I've graduated from a Chemical Engineering department and I am planning to apply for a Master's degree. I wasn't involved in research that produced a publication when I was an undergrad. Is there any other option for academic writing that I can use to strengthen my application?
When you apply to a Ph.D. or research-based Master's degree program, we often look to see how much prior experience you have with the academic research process. This includes successfully working on research alongside a faculty advisor, and when possible producing the oral conference presentations and co-authoring the scholarship (publications) that document the findings.
When faculty evaluate graduate school applicants, we are excited when we see someone who already has experience with the research process that is fundamental to graduate school and when our peers (applicant's former advisors) can recommend her based on her performance. Producing publications is an incredibly important part of the research process, so it is obviously best when someone has seen work through to that finish line. We also understand that this sometimes just doesn't happen for undergraduate researchers for a variety of reasons.
While it is also helpful for us to simply see examples of your writing, this is not really why we value the publications of an applicant. Don't be too worried if you have not yet worked on research leading to publications; you still may be considered a high-potential applicant. Be sure to impress with clear and cogent writing in your Statement of Purpose, on your resume, on your linked webpage/blog, etc. Good luck!
Absolutely. Peer-reviewed publications are the most valuable, but other writing can show your abilities and interests. For unpublished academic work, I recommend posting it at a pre-print server. In Chemical Engineering, this looks like a good one to reach your audience: https://engrxiv.org/ . It's becoming more popular lately: https://cen.acs.org/acs-news/publishing/Chemistry-preprints-pick-steam/97/i3
You can also write about the field, or science, or science and society. The best pieces go to leading outlets like Scientific American, The Conversation, or as an opinion-editorial to major newspapers. That's hard to do, so you can also target smaller services. At the easier level, you can publish yourself, for example at Medium.com, Twitter.com, or Reddit.com. However, you're unlikely to get as many readers as using an existing news service.