d, t, v]

for S_s in M.time_season
for S_d in M.time_of_day
)

if int is type( activity ):
return Constraint.Skip

expr = (M.V_ActivityByPeriodAndProcess[p, t, v] == activity)
return expr

#This is required for MGA objective function
def ActivityByTech_Constraint ( M, t ):

activity = sum(
M.V_Activity[S_p, S_s, S_d, t, S_v]

for S_p in M.time_optimize
for S_s in M.time_season
for S_d in M.time_of_day
for S_v in M.ProcessVintages( S_p, t )
)

if int is type( activity ):
return Constraint.Skip

expr = (M.V_ActivityByTech[t] == activity)
return expr

[docs]def CapacityAvailableByPeriodAndTech_Constraint ( M, p, t ):
r"""
The :math:\textbf{CAPAVL} variable is nominally for reporting solution values,
but is also used in the Max and Min constraint calculations.  For any process
with an end-of-life (EOL) on a period boundary, all of its capacity is available
for use in all periods in which it is active (the process' TLF is 1). However,
for any process with an EOL that falls between periods, Temoa makes the
simplifying assumption that the available capacity from the expiring technology
is available through the whole period, but only as much percentage as its
lifespan through the period.  For example, if a process expires 3 years into an
8 year period, then only :math:\frac{3}{8} of the installed capacity is
available for use throughout the period.

.. math::
:label: CapacityAvailable

\textbf{CAPAVL}_{p, t} = \sum_{V} {TLF}_{p, t, v} \cdot \textbf{CAP}

\\
\forall p \in \text{P}^o, t \in T
"""
cap_avail = sum(
value( M.ProcessLifeFrac[p, t, S_v] )
* M.V_Capacity[t, S_v]

for S_v in M.ProcessVintages( p, t )
)

expr = (M.V_CapacityAvailableByPeriodAndTech[p, t] == cap_avail)
return expr

def EnergyConsumptionByPeriodInputAndTech_Constraint ( M, p, i, t ):
energy_used = sum(
M.V_FlowIn[p, S_s, S_d, i, t, S_v, S_o]

for S_v in M.ProcessVintages( p, t )
for S_o in M.ProcessOutputsByInput( p, t, S_v, i )
for S_s in M.time_season
for S_d in M.time_of_day
)

expr = (M.V_EnergyConsumptionByPeriodInputAndTech[p, i, t] == energy_used)
return expr

def ActivityByPeriodTechAndOutput_Constraint ( M, p, t, o ):
activity = sum(
M.V_FlowOut[p, S_s, S_d, S_i, t, S_v, o]

for S_v in M.ProcessVintages( p, t )
for S_i in M.ProcessInputsByOutput( p, t, S_v, o )
for S_s in M.time_season
for S_d in M.time_of_day
)

if int is type( activity ):
return Constraint.Skip

expr = (M.V_ActivityByPeriodTechAndOutput[p, t, o] == activity)
return expr

def EmissionActivityByPeriodAndTech_Constraint ( M, e, p, t ):
emission_total = sum(
M.V_FlowOut[p, S_s, S_d, S_i, t, S_v, S_o]
* M.EmissionActivity[e, S_i, t, S_v, S_o]

for tmp_e, S_i, S_t, S_v, S_o in M.EmissionActivity.sparse_iterkeys()
if tmp_e == e and S_t == t
if M.ValidActivity( p, S_t, S_v )
for S_s in M.time_season
for S_d in M.time_of_day
)

if type( emission_total ) is int:
return Constraint.Skip

expr = (M.V_EmissionActivityByPeriodAndTech[e, p, t] == emission_total)
return expr

[docs]def RampUpDay_Constraint ( M, p, s, d, t, v):
# M.time_of_day is a sorted set, and M.time_of_day.first() returns the first
# element in the set, similarly, M.time_of_day.last() returns the last element.
# M.time_of_day.prev(d) function will return the previous element before s, and
# M.time_of_day.next(d) function will return the next element after s.

r"""
The ramp rate constraint is utilized to limit the rate of electricity generation
increase and decrease between two adjacent time slices in order to account for
physical limits associated with thermal power plants. Note that this constriant
only applies to technologies with ramp capability, which is defined in set
:math:\textbf{T}^{ramp}. We assume for simplicity the rate limits for both
ramp up and down are equal and they do not vary with technology vintage. The
ramp rate limits (:math:r_t) for technology :math:t should be expressed in
percentage of its rated capacity.

Note that when :math:d_{nd} is the last time-of-day, :math:d_{nd + 1} \not \in
\textbf{D}, i.e., if one time slice is the last time-of-day in a season and the
other time slice is the first time-of-day in the next season, the ramp rate
limits between these two time slices can not be expressed by :eq:ramp_up_day.
Therefore, the ramp rate constraints between two adjacent seasons are
represented in :eq:ramp_up_season.

In Equation :eq:ramp_up_day and :eq:ramp_up_season, we assume
:math:\textbf{S} = \{s_i, i = 1, 2, \cdots, ns\} and
:math:\textbf{D} = \{d_i, i=1, 2, \cdots, nd\}.

.. math::
\frac{
\textbf{ACT}_{p, s, d_{i + 1}, t, v}
}{
SEG_{s, d_{i + 1}} \cdot C2A_t
}
-
\frac{
\textbf{ACT}_{p, s, d_i, t, v}
}{
SEG_{s, d_i} \cdot C2A_t
}
\leq
r_t \cdot \textbf{CAPAVL}_{p,t}
\\
\forall
p \in \textbf{P}^o,
s \in \textbf{S},
d_i, d_{i + 1} \in \textbf{D},
t \in \textbf{T}^{ramp},
v \in \textbf{V}
:label: ramp_up_day
"""
if d != M.time_of_day.first():
d_prev = M.time_of_day.prev(d)
expr_left  = (
M.V_Activity[ p, s, d, t, v ]/value( M.SegFrac[s, d] ) -
M.V_Activity[ p, s, d_prev, t, v ]/value( M.SegFrac[s, d_prev] )
)/value( M.CapacityToActivity[ t ] )
expr_right = M.V_Capacity[t, v]*value( M.RampUp[t] )
expr = (expr_left <= expr_right)
else:
return Constraint.Skip

return expr

[docs]def RampUpSeason_Constraint ( M, p, s, t, v):
r"""
Note that :math:d_1 and :math:d_{nd} represent the first and last time-of-day,
respectively.

.. math::
\frac{
\textbf{ACT}_{p, s_{i + 1}, d_1, t, v}
}{
SEG_{s_{i + 1}, d_1} \cdot C2A_t
}
-
\frac{
\textbf{ACT}_{p, s_i, d_{nd}, t, v}
}{
SEG_{s_i, d_{nd}} \cdot C2A_t
}
\leq
r_t \cdot \textbf{CAPAVL}_{p,t}
\\
\forall
p \in \textbf{P}^o,
s_i, s_{i + 1} \in \textbf{S},
d_1, d_{nd} \in \textbf{D},
t \in \textbf{T}^{ramp},
v \in \textbf{V}
:label: ramp_up_season
"""
if s != M.time_season.first():
s_prev  = M.time_season.prev(s)
d_first = M.time_of_day.first()
d_last  = M.time_of_day.last()
expr_left = (
M.V_Activity[ p, s, d_first, t, v ]/M.SegFrac[s, d_first] -
M.V_Activity[ p, s_prev, d_last, t, v ]/M.SegFrac[s_prev, d_last]
)/value( M.CapacityToActivity[ t ] )
expr_right = M.V_Capacity[t, v]*value( M.RampUp[t] )
expr = (expr_left <= expr_right)
else:
return Constraint.Skip

return expr

def RampUpPeriod_Constraint ( M, p, t, v):

# if p != M.time_future.first():
# 	p_prev  = M.time_future.prev(p)
# 	s_first = M.time_season.first()
# 	s_last  = M.time_season.last()
# 	d_first = M.time_of_day.first()
# 	d_last  = M.time_of_day.last()
# 	expr_left = (
# 		M.V_Activity[ p, s_first, d_first, t, v ] -
# 		M.V_Activity[ p_prev, s_last, d_last, t, v ]
# 		)
# 	expr_right = (
# 		M.V_Capacity[t, v]*
# 		value( M.RampUp[t] )*
# 		value( M.CapacityToActivity[ t ] )*
# 		value( M.SegFrac[s, d])
# 		)
# 	expr = (expr_left <= expr_right)
# else:
# 	return Constraint.Skip

# return expr

return Constraint.Skip # We don't need inter-period ramp up/down constraint.

[docs]def RampDownDay_Constraint ( M, p, s, d, t, v):
r"""
Similar to Equation :eq:ramp_up_day and :eq:ramp_up_season, we use Equation
:eq:ramp_down_day and :eq:ramp_down_season to limit ramp down rates between
any two adjacent time slices.

.. math::
\frac{
\textbf{ACT}_{p, s, d_{i + 1}, t, v}
}{
SEG_{s, d_{i + 1}} \cdot C2A_t
}
-
\frac{
\textbf{ACT}_{p, s, d_i, t, v}
}{
SEG_{s, d_i} \cdot C2A_t
}
\geq
-r_t \cdot \textbf{CAPAVL}_{p,t}
\\
\forall
p \in \textbf{P}^o,
s \in \textbf{S},
d_i, d_{i + 1} \in \textbf{D},
t \in \textbf{T}^{ramp},
v \in \textbf{V}
:label: ramp_down_day
"""

if d != M.time_of_day.first():
d_prev = M.time_of_day.prev(d)
expr_left  = (
M.V_Activity[ p, s, d, t, v ]/value( M.SegFrac[s, d]) -
M.V_Activity[ p, s, d_prev, t, v ]/value( M.SegFrac[s, d_prev])
)/value( M.CapacityToActivity[ t ] )
expr_right = -( M.V_Capacity[t, v]*value( M.RampDown[t] ) )
expr = (expr_left >= expr_right)
else:
return Constraint.Skip

return expr

[docs]def RampDownSeason_Constraint ( M, p, s, t, v):
r"""
.. math::
\frac{
\textbf{ACT}_{p, s_{i + 1}, d_1, t, v}
}{
SEG_{s_{i + 1}, d_1} \cdot C2A_t
}
-
\frac{
\textbf{ACT}_{p, s_i, d_{nd}, t, v}
}{
SEG_{s_i, d_{nd}} \cdot C2A_t
}
\geq
-r_t \cdot \textbf{CAPAVL}_{p,t}
\\
\forall
p \in \textbf{P}^o,
s_i, s_{i + 1} \in \textbf{S},
d_1, d_{nd} \in \textbf{D},
t \in \textbf{T}^{ramp},
v \in \textbf{V}
:label: ramp_down_season
"""
if s != M.time_season.first():
s_prev  = M.time_season.prev(s)
d_first = M.time_of_day.first()
d_last  = M.time_of_day.last()
expr_left = (
M.V_Activity[ p, s, d_first, t, v ]/
value(
M.SegFrac[s, d_first]
) -
M.V_Activity[ p, s_prev, d_last, t, v ]/
value(
M.SegFrac[s_prev, d_last]
)
)/value( M.CapacityToActivity[ t ] )
expr_right = -( M.V_Capacity[t, v]*value( M.RampDown[t] ) )
expr = (expr_left >= expr_right)
else:
return Constraint.Skip

return expr

def RampDownPeriod_Constraint ( M, p, t, v):

# if p != M.time_future.first():
# 	p_prev  = M.time_future.prev(p)
# 	s_first = M.time_season.first()
# 	s_last  = M.time_season.last()
# 	d_first = M.time_of_day.first()
# 	d_last  = M.time_of_day.last()
# 	expr_left = (
# 		M.V_Activity[ p, s_first, d_first, t, v ] -
# 		M.V_Activity[ p_prev, s_last, d_last, t, v ]
# 		)
# 	expr_right = (
# 		-1*
# 		M.V_Capacity[t, v]*
# 		value( M.RampDown[t] )*
# 		value( M.CapacityToActivity[ t ] )*
# 		value( M.SegFrac[s, d])
# 		)
# 	expr = (expr_left >= expr_right)
# else:
# 	return Constraint.Skip

# return expr

return Constraint.Skip # We don't need inter-period ramp up/down constraint.

[docs]def ReserveMargin_Constraint( M, p, g, s, d):
r"""
To assure system reliability of power grid, during each period :math:p, the
sum of available capacity of all reserve technologies (defined by set :math:\textbf{T}^{res})
:math:\sum_{t \in T^{res}} \textbf{CAPAVL}_{p,t}, should not exceed the peak
load plus a reserve margin :math:RES_c. Note reserve margin is typically
expressed in the form of percentage. In Equation :eq:reserve_margin, we use
:math:(s^*,d^*) to represent the peak-load time slice.

.. math::
\sum_{t \in T^{res}} {
CC_t \cdot
\textbf{CAPAVL}_{p,t} \cdot
SEG_{s^*,d^*} \cdot C2A_t }
\geq
DEM_{p,c} \cdot
DSD_{s^*, d^*, c} \cdot
(1 + RES_c)
\\
\forall
p \in \textbf{P}^o,
c \in \textbf{C}^{res}
:label: reserve_margin
"""
# The season and time-of-day of the slice with the maximum average load.
PowerTechs=set()  #all the power generation technologies
PowerCommodities=set()  #it consists of all the commodities coming out of powerplants: ELCP, ELCP_Renewables, ELCP_SOL
for i in M.ReserveMargin.sparse_keys():
if i==g:

if not PowerCommodities:
return Constraint.Skip

for i,t,v,o in M.Efficiency:
if o in PowerCommodities:

expr_left = sum (value( M.CapacityCredit[t] )*
M.V_CapacityAvailableByPeriodAndTech[p, t]*
value( M.CapacityToActivity[t] )*
value( M.SegFrac[s, d] )
for t in PowerTechs if (p, t) in M.CapacityAvailableVar_pt  ) #M.CapacityAvailableVar_pt check if all the possible consistent combinations of t and p

total_generation = sum( M.V_Activity[p, s, d, t, S_v]
for  t  in PowerTechs
for S_v in M.ProcessVintages( p, t ))

expr_right = total_generation*(1 +  M.ReserveMargin[PowerCommodities.pop(),g] )

return (expr_left >= expr_right)

# End additional and derived (informational) variable constraints
##############################################################################

# End *_rule definitions
##############################################################################