Our projects would contribute to the philosophy of sustainable development by creating a new way of energy strategy involved the following gases:

- biogas (biomass gasification/fermentation, pit gas, landfill gas, sewage sludge fermentation),

- other uneconomical gases because of high CO₂, N₂ contents in industrial technologies.

Energetic utilisation of biogas supports the Hungarian governmental concept to increase the 3,6% rate of renewable energy up to 7-8% by the year 2010 in the primary fuel heat consumption.

The estimated biomass potential is about 2,2-3,7 Mtoe, 30-50% of it could be utilised economically by biogas. The amount of communal/household rubbish is 12million tons a year and we also have a large amount of sewage sludge in our bigger cities’ cleaning stations. Organic parts of them are elementary substances of biogas as well. Compressing rubbish to one tenth of its volume will be economical by energetic utilisation of waste recycling.

Many natural gas drilling stations are inactive on the Plain because of the incombustible components of the gas. Gases derived from preparation technology of the natural gas are also unexploited. Our goal is to utilise these lean gases at changing calorific value in time reaching decentralised electricity or CHP production.

We create a knowledge basis of decentralised energy producing systems about utilising lean gases in gas motors, gas turbines and boilers. Building this factual knowledge will determine the technical, logistic, economic and environmental conditions of settlement including the possible plants.

Electric power systems are national and international huge systems while district heating systems are local, municipal or inter-city small systems. Electricity generation has happened in high capacity power plants using high and constant calorific valued fuels (oil, natural gas, and coal, nuclear) that are available in large amounts for a long time. Heat generation supplies local industrial, agricultural, domestic and communal demand. Heat transmission distances are bounded because of many losses.

Lean gases because of their low calorific value and harmful components have been unexploited. Another problem has been caused by the relatively high investment costs of biogas production and its availability in time focused on the safety of energy generation. Quantity of oil and natural gas is obviously limited. Coal runs out much slower, however the gasification technologies do not solve the problem of CO₂ emissions occurring at any fossil fuels. There is a growing need for co-ordination concepts of sustainable development, economics, ecology and social points of view. Inside these barriers exploitation of renewable energy sources comes into the limelight.

We obviously need a new philosophy. No solution for the problem is the collection of fuel for huge power stations. We must spread our energy producer units out to the origins of (bio) fuel. This can only be realised by small power capacity machines, altogether with co-operating electric grid system and existence of heat consumers. The estimated potential in Hungary is about 200-300 MW_e installed capacity summarising these small units, but more optimistic data mention 500-600 MW_e capacity. (Size of a conventional power plant not to be built.)

The basic work of our research is the examination of chemical composition, combustion operation and chemical composition of combustion products in case of lean gases. The major fields are:

- origin of lean gases, chemical composition, calorific value, change of parameters;

- different chemical compositional gases in combustion, theoretical and experimental examination and calculations of combustion processes, regulation;

- chemical composition of combustion products, harmful components into the environment, assuring EU norms.

To reach all above mentioned we

- put together experimental equipment for the examinations of the origin and dynamics of lean gases,

- make experiments at low calorific valued natural gas fountains,

- examine in experimental equipment (e.g. multifuel burner, gas motor) the combustion parameters of gases (speed of burning flame, stability of flame), the best oxygen enrichment ratio for different mixtures, the combustion processes and combustion products.

We already have a mobile measuring equipment (microbus installed system for local measurement and data acquisition) to determine the optimal burning conditions of lean gases.

We examine four fields:

- national potential of lean gases and their availability;

- decentralised energy producer systems;

- effects on the existing heat and electricity supplier systems;

- costs of heat and electrical energy, logistic problems, supporting public policies and forming social awareness.

The work assesses the potential of lean gases, their territorial distribution, the minimal, maximal and average quantity for utilisation, the change of the available quality and quantity on two groups.

- Biogas derives mainly from gasification of animal manure, organic parts of municipal garbage, sewage mud and agricultural secondary products. Therefore biogas must be generated continuously. Generation technologies are well known but the costs of implementations are higher by an order in comparison with conventional power plants. We assess the minimal size of organisations (such as animal farms, garbage landfill, sewage cleaning stations) where a decentralised small CHP unit could be settled to, focused on the expectable rising prices of oil and gas in the future. Additional task is the determination of the possible heat consumers and the scale of their demands.

- Natural gas at low quality standards derives from preparation technology of natural gas for distribution near to drilling stations. Our national reserves of natural gas at decreasing exploitation are estimated for 15-20 years, these lean gases could be utilised for the same period. More facilities based on opening gas fountains that provide gases with more than 8-10% CO₂ content. We must also assess at these plants the economical size of decentralised small CHP units and determine the possible consumers of heat and their demand.

Our work is to determine the scale of power at different plants based on lean gases. The possible machines are gas motors, gas turbines and their co-operation with gas boilers. On every station where heat demand exists, CHP units, otherwise electricity generator units should be settled.

We work out the regulation of our small energy generator units at the selected experimental plants (including calculations of heat circuits), the expectations of operation, the reliability of energy generation and the effects on environment.

Questions are the following:

- what are the restrictions of energy generation (we suppose that the origin of lean gases, not the own limitations of energy generation technologies), so how should we regulate the process, what are the necessary protections to be built out towards electricity and heat supplier systems;

- how strong the fluctuations of power are (changes daily and seasonally), must we install and what capacity gas storage system;

- how can it be supported by other traditional fuels (mainly by natural gas) regarding to the safety of energy supply;

- what are the expectable consequences unwanted because of the harmful components of lean gases and how they affect the lifetime of the equipment;

- what are the effects of combustion products on the environment (need of cleaning, height of exhaust stacks)?

Decentralised CHP units produce heat and electrical energy. Units at small scale (<200-500kW_e) generate electricity on low voltage (0,4kV), while greater units (>500-1000kW_e) on intermediate voltage (6kV). Because of the levels of voltage and territorial distribution, electricity will be fed into the consumers’ grid (230/400V or 10-20kV) to provide by the local Distributor Company. Heat is applicable locally or within an economical distance, usually by hot water, rarely by steam.

Co-operating with the electric power system we take care about the effects on the grid made by the small units. A wide open question is how many of them could be connected to the grid without endangering the safety of electricity supply?

At the co-operation with the heat supply system we examine:

- the hot water temperature difference and mass flow regulation in case of various heat consumers;

- the power of lean gas utilisation equipment (gas motor or gas turbine) and the co-operating boiler to reach the economical ratio;

- how goes the safety of heat supply on, is heat power reserve in need?

We work out the methods of cost calculations determining the specific costs of the generated heat and electrical energy at different expectable oil/gas prices. There are many important components of costs that have been not acknowledged by now (e.g. CO₂-tax, costs of waste accumulation, biogas generation, volume reduction of garbage).

At the same time there will be cost elements not occurring because of waste utilisation and reduction. Price of natural gas today is very low in Hungary making decentralised CHP generation uneconomical. New circumstances must be found even in legal, social and economic ways to help small units’ implementation and distribution acknowledging that:

- biogas originates whether we utilise or not;

- selective collection of garbage in society is essential;

- electricity markets are under liberalisation.

The created basis of knowledge would be justified in practice by measuring gas motors experimentally at Hungarian plants producing lean gases. The stations are:

- gas from biomass fermentation based on animal manure,

- gases based on landfill and sewage sludge fermentation.

In the framework of the research project at both plants we will

- plan the settlement and measurement,

- measure and examine the chemical compositions of fuel and combustion products together with other operation parameters,

- summarise the results and consequences.