green

(no subject)

You know how you run the tap waiting for hot water to come out? That water usually gets wasted. Let's save it, shall we?

Place a drain hole with a stopper along the back edge of a sink. When you need hot water, remove the stopper, move the tap over the drain hole, and run the water until it gets hot. Replace the stopper to prevent other things from entering that drain. The water gets stored in a tank under the sink. There should be a small spigot on the tank, kinda like those you find on camping water jugs, to make dispensing this water easy. You'd access just by opening the cupboard door under the sink. Use this water for coffee, tea, cooking pasta, whatever. Much better than letting it to go waste.
Bridges

(no subject)

Have a solar collector focusing sunlight onto coils containing a high-temperature-capable fluid. Tubing would carry the very hot fluid (800 degrees F or so) into the house, into a "radiator" in the bottom of the oven in the kitchen. The radiator heats the oven, and you cook your food normally.

For temperature control, the pump that moves the fluid could be variable-speed, and shades could be drawn over the soloar collector to either block or limit the amount of solar energy absorbed. You could also have vents at the top and bottom of the oven for airflow.
Bridges

Frankenhybrid

Take one Geo Metro. Add a "mid-engine" electric driveline, and a 96v battery pack. 96v is on the low end for a pure electric vehicle, but I think it would do fine just to supplement the engine. Viola - one home-built Frankenhybrid. You might even be able to keep the rear seat if you're creative with the component placement of the electric driveline.
Bridges

Passive solar air heater

A simple wooden-framed box, insulated on five sides, with a sheet of readily available safety glass (like for sliding glass doors) on one large face. Mount the box to a frame, facing south. The frame would be adjustable so the angle of the box could be adjusted to accommodate changing winter sun angles, similar to PV mounts. Two insulated ducts would be connected to the box, one at the top and one at the bottom. These ducts would carry air from the house to and from the box. The air would get heated in the box, thus providing warm air for the house.
Bridges

(no subject)

Diesel engines can run on straight vegetable oil, but the oil must first be heated to thin it. There are kits on the market to add a secondary fuel tank to hold vegetable oil in diesel cars. Each of those kits has a heat exchanger that uses the engine coolant to heat the oil. Once the veggie oil is warm enough, the driver can switch to the veggie oil tank.

For stationary diesel engines, like backup generators, what about using the sun to constantly heat the engine coolant, and thus the tank of veggie oil? The engine would always be "warmed up", and the veggie oil would be kept thin enough at all times to eliminate the need for diesel or biodiesel to start the engine.
Bridges

(no subject)

How about a modern, electronically controlled, 4.0 liter diesel V6 that would bolt in place of a small block Chevy? Same engine mounts, same transmission bolt pattern, etc. The rest of it would take some work - throttle control, engine electronics - but designing the engine so it can bolt in place of an existing one would open up all kinds of swap possibilities.