[Bioconversion] Fireball Express

[Ken Boak]

Jeff & list,

Thanks for the kind words about the web page.  I found myself under-employed
last year and decided to have a go at something a bit different.  I normally
work with microelectronics and mass produced telecom equipment.

The old Lister CS engines are still very much available in the UK,  found at
farm sales, barn auctions and also on ebay -although the latter has driven
the price of them so high in the last few months.

I guess one enters a project like this witha sort of childhood naievety - no
one told me I couldn't run a 50 year old engine on veg oil in my back
garden - so I just went on a did it!

I have been monitoring my domestic energy consumption for the last 6 years
at this house, and I am fairly aware of how much I use at different times of
the year.

I need about 10kWh of electricity per day to run the home and the office,
and so that rather dictates the size of the engine that I need - the Lister
CS 6hp meets the requirement with power to spare.  It runs happily driving a
3kW alternator, but is also now spinning a permanent magnet dc
motor/generator, for direct charging of a set of lead acid storage
batteries.  The generator makes a great starter motor too, and saves a lot
of hand cranking -especially in the cold weather.

As well as the electrical output, there is plenty of waste heat produced by
a diesel engine.  About equal amounts of energy are available from the
coolant, the exhaust and the crankshaft.  It would be wasteful just touse
the mechanical power and ignore the useful waste heat produced in the
exhaust and coolant.

Our night-time temperatures have just started to dip below freezing for the
last 3 nights, and measurements of  natural gas for the boiler/furnace over
the last few nights show that I have been burning about 60kWh of gas a day
to keep the house and workroom comfortable.

The next step of the project is toefficiently capture some of the waste heat
from the engine, so that I can use that for heating the house and help to
offset my gas bills.

One of the problems is that the shed that contains the Lister engine is
located about 25 feet from the house and  45 feet from the central heating
installation.  It will be necessary to dig a trench and lay insulated pipes
between the engine shed and the heating system.  This will be done over the
next few weeks.

The interesting part of this project will be to try and get the best balance
between running the engine to produce electricity, and running it to
produced heat for storage and later utilisation.

If we assume that I need to run the engine for about 5 hours per day to
produce 10kWh of electricity,  at best there will only be around 20kWh of
recoverable waste heat. This is only 1/3rd of the heat required at this time
of year, and less than 20% when the weather gets colder.

However with a "window of opportunity" of between 8am and 6pm for running
the engine, an alternative strategy might be better, by using an inverter
and batteries to provide the night-time electricity.   About 4kWh is used
between 6pm and 8am for TV, lights, computer etc. This night time load can
easily be met by a set of batteries.   The evening electrical load seldom
exceeds 500W, and after midnight drops to about 170W, and does not pick up
until the "200W office" is turned on again at 8am.

 Part of the strategy is to install a woodstove in our main living area. My
wife likes the temperature around 20C or 70F, and she is quite capable of
putting more logs into a stove when she feels cold.  The stove would get
around 6 hours of use typically per evening and probably contribute 20 to
25kWh in that time.

I am keen to explore heat storage techniques, and I will be fitting a 259
litre (68 uS gallon) hot water tank to act as a heatstore, coupled in with
the woodburning stove. In the summer months, it will act as the heat store
for the solar water heating panels, and in winter will be used to hold
around 20kWh of heat, with the aim of circulating this around at night to
keep the house warm.

By running the Lister for more than 5 hours minimum, possibly as much as 1
hours per day, the extra electricity generated can be used for water heating
with an immersion heater, and powereing a 2kW electrical storage radiator.
The key aspect is being able to store the excess and utilise it efficiently
later on.

With a fuel consumption of 1.66 litres of vegetable oil per hour, the engine
will use at worst  17 litres per day  (4.5 US gallons).

The woodstove will burn around 2kW of wood per hour or about 12kg  per day.

By utilising Lister generator running on veg oil,  woodstove, inverter,
batteries and  heat store, it should be possible to shift the energy
consumption of this property entirely over to renewable fuels.  Current
consumption is  15690 kWh of natural gas per year and 2960kWh electricity.

The next phase will then be to characterise the fuel consumptions using wood
and veg oil, and then move towards a dual fuel system which utilises more
wood/woodchips gasified for running the Lister with a much reduced veg oil
demand.  But that's some time in the future ;-)


regards,


Ken