Risen Energy Jobs in Usa

Energy Transfer, recognized by Forbes as one of America's best large employers, is dedicated to responsibly and safely delivering America's energy. We are driven to inspire our employees to create superior value for our customers, our investors, a sustainable future and giving back to the community where we have long-standing commitments to causes including MD Anderson Children's Cancer Hospital, The Salvation Army, The American Red Cross, Ronald McDonald House and many more.

We value all of our employees who make our growth and success possible. We are proud to offer industry leading compensation, comprehensive benefits, 401(k) match with additional profit sharing, PTO and abundant career opportunities.

Come join our award winning over 12,000 strong organization as we fuel the world and each other!

This position will apply corrosion knowledge and skills to repair, install, troubleshoot, analyze, and perform other predictive and preventative maintenance tasks on assigned equipment, facilities, systems and associated devices contained within gas and liquid facilities and pipelines.

To perform this job successfully, an individual must be able to perform each essential job duty satisfactorily. The essential job duties for this position are listed below:

• Under general direction, provide for design, installation, operation, inspection and maintenance of the cathodic protection systems within an assigned segment of the pipeline system, compressor stations or plant facilities in a reliable and efficient manner while in compliance with the Partnership's procedures and regulatory requirements
• Maintain working knowledge of regulatory requirements, perform associated required tasks, and complete required documentation (OSHA, DOT, EPA, etc.)
• Investigate and analyzes corrosive conditions for existing and/or proposed facilities
• Responsible for corrosion control and associated compliance of cathodically protected pipelines, compressor stations or plant facilities, and other buried, submerged, or above ground facilities
• Proactively conduct pipe-to-soil potential surveys, casing-to-soil readings, rectifier and bond readings, current flows on pipeline, and foreign pipe-to-soil readings and all other structures under cathodic protection on a frequency as stated in SOPs or meet regulatory requirements and document in the corrosion database or other forms, records or reports
• Evaluate protective coating condition including internal, external and atmospheric systems and make repairs as needed, evaluate pipe anomalies and perform remaining strength calculations in accordance with established procedures
• Have an understanding of pipeline internal corrosion mechanisms and related mitigation measures including treatment and testing, collection of samples, bacteria, pH, dissolved H2S, and C02 testing and analysis, and perform chemical requirement calculations
• Perform cathodic protection design including current requirement calculations and soil resistivity testing
• Generate and maintain the reports covering rectifiers, bonds, pipeline isolation and annual corrosion control reports
• Install, maintain and repair rectifiers, anodes systems, cables, bonds, test stations and perform ground bed efficiency calculations
• Evaluate the effects of stray currents from other sources (i.e., traction systems, coal mines, AC transmission lines, etc.) and take the necessary action(s) to mitigate their effect on Energy Transfer facilities
• Read and interpret pipeline maps, as-builts and PLD's
• Must use and operate all pertinent safety equipment when performing duties in potentially hazardous areas (arc flash protective PPE, respirator, hard hat, safety glasses, etc.)
• Must display workmanship consistent with Partnership SOPs industry standards, partnership work practices, applicable codes and/or engineering drawings and sketches
• Insure facilities, grounds, and work areas are maintained in a safe, orderly, and functional manner
• Communicate with other technicians for assistance in effecting repairs when applicable
• Ability to train others in discipline job tasks and to confirm knowledge, skills and abilities of others as an evaluator for partnership skill qualification program dependent upon position level
• Actively participate in PHMSA or State regulatory audits
• Actively participate in partnership safety program and initiatives
• Inspect crew welds on full wrap and pumpkins for acetylene welds and surface pitting that is discovered during corrosion activities such as pipeline recoats and exposure repair
• Comply with partnership safety policies and procedures
• Perform energy isolation lockout/tagout procedures (LOTO)

High school diploma or GED

Required experience is commensurate with the selected job level:

• Level C requires a minimum of 0 2 years of relevant industry experience or equivalent work experience
• Level B requires a minimum of 2 4 years of relevant industry experience or equivalent work experience
• Level A requires a minimum of 4+ years of relevant industry experience or equivalent work experience

• Must maintain valid driver's license in state of residency
• Proficiency with MS Office Suite products
• Ability to train other technicians and/or sign off on qualifications

• Associate of Applied Science Corrosion Technology
• NACE Corrosion Technician or Corrosion Technologist Certification
• NACE CP level II
• Welding school qualifications for inspection of welds

The work environment characteristics described here are representative of those an employee encounters while performing the essential functions of this job.

• Frequent exposure to heat, cold, and other adverse weather conditions
• Working conditions may include confined spaces
• Repetitively standing, walking, bending, stretching, reaching over shoulder height, and climbing ladders up to 25 feet. Occasionally lifting up to 50 lbs with or without assistance
• Subject to call-outs to respond to operational issues and emergencies after working hours, at night, and on weekends and holidays
• Work in and around industrial and construction settings, which may include hazardous products, processes, materials and chemicals, as well as extreme temperature conditions and loud machinery, and may require appropriate personal protective equipment
• Reliable attendance at work
• Occasional overnight travel may be required

The Role:

We are looking for a Director, Environmental Permitting, to lead and scale all environmental functions supporting development, permitting, construction, and operations of on-site power generation to support large data center loads across the U.S.

You will be responsible for leading all environmental strategy, permitting, compliance, and regulatory interface activities for Scale Microgrids Data Center business, providing executive-level oversight of environmental risk management across natural gas generation facilities, data center infrastructure, and electric transmission and distribution assets. You will establish environmental standards, manage agency relationships, oversee consultants, and ensure projects are delivered on schedule and in full regulatory compliance.

This is a leadership role with strategic and operational accountability. Environmental risk can kill a project quietly and expensively, and this role ensures our portfolio moves forward with regulatory certainty, disciplined compliance, and long-term operational stability.

The role reports to our Chief Development Officer, Data Centers, and is based in either our NYC, Ridgewood, NJ, Santa Monica/Oakland, CA, or Chicago offices.

Key responsibilities will include:

Strategic Leadership

• Develop and execute environmental strategies for all projects.
• Identify environmental risks early in project development and integrate mitigation strategies into siting, engineering, and financial modeling.
• Serve as the environmental authority for executive leadership.
• Build and lead the environmental team as the portfolio scales.

Permitting & Regulatory Strategy

• Direct permitting strategy for natural gas generation facilities, data centers, substations, transmission infrastructure, and distribution systems.
• Oversee federal, state, and local environmental permitting, including Clean Air Act permitting (Title V, PSD, minor source permits), Clean Water Act Sections 404 and 401, stormwater and NPDES compliance, wetlands and listed species coordination, cultural resource coordination, and NEPA documentation where applicable.
• Develop permitting schedules aligned with project development milestones.
• Lead negotiations and interface with agencies, including the Department of Environmental Protection, U.S. Army Corps of Engineers, U.S. Fish and Wildlife Service, Fish and Wildlife Conservation Commission, and local jurisdictions and water management districts.

Compliance & Operational Oversight

• Ensure compliance across development, construction, and operational phases.
• Establish internal environmental compliance frameworks and reporting systems.
• Oversee environmental audits and corrective action plans.
• Provide guidance on air emissions monitoring, water discharge compliance, waste management, and spill prevention.

Technical Oversight

• Direct environmental due diligence for land acquisition and project development.
• Oversee Phase I and II ESA processes.
• Evaluate site constraints related to wetlands, species, floodplains, and cultural resources.
• Interpret evolving federal and state environmental regulations and advise leadership accordingly.

Cross-Functional Leadership

• Partner with Development, Engineering, Construction, Legal, and Finance teams.
• Support investor diligence and lender technical reviews.
• Provide environmental risk summaries for board-level presentations.
• Manage third-party environmental consultants and budgets.

Work Environment

• Periodic travel to project locations
• A combination of office, field, and agency engagement responsibilities.

The Ideal Candidate

• Bachelor's degree in Environmental Science, Environmental Engineering, Biology, or related field.
• 10+ years of progressive environmental experience in energy, utility, or infrastructure sectors.
• Demonstrated leadership experience managing environmental programs or teams.
• Deep working knowledge of environmental regulations.
• Experience in permitting natural gas generation and electric infrastructure projects.
• Strong understanding of air permitting for combustion turbines or reciprocating engines.
• Experience interfacing directly with federal and state regulatory agencies.
• Proven ability to manage complex, multi-permit development timelines.
• Strong executive communication skills.

Preferred

• Master's degree in environmental or related discipline.
• Professional certification (e.g., P.E., CEP, CHMM).
• Experience supporting data center infrastructure.
• GIS proficiency and ability to interpret spatial environmental data.
• Experience in microgrid or distributed energy development.

Leadership Competencies

• Strategic thinker who understands how environmental decisions impact capital deployment and schedule.
• Calm and decisive under regulatory pressure.
• Able to balance compliance with development velocity.
• High ownership mindset.
• Strong negotiation skills.
• Comfortable presenting to executive leadership and investors.

This is a great opportunity to have a long-term impact on a fast-paced, private equity backed growth business. Some of the core virtues embraced by Scales' employees include:

• Do the Right Thing
• Act Like an Owner
• Hustle
• Demand Results
• Go Together
• Evolve or Disappear

We offer a competitive compensation package and a comprehensive benefits program including medical benefits, paid vacation and holidays, and 401K matching.

About Scale Microgrids

Scale is redefining resilience, with advanced microgrids that go beyond traditional backup power solutions to give businesses the power to adapt and thrive amid all of today's growing energy challenges. As a vertically-integrated provider of turnkey advanced microgrid systems, Scale combines project design, engineering, and execution expertise with microgrid-as-a-service financing to offer our customers systems that are optimized to deliver maximum value from day one while ensuring ultra-reliable operations and fast time-to-power.

Scale is backed by EQT, a firm with ~$250B in assets, bringing a depth of experience, resources, and capital that will enable Scale to continue pursuing our vision of powering the world with distributed energy. The investment enables Scale to own and operate billions of dollars in distributed generation assets. To learn more about Scale Microgrids, please visit .

About EQT

EQT is a leading purpose-driven global investment organization with EUR 246 billion in total assets under management, divided into two business segments: Private Capital and Real Assets. EQT owns portfolio companies and assets in Europe, Asia Pacific, and the Americas and supports them in achieving sustainable growth, operational excellence, and market leadership. To learn more about EQT, please visit .

Scale strives to attract and retain a workforce that reflects the composition of our customer base and communities. We are committed to providing a work environment that provides everyone with equal access and opportunity to contribute and drive meaningful outcomes. We encourage applicants from all backgrounds to apply and will consider qualified applicants without regard to race, color, religion, sex, sexual orientation, gender identity, or national origin.

Our client, a well-established organization within the energy sector, is seeking a Senior Corporate Oil & Gas Attorney to join its legal leadership team in Houston. This role will work closely with executive leadership and business partners across the organization, providing strategic legal guidance on key initiatives while helping manage risk in a complex and evolving industry.

This position offers the opportunity to step into a high-impact leadership role, overseeing significant legal matters across the business while helping shape legal strategy for a growing organization.

Key Responsibilities

• Provide strategic legal guidance to senior leadership on regulatory matters, risk management, and business initiatives within the energy sector.
• Lead and mentor a team of attorneys and legal professionals, fostering a collaborative and high-performing legal function.
• Oversee complex legal matters including commercial contracts, regulatory compliance, corporate transactions, employment issues, and potential litigation.
• Partner with cross-functional teams to support operational and strategic business objectives.
• Develop and implement legal strategies that align with the organization’s growth plans and evolving regulatory landscape.
• Represent the company in engagements with regulators, business partners, and other external stakeholders when needed.

Qualifications

• Juris Doctor (JD) and active license to practice law in a relevant jurisdiction.
• 10+ years of legal experience, including significant exposure to the oil and gas industry either in-house or within a law firm.
• Demonstrated experience managing complex legal matters and leading legal initiatives or teams.
• Strong background in areas such as commercial contracts, regulatory matters, employment law, transactions, or litigation.
• Excellent communication, leadership, and strategic thinking skills.
• Ability to operate effectively in a fast-paced, dynamic environment.

Preferred Experience

• Prior experience serving as Associate General Counsel or in a comparable leadership capacity within a large energy company.
• Proven ability to influence executive leadership and drive business-focused legal strategies.
• Track record of developing and leading high-performing legal teams.

This is an opportunity for an experienced attorney to play a strategic leadership role within a respected energy organization, partnering closely with executives while helping shape the company’s legal and regulatory strategy.

Who We Are As the largest private-sector power producer in the world and the nation's largest producer of clean and reliable energy, Constellation is focused on our purpose: lighting the way to a brilliant tomorrow for all.

We have been the leader in clean energy production for more than a decade, and we are cultivating a workplace where our employees can grow, thrive, and contribute.

Now integrated with Calpine, our portfolio includes 55 gigawatts of capacity from nuclear, natural gas, geothermal, hydro, wind and solar facilities, with the generating capacity to power the equivalent of 27 million homes.

Our culture and employee experience make it clear: We are powered by passion and purpose.

Together, we're creating healthier communities and a cleaner planet, and our people are the driving force behind our success.

At Constellation, you can build a fulfilling career with opportunities to learn, grow and make an impact.

By doing our best work and meeting new challenges, we can accomplish great things.

Join us in meeting the country's energy needs today and tomorrow.

Total Rewards Constellation offers an extensive selection of benefits and rewards to help our employees thrive professionally and personally.

We provide competitive compensation and a wide-range of benefits that support both employees and their families, helping them prepare for the future.

In addition to highly competitive salaries, eligible employees are offered a bonus program, 401(k) with company match, employee stock purchase program comprehensive medical, dental and vision benefits, including robust wellbeing programs disability and life insurance benefits paid time off for vacation, holidays, and sick days and much more.

Expected salary range of $139,500 to $155,000 , varies based on experience, along with comprehensive benefits package that includes bonus and 401(k).

Travel: Frequent travel to PJM (Norristown, PA) Primary Purpose of Position This individual will be a member of a team dedicated to providing quantitative and qualitative analysis of potential public policy, market design, and commercial strategy initiatives in the PJM Regional Transmission Organization (RTO).

The position will create value through identifying strategic commercial and other business opportunities and advocating for the development of preferred market design and policy objectives and support the execution of those objectives in PJM stakeholder governance processes, with trade groups, ad-hoc coalitions and other stakeholder venues.

The position will advise commercial businesses on opportunities and risks arising from energy market design and additional policies.

The position will have significant responsibility for assuring effective and timely communication of PJM committee activities to affected internal stakeholders.

The ability to work both collaboratively and efficiently with the immediate Constellation PJM team, internal stakeholders, PJM staff, and external stakeholders will be critical.

Primary Duties and Accountabilities Develop, analyze, and advocate for market rules and policies at PJM that support CEG&rsquos businesses and commercial activities.

Identify and analyze emerging trends and policies that present opportunities or risks to CEG.

Understand Constellation business goals, operations and strategies to identify PJM market design reform opportunities Provide timely, clear, concise and complete communication of PJM-related issues to affected internal stakeholders, including senior and executive management, and solicit feedback to integrate into advocacy strategies.

Manage advocacy projects.

Build and maintain strong relationships with PJM management, staff and stakeholders.

Build and maintain strong relationships with internal stakeholders across the company.

Build and maintain strong relationships with industry and government stakeholders.

Develop knowledge of industry and company to increase personal capabilities.

Efficiently and effectively develop, coordinate, and collaborate policy goals and objectives across internal and external stakeholders.

Minimum Qualifications Bachelor's degree in Business, Economics, Marketing, Mathematics, Science, Engineering or related field and 8-years of work experience Working knowledge of electric power industry, especially Regional Transmission Organization markets and operations Basic knowledge of economics, finance, power system operations and power plant operations Proven ability to effectively communicate complex recommendations to a variety of audiences, including senior management Demonstrated ability to creatively solve complex problems Project Management experience Demonstrated excellent written and oral communication skills Analytical skills, attention to detail, critical thinking, problem solving and independent decision making Ability to travel domestically to include overnight Preferred Qualifications Master's Degree in Engineering, Business Administration, or Law Strong interpersonal, communication, and analytical skills with ability to solve new and complex problems quickly d24ad0b8-823f-4e68-a892-2986ccdf7392

Who We Are As the largest private-sector power producer in the world and the nation's largest producer of clean and reliable energy, Constellation is focused on our purpose: lighting the way to a brilliant tomorrow for all.

We have been the leader in clean energy production for more than a decade, and we are cultivating a workplace where our employees can grow, thrive, and contribute.

Now integrated with Calpine, our portfolio includes 55 gigawatts of capacity from nuclear, natural gas, geothermal, hydro, wind and solar facilities, with the generating capacity to power the equivalent of 27 million homes.

Our culture and employee experience make it clear: We are powered by passion and purpose.

Together, we're creating healthier communities and a cleaner planet, and our people are the driving force behind our success.

At Constellation, you can build a fulfilling career with opportunities to learn, grow and make an impact.

By doing our best work and meeting new challenges, we can accomplish great things.

Join us in meeting the country's energy needs today and tomorrow.

Total Rewards Constellation offers an extensive selection of benefits and rewards to help our employees thrive professionally and personally.

We provide competitive compensation and a wide-range of benefits that support both employees and their families, helping them prepare for the future.

In addition to highly competitive salaries, eligible employees are offered a bonus program, 401(k) with company match, employee stock purchase program comprehensive medical, dental and vision benefits, including robust wellbeing programs disability and life insurance benefits paid time off for vacation, holidays, and sick days and much more.

Expected salary range of $152,100 to $169,000, varies based on experience, along with comprehensive benefits package that includes bonus and 401(k).

Primary Purpose of Position Performs advanced regulatory/technical problem solving and provides analysis/insights in support of plant and fleet regulatory activities.

Possesses superior knowledge in functional discipline and its practical application and has excellent knowledge of applicable industry codes and regulations.

Understands interrelations and functions of various organizations (e.g., Nuclear Regulatory Commission (NRC), Institute of Nuclear Power Operators (INPO), Nuclear Energy Institute (NEI), North American Electric Reliability Corporation (NERC) etc.) related to nuclear power.

Functions as a leader with recognized level of expertise in the regulatory area and is a subject matter expert.

As a subject matter expert, leads industry trade groups and works with regulatory agencies to influence programs, projects and regulatory decisions.

Develops relationships with key stakeholders and is recognized by peers and supervisors as an expert in his/her respective regulatory area.

Trains, mentors and coaches' station and corporate regulatory personnel, and develops and provides training as appropriate.

Primary Duties and Accountabilities Perform advanced regulatory and technical tasks and provide insights in support of plant and fleet regulatory activities.

Provide initial or complete task management of regulatory issues.

Assure all regulatory products prepared or overseen are in accordance with applicable procedures, licensing basis, industry codes, standards, and all regulatory requirements.

Provide regulatory/technical expertise and leadership through direct involvement to resolve regulatory issues in assigned programs and other regulatory areas, as necessary.

Perform independent and in-depth research, reviews, studies and analyses to develop, manage and implement regulatory activities, related to plant safety, reliability, maintainability, and availability ensuring compliance to site's needs, regulatory requirements, and corporate policies.

Provide industry leadership and interface directly with regulatory decision-makers and support staff to influence and drive regulatory decisions and policies consistent with Constellation's goals Train and mentor corporate and station regulatory personnel and other functional areas in subject matter areas of expertise Provide strategic recommendation on technologies and techniques to improve performance, simplify operation, reduce costs, reduce regulatory burden, correct regulatory non-compliances, or comply with changes in codes or regulations.

All other job assignments and/or duties pursuant to company policy or as directed by management to include but not limited to: (Emergency Response duties and/or coverage, Department duty coverage and/or call out, and positions outside of department in support of outage activities etc.).

Minimum Qualifications Bachelor's degree in Engineering or equivalent technical degree Minimum of 10 years of professional relevant nuclear power or North America Electric Reliability Corporation (NERC) professional experience and exceptional performance Superior regulatory/technical expertise in a specific area (e.g., licensing actions, reportability, performance improvement, etc.) and recognized regulatory resource (internal/external) Strong written and oral communication skills Approval of VP Licensing & Regulatory Affairs required to obtain this classification (and recommendation of Sr.

Manager Licensing /Director-Licensing/Regulatory Assurance Manager and Site Vice President, as applicable) Maintain minimum access requirement or unescorted access requirements, as applicable, and favorable medical examination and/or testing in accordance with position duties Preferred Qualifications Previous Senior Reactor Operator (SRO) license/certification Advanced technical degree or related coursework Highly seeking previous Nuclear, NRC, Regulatory or Licensing experience d24ad0b8-823f-4e68-a892-2986ccdf7392

Are you interested in being part of an innovative team that supports Westinghouse’s mission to provide clean energy solutions? At Westinghouse, we recognize that our employees are our most valuable asset and we seek to identify, attract and recruit the most qualified talent while recognizing and encouraging the value of diversity in the global workplace.

About the role:

As a Global Lead Manufacturing Engineer you will partner with manufacturing sites and the Quality Assurance functions to develop excellence in manufacturing execution (throughput, quality, productivity, velocity) and to achieve manufacturing process development to ensure manufacture of both legacy and new products. This will include managing process development / optimization programs, and working with product design to ensure Design to Value and Design to Manufacture. Also included is the identification of needed CAPEX investment and business case development of new improvement projects at the fuel manufacturing sites. Travel will be required for this position.

This is a hybrid position reporting to the Director of Manufacturing Engineering. While the role is officially remote, there is a strong preference for candidates who are geographically located near one of our U.S. fuel manufacturing sites in Columbia, NC; Blairsville, PA; or Ogden, UT. Occasional in-office presence will be required based on business needs.

The role involves supporting global manufacturing operations and will require regular travel (30–40%) to international manufacturing facilities. Candidates should be comfortable working independently in a remote environment while maintaining close collaboration with cross-functional teams across multiple locations.

Key Responsibilities:

• Develop strategies for optimizing and streamlining legacy fuel manufacturing operations in partnership with manufacturing sites and functional leads.
• Lead a structured problem solving approach to capture opportunities and close gaps in the manufacturing processes.
• Analyze existing processes and identify value-added and non-value-added activities to solve design challenges
• Lead product line optimization through employing digital and automation technologies, streamlining flow paths, and identifying needed equipment upgrades and new manufacturing process / technology capabilities.
• Partner with GOS Quality and manufacturing sites to increase the capability of manufacturing processes to produce quality products by preventing defects and eliminating waste. Create and deploy strategies for Advanced Product Quality Planning (APQP).
• Partner with manufacturing sites on standardization of production processes, procedures and best practice sharing.
• Develop feasibility studies for new projects / process, capacity upgrades, business case for needed investment or expenditure.
• Work with WEC Site / Engineering teams on Design to Value / Design to Manufacture programs to improve Product manufacturability
• Metrics Accountability – Safety & EHS, Delivery, Quality, Cost, Cost Out, Skills Deployment, Corrective Action Completion.

Qualifications:

• Bachelor’s degree in engineering
• 10-15 years in operations, engineering, quality, or program management with demonstrated experience in manufacturing process development and optimization. Minimum 2 years of experience in the nuclear or related energy industry.
• Certified Six-Sigma Black Belt and Certified Manufacturing Engineer (SME CMfgE) or PMI certification.
• RCFA & FMEA Programs, Continuous Improvement, Lean & Reliable Manufacturing - Quality Systems and Manufacturing 4.0 Engineering technology.
• Promote improvements and measurable results in a global manufacturing environment.
• Demonstrated continuous improvement skills.

We are committed to transparency and equity in all of our people practices. The base salary range for this position, which is dependent upon experience, qualifications and skills, is estimated to be $116,800.00 to $146,000.00 per year.

Why Westinghouse?

Westinghouse Electric Company is the global nuclear energy industry’s first choice for safe, clean, and efficient energy solutions. We enable our delivery of this vision by living our value system:

• Safety and Quality
• Integrity and Trust
• Customer Focus and Innovation
• Speed and Passion to Win
• Teamwork and Accountability

Westinghouse offers competitive benefits to all our employees around the globe to keep them healthy and enhance their well-being. In the U.S. the following are representative of what we offer:

• Competitive Salary
• Comprehensive Health, Wellness and Income Protection Benefits
• 401(k) Savings Plan with Company Match
• Paid Vacations and Holidays
• Opportunities for Flexible Work Arrangements
• Educational Reimbursement Program
• Employee Referral Program

While our Global Headquarters are located in Cranberry Township, PA, we have over 9,000 employees working at locations in 19 different countries. You can learn more by visiting is an Equal Opportunity Employer including Veterans and Individuals with Disabilities.

Employment opportunities may require access to information which is subject to the export control regulations of the United States. Hiring decisions for such positions are required by law to be made in compliance with these regulations. Applicants for employment opportunities in other countries must be able to meet the comparable export control requirements of that country and of the United States.

By applying to this job and providing your mobile number, you are agreeing to receive an initial text from Westinghouse, which you will have the ability to opt out of upon receipt. Message and data rates may apply. Message frequency varies