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The Top Companies in the Energy Sector

top ten energy companies

In the US alone, there are over 3,000 companies working in the energy sector. These energy companies deal with coal, oil, natural gas, and electricity production/generation and distribution. Together, they make the US economy run. However, there are new energy companies springing to life every week or so, and understanding who the biggest players in the energy field are is becoming more and more difficult. 

Tesla, for example, is partly an energy company. It generates electricity through solar panels and solar shingles. However, although the company receives a lot of publicity, it does not mean that it is one of the biggest energy companies in the country. Most large US companies working in the energy field or the energy industry are international companies, with daughter companies abroad – like the EU, Australia, and Asia. 

So, if you are looking for investment opportunities in the energy field or would simply like to stay informed, this is the right place for you. Here, we list major energy companies, together with details about their work, market cap, and other useful information so that you could make informed decisions. However, as the energy field is so vast, we have to take into consideration different types of energy and we have to take a closer look at the energy sector. 

What is the Energy Sector?

So, what companies are in the energy field or in the energy sector? Well, before we answer that question, we have to take a look at several different terms: energy industry, energy sector, and energy field. Although it may seem that these terms are interchangeable, they are not. 

The energy industry is an umbrella term that stands for all other (sub)industries that work in the energy sector. The energy industry of any country is a huge industry and it supports all other industries. Without an energy industry, there is no transportation, and no electricity, or heat. 

The energy sector is made up of all the companies that work in the energy industry. These are all the companies dealing with energy sources and their exploration, exploitation, and energy conversion. The energy sector mostly deals with the energy used in heating and transportation, as well as the energy used in the energy and production industry. 

The energy field is the widest term of all. It is somewhat political in nature, and it focuses on both the energy sector and the energy industry. The term also means energy policies issued by governments and it is usually talked about when politicians talk about changes and adaptations. The energy field is very wide, and it also refers to theoretical findings, funding, and future technologies. 

Types of Energy Companies

Since the energy field is so vast and the energy companies so numerous, we have to categorize them. There are many types of categorizations, but considering the recent talks about energy efficiency, energy consumption, and the transition to renewable resources, we’ve decided to focus on energy companies by the type of energy they exploit. Based on the energy source, we can say there are the following types of companies: 

  • Oil and gas companies, 
  • Electrical power companies, 
  • Nuclear power companies, and 
  • Renewable energy companies. 

Although some sources say that renewable energy companies and nuclear power companies are subcategories of electrical power companies, we have decided to keep them as separate categories. This way, we can focus on all three common sources of electricity used in the US: 

  • Electrical power companies – drawing energy from fossil fuels, such as coal, oil, and gas, 
  • Nuclear power companies – relying on nuclear fission to generate power, and 
  • Renewable energy companies – drawing power from naturally replenishing power sources, such as: 
    • Sun, 
    • Wind, 
    • Hydro, and 
    • Biomass. 

Oil & Gas Companies

Oil and gas companies are numerous. These are usually gigantic companies with branches in many countries of the world. These operations are vital to the economy, so they are heavily subsidized by the governments. Although these companies are vital to the economy, the very fact that they pollute as much as they do is likely to force these energy companies to shift from fossil fuels to renewables and biofuels, such as biodiesel, bio-petroleum, biogas, and biomethane. 

There are many more, but these biofuels show a high likelihood of taking over the energy market. In the meantime, these companies deal with the exploration, exploitation, or recovery of fossil fuels (oil and gas drilling), and they also process whatever fuel they unearth. These companies also work on international markets, supplying coal, oil, and gas to the world. 

Refining and Pipeline Companies

Refining and pipeline companies, on the other hand, deal with processing crude oil for further energy production. Crude oil does not have many applications and has to be processed before it is sent elsewhere for use. Crude oil is turned into: 

  • Petrol, 
  • Diesel, 
  • Heating oil, 
  • Lubricants used in the automotive industry, 
  • Oils used in cars, 
  • Plastics, 
  • Chemicals used in medicine, 
  • Perfumes, 
  • Fertilizers, 
  • Bitumen, 
  • Asphalt, and hundreds of other products that you rely on in your daily life. 

Pipeline companies, on the other hand, ensure that the oil extracted from the Earth can be delivered to the refineries. As transporting all this oil would be costly and inefficient, pipelines are formed, which allow the transportation of fuels to the refineries. This way, the costs are kept at bay, roads are spared, and a lot of energy is saved, as transporting fuels by means of a pipeline is cheap and efficient, and takes very little time. 

Although the oil industry pollutes a lot, it is a necessary part of the economy. The gas industry, for example, ensures a source of electrical energy, that is used to power cars and heat homes. Oil and gas reserves that help stabilize fuel prices throughout the country are replenished by means of these companies. Furthermore, liquefied natural gas facilities help stabilize and transport natural gas, which can then be easily transported to the parts of the country that have no oil and natural gas fields of their own. 

Electrical Power Companies

Electrical power companies keep the lights on throughout the country. Not only that, but they also ensure that all the buildings, including hospitals, and other kinds of institutions can do their job uninterrupted. They also support bans and transportation, especially with the development of electric cars in the past decade. 

Electrical power is considered to be a clean energy source, at least cleaner that the energy we get from the oil industry. However, the reality is different: this form of energy can be as polluting, depending on the source of energy used to generate electricity. Coal, oil, and natural gas can all be used to produce electricity. Coal is the most polluting of all, with oil taking second place. 

Natural gas, on the other hand, burns more cleanly than the other forms of energy and produces less CO2 – a greenhouse gas. Natural gas has also been dubbed a “transitional fuel” that the world will mostly rely on during its transition to clean energy sources, such as solar, wind, and hydro. Currently, this is one of the most widely used forms of energy in the US. 

Many of these energy companies focus on efficient energy solutions and nullifying the losses. Currently, the US is modernizing its power grid, with the aim of reducing power losses through the grid and ensuring that all the energy produced can be utilized. Electric energy in the US has a wide range of possible applications: 

  • Producing heat, lights, etc. while insisting on energy efficiency, 
  • Ensuring power supply for domestic, commercial (business), and industrial energy consumption, 
  • Production and processing sector, 
  • Food production, 
  • Pharmaceutical industry, 
  • Banking and computational energy needs, 
  • All other sectors, industries, and transportation purposes rely on electrical energy. 

Nuclear Power Companies

Nuclear power companies, on the other hand, produce energy (usually electrical energy) using nuclear fuels. These fuels do not release any Greenhouse Gasses (GHGs), but they do create some amount of radioactive waste. These fuels are considered green, although not renewable. 

Nuclear energy is one of the cheapest we currently have – and that is thanks to a high level of energy efficiency. Nuclear energy provides a lot of jobs in the energy sector, employing as many as 43,000 people in the US alone. Rising global pollution levels and the need to part with fossil fuels have restarted the political debate where we should see if nuclear is one of the acceptable energy technologies for expansion or not. 

The biggest issue with nuclear energy is that nuclear waste cannot be disintegrated and that it cannot be destroyed. This waste will stay as it is (radioactive) for thousands of years to come. Although every nuclear company focuses on safety first, the examples of Chernobyl and Fukushima tell us that there is no such thing as being overly cautious. 

However, the developments in the field of micro-nuclear power plants and the moves in nuclear fusion technology may usher in nuclear as one more form of transitional energy source. While energy technologies are being developed, the world simply cannot produce enough wind turbines and solar panels to ensure that 100% of our energy needs are satisfied. 

Renewable Energy Companies

On the other side of the spectrum are renewable energy companies. These companies rely on renewable sources to generate power – renewable energy naturally replenishes and so, it is always available. Solar power generation and wind power are just some examples of this versatility group of companies and the energy sources they use. There are several forms of renewable energy that can be used to produce power here: 

  • Solar energy is mostly produced through solar panels, solar collectors (solar water heating systems), or solar focal farms, 
  • Wind energy, used in vertical and horizontal-axis wind turbines, 
  • Biomass energy, used in the form of pellets, biomass for burning, aerobic and anaerobic digesters, 
  • Biogas energy systems – usually connected to anaerobic digesters, these systems can also draw on energy from landfill gas and animal manure, 
  • The energy of waves is highly underutilized, but has a lot of promise, 
  • The energy of ocean currents, as it is also highly underutilized, and can provide renewable energy to power the world, 
  • Hydro-energy, used in the form of hydro accumulations, and pumped hydro, 
  • Geothermal energy is not used enough. It can be used in geothermal systems both for heating and electricity generation. However, as geothermal is not available everywhere, it is probably best for local uses, without significant portions of the power grid relying on it. 

One of the biggest obstacles to the faster development and wider deployment of renewable energy is its high intermittency. Solar power companies in the energy sector, for example, only work during the day, with a handful having enough solar storage to supply energy during the night. The same goes for wind, while other forms of renewables have a more seasonal character – biomass availability is, for example, very low in the winter months. 

However, cogeneration capacities and developments in storage technology can help limit or even completely overcome this issue. Namely, pumped hydro, gravity-based storage solutions, and other similar net-zero emissions solutions can store excess power supply and make for responsible energy consumption with less waste and lower energy costs. 

Companies in the Energy Field

best utility companies to work for

Energy systems employed by these companies make the world go around. These companies ensure that our energy needs are satisfied, that our cars can run, and that our homes are warm in the winter and cool in the summer. In most cases, various energy systems are employed to ensure that the systems are stable and reliable, with little downtime and little inconvenience to the end customers. Let’s have a deeper dive into these largest energy company names: 

ExxonMobil Corporation

ExxonMobil Corporation is a global energy and petrochemical company. It operates in more than 200 countries and territories and has a diverse workforce of over 75,000 people. It is the world’s largest publicly traded international oil and gas company, providing energy that helps underpin growing economies and improve living standards around the world. ExxonMobil Corporation is committed to addressing the world’s challenging energy needs in an economically, environmentally, and socially responsible manner.

Duke Energy

Duke Energy is one of the largest energy companies in the United States. Duke Energy’s businesses include regulated utilities and merchant energy businesses. The regulated utilities provide electric and gas service to approximately 7.5 million customers in six states – North Carolina, South Carolina, Florida, Indiana, Ohio, and Kentucky. The merchant energy businesses include 9,700 megawatts of regulated generation, 7,800 megawatts of unregulated generation, and 2,300 megawatts of demand response and energy efficiency.


Chevron Energy is an American oil and gas company that is headquartered in San Ramon, California. Chevron Energy is a subsidiary of Chevron Corporation, one of the largest oil companies in the world. Chevron Energy’s primary business is the exploration and production of crude oil and natural gas. Chevron Energy also has a strong focus on innovation and technology, with a dedicated research and development team.


Exelon is a leading provider of electricity and gas in the United States, with over 10 million customers. They are also the largest competitive U.S. power generator, with a diverse portfolio of nuclear, gas, coal, and renewable energy. Their mission is to provide safe, reliable, and sustainable energy solutions for their customers. 

Southern Company

Southern Company is one of the largest energy companies in the United States. They are headquartered in Atlanta, Georgia, and serve nine states: Alabama, Arkansas, Florida, Georgia, Louisiana, Mississippi, North Carolina, South Carolina, and Tennessee.

Southern Company’s main businesses are electric power generation and natural gas distribution. They own and operate electric utilities, including four investor-owned electric companies (Alabama Power, Georgia Power, Gulf Power, and Mississippi Power) and two electric cooperatives (Central Alabama Electric Cooperative and Wheeler Electric Membership Corporation). Southern Company also owns and operates a natural gas utility (Alabama Gas Corporation) and a natural gas pipeline system (Southern Natural Gas Company).


ConocoPhillips is an American multinational energy corporation with operations in more than 30 countries. The company is engaged in the exploration, production, transportation, and marketing of crude oil and natural gas. ConocoPhillips was founded in 1917 as the Continental Oil and Transport Company. The company was later renamed ConocoPhillips in 2002. ConocoPhillips is headquartered in Houston, Texas.

Dominion Energy

Dominion Energy is a leading energy company that provides electricity and natural gas to more than 7 million customers in the United States. The company also owns and operates a large fleet of power plants, including nuclear, coal, and gas-fired plants, as well as renewable energy facilities. Dominion Energy is committed to providing clean and affordable energy to its customers and is a leader in the fight against climate change.

Enterprise Products

Enterprise Products is a leading provider of energy products and services. It is dedicated to helping its customers meet their energy needs in a safe, reliable, and efficient way. They offer a wide range of energy products, including electricity, natural gas, and renewable energy. They also provide energy services, such as energy efficiency, demand response, and load management. 

Sempra Energy

Sempra Energy is a Fortune 500 energy conglomerate with operations in more than 30 countries. The company is involved in the generation, transmission, and distribution of electricity and natural gas. Sempra Energy also has a large portfolio of renewable energy projects. The company’s operations are organized into four main business segments:

  • Sempra Utilities: This segment includes the company’s regulated electric and gas utility businesses in the U.S.
  • Sempra International: This segment includes Sempra Energy’s energy businesses in Latin America and Europe.
  • Sempra Renewables: This segment includes the company’s renewable energy development and investment businesses.
  • Sempra LNG: This segment includes Sempra Energy’s liquefied natural gas businesses.


Schlumberger is a technology company that provides services and equipment for the oil and gas industry. Schlumberger’s main product is a type of oilfield equipment known as a ‘logging tool’. This tool is used to measure the properties of rock formations and oil reservoirs. Schlumberger also provides other services such as seismic data acquisition and processing, well testing, and reservoir characterization.

In addition to its services and equipment, Schlumberger also provides software and consulting services to the oil and gas industry. Schlumberger’s software products are used for exploration, drilling, production, and reservoir management. The company’s consulting services help oil and gas companies to optimize their operations and improve their performance.

Phillips 66

Phillips 66 is an energy company with a diversified business portfolio. The company operates in three segments: midstream, chemicals, and refining. Phillips 66’s midstream segment gathers, processes, and transports crude oil and natural gas. The company’s chemicals segment manufactures and markets chemicals and plastics. Phillips 66’s refining segment processes crude oil into petroleum products, such as gasoline, diesel, and jet fuel.

Kinder Morgan

Kinder Morgan is a leading energy infrastructure company. It owns and operates vital energy assets across North America, including natural gas and oil pipelines, terminals, and coal and power plants. Their assets provide critical services to businesses and communities across the continent. It transports natural gas to homes and businesses and delivers oil and refined products to gas stations and airports. 

Marathon Petroleum

Marathon Petroleum Corporation is an American petroleum refining, marketing, and transportation company headquartered in Findlay, Ohio. The company was a wholly owned subsidiary of Marathon Oil until a corporate spin-off in 2011.

Marathon Petroleum operates the nation’s largest refining system, with a crude oil refining capacity of more than 3 million barrels per day in its 15 refineries. The company also has a strong marketing presence, with a nationwide network of approximately 7,700 Marathon-branded retail outlets. Marathon Petroleum also transports crude oil and refined products through its integrated system of pipelines, barges, and tanker trucks.

American Electric Power

American Electric Power (AEP) is one of the largest electric utilities in the United States, with over 5 million customers in 11 states. AEP runs several different types of generation facilities, including coal, natural gas, nuclear, and hydroelectric power plants. The company also owns and operates a large transmission system that delivers electricity to its customers.

AEP’s mission is to provide affordable, reliable, and sustainable electricity to its customers. The company is committed to investing in cleaner energy sources and technologies to help achieve this goal. AEP has set a goal to reduce its emissions by 80% by 2050, and it is well on its way to meeting this target.


Uplight energy company uses a variety of clean energy technologies to provide services that help utilities and other energy companies transition to a low-carbon future. It works with utilities to provide them with the resources they need to make the switch to cleaner energy sources, and it also helps other energy companies develop and deploy new clean energy technologies. In addition, it provides consulting services to help government and industry leaders make informed decisions about the energy transition.

Romeo Power

Romeo Power is a global technology company that designs, manufactures, and markets advanced battery solutions. The company’s products are used in a wide range of applications, including electric vehicles, energy storage systems, and consumer electronics.

Romeo Power’s products are based on cutting-edge battery technology that enables them to outperform traditional lead-acid batteries in terms of energy density, power density, and safety. This makes the company’s products ideal for a wide range of applications that require high performance and reliability.


Mosaic Energy company is a sustainable energy company that provides affordable, clean energy to businesses and homeowners. We believe that energy should be sustainable, reliable, and affordable for everyone. We are committed to providing our customers with the best possible products and services to help them save money and reduce their environmental impact.


PosiGen is a green energy company that provides affordable solar power to homeowners and businesses. PosiGen was founded in 2011 with the mission of making solar power more accessible to everyone. PosiGen is headquartered in New Orleans, Louisiana, and has locations across the United States. PosiGen solar panels are designed to be installed on any type of roof, and they come with a 25-year warranty. 

LGCY Power

LGCY Power is a solar energy company that provides solar panel installation and maintenance services to homeowners and businesses. It offers a solar lease program that allows customers to lease solar panels from it and pay for the electricity they generate. In addition, it sells solar panel systems to customers who want to purchase their own panels.


Invenergy is a leading renewable energy company. It develops, owns, and operates large-scale, utility-grade renewable energy generation facilities in the United States, Canada, Mexico, and Europe.  Across its generation portfolio, Invenergy has ownership interests in 196 wind farms, five solar facilities, four natural gas-fired power plants, and one battery storage project. Collectively, its projects have a capacity of nearly 19,000 megawatts (MW) and its facilities are capable of producing enough electricity to power more than 16 million homes.

NRG Energy

NRG Energy is an energy company that provides electricity to residential, commercial, and industrial customers. The company operates in 48 states in the United States and Canada, and its headquarters are in Princeton, New Jersey.NRG Energy is a publicly traded company, and its common stock is listed on the New York Stock Exchange. As of December 31, 2019, NRG Energy had a market capitalization of $16.4 billion.

Parker Hannifin

Parker Hannifin is an energy company that provides products and services to the oil and gas industry. We are a leading provider of hydraulic and pneumatic systems, as well as a variety of other products and services. We have a long history of providing quality products and services to our customers, and we are committed to continuing this tradition.


Enviva is a renewable energy company that specializes in the production of biomass pellets. These pellets are made from wood and other plant materials and are used as a low-carbon alternative to fossil fuels. Enviva’s pellets are used in power plants around the world, providing a cleaner and more sustainable source of energy. The company also partners with landowners and forest managers to help sustainably source the wood for their pellets, ensuring that the forests are managed in a way that benefits the environment.

NextEra Energy, Inc.

NextEra Energy, Inc. is an energy company engaged in the generation, distribution, and transmission of electricity through its subsidiaries. It is also the world’s largest generator of renewable energy from the sun and wind. The company has operations in 27 states and Canada, and its headquarters are in Juno Beach, Florida.

National Grid

National Grid is one of the largest electric power transmission and distribution companies in the world. The company transmits and distributes electricity and natural gas to homes and businesses through a network of underground and overhead cables, pipes, and wires. National Grid also owns and operates a number of gas and electricity generation plants.


Luminant energy company’s electric power generation segment operates power plants that use various fuel sources, including coal, natural gas, nuclear, and solar. The company’s electric power marketing segment sells electricity to wholesale and retail customers. Luminant energy company’s coal mining segment produces and sells coal to electric power generation companies.


nVent is an energy company that provides innovative solutions to help customers optimize their energy usage. nVent offers a variety of products and services to help customers save money and reduce their carbon footprint. It is committed to helping customers save energy and money and make the world a better place.


ONSEMI is an American energy company that provides engineering and technical services to the oil and gas industry. They help their clients extract, transport, and refine oil and gas. They also help with the development of renewable energy projects. ONSEMI has a wide range of experience in the energy sector and is one of the leading providers of engineering and technical services in the United States.

World Fuel Services

World Fuel Services Corporation is a global energy management company that provides a broad range of energy products and services to customers around the world. The company’s businesses include aviation, marine, land, and commercial and industrial customers. World Fuel Services helps customers manage their energy costs by providing a variety of products and services including fuel, lubricants, and related services. The company also provides marketing and risk management services to customers.

Lutron Electronics

Lutron Electronics Company is an American lighting control manufacturer headquartered in Upper Saucon Township, Pennsylvania. Lutron manufactures lighting control products and systems for residential and commercial applications. Its products include dimmers, switches, light sensors, and blinds and shades. The company also offers home automation products, including lighting control systems, home audio systems, and home security systems.


Who are the Big 7 Energy Suppliers?

Based on their market share, the big 7 energy companies are: 
• EDF Energy, 
• E. ON Next, 
• OVO Energy, 
Octopus Energy
• British Gas 
• ScottishPower, and 
• Shell Energy. 

What is the Most Profitable Renewable Energy?

The most profitable renewable energy is the one that needs the least input and maintenance. Wind and solar come at the top of the list, followed by other renewable energy sources, such as dams that requires a lot of operations and management personnel). Harnessing wave energy and pumped hydro also demand a lot of maintenance, so they may not be as profitable as some other forms are. 

Who Produces the Cleanest Energy?

Wind and solar energy are among the cleanest energy sources there are. In the US, Green Mountain Energy produces all of its power from these two renewable sources. Unlike hydro and pumped hydro, they also have a very low environmental footprint. 

What is the Fastest-Growing Energy Sector?

The fastest-growing energy sector is green energy. Renewable energy resources are among the best energy sources we have, as they demand no input, no live feed, and very little maintenance. With a long plant life of upwards of 25 years with virtually no maintenance, they cost little to run and produce enough energy to power a significant portion of the world, even today. 


Many US companies can produce reliable renewable energy. However, as the US power grid is still in the transition phase, other energy systems are necessary as well. They rely on oil production companies, and fuels such as diesel fuels, petroleum, and natural gas. Although gas and oil pollute a lot, more responsible energy consumption is necessary to ensure that we get to enjoy cleaner air, and nature, and a lower energy bill. 

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