The exhaust heat recovery system (1) comprises: an evaporator (2); an expander (3); a condenser (5); a circulation pump (7); a circulation flow path (6) for circulating a working medium therethrough; cooling medium piping (8) which is connected to the circulation flow path (6) and causes a portion of the working medium sent out from the circulation pump (7) to be diverted to flow into the condenser (5); a cooling-side opening/closing valve (13) for switching between a state in which the working medium can flow into the cooling medium piping (8) and a state in which the working medium cannot flow thereinto; and a control unit (10) for performing the switching control of the cooling-side opening/closing valve (13). When a condition under which the temperature of the working medium flowing into the condenser (5) becomes higher than or equal to a predetermined temperature is satisfied, the control unit (10) controls the cooling-side opening/closing valve (13) to switch to the state in which the working medium can flow into the cooling medium piping (8).

The exhaust heat recovery system (1) comprises: an evaporator (2); an expander (3); a condenser (5); a circulation pump (7); a circulation flow path (6) for circulating a working medium therethrough; cooling medium piping (8) which is connected to the circulation flow path (6) and causes a portion of the working medium sent out from the circulation pump (7) to be diverted to flow into the condenser (5); a cooling-side opening/closing valve (13) for switching between a state in which the working medium can flow into the cooling medium piping (8) and a state in which the working medium cannot flow thereinto; and a control unit (10) for performing the switching control of the cooling-side opening/closing valve (13). When a condition under which the temperature of the working medium flowing into the condenser (5) becomes higher than or equal to a predetermined temperature is satisfied, the control unit (10) controls the cooling-side opening/closing valve (13) to switch to the state in which the working medium can flow into the cooling medium piping (8).

A distributed Biogas Combined Heat and Power (CHP) Generator can provide automatically hot water and electricity for local applications. Since biogas is produced by an anaerobic digester from human, animal, kitchen and agriculture's wastes, it is a short term recycled product from the photosynthesis of CO.sub.2, and has a net zero carbon emission.

The sulfur compounds in the biogas can be removed by the following steps: (1). converting all sulfur compounds into H.sub.2S by the hydrogen produced from the biogas over Pt group metal catalysts; (2). adsorbing the H.sub.2S at high temperature by the regenerable Pt group metal catalyst and adsorbents.

The desulfurized biogas is further converted by an ATR/CPO reformer or a steam generating reformer to produce various reformates, which can be connected to a downstream IC engine/gas turbine, and/or a steam turbine to drive electric generators for generating electricity. The hot reformate and the exhaust gases can be cooled in heat exchangers to produce hot water/hot air.

A distributed Biogas Combined Heat and Power (CHP) Generator can provide automatically hot water and electricity for local applications. Since biogas is produced by an anaerobic digester from human, animal, kitchen and agriculture's wastes, it is a short term recycled product from the photosynthesis of CO.sub.2, and has a net zero carbon emission.

The sulfur compounds in the biogas can be removed by the following steps: (1). converting all sulfur compounds into H.sub.2S by the hydrogen produced from the biogas over Pt group metal catalysts; (2). adsorbing the H.sub.2S at high temperature by the regenerable Pt group metal catalyst and adsorbents.

The desulfurized biogas is further converted by an ATR/CPO reformer or a steam generating reformer to produce various reformates, which can be connected to a downstream IC engine/gas turbine, and/or a steam turbine to drive electric generators for generating electricity. The hot reformate and the exhaust gases can be cooled in heat exchangers to produce hot water/hot air.

A method for the combustion of ammonia, wherein a first combustion chamber (2) receives ammonia (4) and hydrogen (5) in controlled proportions, and an oxygen-containing gas. Combustion of the ammonia and hydrogen produces NH.sub.2.sup. ions among other combustion products (22). A second combustion chamber (3) receives the combustion products (22) from the first combustion chamber and receives further ammonia (4) and further hydrogen (5) in controlled proportions, wherein combustion produces nitrogen oxides among other combustion products (24). A third combustion chamber (14) receives the nitrogen oxides along with further ammonia and further hydrogen in further controlled proportions along with further oxygen-containing gas, such that the nitrogen oxides are combusted into nitrogen and water.

A method for the combustion of ammonia, wherein a first combustion chamber (2) receives ammonia (4) and hydrogen (5) in controlled proportions, and an oxygen-containing gas. Combustion of the ammonia and hydrogen produces NH.sub.2.sup. ions among other combustion products (22). A second combustion chamber (3) receives the combustion products (22) from the first combustion chamber and receives further ammonia (4) and further hydrogen (5) in controlled proportions, wherein combustion produces nitrogen oxides among other combustion products (24). A third combustion chamber (14) receives the nitrogen oxides along with further ammonia and further hydrogen in further controlled proportions along with further oxygen-containing gas, such that the nitrogen oxides are combusted into nitrogen and water.

A multi-energy-form output energy tower for stepwise recovering waste heat of a gas engine, comprising an internal combustion engine (1), wherein the present invention also comprises a steam Rankine cycle system (2) which is capable of heat exchanging with the high temperature exhaust exhausted from the IC engine (1) to make the steam turbine (22) do expansion work. An organic Rankine cycle system which is respectively heat exchanged with high temperature exhaust, jacket water and charge air which are exhausted from the IC engine (1), and with condensation heat in the steam Rankine cycle system (2) to do expansion work; a lithium bromide refrigerator (4) which uses jacket waterpart of jacket water discharged from the IC engine (1) as a heat source of the absorption cooling system for heat exchange; and a hot water heat exchanger (5) connected with a high temperature exhaust of the IC engine (1) for heating domestic water. The energy tower of the present invention adopts multiple waste heat recovering methods and combines cooling, heating and power supplying methods, which improves comprehensive energy utilization efficiency of the system and achieves the effects of energy saving and emission reduction.

A multi-energy-form output energy tower for stepwise recovering waste heat of a gas engine, comprising an internal combustion engine (1), wherein the present invention also comprises a steam Rankine cycle system (2) which is capable of heat exchanging with the high temperature exhaust exhausted from the IC engine (1) to make the steam turbine (22) do expansion work. An organic Rankine cycle system which is respectively heat exchanged with high temperature exhaust, jacket water and charge air which are exhausted from the IC engine (1), and with condensation heat in the steam Rankine cycle system (2) to do expansion work; a lithium bromide refrigerator (4) which uses jacket waterpart of jacket water discharged from the IC engine (1) as a heat source of the absorption cooling system for heat exchange; and a hot water heat exchanger (5) connected with a high temperature exhaust of the IC engine (1) for heating domestic water. The energy tower of the present invention adopts multiple waste heat recovering methods and combines cooling, heating and power supplying methods, which improves comprehensive energy utilization efficiency of the system and achieves the effects of energy saving and emission reduction.

An energy utilization system includes a circulation circuit. The circulation circuit includes a pump, a heating section, an electrolytic reduction apparatus, and a thermal energy recovery section. The pump receives a heating medium and outputs the heating medium. The heating section heats the heating medium by using renewable energy or energy obtained from waste heat. The electrolytic reduction apparatus heats an electrolytic solution with heat from the heating medium. The circulation circuit circulates the heating medium. A method for producing a carbon-containing material includes heating a heating medium circulating in a circulation circuit by using renewable energy or energy obtained from waste heat, and performing electrolytic reduction by heating an electrolytic solution with heat from the heating medium that has been heated.

One embodiment relates to a methanation method comprising the conversion into methane (CH.sub.4) of CO.sub.2, in particular CO.sub.2 gas, originating from, in particular diverted or obtained from, power plant flue gas from a power plant fired with carbon-containing fuel, in particular carbon-containing gas, and having a connected water/steam circuit, said method being performed in a methanation plant. Some embodiments provide a solution that makes it possible to couple a power plant and a methanation plant to one another in an energetically favorable manner.