MANY D.C. Envi internships!

TNC
https://careers.nature.org/psp/tnccareers/APPLICANT/APPL/c/HRS_HRAM.HRS_APP_SCHJOB.GBL?Page=HRS_APP_SCHJOB&Action=U&FOCUS=Applicant&SiteId=1WWF
https://careers-wwfus.icims.com/jobs/search?ss=1&searchKeyword=internship&_ga=1.66799406.1223903018.1486678310&mobile=false&width=1000&height=500&bga=true&needsRedirect=false&jan1offset=-300&jun1offset=-240

World Resources Institute/WRI
http://www.wri.org/internships-wri

Department of Energy
https://energy.gov/student-programs-and-internships

https://energy.gov/eere/about-us/employment-opportunities-eere/eere-internships-and-fellowships

http://www.orau.org/ornl/undergraduates/

http://orise.orau.gov/science-education/internships-scholarships-fellowships/

National Renewable Energy Lab, Golden Colorado
https://www.nrel.gov/careers/internships.html

https://www.indeed.com/q-Energy-Policy-Internship-l-Washington,-DC-jobs.html

ACORE/American Council on Renewable Energy
http://www.acore.org/about/internship-program

Clean Air Task Force
http://www.catf.us/contact/internships/

EESI
http://www.eesi.org/internships/policy

SEIA: Solar Energy Industries Association
http://www.seia.org/about/seia/jobs-seia

CSIS
https://www.csis.org/about-us/internships

EDF: Env Defense Fund
https://www.edf.org/jobs/internships-fellowships

American Geoscience Institute
https://www.earthmagazine.org/jobs-at-agi

Oceana
http://oceana.org/about-oceana/employment-opportunities