Renewable energy cost modeling database provide a great way to understand the cost implications of the offshore wind farm projects. Based on a component cost projection technique through the determination of curves based on the variables that most significantly influence the cost-capacity relationship, this generates multiple parameters where specifications of great importance are also defined, such as losses electricity and energy efficiency among others.
The general scheme of the database with a complete exposition of the variables involved and their cost implications, generates projections to estimate the different components, including projections of operating and maintenance costs.
Reference from: A parametric whole life cost model for offshore wind farms, Mahmood Shafiee, Feargal Brennan1 & Inés Armada Espinosa - Springer-Verlag Berlin Heidelberg 2016
OPEX / ABEX
OFFSHORE WIND-FARM CAPITAL EXPENDITURE - CAPEX - ESTIMATION MODEL (CLASS 5-4)
Based on the extensive literature and bechmarkings, the cost drivers of offshore wind projects mainly fall into five categories:
- Pre-development and consenting (P&C),
- Production and acquisition (P&A),
- Installation and commissioning (I&C),
- Operation and maintenance (O&M) and
- Decommissioning and disposal (D&D) .
These cost categories are then subdivided into their constituent elements, and a database is built for each cost element.
The development of an offshore wind farm normally begins around 5 years before the time when the installation is executed. From the first idea to the start of the project, many procedures, studies and paperwork must be accomplished to ensure the technical/economical feasibility.
These costs are related to:
- Project management (CprojM),
- Legal authorization (Clegal),
- The conducted surveys (Csurveys),
- Engineering activities (Ceng) and
- Contingencies (Ccontingency).
CP&C = CprojM + Clegal + Csurveys + Ceng + Ccontingency
The production and acquisition (P&A) cost includes all costs associated with the procurement of:
- Wind turbines (CWT),
- The support structure or foundation (CSS),
- The power transmission system (CPTS) and
- The monitoring system (Cmonitoring).
|Rotor diameter (D, in m) and RPC (MW)||D = 59.354(RPC)0.47|
|Rotor speed (Rspeed, in rpm) and RPC (MW)||Rspeed = 22.781(RPC)−0.3595|
|Hub height (HH) and rotor diameter (D)||HH = D/0.255(D)0.3464|
|Hub mass including pitch, bearing and driver system (M(pb+ds), in t) and RPC (MW)||M(pb+ds) = 8.6421(RPC)1.1194|
|Rotor mass including hub, pitch system and blades (M(hb+ps+bl), in t) and RPC (MW)||M(hb+ps+bl) = 18.453(RPC)1.1357|
|Mass of main rotor shaft (M(ms), in t) and RPC (MW)||(M(ms)) = 0.2415(RPC)2 + 3.0699(RPC)|
|Mass of main bearing (M(mb), in t) and RPC (MW)||M(mb) = 0.1246(RPC)2 + 1.2623(RPC)|
|Mass of rotor, drive-train support structure and nacelle (M(r+d+n), in t) and RPC (MW)||M(r+d+n) = 37.45(RPC)0.984|
|Mass of all components at top of tower (M(thm), in t) and RPC (MW)||M(thm) = 55.9216(RPC)1.0341|
|Reference: Effect of RPC on size and mass of wind-turbine components (Tong, 2010)|
The installation and commissioning (I&C) phase involves all activities related to the construction of offshore wind farms. The costs incurred at this stage include those related to:
- Port (CI&C-port),
- Installation of the components (CI&C-comp),
- Commissioning of the wind turbines and electrical system (Ccomm), and
- the construction insurance (CI&C-ins).
CI&C = CI&C‐port + CI&C‐comp + Ccomm + CI&C‐ins
OFFSHORE WIND FARM PROJECT OPERATING EXPENDITURE - OPEX - ESTIMATION
The operation and maintenance (O&M) cost of an offshore wind farm is divided into two parts, one for the operational expenses (CO) and the other one for the maintenance expenses (CM).
CO&M = CO + CM
The operational expenses of an offshore wind project include the rental/lease payments (Crent), the insurance costs (CO&Mins) and the transmission charges (Ctransmission).
CO = Crent + CO&M‐ins + Ctransmission
The maintenance activities aim to maximize the availability of offshore wind turbines while minimizing the costs associated with random failures. The maintenance costs can be categorized into two types, direct (CM-direct) and indirect (CM-indirect). Then,
CM = CM‐direct + CM‐indirect
OFFSHORE WIND-FARM DECOMMISSIONING & ABANDON EXPENDITURE - DECAB OR ABEX - ESTIMATION MODEL (CLASS 5-4)
The decommissioning and disposal is the final stage of a wind project life cycle, whose procedure is the reverse of the installation and commissioning (I&C) process. The wind turbines at the end of their anticipated operational life are decommissioned, the wind farm equipment depending on the chosen waste management strategy are either removed or recycled, the offshore site is cleared and, lastly, some postdecommissioning monitoring activities are performed.
CD&D = Cdecom + CWM + CSC + CpostM
Cdecom, CWM, CSC and CpostM represent the costs associated with, respectively, decommissioning, waste management, site clearing and post-monitoring.
The decommissioning cost consists of the costs associated with port preparation (CD&D-port) and removal operations (Cremov). Then, the decommissioning cost is given by:
Cdecom = CD&D‐port + Cremov
The cost of port preparation, CD&D-port, can be calculated as
CD&D‐port = Cport‐use + Cport‐labour
Where: The port labour cost is calculated by multiplying the average labour-day required (Nl-d) by the fixed daily labour rate (Lr), i.e.
Cport‐labour = Nl‐d x Lr
For the cost of removal operations, the ecuation:
Ctrans = Nv‐d x Vr
Can be applied considering that less specialized vessels are required for decommissioning activities.
The waste management strategy determines how the wind farm elements will be disposed. The main disposal options available are as follows: reuse, recycle, incineration with energy recovery and disposal in a landfill site (Department of Energy and Climate Change DECC 2011). Independently from the waste treatment option chosen, the materials must be first processed into smaller pieces and then transported to predetermined locations which incur the costs CW-proc and CW-trans, respectively. A fixed fee has also to be paid when the materials are taken to a landfill (Clandfill). Then,
CWM = CW‐proc + CW‐trans + Clandfill –SV
SV ($) represents the salvage (residual) value of the decommissioned assets.
Following the decommissioning of the offshore wind farm, the whole site must be cleared in accordance with the approved regulations. Site clearance involves the removal of all assets of the offshore wind project. The cost associated with site clearance is calculated by multiplying the site area in square kilometres (A) by the clearance cost per unit area (CSC-unit), i.e.
CSC = A x CSC‐unit
Some of the offshore wind components (e.g. cables) may not be fully removed through the decommissioning process. For this reason, a post-decommissioning monitoring and management plan is required to identify and mitigate the risks that may be posed by remaining materials on the seabed. The cost of a post-decommissioning monitoring programme (CpostM) is determined according to several factors such as scale, nature and the conditions of remains (Department of Energy and Climate Change DECC 2011). This cost is considered to be fixed.
OFFSHORE WIND FARM MATERIAL, FABRICATION AND INSTALLATION - DATABASE COST ETIMATION MODEL (CLASS 3-2)