Earth Day is April 22, and we are looking at Maryland's energy and sustainability industry and highlighting companies throughout the state that are working towards smarter energy use and greener living.

In Maryland, our more than 1,200 energy and sustainability firms generate an estimated $8 billion in gross state product. Through numerous state resources, we are looking to ensure that number keeps growing for years to come.

In the coming months, the Maryland Green Registry Leadership Awards will honor local companies celebrating environmental successes. This annual event focuses on the achievements of Maryland Green Registry members that are committed to continuing sustainable practices. Businesses can become registry members for free and have until the end of the month to apply for a green leadership award.

Three-time award winner Thermo Fisher Scientific believes improving environmental sustainability is an ongoing process. With offices in Frederick and Walkersville, this biotechnology company has been a member of the Maryland Green Registry since 2011, with a strong focus on conserving resources, minimizing waste, and reducing greenhouse gases. The company has also been recognized by Frederick County, The National Conference on Citizenship, and the Dow Jones Sustainability World Index for its impact on the community.

Newer to the program is Hamilton Associates, an Owings Mills-based parent company of three manufacturers. Hamilton pulls the three businesses together with one shared vision: to improve the world through responsibly manufactured products. The company received a leadership award last year for reducing its energy usage by 20 percent—upgrades to HVAC systems, fixing air leaks, and retrofitting LED lighting all helped the company become more energy efficient. Hamilton also encourages its employees to participate in reusing materials and hosted a demonstration on creating garden planters out of leftover wooden pallets.

Other registry members all throughout the state are working towards reducing their carbon footprint, including GM Baltimore, Habitat for Humanity, Linganore Winecellars, NASA/Goddard Space Flight Center, and various hotels, government agencies, universities, and state parks. Read the full list of members by clicking here.

Companies outside the registry are also looking to make eco-friendly changes in Maryland. Based out of Linthicum, The Wilburn Company is a commercial cleaning service dedicated to not only cleaning buildings and businesses, but also making sure they help keep the environment clean. The company recently received a new GS-42 certification from Green Seal, which ensures that Wilburn's services meet the certifier's impressively high standards. The company must reduce chemical waste and solid waste, as well as continue workforce training for employees, to keep its certification.

"We are not just janitors, we are environmental hygienists," said Robert Baldwin, vice president of The Wilburn Company. "We are impacting people's lives by directly affecting their health, their economics, and their work performance all while protecting the environment."

It's not only up to the business community to help keep our planet clean. If you're an individual looking to make an environmental difference outside of the workplace, check out these volunteer opportunities compiled by the Maryland Department of the Environment.

Read more about energy and sustainability in Maryland.