Rīgas Tehniskā universitāte Enerģētikas un elektrotehnikas fakultāte Vides aizsardzības un siltuma sistēmu institūts DEVELOPMENT OF DH SYSTEMS - COGENERATION VERSUS ENERGY EFFICIENCY OF END USER Dagnija Blumberga, Gatis Bazbauers, Andra Blumberga, Ginta Cimdina, Claudio Rochas Institute of Energy Systems and Environment, Riga Technical University

Vides aizsardzības un siltuma sistēmu institūts 2 Large CHP and DH system development features Cogeneration load decrease Energy efficiency of buildings improvement Energy consumption of DH system decrease Load dispersion large Technological development Dispersed energy generation Diversification energy generation and supply as well as energy resources Innovative technologies

Case study:To be or not to be. Riga DH system (part of Daugava river right bank) Large energy sources 4 CHP CHP 1 – RTEC 1 – 144 MWe (natural gas) CHP 2/0 – RTEC 2 – 200 MWe (natural gas) – before 2000 CHP 2/1 – RTEC 2/1 – 400 MWe (natural gas) CHP 2/2 - RTEC 2/2 – 400 MWe (natural gas) Vides aizsardzības un siltuma sistēmu institūts 3

Historical data Vides aizsardzības un siltuma sistēmu institūts 4

5 Riga DH load duration curve. Existing situation

Vides aizsardzības un siltuma sistēmu institūts 6 Changes in thermal energy demand Today energy efficiency measures have been introduced in 21 apartment buildings only, which constitute less than 1% of the total number of the apartment buildings in Riga. The consumption of thermal energy in the existing buildings most likely will decrease by 20 – 30 % (in some cases by 50%). The newly constructed apartments could increase thermal energy consumption, however the increase over the next year period will not offset the reduction in consumption which will be gained through the introduction of energy efficiency measures.

Vides aizsardzības un siltuma sistēmu institūts 7

8 Riga DH load duration curve. Forecast

Vides aizsardzības un siltuma sistēmu institūts 9 Scenarious Scenario 1. Continue to operate in regime when each plant operates for 3000 hours/year Scenario 2. Heat load is covered by Riga TEC2/1 by using heat storage systems Scenario 3. Natural gas is replaced by wood fuel in Riga TEC 1 and heat storage is installed

Thermal energy production and accumulation Vides aizsardzības un siltuma sistēmu institūts 10

Economical data Vides aizsardzības un siltuma sistēmu institūts 11 Scenario 3. Natural gas is replaced by wood fuel in Riga TEC 1 and heat storage is installed Scenarios 123 Heat produced, GWh th /year 1764 Electricity produced, GWh e /year Natural gas consumption, GWh f /year Wood fuel consumption, GWh f /year 3093 Fuel costs, MLs/year Capital costs, MLs/year Operation and maintenance costs, MLs/year 1779 Total costs, MLs/year Costs of electricity, Ls/MWh e A

Vides aizsardzības un siltuma sistēmu institūts 12 Conclusions Existing situation. The thermal energy consumption of the Riga right bank DH system is possible to cover demand with the existing, recently reconstructed cogeneration station at Riga TEC 1 and the first unit of TEC 2 (RTEC-2/1). However, the Riga TEC-2 first unit will operate only 3000 – 5000 hours per year. Forecast of heat load. The thermal energy consumption will decrease by 20 – 30% because of the energy efficiency measures..

Vides aizsardzības un siltuma sistēmu institūts 13 Conclusions No expanding of natural gas cogeneration regime. If the equipment of the new second unit of Riga TEC 2 is connected to the DH system of Riga and will operate in cogeneration mode for 3000 hours/year then it would require operation of the equipment of Riga TEC 1 or Riga TEC 2 first unit in the condensation mode. Future for biomass cogeneration. An economic comparison of the three scenarios indicates that the lowest costs of electricity may be obtained if wood- fired cogeneration plant in combination with seasonal heat storage system is installed instead of the gas- fired gas turbine combined cycle cogeneration plants.