20170925Utah_OCS Set 4 (1-12).pdf

1407 W.North Temple
ROCKY MOUNTAIN Salt Lake City,UT 84116
POWER
A DIVISION OF PACIFICORP
September 1,2017
Béla Vastag
Office of Consumer Services
160 East 300 South
Salt Lake City,Utah 84111
[e-mail](C)
RE:UT Docket No.17-035-39
OCS 4th Set Data Request (1-12)
Please find enclosed Rocky Mountain Power's Responses to OCS 46 Set Data Requests 4.1-
4.12.Provided on the enclosed Confidential CD are Confidential Attachments OCS 4.1 -(1-2)
and 4.5 -(1-3)and Confidential Responses to OCS 4.1 and 4.8.Confidential information is
provided subject to Public Service Commission of Utah (UPSC)Rules 746-1-602 and 603.
If you have any questions,please call Tarie Hansen at [phone].
Sincerely,
Bob Lively
Manager,Regulation
Enclosures
C.c.Erika Tedder/DPU [e-mail]@ugakgov(C)
Dan Kohler/DPU [e-mail](C)
Dan Peac/DPU dpeaco daymarkea.com (C)(W)
Aliea Afnan/DPU [e-mail] (W)
[e-mail](W)
Philip Hayet/OCS [e-mail] (C)
Gary A.Dodge/UAE [e-mail]_m (C)
Kevin Higgins/UAE [e-mail] (C)
Neal Townsend/UAE [e-mail](C)(W)
17-035-39 /Rocky Mountain Power
September 1,2017
OCS Data Request 4.1
OCS Data Request 4.1
CONFIDENTIAL REQUEST-Regarding Historic vs.Projected Market Impacts:
(a)Please provide a summary of historic market purchases and sales volumes,dollars,
and average prices by month by wholesale market since the Company began
participating in the EIM.
(b)Has the Company performed any analysis comparing the SO or PaR model purchase
and sales energy results to historical purchase and sales energy results to validate the
reasonableness of the modeled results.If so,please provide any work papers and
reports,of such comparisons the Company has conducted.If not,please explain why
not,especially if market purchases and sales are expected to be a significant driver of
the benefits of the repoweredwind.
(c)It appears that consistently across SO fuel and CO2 cases,a significant portion of the
benefits are driven by purchases and sales at the MIDC market,as a result of the
repowered wind projects.What basis does the Company have to believe that over the
2020 to 2050 time-period,it is reasonable that the repowered wind projects would be
able to derive such significant benefits from purchases and sales at the MIDC market?
(d)In lightof PacifiCorp's participation in the EIM,and consideration of joiningthe
CAISO,please explain why the benefits of the repowered wind projects derived in the
SO from transactions at COB are so small when compared to the benefits derived
from transactions at MIDC?
(e)Please explain why that when compared to all 9 cases in the SO Repower analysis,
the Low Gas,Mod CO2 case produces dramatically higher benefits
associated with transactions at MIDC compared to the
benefits produced by transactions at any other market.
(f)Please explain why that when compared to all 9 cases in the SO Repower analysis,
the High Gas,Mod CO2 case produces such high benefits
associated with transactions at Four Corners.The benefits from transaction at Four
Corners in that case are 4 to 5 times greater than then benefits at Four Corners in any
other fuel/CO2 cases considered.
Response to OCS Data Request 4.1
(a)Please refer to Confidential Attachment OCS 4.1-1,which provides actual data since
the Company began participating in the energy imbalance market (November 2014).
(b)PacifiCorp has not conducted the requested analysis.It would not be appropriate to
compare historical purchases and sales to forecasted purchases and sales,particularly
17-035-39 /Rocky Mountain Power
September 1,2017
OCS Data Request 4.1
as it relates to new assets with a 30-year life.Historical market purchases and sales
are based on a varietyof market and operational conditions (i.e.,natural gas prices,
power prices,regional resource mix,regional load,market structure,etc.),which can
vary significantlyfrom a long-term forecast of market and operational conditions.
(c)The system value of a purchases and sales cannot be evaluated in isolation of total-
system costs.The forecast of system purchases and sales included in the Company's
economic analysis of the wind repowering project is tied to least-cost dispatch of
system resources under a range of potential future price-policy scenarios.
Consequently,any change in system purchases and sales is consistent with changes in
other system variable costs,includingsystem fuel costs.The wind repowering project
will increase the amount of zero-fuel cost energy on PacifiCorp's system.This zero-
fuel cost energyis reasonablyexpected to lower net power costs by displacing system
resources that have higher dispatch costs or by supporting increased market sales,
whether at the Mid-Columbia (Mid-C)market or any other market hub across the
region dependingupon market price spreads and availability of transmission.
(d)Several factors can influence the forecasted location of market purchases and sales,
includingthe location,volume,and type of resources in the portfolio,the price spread
between market hubs,and the transmission available to monetize any value in these
price spreads relative to the cost of system resources.The Company has less
transmission access to support transactions at the California-Oregon Border (COB)
when compared to the Mid-C market,which is generally reflected in projected market
activity at these two locations.
(e)Please refer to the Company's response to subparts (c)and (d)above.Outputdata
from the System Optimizer model (SO model)indicate that benefits associated with
Mid-C purchases and sales are $330 million favorable to the medium natural gas,
medium carbon dioxide (CO2)price-policy scenario as compared to the low natural
gas,medium CO2 price-policyscenario.Note:while a "sale"provides revenue and
contributes to offsetting system costs and a "purchase"contributes to system costs,
the SO model reports both sales and purchases as a positive value for any given
simulation.The apparent sign reversal from the value stated in the question relative to
the Company's calculated figure quoted above is likely due to this treatment of the
numerical values in the file data.
Nonetheless,the approximately $330 million difference between outcomes over the
20-year period is a consequence of the SO model optimizing the system such that the
value of purchases and sales at Mid-C in the medium natural gas,medium CO2 price-
policy scenario present a "benefit"when compared to the low natural gas,medium
CO2 price-policy scenario.As noted earlier,variations between price-policy scenarios
can be driven by a broad range of variables and the net system cost or benefits from
purchases and sales cannot be evaluatedin isolation of total-system costs.For
instance,in the low natural gas,medium CO2 price-policy scenario,the case with
repowering includes a 458 megawatts (MW)natural gas-fired combined cycle project
17-035-39 /Rocky Mountain Power
September 1,2017
OCS Data Request 4.1
in the west in 2030 that is not included in the case without repowering.Changes in
the presence of this generating facility in the portfolio affects system energy balances
and market transactions.
Please refer to confidential work papers supporting the Direct Testimony of Company
witness,Rick T.Link,specifically:
Folder:SO Model Inputs-Outputs.zip\SO Model Inputs-Outputs\Price-emissions
scenarios\Repower,the file entitled "EGCC-RPE-EGN-LM\MktTrade-EGCC-
RPE-EGN-LM0000",and
Folder:SO Model Inputs-Outputs.zip\SO Model Inputs-Outputs\Price-emissions
scenarios\Repower,the file entitled "EGCC-RPE-EGN-MM\MktTrade-EGCC-
RPE-EGN-MM0000".
Please also refer to Confidential Attachment OCS 4.1-2.
(f)Please refer to the Company's response to subparts (c),(d),and (e)above.An
analysis of the detailed market output data does not support that Four Corners (4C)
produces four to five times the benefits seen in other cases.4C benefits over the 20-
year study period are approximately $380 million in the high natural gas,medium
CO2 price-policy scenario,compared to an approximately $508 million benefit in the
medium natural gas,medium CO2 price policy-scenario and a $330 million cost in the
low natural gas,medium CO2 CRSC.
Within the high natural gas,medium CO2 price-policy scenario,Palo Verde (PV)
reports a much larger "benefit"(approximately $860 million).
In addition to the files compared in subpart (e)above,the followingfile,provided
with the confidential work papers supporting Mr.Link's Direct Testimony,was
examined:
Folder:SO Model Inputs-Outputs.zip\SO Model Inputs-Outputs\Price-emissions
scenarios\Repower,the file entitled "EGCC-RPE-EGN-HM\MktTrade-EGCC-
RPE-EGN-MM0000".
Please also refer to Confidential Attachment OCS 4.1-2.
Confidential information is provided subject to Public Service Commission of Utah
(UPSC)Rule 746-1-602 and 746-1-603.
17-035-39 /Rocky Mountain Power
September 1,2017
OCS Data Request 4.2
OCS Data Request 4.2
Regarding market impacts expected from repowering:
(a)Please explain if/how repowering provides market benefits and additional access to
the spot energy markets.
(b)Please explain if/how repowering provides market benefits and additional access to
the Mid-Columbia market.
(c)Please explain if reduced purchases and increased sales at the Mid-Columbia market
would be facilitated by specific repowering projects more so than others (for
example,does transmission constrain the repowered Wyomingwind projects access
to the Mid-C market).
(d)Do the significant benefits from increased market sales at Mid-C derive primarily
from the repowered wind projects in Washington and Oregon versus the repowered
wind projects in Wyoming?
(e)Please perform the PaR and SO analysis assuming only the Washington and Oregon
re-powering projects are completed.
(f)Please perform the PaR and SO analyses assuming only the Wyomingre-powering
projects are completed.
Response to OCS Data Request 4.2
(a)Repowering provides market benefits as more zero-fuel-cost energy is generated and
available to serve load or sell into the market.Repowering does not provide
additional access to spot energy markets.
(b)Repowering provides market benefits as more zero-fuel-cost energy is generated and
available to serve load or sell into the market.Repowering does not provide
additional access to the Mid-Columbia (Mid-C)market.
(c)Please refer to the Company's response to OCS Data Request 4.1 subparts (e)and (f)
for clarification of market sales and purchases benefits.Portfolio results are based on
total-system interactions and not driven by projects or locations considered in
isolation.
(d)Please refer to the Company's response to OCS Data Request 4.1 subparts (e)and (f)
for clarification of market sales and purchases benefits.Portfolio results are based on
total system interactions and not driven by projects or locations considered in
isolation.
(e)PacifiCorp has not performed the requested analysis.
17-035-39 /Rocky Mountain Power
September 1,2017
OCS Data Request 4.2
(f)PacifiCorp has not performed the requested analysis.
17-035-39 /Rocky Mountain Power
September 1,2017
OCS Data Request 4.3
OCS Data Request 4.3
After the wind projects are repowered,the wind generators will increase in capacity,and
will be able to produce more energy.Without transmission upgrades,will there be an
increase in the number of times when wind turbines will have to be limited in some way
due to transmission constraints?If so please explain how the system operators will
operate the units under this situation.For example,will dump energy occur?If
transmission constraints are not likely to increase with the repowered wind,please
explain why not?
Response to OCS Data Request 4.3
The maximum output of each wind facility is limited to the capacity specified in the large
generator interconnection agreement (LGIA)for each project.Because repowering
increases output over a varietyof wind conditions,much of incremental output occurs at
levels below the current maximum output specified in the LGIA of each wind facility.If
the LGIAs are not modified to accommodate the increased capacity of repoweredwind
facilities,system operators will restrict energy output to ensure it remains within the
LGIA limits when wind conditions would otherwise cause energy output from the wind
facility to exceed the capacity specified in the LGIA.If the LGIAs are modified to
accommodate the increased capacity of each wind facility,system operators will not need
to curtail energy output for the purpose of ensuring energy output falls within the LGIA
limit.As noted in the Direct Testimony of Company witness Rick T.Link,the average
incremental energy output from repoweredwind facilities is 19.2 percent if the LGIAs
are not modified and 20.8 percent if the LGIAs are modified (lines 297-300).
Regardless of the LGIA limits,under system conditions where total energy production
net of load exceeds available transmission,system operators will economically re-
dispatch system resources.Under these conditions,system operators will typically first
reduce dispatch from coal units while maintaining minimum generation levels.If further
re-dispatch is needed,system operators will then typically limit output from non-
qualifying facility (QF)wind projects that are not qualified for production tax credits
(PTCs).If additional re-dispatch is needed,system operators will then limit output from
non-QF wind projects that qualify for PTCs.Lastly,system operators will limit output
from QF projects as necessary to maintain reliable operation of the transmission system.
17-035-39 /Rocky Mountain Power
September 1,2017
OCS Data Request 4.4
OCS Data Request 4.4
Are there times in the SO or PaR analyses when the amount of wind energy in an hour
exceeds the transfer capability input in the model from the region where the repowered
wind resources are located,particularlythe Wyomingwind projects?If so how does the
model treat that energy,for example does the model report dump energy,and how is it
priced out in the SO and PaR?If not,please explain why.
Response to OCS Data Request 4.4
Yes.Dumped energy is captured and evaluated on the basis of Planning and Risk (PaR)
model results,which has more advanced unit-commitment and dispatch logic relative to
the System Optimizer model (SO model).Wind resources are modeled as non-
dispatchable,resulting in dumped energy when wind generation exceeds a combination
of reachable load and markets.
Because dumped wind energyrepresents curtailment of zero-cost wind resources,the
economic impact is primarily a result of lost production tax credits (PTCs).Dumped
energy only results in lost PTCs when dumped energy exceeds the generation from non-
PTC eligible wind resources in a constrained area.In the price-policyscenarios included
in the filing,the curtailment of non-PTC eligible wind resources was sufficient to cover
the identified dumped energy volumes and avoid lost PTCs.
Dumped energy is provided in the "PaR_CostByYr"worksheet of the "PaR Stochastic
Summary"file for each simulation (with and without repowering)and for each price-
policy scenario.
17-035-39 /Rocky Mountain Power
September 1,2017
OCS Data Request 4.5
OCS Data Request 4.5
Please refer to the Company's response to OCS 1.12.Please provide complete and
differentiated responses for both FOT and system balancing transactions.
(a)Please be more specific to explain how market depth was modeled in the Repowering
analysis.In other words,are the markets themselves constrained with a market depth
input variable/logic,or is the only limit on the amount of sales that can be made at
any of the markets,the market price and the transmission transfer capacity inputs that
are modeled?
(b)If market depth inputs were modeled,please provide the market depth inputs assumed
in the Repowering analysis.
(c)Please provide an explanation of how the Company modeled market depth in the last
General Rate Case and provide the inputs that it modeled in GRID.Please provide
work papers showing the derivation of those market depth inputs,and if there are
differences in market depth assumptions between what was used in the General Rate
Case and what is being used in the Repowering Study,please explain the differences
and the reason different assumptions were used.
(d)Please provide evidence and supporting documentation for the volume of market
transactions the company has historicallybeen able to make at each market hub.
Response to OCS Data Request 4.5
The Company's response to subpart (a)applies to both system balancing transactions and
front office transactions (FOTs).The attachment referenced in the Company's response
to subpart (b)contains independentworksheets for system balancing transactions and
FOTs.
(a)Market depth is modeled as FOT limits.Transmission capacity can also restrict
market transactions.
(b)Please refer to Confidential Attachment OCS 4.5-1.
(c)In the last general rate case,Docket 13-035-184,market capacity limits were modeled
based on the 48-month average of short-term firm (STF)sales,by month and heavy
load hours (HLH)/lightload hours (LLH).Limits are modeled for the California-
Oregon Border (COB),Four Corners (4C),Mead,and Mona markets.No market
capacity limits are modeled for the Mid-Columbia (Mid-C)or Palo Verde (PV)
markets since they are frequentlyused for large volumes of forward transactions and
are relatively liquid.Since the last general rate case,the Company has updated the
historical period used to set the market capacity limits but has not modified the
methodology.Please refer to Confidential Attachment OCS 4.5-2,which provides the
17-035-39 /Rocky Mountain Power
September 1,2017
OCS Data Request 4.5
market capacity data from the last GRC.
(d)Please refer to Confidential Attachment OCS 4.5-3 which provides the volume of
market transactions by market for calendar year 2013 through 2016.
Confidential information is provided subject to Public Service Commission of Utah
(UPSC)Rule 746-1-602 and 746-1-603.
17-035-39 /Rocky Mountain Power
September 1,2017
OCS Data Request 4.6
OCS Data Request 4.6
Refer to DPU 3.18 and DPU 4.1.It appears the Company has performed analysis of each
existing wind turbine to assess the expected remaining life of each unit.Please provide
the remaining useful life estimates for each wind facility under consideration for re-
powering.Please itemize assessments if separate estimates have been conducted for
energy collection systems,gearboxes,blades,nacelles,foundations,etc.If different lives
for components are identified,please provide a single remaining useful life/retirement
date that represents the project as a whole.Provide any work papers,reports,studies,etc.
that the Company has performed or reviewed in developing these estimates.
Response to OCS Data Request 4.6
The Company objects to this request to the extent it requires development of a special
study or information not maintained in the ordinary course of business.Without waiving
this objection,the Company responds as follows:
The Company has not performed the analysis assumed to have been performed in this
data request.The Company estimates that the remaining useful life of each facility is
consistent with its current depreciable life,which reflects a 30-year asset life.The
Company's assessment of the remaining useful life of the energy collection systems at
the wind facilities,as described in the Company's response to DPU Data Request 4.1,is
based upon general utility industryestimates of the useful life of direct-buried conductor.
17-035-39 /Rocky Mountain Power
September 1,2017
OCS Data Request 4.7
OCS Data Request 4.7
When comparing the case without repowering to the case with repowering,
approximately 70 MW of additional capacity is acquired through the repowering.When
the PaR study period ends in 2036,the Company extends the PaR study through 2050 and
has determined that the repowering will provide an additional 10 years of life on 1,000
MW of wind capacity.Duringthe extensionperiod,the Company computes a benefit of
having 1,000 MW of wind capacity,and it calculates its estimate of the benefits during
that period from the calculated benefit of having 70 MW of incremental repowering
capacity that occurred before 2036.
(a)Provide evidence/theCompany's justification for the reasonableness of assuming that
the benefit of the 1,000 MW during the extensionperiod could be linearly scaled
from the benefit of the 70 MW up to 2036.
(b)Has the Company ever performed an economic analysis in which it derived extension
period benefits in a similar manner?If so,please identifythe proceeding,and provide
the testimony of the witness that supported such a methodology.
Response to OCS Data Request 4.7
(a)The Company is not clear how the Office of Consumer Services (OCS)established
that approximately 70 megawatts (MW)of additional capacity is acquired through
repowering.The Company assumes OCS is referring to the potential incremental
increase in repowered wind capacity.Based on the foregoing assumption,the
Company responds as follows:Please refer to the Direct Testimony of Company
witness Rick T.Link,lines 455-501.The calculation as explained captures all
measured system impacts caused by wind repowering,intentionallyfocusing on the
2028 through 2036 time frame.The benefits are calculated as the change in system
costs divided by the change in wind volume due to repowering between the two
simulations (with and without repowering).This dollars per megawatt-hour ($/MWh)
result is a reasonable proxy for impacts beyond 2036.
(b)Yes.The Company used this method in assessing extended benefits in the 2017
Integrated Resource Plan (Docket 17-035-16),prompted by the unique nature of this
time-limited,high-value opportunity.More generally,the extrapolation of data using
levelized values is a common and accepted analytical method.
17-035-39 /Rocky Mountain Power
September 1,2017
OCS Data Request 4.8
OCS Data Request 4.8
CONFIDENTIAL REQUEST-From the "TieCF..."SO output file,there appears to be
about a
transmission tie when
comparing the wind repowering case to the base case.Please explain why this difference
in assumptions exists.
Response to OCS Data Request 4.8
The difference is related to the reliability associated with outages of transmission system
elements.
17-035-39 /Rocky Mountain Power
September 1,2017
OCS Data Request 4.9
OCS Data Request 4.9
Please see Repower Results Direct Testimony.xlsm,Tab =Price-Policy Annual -PaR at
line 72.The repowering benefits seem unusual in that the NPC ($/MWH)go from
$68.39/MWH in 2030 to $190.79 in 2032 to $40.85/MWH in 2035.It would seem that a
benefit as high as $190.79/MWH is quite a large value given that the added wind is
approximately just 70 MW.Please explain the reasonableness of these NPC benefits.
Response to OCS Data Request 4.9
Referencing the confidential work paper supporting the Direct Testimony of Company
witness,Rick T.Link;specifically the file entitled "Repower Results Direct Testimony",
the tab entitled "Price-Policy Annual -PaR",the Company responds as follows:
The system value of net power costs (NPC)benefits cannot be evaluatedin isolation of
total-system costs.The forecast of NPC benefits included in the Company's economic
analysis of the wind repowering project is tied to least-cost dispatch of system resources
under a range of potential future price-policy scenarios and reflects changes in the
resource portfolio in cases with and without wind repowering.Consequently,any change
in NPC is consistent with changes in other system variable costs,includingsystem fuel
costs and changes in the resource portfolios between cases with and without repowering.
For instance,while NPC benefits exceed $190 per megawatt-hour ($/MWh)in 2030,this
is largely offset by an increase in fixed system costs (cell T77 of the referenced work
paper).While the net benefits of any given line item for any given year can vary,the total
system benefits (row 79 of the referenced work paper)are reasonable and consistent with
changes in the resource portfolio for any given price-policyscenario.
17-035-39 /Rocky Mountain Power
September 1,2017
OCS Data Request 4.10
OCS Data Request 4.10
Please see Repower Results Direct Testimony.xlsm,Tab =Price-Policy Annual -PaR at
line 72,and Tab =PaR Sensitivityat line 75.Explain why the Company's repowering
NPC $/MWh benefit appears to be so much higher in the Repowering analysis than it is
in the PaR Sensitivity analysis?
Response to OCS Data Request 4.10
Referencing the confidential work paper supporting the Direct Testimony of Company
witness,Rick T.Link;specifically the file entitled "Repower Results Direct Testimony",
the tab entitled "Price-Policy Annual -PaR"and the tab entitled "PaR Sensitivity",the
Company responds as follows:
For this specific line item,the change in net power costs (NPC)calculated on a dollars-
per-megawatthour ($/MWh)basis is greater in the wind repowering case than in the
referenced sensitivityanalysis that also includes new wind and transmission.The system
value of NPC benefits cannot be evaluatedin isolation of total-system costs.The forecast
of NPC benefits included in the Company's economic analysis of the wind repowering
project and in the referenced sensitivityanalysis is tied to least-cost dispatch of system
resources under a range of potential future price-policy scenarios and reflects changes in
the resource portfolio.Consequently,any change in NPC is consistent with changes in
other system variable costs,includingsystem fuel costs and changes in the resource
portfolios between cases with and without repowering.The nominal levelized total
benefit of the sensitivitycase with wind repowering and new wind and transmission is
$38.97/MWh (cell C82 in "PaR Sensitivity"tab).This figure is higher than the
$34.46/MWh nominal levelized total benefit from the repower case without new wind
and transmission (cell C79 in the "Price-Policy Annual -PaR"tab).
17-035-39 /Rocky Mountain Power
September 1,2017
OCS Data Request 4.11
OCS Data Request 4.11
Please explain why the Company believes that it is reasonable that the benefits in the
Repowering PaR analysis through 2036 ranges from a dis-benefit of $43 million to a
positive benefit of $80 million,yet when the results are extended to 2050,the range is
much greater,with a low benefit of $41 million and a high benefit of $589 million.In
other words,explain why the benefits increase so dramatically when the study period is
extended from 2036 to 2050.Note that the increase in benefits in the New
Wind/Transmission case when the PaR benefits are extended is not nearly as significant
as in the Repowering analysis.
Response to OCS Data Request 4.11
Please refer to Direct Testimony of Company witness,Rick T.Link,lines 493 to 501:
"Beyond the 2036-through-2040 time frame,the change in wind energy
output between a case with and without repowering reflects the full energy
output from the repowered wind facilities that would otherwise be
retired."
This step change does not occur with the new wind and transmission projects for which
all generationis incremental from the beginning to the end of the project life.
17-035-39 /Rocky Mountain Power
September 1,2017
OCS Data Request 4.12
OCS Data Request 4.12
In comparing SO to PaR results in the Repowering analysis,it appears that the SO has
greater benefits in every fuel/CO2 case compared to the PaR results.However,when the
same comparison is made in the New Wind/Transmission case,the SO has lower benefits
in every case except for 2 (High Fuel/Zero CO2,and High Fuel/Med CO2)cases.Please
explain the reasonableness of these results switching direction in these two studies,and
rule out the possibility of any errors in the analysis.
Response to OCS Data Request 4.12
Please refer to the Company's response to OCS Data Request 1.4.The System Optimizer
model (SO model)and Planning and Risk (PaR)model are generally mutuallyreinforcing
in terms of magnitude and direction,but they are different and specialized models.The
SO model is a capacity expansionmodel operating with less granularityand without the
benefit of stochastics.
In general,the SO model will tend to find more benefit in the optimal portfolio that it has
produced.The PaR model is better suited to find granular benefits (and minimize costs)
when addressing the nuances of dispatch and transmission restrictions.Given the large
incremental changes in incremental energy represented by the new wind and transmission
projects,the PaR model tends to find opportunities that outweigh the advantage of the SO
model producing the portfolio.