Leadership Team


Greg Marken, President, CEO and Treasurer

Greg is the President, Chief Executive Officer and Treasurer of ADES since July 2020. Prior to his appointment as President and Chief Executive Officer, Greg served as the Chief Financial Officer, Treasurer and Secretary from March 2018 through June 2020. He also has previously served as the Company’s Chief Accounting Officer and various other roles with the Company. Greg also serves as a Manager on the Board of Managers of Tinuum Group, LLC. and a Manager and Officer of other ADES subsidiaries. Greg has over 15 years of experience related to accounting, finance and leadership of various teams.

Prior to joining ADES, Greg was a Senior Manager in the assurance practice at Ernst & Young, LLP in both Dallas and Denver, where he served at a variety of public and private clients.

Greg earned his bachelor’s degree in Accounting and his master’s degree in Finance from Texas A&M University. Greg has a CPA license in Texas and Colorado and is a member of the AICPA and the Colorado Society of CPAs.


Joe Wong, Chief Technology Officer

Joe serves as Chief Technology Officer and has over 35 years of industry leadership experience in Research & Development, product development and business growth in specialty materials. Prior to joining Advanced Emissions Solutions in 2018, Joe served as the Chief Technology Officer for ADA Carbon Solutions since 2011. 

Before ADA Carbon Solutions, Joe worked three years in private consulting, and spent 21 years with MeadWestvaco Corporation in senior leadership positions for the Specialty Chemicals and Research & Development sectors. 

Joe holds a PhD. in Chemical Engineering from the University of Texas.


Morgan Fields, Vice President of Accounting

Morgan Fields joined ADES in 2021 and currently serves as the Vice President of Accounting. Morgan has more than 15 years of accounting and consulting experience, including consulting with the company on various projects since 2019.

Prior to joining ADES, she served as the Chief Accounting Officer for Rezolute, Inc. and as an Assurance Director for RSM US LLP.

Morgan holds both a Bachelor of Arts and a Master’s Degree in Accounting from the University of Northern Iowa.


Dennis Sewell, Vice President of Manufacturing

Dennis Sewell joined ADA Carbon Solutions in 2009 and currently serves as the Vice President of Manufacturing. Dennis has more than 25 years of industrial manufacturing experience and has served in various leadership roles at the company.

Prior to joining ADA, Dennis held various positions at ExxonMobil, International Paper Company, and Honeywell Specialty Materials.

Dennis holds a Bachelor of Science in Electrical Engineering from Louisiana Tech.


Oscar Velasquez, Vice President of Sales

Oscar Velasquez joined ADA Carbon Solutions in 2016 and currently serves as Vice President of Sales. Oscar previously served as National Sales Manager for ADA Carbon Solutions. Oscar has more than 7 years of leadership experience in specialty chemicals (activated carbon) and product life cycle management.

Prior to joining ADA, he worked as a Sales Representative with Occidental Chemical.

Oscar holds a Bachelor of Arts in Business Administration with a focus on Sales and Marketing from Baylor University.


Lorraine Lang, Vice President of HR

Lorraine Lang joined ADA Carbon Solutions and currently serves as the Vice President of Human Resources. Lorraine has ~15 years’ Human Resources leadership experience in the Specialty Chemicals Industry.

Prior to joining ADA Carbon Solutions, Lorraine was the Human Resources Manager for Sun Chemical Shared Services. Lorraine has a Bachelor of Arts degree from Bowling Green State University and a Master’s degree in Business Administration from Thomas More College. Lorraine is certified by the Society of Human Resource Management (SHRM) as both a Senior Professional of Human Resources as well as a SHRM Senior Certified Professional.