> significant quantities of oils grown used in cooking and discarded What is a "significant quantity"? Significant in terms of volume relative to a single rest

> significant quantities of oils grown used in cooking and discarded What is a "significant quantity"? Significant in terms of volume relative to a single restaurateur? Or significant in terms of megajoules as a percentage of say, the shipping industry? (Or we can be generous and just narrow it down to the dredging industry). Put another way, what is the recoverable megajoules of all of the Netherlands discarded cooking oil in a year as a percent of megajoules needed for all the dredging the Netherlands does in a year? My gut tells me it trends towards negligible. All for recycling, but biofuel refiners already specializing in this do at most 5-20% recycled biooil : traditional oil blends. Don't know why they don't sell "pure" recycled biofuels, but it's probably a mix of availability and performance needs. Should always question yourself: "if it's so simple, why haven't the people already doing this commercially figured it out yet?" You'll truly understand the space if you can produce a good answer to that (and you'll have a business model if you can enunciate why their constraints or limits are wrong). ---- > What is the EROI on batteries surely under 1. EROI is used for energy sources. Batteries are an energy store. You can still do a similar "how much energy can I get out of this vs. embodied energy to create it" analysis, but energy out is measured over all the cycles in the useful lifetime of the device. It's a slightly different concept, and that metric is called Energy Stored on Energy Invested (ESOI). Lithium ion are about a 10:1 - 30:1.