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Offshore wind projects: Assessing the environmental impact

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An overview of rules and developments in Australia, Germany, Japan, Mexico, the UK and the US

Navigating environmental issues in offshore wind project development

Around the globe, opportunity is on the rise, but regulatory and political challenges persist

Throughout the world, many national and local governments are creating regulatory and commercial environments to encourage developers, lenders and investors to build, finance and invest in offshore wind energy. This has led to an upswing in the number of offshore wind projects being planned and built around the world. Renewable energy generated by offshore wind power is typically consistent with nations' climate change commitments under the Paris Agreement to reduce greenhouse gas emissions. However, offshore wind farms have unique impacts, which are addressed through environmental and natural resource policies and rules.

Governments in many of the key markets for offshore wind investment typically require the environmental and social impacts of a proposed offshore wind project to be assessed and mitigated. The complexity, sophistication and duration of the environmental impact assessment process varies across jurisdictions, and must be carefully evaluated by potential developers and investors. Project proponents also need to be mindful that in most jurisdictions, although to varying degrees, the environmental and social impact assessment
is subject to public scrutiny and comment, and can also be vulnerable to legal challenges.

This report offers an overview of key environmental risks raised by offshore wind projects in six key jurisdictions: Australia; Germany; Japan; Mexico; the UK; and the US. Offshore wind farms operate in many of these jurisdictions. In others, they are increasingly attractive because of higher offshore wind speeds and capacity factors, shallow ocean depths and supportive government policies. We summarize how regulators in these jurisdictions require project proponents to consider impacts to birds, bats, fish and marine mammals during the development process. We also assess how noise associated with the construction and operation of offshore wind projects must be addressed. Finally, we focus on the aesthetic considerations, decommissioning requirements and impacts to fishing, navigation and transportation that arise in the planning, construction and operation of an offshore wind project.


Offshore wind projects face challenges that are not addressed by the regulatory system established for onshore projects


A complex and sophisticated planning and approval process does not prevent opponents from raising environmental challenges—even after project approvals are awarded


Despite strong government support and growing capacity, a lengthy approval process may slow progress


With no offshore precedents, project proponents may find complexity, inconsistency and opportunity

United Kingdom

A global leader in offshore wind power capacity, the UK has seen rapid expansion in the sector

United States

As the offshore wind industry begins to take off, environmental impacts remain key concerns

Offshore wind power gains ground but faces environmental challenges

To maximize its potential, industry players will have to navigate an often-complex web of national, state and local environmental regulation


With no offshore precedents, project proponents may find complexity, inconsistency and opportunity

10 min read

In Latin America, Mexico has been a leader in the development of onshore wind energy plants. However, no offshore projects have yet been developed. Given the lack of offshore precedents in Mexico, the following summarizes most important environmental provisions that should apply.


The general law for ecological balance and environmental protection

The General Law for Ecological Balance and Environmental Protection (General Law) was originally enacted in 1988 to serve as a general code covering all areas of environmental law, from which secondary provisions would be enacted. While subsequent environmental laws covering specific areas such as biodiversity protection, renewable energy, forest land and climate change superseded the General Law, it still regulates the Environmental Impact Authorization (EIA), one of the most important and complex authorizations required by any wind project.

The General Law's Regulations on Environmental Impact Assessment require an EIA issued by the Federal Ministry of Environment and Natural Resources (SEMARNAT), which will review the environmental impact statement (MIA) filed by the developer. The MIA, a complex legal and technical document, serves primarily to identify and mitigate environmental impacts applicable to all project phases, from site preparation, construction, operation, maintenance and decommissioning, to proving compliance with applicable federal, state and local environmental and land use regulations.

When a specific activity is not regulated by a secondary provision, especially an Official Mexican Standard (NOM), SEMARNAT has considerable discretion for performing the environmental impact assessment. Although a NOM project was published in 2006 for regulating wind farms to be established in rural areas, it was canceled in 2014 before it could be enacted as an enforceable standard. There is no NOM for offshore wind farms.

As a result, the process for securing an EIA may prove lengthy, and criteria may differ for similar projects when analyzed by different officials or offices of the ministry (either the central Direction General for Environmental Impact and Risk or state delegations of SEMARNAT).

Local governments are also consulted during the environmental impact assessment procedure to confirm that the project will comply with local environmental and land provisions. In some cases, SEMARNAT may decide to open the environmental impact assessment to community consultation, where the project proponents will have to discuss the details of the works to be performed, their potential impacts, as well as mitigation, prevention and compensation measures to be undertaken.

Community consultation has raised problems because it commonly delays SEMARNAT's environmental impact assessment and may draw the attention of several interest groups that may decide to oppose the project based on environmental, social or cultural arguments (especially in cases where indigenous communities may be affected). Offshore projects could provide solutions that avoid raising social issues commonly associated with onshore wind farms, although some specific communities, such as fishing towns, could still raise complications.

In addition to the EIA, the social impact authorization (SIA) is also important. Issued by the Ministry of Energy prior to construction of new projects, it is required to obtain other permits and approvals from the energy authorities.

The forest land use authorization, required for removal of vegetation and also granted by SEMARNAT, is commonly required for onshore projects. But it could also be required for an offshore project given the effects of the transmission line and any other infrastructure to be built on land. It is important to consider that there are legal restrictions regarding the removal of some flora species, such as the mangrove, which are further explained below.

Projects that could affect indigenous communities may require prior consultations with those communities. Related to this, places with an important archaeological or historical value, such as the Mayan coast, may also require prior consent from the federal authorities. These consultations and authorizations, as well as the SIA, are not strictly environmental, but may influence SEMARNAT in its environmental impact assessment regarding the authorized uses of the project area.

Offshore projects could provide solutions that avoid raising social issues commonly associated with onshore wind farms.


Impacts to bird and bat species

Mexico is a mega-diverse country, meaning it has some of the world's most important populations of flora and fauna. These are protected by Mexican environmental laws, as well as several international treaties to which Mexico is a party, such as the Convention on Biological Diversity and the Ramsar Convention. These treaties protect specific fauna species—including birds and bats—or their habitats, which may include maritime areas.

Several bird and bat species are classified under a determined legal protection scheme, pursuant to the General Law of Wildlife and NOM-059-SEMARNAT-2010, and SEMARNAT will require more stringent mitigation and prevention measures to be offered and implemented by project proponents when a wind farm may affect protected species. Even if there is no NOM that establishes technical requirements in this regard, developers are commonly required to establish a bird and bat protection plan, preferably based on international or foreign standards, which will include monitoring requirements to undertake before construction and until the operation phases end.

More stringent requirements may be issued or an EIA may be denied when a project is intended for development in a natural protected area, as further explained below.

After issuance of an EIA, project developers will be required to file with SEMARNAT a periodical report addressing the results of the monitoring activities performed pursuant to the mitigation plan presented to the authority, or required to be prepared pursuant to the terms and conditions of the authorization.


Visual impacts

Visual pollution is poorly regulated in Mexico, since the General Law merely mentions it in its article 155, forbidding the "generation of visual pollution," pursuant to the limits specified in NOMs. However, since no NOMs have been issued regarding visual pollution, the authorities have little guidance as to implementation.

Nonetheless, visual impacts may be relevant when the federal and local authorities prepare land use plans, specifying which activities are allowed in specific and well-defined regions. When preparing an environmental land use plan, or in the case of an offshore project, an environmental maritime use plan, authorities may address other intended uses of the areas, such as tourism, and forbid certain activities in such locations due to their visual impacts.

When SEMARNAT conducts an environmental impact assessment to decide whether to grant an EIA, it addresses those use specifications for a specific area established in the environmental maritime use plan. If an EIA is issued, SEMARNAT focuses on the same specifications to determine the terms, conditions and limits or mitigating measures to establish for the project.

Local authorities may also play an important role in the process of securing authorizations for an offshore project if they determine that potential visual impacts make the wind farm incompatible with the area's other uses (mainly tourism or cultural). Even an offshore wind farm may require a transmission line or other infrastructure to be built inland. This would require obtaining a concession for the use of the federal maritime land zone from SEMARNAT. In the application process, it is necessary to obtain a consent letter from the local authority specifying that the use for the concession is compatible with other land uses authorized by the municipality. If the local authority determines that the project, due to its visual impacts, may affect other intended uses of the area, it can decline to issue the required consent letter, preventing SEMARNAT from granting the required concession.

Mexico has some of the world's most important populations of flora and fauna, which are subject to several international treaties.


Impacts to marine species

The impacts to marine species will be commonly addressed by the authorities when preparing an environmental maritime use plan for a specific region. Also, a natural protected area may be established in a zone that has specific relevance for biodiversity effects due to the existence of important species of flora or fauna. In the case of fauna species, marine mammals and sea turtles are especially relevant, as well as some species of fish and maritime invertebrates.

In the case of sea turtles, NOM-162-SEMARNAT-2012, issued in 2013, establishes technical requirements for their protection, recovery and management in their breeding habitats. For projects that will affect the coast in areas where sea turtles breed and make their nests, it is common for SEMARNAT to require the establishment of a breeding center for turtles to be managed by the developer, following the requirements of this standard and of the General Law of Wildlife, as a condition for the project's authorization.

As for flora species, it is important to note that the mangrove has been awarded a special kind of protection by the General Law of Wildlife. In addition, the mangrove was already included in the list of NOM-059 as a specially protected species. When amended in 2007, the General Law of Wildlife included article 60 TER, which established a prohibition on performing any work or activity that may affect the hydrological flow of the mangrove, its ecosystem and its area of influence, as well as interactions between the mangrove, rivers, dunes, corals and the adjacent maritime area.

This new provision resulted in controversies, and several offshore or coastal projects planned for, or influencing, coastal areas ultimately were not approved. Opinions differ within SEMARNAT regarding the interpretation of article 60 TER. As a result, similar projects obtained different results when submitted for their environmental impact assessments.

Currently, NOM-022-SEMARNAT-2003 is a useful guideline for determining if a project may affect the mangrove and if its impacts may be properly mitigated. It establishes technical specifications for the preservation, conservation, sustainable use and restoration of coastal wetlands in mangrove areas. This standard, though issued prior to the amendment of the General Law of Wildlife, is commonly used during environmental impact assessments to confirm whether a mangrove area will be affected. It provides a more certain guideline that has limited the discretion of the environmental authorities when evaluating a project for purposes of granting an EIA, or a forest land use change authorization when other flora species are to be removed (usually required for the transmission line).

Finally, it is important to note that Mexico has established several federal natural protected areas, including maritime ones, where many activities are strictly forbidden or limited. Areas with an important environmental context, such as the Sea of Cortez, may present extreme complications for a project's implementation, not only due to existing legal restrictions, but also to social opposition that may negatively influence the authorities in their environmental impact assessment.



In addition to prohibiting visual pollution, article 155 of the General Law prohibits the emission of noise, vibrations, thermal and luminous energy beyond the limits established by applicable NOMs.

In this regard, NOM-081-SEMARNAT-1994 was issued to establish maximum allowable limits for noise emissions generated by fixed sources, as well as the method for measuring noise. SEMARNAT will request compliance with this standard for all phases of the project, including its construction and operation. The original text of this standard established maximum allowable levels of 68 A-weighted decibels (dBA) from 6:00 a.m. to 10:00 p.m., and of 65 dBA from 10:00 p.m. until 6:00 a.m.

However, the standard was modified in 2013, establishing maximum allowable limits depending on the kind of area where the facility is located—residential, commercial and industrial, schools or ceremonial and entertainment—so it should not apply to offshore wind farms. It is likely that for an offshore project, SEMARNAT could consider the limits established by the standard prior to the amendment, or request a specific study for limits that could prevent any major impacts for the specific area where the project is to be developed.



Although no provisions address the decommissioning of wind farms, SEMARNAT will commonly require project developers to include it within the MIA environmental impact projections and to establish related mitigating and preventive measures. Absent proper regulation, this phase of any wind project remains quite open to SEMARNAT's discretion while performing an environmental impact assessment.

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