Solar and wind electric generation systems are affordable and efficient, but there are a many areas of the U.S. where wind systems are not feasible, and few localized areas where solar systems are not feasible. A diesel powered generator with a large underground tank is reliable, but under adverse conditions the tank could run dry. Fortunately there are two systems capable of generating electric power with wood, a fuel readily available in most parts of the country.
Gasification is a process of burning wood or other solid biomass in a specialized
combustion vessel (basically an upside-down wood stove) that generates hydrogen
and carbon monoxide (CO) gases as by-products of the high temperature combustion.
The exhaust gases can then be used to fuel an internal combustion engine. Gasifiers
were used across Europe during WWII to power tractors, trucks and buses when
gasoline was not available. The return of gasoline after the war caused gasification
to drop off the radar. A group of American pioneers have revived the technology
and made great strides in bringing this lost technology back to the market.
All
Power Labs in
California sells do-it-yourself kits and complete gasifier systems, known as
gasifier
experimenter's kits (GEKs). GEKs have been used to power cars and generators,
it is potentially a complete solution. GEKs are operating around the world.
GEKs
is an open source project, that is, the plans are free and users are encouraged
to experiment and share their knowledge. The design and operation of the gasifier
requires wood blocks/chips, pellets or similar sized fuel. Split firewood is
not an option when operating on a small scale.
The other option is small scale steam. Steam engines powered the industrial
revolution and were in use well after the advent of petroleum products and
the electrical grid. Mike
Brown in Missouri manufactures a range of small scale
steam engines, from 1-to-20 horsepower.
Operating a steam engine requires specialized knowledge and skills, steam is
dangerous in inexperienced hands. Mike Brown has a package of instructional
materials for sale and will insist you do your homework before purchasing of
one of his engines.
Steam engines require a boiler to generate the steam to drive the engine.
Boilers can be made from copper tubing and junkyard scrap for a few hundred
dollars
providing there is a metal worker in the neighborhood; plans and a how-to video
are available from Mike Brown. ASME-certified boilers are available in limited
quantities.
Both systems will generate electricity when gasoline, diesel and propane fuels
are unavailable, the sun isn't shining and the wind isn't blowing . These systems
are best suited for short term backup power or as a supplement to a solar/wind
system. Neither system is “off the shelf” ready, they both require
back yard engineering skills and American ingenuity Both systems require a
stock of wood or other solid fuel to operate for any extended time. They both
require tending and maintenance. Relying on steam or gasification for a year-round
supply of electricity for a retreat is unrealistic in most cases . Note however
that life in the future may become very unrealistic.
But will these systems power a retreat? If you had a 3 hp steam system the
answer is yes. I did some rough calculations; in which I could be off by ±25%.
I am assuming a battery bank for storage. A 3 hp system steaming for 6 hours
per day for a month would generate approximately 400 KW. For comparison, 400
KW is less than one half of what the average American household uses in a month,
but far
more
than
most solar or wind systems will generate. We get by on less than 400 KW per
month and the retreat is all electric, including hot water, range and refrigerator
and I run many power tools in the shop. 400 KW is a huge amount of electricity
in terms of the creature comforts it can provide. Under emergency conditions
100 KW/month would drive a well pump, laptop, lights, radios and cell phone
chargers.[JWR Adds: Don't forget that when drawing DC power
from a battery bank, that inversion to AC with a modern inverter is about 80%
efficient in typical use, and they can be about 90% efficiency under optimal
conditions. To
understand
the concepts of kilowatts and kilowatt hours (KWh), see
Wikipedia.)
If oak were used for fuel it would take 13 cords of firewood per year (that
is a lot of wood). At $225 per cord it would cost approximately $3,000
per year plus many hours of manual labor. This is not what the modern American
considers
convenience, but under lock-down conditions you may be the only one within
100 miles that is powered up after a week. Under emergency conditions you will
be at home with enough time on your hands to stoke the fire every hour. I have
not done a similar analysis of the gasifier. A gasifier is a very efficient
use of biomass, I would expect you can achieve much the same results as a steam
system. GEK users will be happy to share what they know.
Gasifier
Pros: Technically within the range of the do-it-yourselfer. Will power many
internal combustion engines. Will burn chipped/blocked wood and forest scrap,
walnut shells and more. Waste heat from the gasifier and IC engine can be used
to heat water (which can be used to heat a home). The exhaust gas from the
IC engine is water vapor and there is no smoke, the smoke has been converted
to a combustible gas.
Cons: Requires small, consistent-sized fuel such as dry wood chips. Generates
carbon monoxide (CO), a deadly gas although this gas can be used to fuel an
outdoor stove. Cannot be installed within a living space (same with steam).
Limited
supply,
however
plans are free and a gasifier can be built with scrap steel and junkyard parts
by any welder/metal worker.
Cost: Approximately $1,000-3,000 (not including engine, generator or storage
batteries).
Steam Engine
Pros: The most reliable and simple of backup systems. Quiet. Steam can be used
for multiple purposes including space and water heating and making bio-fuels,
including alcohol. Can be powered with both solid and liquid fuels.
Cons: Requires a good bit of self-study. Potentially hazardous. Limited source
of supply for engines and boilers although both should last a lifetime and
be worth their weight in silver should it come to that.
Cost: Approximately $7,000 for 3 hp engine and boiler (not including generator
or storage batteries), the greater part of the cost for a manufactured boiler.
Steam engines are precision machines available in limited quantities. Cost
aside, it could be months before you take delivery, but remember patience is
a virtue. If time and money is of the essence then the GEK is the best bet;
a team of garage mechanics could have a GEK up and running in a week. GEKs
can be manufactured from plans without royalties, potentially a great business
opportunity.