Andrew Good Posted about 2 years ago Bjarke Ingels: Hedonistic sustainability I believe a lot has to do with capturing the exhaust gases kind of like modern diesels do. Generally I believe the technologies are called exhaust scrubbing. Mercedes calls theirs BlueTek and this video explains it pretty well http://www.youtube.com/watch?v=q5STGppxcdw The exhaust scrubbing has cleaned up diesel engines immensely, but another big thing was adding turbo chargers to them. It cuts down on the soot and, combined with more recent technology, has made them more efficient. I'm sure if they don't use something with a similar effect of the turbo, they might do something like BMW's Turbosteamer concept from a few years ago. Recapturing the waste heat from burning trash and turning it into steam that could create more energy or feed it back into the loop as a scrubbing agent would be one of the options that would give them. This shows a little bit of that concept: http://www.mandiesel-greentechnology.com/article_006962.html Also some other things to consider is if you spend more on materials like special plastic building blocks, you might just save that same cost by not having to pay for additional crew to construct it. Think about assembling Lego blocks versus the traditional supports, rebar, insulation, bracing, and other things that require specialists in different fields, etc. If you couldn't tell, I really like diesel engines. I own a 1981 VW diesel Rabbit that gets over 40mpg still. If I can run my 1981 VW on vegetable oil that local restaurants go through by the gallons every day, then I'm not sure why we think we have to depend on oil. Diesels can run pretty much anything. The first diesel ran on peanut oil and I read about a guy that ran a diesel in a pit which you couldn't hear above ground and he would burn used trans fluid from a local mechanic 24hrs a day and he rarely ever had an electric bill. Most of the time the power company paid HIM since he was putting power back on the grid!