Midstream assets, specifically pipelines and processing centers, play a crucial role in America's energy future. The industry is growing rapidly, and may play a crucial role in the future of your portfolio. There are many companies to keep an eye on, and it's an industry worth watching. Here's a recap of this week's highlights and lowlights.

Trading commodities
Analysts and investors implored TransCanada (NYSE: TRP) this week to stop thinking about the Keystone XL and get busy fixing the disaster that has befallen its Mainline pipeline. Essentially, the U.S. gas boom cut the legs out from under TransCanada's gas market. Volumes on the gas pipeline fell, forcing the company to increase transmission rates, forcing sellers to pass higher costs onto their customers. If nothing changes, the pipeline that makes up 15% of TransCanada's assets is expected to run at 1/3 its capacity by 2014. The solution? Switch to oil.

The Mainline is actually made up of five pipelines, all of which ship natural gas. If TransCanada converts one pipe to oil, it can ship 900,000 barrels per day from Alberta to Ontario, significantly improving the economics of the line.

The company needs to do something. It reported earnings Friday morning, and profit dropped 23%.

Midstream transition
The Global Infrastructure acquisition of Chesapeake Midstream Partners is complete, and now the entity is getting a name change. Access Midstream Partners (NYSE: ACMP) and its brand-new ticker officially hit the New York Stock Exchange on Tuesday.

On Friday morning, Access Midstream announced a second-quarter distribution of $0.42 per limited partner unit. It marks an increase of 15.9% year over year.

Earnings to come
It was a slow week for midstream news, but looking ahead to next week things should get a little more interesting. Enterprise Products Partners (NYSE: EPD), Enbridge (NYSE: ENB), and Magellan Midstream report second quarter earnings over the first two days of August. It will be interesting to see if Enterprise takes a hit on declining NGL prices, but most eyes will be on Enbridge -- the company that can't seem to get out of its own way right now.

Foolish takeaway
Midstream is where it's at, folks. The energy industry will spend an estimated $130 billion to $210 billion expanding natural gas infrastructure over the next 20 years. After all, the more oil and gas that flows through those pipelines and processing centers, the more cash there is to flow into your pockets. Stay on top of all the midstream action by adding the companies above to My Watchlist.