If you live out in unsecured space and especially wormhole (WH) space, you probably have heard about mineral compression. In EVE Online, all items take up volume (measured in meters cubed or m3)
The further away from high sec you live, the more likely you will, at some point, need to move items from unsecured space to a market hub in high sec. People rarely ever use T1 haulers or T1 freighters. They are too slow, too weak and too expensive (freighters) to throw away on a fool's errand. Jump freighters have a good niche market here, but they are upwards of 6bil ISK and take a long time to skill up. They are not something the everyday EVE pilot can jump in and play Russian Roulette with pirates with. Many players opt for the Covert Ops transport like the Prowler or Viator. They can warp cloaked, have a quick align time and are a little more sturdy than T1 industrials. To counter their abilities, they have a much smaller cargo hold capacity. More than half as small as their T1 industrial counterpart. They don't have any specialized cargohold either like some of the T1 industrials were given a few expansions ago. If you need to move a lot of minerals, you will be making multiple trips. There are two options that you have right now available to make it a little more efficient.
Mineral Compression: The Rorqual is able to compress minerals so that they take up less m3 than they would uncompressed. It turns minerals like tritanium into dense cubes that take up far less volume than the uncompressed version. When you move the cube back to high sec, you take it to a friendly NPC station and refine the cube to get minerals again.
Module Compression: EVE players are very creative. They have plenty of time to work out all the intricacies and loopholes. From the creators if such activities like webbing friendly freighters for faster warp times and MWD/Cloak trick for T1 industrials, they bring us module compression. Basically, what it means is this: when you build modules, they require minerals. The finished product is often smaller in volume than the minerals themselves. I believe nanofiber upgrades were a item for this activity. You then follow the same process as above. Reprocess for 100% and you have beat the system. The max reprocessing rate for non ore or ice (basically any module, ship and charge) will be 55%. This will put a stop to module compression.
CCP is taking a look at the mechanics behind refining and reprocessing. Here is an overview on what is in the works. You can also find the Reprocess all the things! dev post here.
Right now, you can get 100% refining pretty much anywhere without maxing out skills. It also makes the Rorqual's ability to compress ore less of a benefit. That was supposed to be an important part of the Rorqual, and it could be utilized better. CCP is going to reduce the refining efficiency but they are going to buff the output mineral total to sort of offset the efficiency loss.
If this change goes live, a player with max skills but without the reprocessing implant (+4%) will ~3% less reprocessed minerals from ore/ice. I can hear the care-bear cries and the flood is incoming. All of this could change, and overall, it wont be the end of the world. CCP will counteract this buy raising the Rorqual compression ratio outputs by ~38%. They are also making modifications to outpost upgrades and leveling the playing field across races. Right now, Minmatar outposts get a 50% buff to reprocessing while the 3 other races get a 30% buff. All outposts in the future will have a 50% buff.
All of this is subject to change, but it looks like it could be implemented in the summer expansion. Stay tuned to the CCP Dev Blogs and I will continue to watch how things are progressing.