MLI 15 IIE - Gob

Informe Brian entregable 2d 150615_final Page 1 of 11

Brian McNiff 43 Dog Island Rd Harborside, ME

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Risk / Benefit Analysis of Manufacturing MEM Blades in Mexico

Brian McNiff

Document: MLI_15_IIE-10a_MEM_riskanalysis_Task2d_150615.docx Contract: MCNIFF/E/NC/18165

Deliverable 2d, Rev 1.2 Date: 21 June 2015

1 OVERVIEW

This report presents a risk/ benefit tradeoff analysis for manufacturing blades for the 1.2 MW Mexican Eólico Machina (MEM) project in Mexico compared to acquiring them abroad. In general, risks are defined as items that could possibly contribute to not meeting key aspects of the objectives of the project, and, conversely, benefits are items that contribute positively to the goals and objectives of the project. There are, of course, risks and downsides to any action taken, but the goal here is to evaluate the possible actions that can result in a higher benefit compared to the anticipated risk. There is a decided lack of public data to numerically quantify the risks, costs and benefits of the actions and activities involved in the manufacturer of the MEM blades, unfortunately. As such, this analysis is presented qualitatively with some numerical assignment of risk probability and consequence scoring based on this assessment and personal experience. The project objectives are re-stated in the next clause in order to lay the basis for the evaluation. This is followed by a description of the approach used. This report is a part (deliverable 2d) of the McNiff review of capabilities within the MEM collaborative to manufacture MW scale wind turbine (WTG) blades in Mexico. This work was performed under contract with the Instituto Investigaciones Electricas (IIE) as per McNiff proposal (MLI proposal 14MIIE_1 TDR blades 26Dec2014.pdf) in response to the blade consultancy terms of reference (TDR_Rotor_Blade_Consultancy.pdf) under IIE project ME-X1011. 2 MEM PROJECT OBJECTIVES

The MEM project objectives are restated here for guidance and reference:

1. consolidate and advance skills and knowledge to design MW wind turbines


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2. promote and strengthen a supply chain in Mexico for wind energy related goods and services

3. consolidate and advance local, high tech capabilities needed to manufacture, assemble, test, certify, install, operate and maintain MW scale turbines

4. support the development of a 1.2 MW turbine for distributed generation in Mexico and promote local use by small power producers.

3 APPROACH

As noted, there is a lack of substantive public data that would allow us to numerically quantify the risks, costs and benefits of the actions and activities involved in the manufacture of the MEM blades in Mexico versus abroad. Therefore, the approach must include subjective assessments of these elements of risk and the effect of mitigation actions recommended in previous documents. A method is put forth here:

- identify the risks (what can go wrong) and benefits for each of the major activities; - assess a probability or likelihood of the occurrence for these risks for manufacture both in-

country and abroad; - describe the consequence of such risks and how they may impact project goals and provide

a rating of importance (critical = 5, low importance = 1); - describe the recommended risk mitigation methods presented in previous documents and - assess an improvement on the risk probability.

This analysis is presented qualitatively with risk probabilities and importance scoring based on personal opinion and experience. 4 PROJECT RISKS AND BENEFITS

4.1 APPROACH AND RATIONALE

As detailed in McNiff deliverable 2a, there are significant amounts of the required capabilities within the collaborative and interested industrial partners in Mexico for fabricating a set of blades for the MEM project in-country. A summary of capabilities matched to requirements is included in Table 2. As presented in McNiff deliverable 2c (MLI_15_IIE-7a_MEM_augment_Task2c_150604.docx), these capabilities would need to be supplemented to reduce uncertainty and improve the probability of success of the project. In Clause 3.4.1 of that document, the identified supplementary capabilities are discussed and listed. The rationale for including those specific capabilities are described in Table 1 as a function of perceived risks of “things that can go wrong” in the project resulting in some tangible deficiency with the blades, increase to the project cost or delays in the schedule. Arguably, this approach emphasizes deficiencies and negative impacts without giving weight to the benefits. To balance that the benefits to the project are explicitly stated in Table 1 for each of these capability areas. The benefits are, for the most part, actions that meet the objectives restated above in Clause 2 (promoting and consolidating Mexican capabilities in wind energy) as well as being able to deliver the final blades in the 3 year project period. While difficult to quantify, they are listed to provide a relative merit or positive impact.


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4.2 RISK CATEGORIES

In, for instance, a failure mode and effects analysis (FMEA) participants and stakeholders are encouraged to identify specific items that can go wrong and have some uncertainty associated with it or that the project success is highly dependent on. These are then assessed for risk, probability of occurrence, and the consequences or impacts on the project. When identifying possible deviant results of actions or decisions in this project, I tried to remain generic and focused on broader areas of expertise. This allows for a more inclusive matching of required supplementary capabilities to the specifically identified gaps in Mexico (Table 2). This is what is presented in Table 1. The following clause presents a more involved discussion of this.

Table 1 Risk of action in Mexico Item Task Risk Benefit

1a Aerodynamic design

In-experienced analysis team gets aerodynamics wrong resulting in poor power performance and reduced energy production (possible abroad also)

Build WTG aerodynamic design capability in country

1b Structural design

In-experienced team gets structural design and analysis wrong resulting in premature blade failure, early failure -23 test (possible abroad also)

Improved WTG blade design capability in country

3, 4 Manufacturing process

poor manufacturing process design results in reduced strength or stiffness blades, schedule delay and/ or cost increase due to remedies

Broader large scale FRP capability in country

5 Planning and management

Poor project planning and integration results in bad blade, increased costs or schedule delays

Integration experience in country

6 Acceptance Inexperienced team misses major as-built FRP deviations (voids, bad bonds, laminate errors, etc) that results in compromised material properties and reduced blade life

Blade inspection experience, useful in future maintenance inspections/ repairs

7c Certification Poor understanding of or inadequate preparation for the certification process causes delays and increased cost

Experience gained in WTG certification

7a Blade structural testing

No difference in risk, performed abroad since blade testing per IEC 61400-23 (NREL, CENER, ECN, DNV/ DTU, etc) best left to an accredited test lab

In-country learning by observing and assisting the process

1, 7 Lightning protection

Get lightning protection system wrong, risk is outer blade damage during operation (repairable)

Experience in country

4.3 DETAILED DISCUSSION

For each of these areas of concern, I have included some reasoning and rationale for assigning a relative risk and a weighting of importance to the project. The risks and impacts are summarized in Table 3.

4.3.1 Aerodynamic design

The WTG blade design computer codes have converged and matured significantly in the past 30 years mostly due to international cooperation and validation efforts led by NREL, ECN, Risoe/ DTU and others. In that period, significant airfoil design and testing has been carried out specific to the WTG application requirements:

- buildable airfoil designs with insensitivity to roughness; - predictable root area transition airfoils; - broad high lift/ drag operating ranges;


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- smooth performance in the appropriate range of Reynolds numbers; and - well characterized aerodynamic response and properties from static and dynamic testing.

This has resulted in a useful selection of custom airfoils and very good modeling tools to estimate the complete lifetime design loads and expected production energy using the requirements from IEC 61400-1. However, these available tools require some skill and experience to use effectively and a good understanding of the limiting assumptions comes with experience, e.g. – uncertainties of stall, tolerable manufacturing variations in as-built airfoils, dynamic effects, control effects. For this reason I have estimated that errors may be made by engineers in Mexico who have not been through the process before even if trained on the use of the software tools. With the careful selection of an advisory group to review and critique the in-country design effort, this can be improved up to the current state-of-the-art.

4.3.2 Structural design

The structural properties of a wide variety of FRP laminates common to WTG blades have been well characterized through independent work and cooperation by researchers such as Sandia Labs/ Montana Statue University, ECN/ TU Delft and Risoe/ DTU. Large databases of material strength and fatigue properties from their extensive testing of hundreds of laminate arrangements have provided good s-N fatigue curves. Sub-component tests have also provided good guidance on how to scale this data. DNVGL-SE-0074_2014-12.pdf, Appendix B and the soon to be published IEC 61400-5 will provide guidance on usage of these materials data and the recommended knockdowns for design. Some groups have developed “laminate builder” software that have become common in the FRP industry specific to wind turbine blades structural design and analysis. Again, these tools require some skill and experience to use effectively and understanding the limiting assumptions comes with experience, e.g. – effective root stiffness transitions, properly implementing ply drops, modeling bonds, etc. Therefore, errors may be made by engineers in Mexico who have not been through the process before. This is not as pronounced as the aerodynamic part due to local FRP knowledge at the industrial research groups. With the careful selection of an advisory group to review and critique the in-country design effort, this can be improved up to the current state of the art.

4.3.3 Manufacturing process design and implementation

Fabricating consistent, high specific strength FRP (high strength for a given weight) is rather key to wind turbine blades of this size. Since this structure is highly loaded and rotating, the mass and stiffness tradeoffs become critically important due to localized stability, tip deflection limits and dynamic effects Designing and implementing a process that has a minimum of 50/50 glass to resin ratio (or higher – 70/30 is observed in some parts of current blades)) is a reasonably achievable goal, but hand layup can’t normally achieve this without augmenting (automated wetting, vacuum bagging, etc).


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Some automated resin transfer method (RTM) is the norm in the industry, but there are also potential pitfalls with these processes at this scale (keeping laminate in place during infusion, fiber misalignments, voids, etc). There are, as mentioned in previous documents, other risks from blind bonding of structural elements, hub/ blade bolt integration, leading and trailing edge bonds, etc. Skilled hand layup and RTM have been documented as capabilities in the MEM collaborative, but at a smaller scale compared to the 1.2 MW blades. Of course, the Mexican industrial research centers and UAQ have significant capabilities in advanced FRP materials and process knowledge appropriate to scaling this up. So, there are potential risks of implementation of an effective manufacturing process with existing capabilities. As above, these can be mitigated to very close to the state-of-the-art with careful selection of consultant expertise.

4.3.4 Planning and management

In my estimation, the industrial research centers have all the required project planning and management capabilities. Obviously, the external expertise brought in to augment local capabilities need to be involved in reviewing and commenting on task schedules appropriate to their expertise. The improvement of planning from this expertise is included as a part of mitigation.

4.3.5 Quality and acceptance

There are two main sensitive elements of assuring high quality blades during and after the manufacturing process. Even at the quantity of 4 blades for the MEM project needs, quality assurance needs to be defined and tracked throughout the process to assure consistency of material strength and the proper weight and stiffness distribution as per the design. Also, in the final stages of manufacturing, the blade needs to be inspected to verify that it is built to the design:

- Inspect for voids or laminate errors; - Inspect for bad bonding areas and surface defects; - measuring weight and CG location (for balancing rotor also); - measuring tip deflection when applying a simulated static design load with weights; and - measuring first flap and edgewise Eigen-frequencies.

The first element is a function of good quality control practices, which are in place and apparently used effectively in many of the visited organizations in the collaborative. Whether in Mexico or outside, the quality system should be inspected and verified that material and process risks are controlled, but it is assumed that the risk of deviance is the same. The second element is acceptance testing – is this built according to the design? The risk is higher in-country given the inexperience with blades, but there is experience in the MEM collaborative with assembling complex FRP structures, just not to the scale or subject to such complex loading. Again, this can be mitigate with an advisory group. The consequence of missing something at this stage can be rather significant since it is expected that deviant bits may result in premature failure at the certification testing or in the field under actual operating loads.


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4.3.6 Certification

4.3.6.1 Documentation

A third party review of the design is the fundamental goal of certification. Blade component certification is allowed for in IEC 61400-22 certification framework, but it is not a cookbook like prescriptive process. Fortunately, DNV-GL has issued documents that detail the requirements for certification including blade components, (DNVGL-SE-0074_2014-12.pdf, Clause 3 and Appendix B) and an overarching guidance standard for wind turbine blade design and manufacture (DNV-DS-j102_2010-11.pdf). A complete set of design documentation including all steps of the design, manufacturing and validation process needs to be maintained to allow for the design review part of component certification to be performed quickly and efficiently. Otherwise, there will be a number of iterations of questions, requests, inspections, reviews etc that may cause delays and cost over-runs. It is interesting to note that the blade component design review does not include a review of the aero-elastic analysis – the provided loads are assumed to be correct. This is not the case in the complete turbine type certification. This will be performed at some point for the complete MEM. Once again, there are risks from in-country in-experience reflected in the probability of occurrence that can be mitigated with good advice.

4.3.6.2 Blade structural testing

I recommend utilizing internationally recognized, experienced test labs to perform blade structural testing. The advantage is that these test labs are commonly accredited for, mostly, effective documentation, quality control and adherence to standardized processes. This eliminates the need for the certification bodies to do this and may save some time and costs accordingly. The downside of course is that they are all non-Mexican. The certification agencies will allow local testing but they will inspect the process, attend much of the actual testing and dictate test requirements that may not be needed just to reduce their perceived uncertainty. This may cause increased costs and delays. Another advantage of using these experienced labs is the personnel there have seen much and can bring their experience in to effectively diagnose problems and advise on remedies or fixes. Its also not unusual for them to have high tech inspection equipment on the shelf that can be used should the need arise (and the expertise to use and interpret).

4.3.6.3 Lightning protection

The same could be said for using high voltage labs (testing as recommended in IEC 61400-24) to evaluate the effectiveness of strike termination systems outboard on the blade – these are the most problematic parts of the lightning protection system. 4.4 CONSEQUENCES OR IMPORTANCE TO THE PROJECT

There are differences in how important these various risks are and how they may impact project goals. To quantify the impact or the consequence of that particular item going wrong is difficult especially in the aggregated categories I have identified. Nonetheless, a rating of importance to


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the project success has been estimated for each the categories where critical = 5 and low importance = 1.This is also included in Table 3. 4.5 RISK MITIGATION

In the previous documents from this consultancy, the approach to augmenting and supplementing the local capabilities have been detailed (McNiff deliverables 2a, 2b, 2c). Clearly, bringing in this expertise improves the probability of occurrence of the identified deviant situations. The effect of this improvement is also included in Table 3. 4.6 ESTIMATED SCHEDULE

As a reality check, I contacted different colleagues in blade design and fabrication, mold fabrication, WTG certification, blade structural testing and lightning protection system testing as regards average time estimates for completing those elements of process. Figure 1 shows a Gannt chart constructed with that information that shows being able to deliver a set of blades within 2 years. The assumptions used are realistic, but there is clearly enough room to accommodate organizational delays that may manifest within complex multi-party projects. 5 SUMMARY AND RECOMMENDATIONS

My interpretation of the key objectives of the MEM project is to promote and improve the Mexican capabilities in wind turbines and encourage the development of local supply chain and support services for a growing Mexican wind energy industry. It is also critically important to produce reliable, high quality blades within the 3-year project period. Previous deliverables provided an assessment of the local capabilities matched to those capabilities required to successfully produce a set of quality blades within the project period. Gaps were identified and strategies to fill those gaps were presented and recommended. There are risks with any endeavor, and this document provides an assessment of the risks and benefits of building the MEM blades in Mexico versus acquiring them abroad. The decision to fabricate blades in Mexico or abroad was assessed in terms of risks that may compromise the objectives and goals, and actions that may benefit achieving those goals. The previously recommended strategies were also evaluated in terms of mitigating the identified risks. The summary in Table 3 shows that the risks are a higher for fabricating in Mexico but not by a large margin. In my opinion this difference is offset by the benefits of fostering an indigenous Mexican wind industry. It is also suggested that due care should be given to these risks areas to mitigate the effects further than anticipated here. In my estimation, based on this and the draft schedule in Figure 1, it is viable to manufacture the MEM blades in Mexico in less than 3 years with a tolerable risk.


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Table 2 Requirements Matched to in-Country Capabilities

(Ratings: 5 = ideal match to requirements, 1= poor match )

Required Critical Capabilities Organization Match Rating

Notes

1 Wind turbine blade design need expert review

1a – aerodynamic design and aero-elastic modeling

IIE, CIDESI, CIATEQ, UAQ

3 limited - trained in use of models

1b – planform design and structural integration and analysis

IIE, CIDESI, CIATEQ, UAQ

3 limited - trained in use of models

2 High performance composite engineering expert review

2a – High strength/ weight, laminate knowledge

CIDESI, CIATEQ, Dow

5

2b – structural analysis, FEA modeling IIE, CIDESI, CIATEQ

4

2c – use FRP material property & fatigue data bases

CIDESI, CIATEQ

4 important?

3 Process manufacturing experience using FRP

Global, TEMACO, Dow

4

3a – RTM or other well developed laminate system

Global, CIDESI, CIATEQ, Dow

4 smaller scale

3b – workers experienced in FRP fabrication for material cutting, layup, inspection and finish

Global, TEMACO

4 smaller scale

3c – Mature quality system (9001) for repeatability

Global, Dow 4 lacking WTG knowledge

4 Experience fabricating accurate molds & tooling

Global, TEMACO

4 medium scale

4a – Multiple elements, clam-shell molds, compound curves, joints, blind bonding, steep laminate transitions

Global, TEMACO

3 WTG specific

4b – Plug, molds, substructures (root, spar, beams)

Global, UAQ, CIDESI

4

5 Project management IIE, CIDESI, CIATEQ

5

5a – project planning, management and execution

IIE, CIDESI, CIATEQ

5

5b – budgeting and resource management planning

IIE, CIDESI, CIATEQ

5

6 Acceptance testing - manufacture review

6a – As-built coupon strength and composition tests,

CIATEQ, CIDESI

5

6b – Geometrical accuracy – airfoil & planform

CIATEQ, CIDESI

3 WTG specific

6c – Inspections for poor bonds, voids, Somerset 3 WTG specific


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Required Critical Capabilities Organization Match Rating

Notes

laminate discontinuities, etc using NDT (NDT), CIATEQ, CIDESI

6d – Measuring weight and CG location, stiffness, eigen-frequencies

need WTG specific advice

- basic knowledge

7 Certification

7a – wind turbine blade testing experience 1

7b – experience in any product certification CIATEQ 2 Do they certify ?

7c – experience specific to wind turbine certification

1

Notes: UAQ = Autonomous University of Querétaro


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Table 3 Comparative risk summary

What can go wrong?

(see Table 1)

Likelihood Importance to Project Risk mitigation actions Improved likelihood

Mexico Abroad Consequences Rating Mexico Abroad

1a Aerodynamic errors – airfoil selection, poor modeling & analysis,

15% 5% Reduced energy production, increased loads

4 External consultants to provide review and oversight

5% 5%

1b, 2

Deficient structural design 15% 5% Reduced operating life


5% 5%

2, 3 Poor manufacturing process design

20% 5% Reduced operating life


10% 5%

3, 4 Poor fabrication from inexperienced labor & techniques



10% 5%

5 Poor project planning and integration

10% 10% Deficient blade, increased cost, delays

4 good selection of project lead, require thorough review and requirements

5% 5%

6 Inexperienced inspection team misses major as-built FRP deviations

25% 7% Poor material, Reduced operating life


10% 7%

7 inadequate preparation for certification process

15% 5% delays and increased cost


5% 5%

7 Large scale design problem not revealed in blade testing


5 Test facility abroad to perform tests in both cases

2% 2%

1, 7 Inadequate lightning protection system

10% 10% Increased operating costs due to repairs


5% 10%

Note: importance rating is 5= critical importance, 1= low importance to project


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Note: estimates from personal communication with TEMACO (mold fabrication), Wetzel Engineering (blade design and fabrication), DNV-GL (certification), NREL (blade testing) and Lightning Technologies (lightning protection testing).

Figure 1 Estimated Schedule for In-Country Manufacturing

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