Great interview, thanks for that. I think I’ll get that ebook, now that I got my iPhone today (you Americans are still doing something right!)
I’m glad Chris mentioned wood as an energy source because that’s something I have been thinking about lately, specifically how to turn it into electricity. It makes a lot of sense, especially for temperate climates.
In summertime, generating enough electricity to power your home and electric car isn’t too difficult, provided you have a decent sized lot. Solar panels will do it no problem for most situations and you wouldn’t really notice too much of a difference in your ability to do things that require energy – even drive 100 miles if you want. Throw in a wind turbine in appropriate locations and there you go.
But in winter it’s a different story because you aren’t going to get enough energy from your solar panels. But then in winter we are also doing something else to get energy … we are burning wood in our wood stove. I don’t know about everyone else, but when our stove gets going, we have to open the windows to cool the place down. They aren’t highly efficient either as lots of heat goes up the flue. To keep the fire going they have to be a certain size which means they are going to waste a lot of heat.
Wood contains 15 megajoules of energy per kg so if you burned 10 kg and let’s say converted 10% of that into electricity then that’s 4 kilowatt hours, not too bad! And the other benefit is that the other 90% is waste heat, which is exactly what you are burning wood to produce in the winter anyways! This is "cogeneration" which takes advantage of the inefficiencies inherent in the second law of thermodynamics to do useful things with the byproduct heat.
I did some preliminary internet searching and found some Canadian guys who made a wood fired steam generator to make electricity but this is not at all practical for the average person because it is noisy, complicated, and dangerous. It uses a complete Rankine cycle which reuses the same water to make new steam.
But a much simpler system would just be an open steam generator. You’d fill up a reservoir with clean water and this would feed a series of tubes or plates on the shell of the wood stove. This would basically be a boiler, and the water would boil and feed into a low pressure storage tank and then run through a little steam turbine to vent outside. The turbine would charge your battery bank, just like a wind turbine. You could also put the exhaust steam / water through a heat exchanger to recover some of the heat for your hot water tank.
It would use up water of course but around where I live we have more water than we know what to do with in winter. And because the water wouldn’t likely be pure (although you could run it through a de-ionizer), then you’d get scale build-up inside the boiler section but once a month you could soak it in vinegar.
So far I haven’t seen these things available but I imagine they will become more common as energy becomes more expensive. With this setup you really wouldn’t have any noticeable impact to your overal energy constraints between summer and winter (assuming you aren’t living in an apartment and have room to set all this stuff up), you’d simply be using different methods to harness energy (solar panels and steam turbines) and different ways of using it (electric cars).
Wood is pretty common, and with no more new houses being built for a very long time into the future, all that construction lumber that is no longer being bought needs to go somewhere, like ground up into wood pellets! Plus wood is sustainable; many of Canada’s forests just burn to the ground if they aren’t cut down by us first, so we might as well burn them in our stoves to produce electricity instead!
Back in the day studying forestry, we learned about how a lot of the forests held privately in eastern North America are not very productive at producing biomass because they have been selectively logged several times, which basically means that they were "high graded", ie the best trees were taken out and the remaining poor stock left to occupy the site and prevent young vigorous trees from getting establishing. This has also stifled the monetary gains that the owners of this land can realize, because it isn’t producing good wood. I imagine a program to improve the productivity of these degraded forests would help increase the ability of local woodlots to provide energy for homeowners.
Edit: I just found this video of a miniature steam turbine. Pretty easy.