With the largest concentration of Aviation firms in the state, the Oklahoma City area supports 265 firms with 38,000 workers. Biotechnology: The Oklahoma City area's bio-science presence is garnering national and international attention. With companies dedicated to bio-science goods and services production, as well as education and research testing, career paths are plentiful in this industry, which directly employs 44,000 workers. Energy: With abundant oil, natural gas reserves and wind power, Oklahoma City is home to the headquarters of Fortune 500 energy companies, and some of the largest energy companies in the state. Transportation & Logistics: Oklahoma City offers careers in the transportation and logistics industry. Some areas include airport operations, railroad transportation, freight trucking and warehouses. These categories includes advertising and public relations; computer system design; employment services; research, development and consultants.