Vaarst - Fjellerad 0.5MW digester finally underway
Gas Bag sold to Important University Biogas Plant.
AJAX spares - from the Practically Green Online Warehouse
[Practically Green News Index 1996 - 1997]
After two years of complex contractual and social organisation problems the construction of the 0.5MW (electrical) Vaarst-Fjellerad Biogas Plant near Alborg in Denmark has begun.
The digester project is a co-operative development supported by the European Commission's DGXVll Energy Division and involving Planenergie, Jysk Biogas A/S and Practically Green Environmental Services. The finished plant will be operated and run by a new 'owning and operating' company set up for the purpose - its shareholders are the farmers who deliver slurry to the plant. Jysk Biogas will deliver the plant as a turnkey system to the Owning Company and all other players will subcontract to Jysk Biogas.
The digester system will have inputs of Pig and Cattle manure in the proportions found in the local farms - about 50% of each - 110 tonnes per day total input. In addition to this a further 31 tonnes per day of highly active industrial organic waste will provide a cash income and save considerable landfill charges. The liquid fertiliser from the plant will be returned to the farmers donating the slurry.
Four technically advanced input tanks have been constructed to hold and prepare the waste for digestion, a slurry and manure tank, an industrial waste tank, a bleaching clay tank and a newly designed Municipal Solid Waste tank to take source separated MSW.
The two tank digester system is operated as a pair of conventional stirred tank reactors at thermophilic temperatures.
Gas will be stored in a 2500 cubic meter gas store and burned in a CHP unit which will provide hot water to the town's district heating system and electricity to the grid.
The total contract cost of the plant is 34,000,000 DK.
Practically Green is delighted to have been chosen as the supplier of
an 6 meter diameter hemispherical biogas bag to De Montfort University to
enable their new research digester (under construction) to store gas overnight
for use in the daytime when power is most expensive. The gas bag is a hemispherical
design see: Practically Green Depollution Equipment
Catalogue.
25 cubic meter biogas storage bags at Lyttle's digester in Northern Ireland.
Solar House (the headquarters of Practically Green) has stimulated a massive amount of interest. The main question asked is "How does it work?" So here it is in a nut shell.
The core of the building is a 'box' with very high levels of insulation all round - 0.5 meters (18") in the floor and roof space, 300mm in the walls. All doors to the outside have a vestibule or utility room (at the rear) to act as an air lock so that on a windy day air does not whistle through the structure - the inner doors all have automatic closing devices.
Windows are also built to the highest economic specification, argon filled , wide cavity, thermal coatings on the inner glass sheet - but only double glazed. This arrangement increases the insulation value to something approaching a triple or quadruple glazed unit but the cost of argon filling a double glazing unit is a pound ($1.6) and coated glass is now readily available. We never see condensation on these windows.
The sun shines on the well glazed south side. The glazing, building orientation, insulation, occupation levels and other features have been programmed into a computer and the passive solar performance of the building has been calculated.
On the basis of this calculation, a solar powered space heating system has been devised. Its main functions are to distribute heat from the hot south side to the cold north side and to harvest energy from the massive south side rof area. This technology uses Practically Green's "HOTILE ROOF (tm)" structure. Air drawn into the building by a very small fan is preheated by the whole area of the south facing roof. The system is sensitive to 30 minutes of direct sunlight on a February frosty day - 15 minutes to defrost the roof and 15 minutes to heat air!
The incoming air then receives a second boost of heat in an air to air heat exchanger. Heat for this second heating boost comes from the hot, wet, stale air extracted from the house especially from the kitchen and bathroom areas. Thus if a pot is boiling on the kitchen gas stove, the heat from the steam heats the office and living areas but the condensation is drained away from the air to air heat exchanger leaving the house dry as well as warm - result no black mould! The cool stale air is high in Carbon Dioxide and since plants grow on this waste gas, we will eventually install a greenhouse over the vent on the west wall and use the Carbon Dioxide to stimulate the growth of tomatoes - commercial growers have to burn propane to achieve the same effect!
The core of the building is heated through the windows and PG HOTILE ROOF when the sun shines - this also warms the high thermal mass concrete walls and floors inside the insulated box. These high mass areas absorb heat in the summer daytime giving cool summer temperatures in all the rooms. In the winter and at night, the warm concrete mass in the floor and walls heats the house. Does it get too warm in the summer? NO! Apart from the absorption of heat into the heavy concrete structure, two other factors are in our favour. The first is that the sun becomes vertical in the summer and shines at a narrow angle on the windows - there is also an overhang on the roof to cast a shadow onto the window when the sun is high. The second factor is a switch that enables the occupier to switch off the incoming air from the roof whilst leaving the extract fan to the room 'on' - an open window and fly screen provides cool summer air without the flies.
Question: What happens when there is 5 weeks of freezing fog? Answer in week 3 you turn on the focal point fire! - but then that does not happen very often. In the long winter of '96-'97 we turned off the gas supply (actually emptied the tank and left it empty for two weeks). After a couple of weeks of no auxiliary heating from towl rails, gas cooker or focal point fire, with night time temperatures down to -5 degrees C and daytime temperatures not much above freezing, the house temperature found its equilibrium at 12 degrees C - the heat source was 5 people!. That is chilly and uncomfortable for sitting in even though there are no draughts - another 6 degrees C are needed for comfort. However it should be noted that in our last house we could only manage 14 degrees C in similar conditions with the oil fired central heating full on!
In line with our goal of producing Zero net Carbon Dioxide burden to
the earth's atmosphere across the boundary of the site, this year we have
installed a wood fired kitchen heater that can take 24" long logs.
It is not fully operational yet as the chimney is not yet tall enough but
this will be extended and insulated to accommodate the burning characteristics
of the burner. In the winter this will provide a very cozy corner in the
kitchen and the air to air heat exchanger will spread the heat to the rest
of the house without the need for radiators. The advantage of this to the
environment is that trees grown for burning (ASH - fraxinus sp.)
absorb carbon dioxide before we cut them down, thus the effect of using
these to fuel the house for a few weeks in winter is to reduce the Carbon
Dioxide burden on the planet and provide a habitat for wildlife at the same
time.
[further technical details and perfomance record]
Ajax gas engine spares can now be ordered from our online catalogue. Simply quote the catalogue number of the component in an email, the quantity required and we will send by return a price including delivery charges and arrange immedate shipment via cheap slow transport or more expensive courier as required. Most of the common spares are off the shelf at Practically Green's Warehouse.
| ANNUAL HEAD MAINTENANCE | ||
| 65 | Tool - Thimble for protecting rod packing when reassembling (Reuseable) | each |
| 66 | Compression Rings (piston rings DP165) | each |
| 67 | Ring Set, Packing (packing for piston rod) DP 165 | set |
| 68 | Gasket DP165 Head | each |
Each engine owner will be contacted in January with an offer on an annual
maintenance spares kit - we hope this will stimulate owners to do some preventative
maintenance on the engines at least once per year! A few seals can maintain
efficiency and reduce oil consumption even if the unit do tend to run for
several years without perceived problems.
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Practically Green News is the newsletter of Practically Green Environmental Services. Practically Green, Practially Green News and Practically Green Environmental Services are trade marks belonging to Dr.L.K.Gornall. AJAX is the trade mark of Cooper Energy Services. The articles in this newsletter represent the views of Practically Green Environmental Services. Whilst every attempt is made to represent products and services accurately, errors can occur and no liability can be accepted for errors and omissions. This newsletter is not a contract.