Heating Martins Katalin ELTE Atomfizikai Tanszk Exergy and

Heating Martinás Katalin ELTE, Atomfizikai Tanszék

Exergy and Industrial Ecology • Case study – District heating

District Heating and Cooling? Market Failor • EU – good – the future Or • Hungary – uneconomic – the past » MARKET FORCES TO LEAVE THE DH SYSTEM

Prices Ft/MJ • • HEAT PUMP WOOD COAL GAS DH ELECTRIC PB-GAS 1, 5 2, 5 3, 1 3, 6 4, 5 6, 0 7, 1

The four laws of thermodynamics • 0. Bodies in contact with each other assume the same temperature. • 1. energy conservation • 2. Any transformation leads to losses • 3. When the temperature of a system is zero (K) entropy reaches a constant value.

Heat pump • 1 GJ heat • -3 C environment • 27 C room 1* 30/300 = 0, 1 GJ electric energy

Exergy • Exergy is a term that is used to show the maximum work a system can produce

Exergy • All the differences: • B = (T-To)S – (p -po)V +… • Thermal part • B = Q (T – To)/T

Laws of Nature • Exergy – no production • Every transformation leads to losses

Exergy of heating 1 GJ Heat Inside temperature 20 20 outside temperature 20 10 0 -10 B 0 0, 03 0, 06 0, 1

Exergy of with gas heating 1 GJ Heat Inside temperature 20 20 20 outside temperature 10 0 -10 Exergy loss 0, 97 0, 94 0, 9

Solution - cogeneration All energy end up as heat

Cogeneration • Present practice • 50% less fuel for heating

Exergy price comparision • • HEAT PUMP WOOD COAL GAS DH ELECTRIC PB-GAS PRICE Exergy Ex-price Ft/MJ 1, 5 2, 5 3, 1 3, 6 4, 5 6, 0 7, 1 MJ/MJ 0, 9 1, 7 1, 4 1, 2 0, 6 3, 0 1, 2 Ft/MJ 1, 7 1, 5 2, 3 2, 6 7, 5 2, 0 5, 1

Advantage of DH 1. Can utilize energy with low value (exergy) utilize loses from many other processes (CHP, waste incineration) 2. Easy to change fuel – few units 3. Easy flue gas cleaning – few units 4. Big share of cost are investment cost – steady prices, money stay in the local community

Hungary • Főtáv Zrt – 2007 - 12 Md GJ • 4500 Ft/GJ Energy – from gas – 8, 5 Md Ft from PP – 23, 8 Md Ft electricity 1, 3 Md Ft wages 2, 2 Md Ft other 17, 8 Md Ft

Győrhő Zrt • 2790 Ft/GJ • In Győr DH is cheaper than the gas heating. •