FA (forced air or fan assisted) and ND (natural draft) versions of TLUD
stoves have existed since the original work by Tom Reed (both types) and
Paal Wendelbo (only ND) in the 1980s – 1990s. No need to describe them
here. Check the written documents.
What is not discussed much is the relative cost of these two major
types. Of course, the QUALITY of the stoves will impact the price, but
let’s assume that quality is similar, such as using stainless steel in
key parts, and using modern manufacturing with possible high volume
production . Such stoves already exist or are nearly ready for the
market, but are often overlooked.
In my opinion, many TLUD stoves are “over-weight”, being made of metal
far thicker than is necessary. But assume similar weight optimization
for both the ND and FA TLUDs.
Basically, a TLUD is a fuel chamber with additonal walls and legs in
various configurations. The differences because of ND or FA are
primarily because of needed draft for combustion quality:
1. ND needs natural draft, and therefore vertical rise is important for
negative pressure. An “internal chimney” (or riser before the gases get
to the pot), or a chinmey after the pot is essential.
2. In contrast, FA needs draft, but it is from a the push of a fan or
The costs of “chimney components” vs the costs of “fan components”
becomes the crucial issue. And there are expensive and inexpensive
variations of both.
But from what I am seeing, the chimney costs remain constant in each
cultural context. Many Latin American stoves utilize chimneys, as do
stoves in mountainous and cold-climate areas.
But for the fan components, costs have been reducing and reducing more
while the general availability of getting the few Watts of electrical
power is becoming easier and more widespread, essentially being costs
covered by other desires such as lighting and charging mobile phones.
Basically, the costs to make a real chimney-based stove vs the componets
in a functional FA TLUD stove are about equal now, and will be lower for
the FA TLUDs as volume production kicks in.
Today, 2017, if a society (or individual household) has economically
sustainable grid electricity, or a solar-powered lighting system, or
established battery-recharging services, (and the education and
experience to reasonably care of an electronic device), a FA TLUD will
be a reasonable addition to the household.
Certainly, in ASPIRATIONAL TERMS, households will move toward the
Fan-Assisted TLUD stoves, with cleaner combustion that can compete very
well with LPG on cleanliness, while being environmentally and
In terms of clean combustion of source-fuels that are dry biomass such
as wood, TLUD stoves — especially with fans — are head and shoulders
above any “ICS” (Insufficiently Improved Cooking Solution) stoves that
use solid fuels.