District heating production units in Helsinki metropolitan area

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District heating energy production in Helsinki metropolitan area is divided by three energy companies in 2007; Fortum Power and Heat Oy, Helsingin Energia and Vantaan Energia Oy. These companies energy production units are listed in following table.

.	.	.	.	.	.	HEAT OUTPUT	HEAT OUTPUT	HEAT OUTPUT	.	.	.
DISTRICT HEATING COMPANY AND NAME OF THE PRODUCTION UNIT	Type of production unit	Connected to a CHP	Year started up	Number of boilers	Type of the boiler v/h	Via turbines	Direct from boilers	Total	Power output	Main fuel	Capacity of heat pump
.	4.1	4.2	4.3	4.4	4.5	4.6	4.7	4.8	4.9	4.10	4.11
.	.	.	.	.	.	MW	MW	MW	MW	.	MW
Fortum Power and Heat Oy, Espoo
Kivenlahti	klk	-	1974	2	v	-	-	130,0	-	bio	-
Suomenoja 4	klk	1	1989	1	v	-	-	35,0	-	maka	-
Tapiola	klk	-	2002	2	v	-	-	160,0	-	rpö	-
Suomenoja 1	klk	1	1977	1	h	-	-	160,0	-	rpö	-
Suomenoja 3	klk	1	1986	1	v	-	-	70,0	-	kihi	-
Vermo	klk	-	1985	2	v	-	-	80,0	-	rpö	-
Kaupunginkallio	klk	-	1991	2	v	-	-	80,0	-	rpö	-
Otaniemi	klk	-	2001	3	v	-	-	120,0	-	rpö	-
Auroranportti	klk	-	1998	1	v	-	-	15,0	-	kpö	-
Juvanmalmi	klk	-	2000	1	v	-	-	15,0	-	maka	-
Kalajärvi	klk	-	2000	2	v	-	-	5,0	-	maka	-
Vermo	klk	-	2007	2	v	-	-	90,0	-	rpö	-
Masala	klk	-	..	5	v	-	-	18,0	-	maka	-
Kirkkonummi (keskusta)	klk	-	..	..	v	-	-	31,0	-	maka	-
Suomenoja 1	lvl 1	-	1977	1	-	162,0	-	162,0	75,0	kihi	-
Suomenoja 2	mlvl 2	-	1989	1	-	-	-	80,0	49,0	maka	-
Helsingin Energia
Alppila	klk	-	1964	4	v	-	-	164,0	-	rpö	-
Munkkisaari	klk	-	1969	5	v	-	-	235,0	-	rpö	-
Ruskeasuo	klk	-	1972	4	v	-	-	280,0	-	rpö	-
Lassila	klk	-	1977	4	v	-	-	334,0	-	maka	-
Patola	klk	-	1982	6	v	-	-	240,0	-	rpö	-
Salmisaari	klk	1	1978	3	v	-	-	120,0	-	rpö	-
Salmisaari	klk	1	1986	1	v	-	-	180,0	-	kihi	-
Salmisaari	klk	1	1977	1	h	-	-	8,0	-	rpö	-
Jakomäki	klk	-	1968	2	v	-	-	56,0	-	rpö	-
Myllypuro	klk	-	1978	2	v	-	-	240,0	-	rpö	-
Vuosaari	klk	3	1989	3	v	-	-	120,0	-	maka	-
Hanasaari	klk	2	1977	1	h	-	-	56,0	-	rpö	-
Katri Vala	lp	-	2006	5	-	-	-	90,0	-	muu	30,0
Salmisaari	lvl 1	-	1984	1	-	300,0	-	300,0	160,0	kihi	-
Hanasaari	lvl 2	-	1973	2	-	420,0	-	420,0	228,0	kihi	-
Vuosaari	lvl 3	-	1991	4	-	580,0	-	580,0	630,0	maka	-
Helsinki-Vantaan lentoasema
Lämpökeskus	klk	-	1976	4	v	-	-	32,0	-	rpö	-
Vantaan Energia Oy
Pähkinärinne	klk	-	1974	2	v	-	-	46,6	-	rpö	-
Koivukylä	klk	-	1972	4	v	-	-	145,0	-	maka	-
Hakunila	klk	-	1972	2	v	-	-	80,0	-	maka	-
Martinlaakso	klk	1	1976	1	v	-	-	60,1	-	rpö	-
Metsola	klk	-	1977	2	v	-	-	17,4	-	rpö	-
Katriina	klk	-	1990	2	v	-	-	3,6	-	bio	-
Maarinkunnas	klk	-	2002	5	v	-	-	200,0	-	maka	-
Martinlaakso 2	lvl 1	-	1982	1	-	135,0	-	135,0	80,0	kihi	-
Martinlaakso 1	lvl 2	-	1975	1	-	120,0	-	120,0	60,0	maka	-
Martinlaakso Gt	mlvl 3	-	1995	1	-	-	-	75,0	58,0	maka	-
Katriina	mlvl 4	-	1994	1	-	-	-	0,6	0,4	bio	-
Col. 4.2		Col. 4.10
klk	= stationary heating plant	kihi	= coal
lp	= heating pump	rpö	= heavy fuel oil
lvl	= steam power station	kpö	= light fuel oil
mlvl	= other power station	jtu	= milled peat
ptu	= sod peat
Col. 4.5		maka	= natural gas
popu	= forest fuel
v	= water	tept	= industrial wood residues
h	= steam	pjät	= black liquour
bio	= biogas
kipa	= recovered fuels
sek	= Industrial reaction heat
säh	= electricity
muu	= other

Note! Masala and Kirkkonummi production units are located in Kirkkonummi and not in Helsinki metropolitan area.

Thermal energy production plants connection to the district heating network can be done simplified in two ways; direct and indirect. Direct connection means, that the same water flows in district heating network as in district heating plant boiler. This method is mostly used in small scale energy production plants. It is quite cheap to realize, but in other hand it will put some restrictions to fuels and boiler temperatures for example.

Indirect connection means that in thermal energy production plant boiler flows different water than in district heating network. The plant and district heating network are connected with condenser. There’s many kind of condensers, but the main idea is that the two water flows doesn’t physically mix together. Indirect connection is mostly used in larger steam turbine plants, but it can be used in small scale plants too (Huovilainen & Koskelainen, 1982, s84).

• • Regulations for district heating plants

Directive for protecting environment and lowering emissions, so called IPPC – directive, requires information exchange between countries and industry of best available technique (BAT). Based on this information exchange BAT-correlation documents are formed, so called BREF- documents (BAT Reference Documents), which were made for over 50 MW plants in year 2004. BREFs for small scale energy production plants are not determined yet. Finnish environmental law requires use of best technique available. In small scale energy production plant cases have implied old air pollution law, which is from year 1987. Emissions caps do not imply to current techniques, so permission policy for small scale energy production plants have been diverse in last years (Jalovaara et all. 2003).

National assessment for BAT-technique for Finnish 5-50 MW energy production plants was made for uniting the permission policy in year 2003. BAT-levels are not emission caps; they are only to help authorities set emission caps when the local conditions are taken into account (Jalovaara et all. 2003).

Finnish environmental law (86/2000) 20 § requires that action, which is or may be dangerous to environment, have to have permission to do it. Actions that require permission are more closely described on Finnish environmental regulation 1 § (169/2000), which part three mentions energy production. Part three divides to two parts; to nuclear plants and to oil, mineral coal, wood, peat, gas or other flammable material using combustion plants, of which total fuel energy output potential is over 5 MW or which used total fuel energy output potential in a year is at least 54 terajoules (TJ). Energy production plant may have more than one boiler and permission will be given applying combined total fuel energy output potential in the boilers. If the total fuel energy output potential are less than mentioned above, but the plant is located in ground water area, it will require permission as well.

Environmental regulation third moment mentions also, that landfill and disposal plants such as incineration plants requires environmental permission also.

Authorities permit jurisdiction is regulated in environmental protection regulation second moment. It says that community council will handle permissions, if energy production plant total fuel energy output potential is over 5 MW but less than 50 MW. Over 50 and less than 300 MW plants permissions handles the aerial environmental administrations. Over 300 MW plants permissions will be handled in environmental permission agency (Jalovaara et all. 2003).

In environmental protection regulation 41 § are closer regulations for already exiting 5-50 MW plants and in 43 § for over 50 MW energy production plants statutory permission procedure. Small scale plants there are only one emission norm (Finnish government decision 157-1987), which is for particle emission and does not fulfil the best available technique requirements (Jalovaara et all. 2003).

• • Less than 50 MW district heating plants

In Finland energy production plants total fuel consumption was 580 PJ in year 2001 about which 13 % were used in less than 50 MW energy production plants. There are energy productions plants, which fuel energy output less than 50 MW, numerically about 1400 and larger plants roughly 200 in Finland (Jalovaara et all. 2003). Significant part of these small scale energy production plants is backup and peak heating units, which are not constantly in use during a year. In table BY is presented different fuels content of the small scale plants.

Table BY. Fuels consumption in less than 50 MW plants in year 2001. (Jalovaara et all. 2003)

.	Mineral coal	Heavy fuel oil	Light fuel oil	Natural gas	Peat	Wood	other	Total
TWh	0,8	5,1	0,2	4,4	2,0	4,6	3,3	20,4
%	4	25	1	22	10	23	16	100

Other fuels in table BY are mainly industries process based fuels, like waste- and biogases, coke, pine oil, hydrogen and solid fuels, like recycling fuels (REF = REcovered Fuel and RDF = Refuse-Derived Fuel), industrial, plastic, municipal and pulp waste. These can be burned as main or supplementary fuel.

Small or mediocre scale energy production plants are either heat-only and vapour production stations or backpressure power plants, which produce combined electricity and heat or vapour. Among the small scale energy production plants there are technically none electricity-only production plants (Jalovaara et all 2003).

Thought most of the fuel consumption in energy production happens in over 50 MW boiler plants, most of them also got most efficient flue gas cleaning systems, so emissions per produced energy are lower than the small plants. On small scale boiler plants potential to reduce emissions are higher, because authorities haven’t required as good emission reduction systems as on bigger plants.

In year 2007 fine particle assessment was made and possibility to reduce fine particle (PM2.5) emissions was evaluated. In the report assessed that less than 5 MW boiler plants affects almost half of energy productions fine particles emissions, thought they use only 4 % of the sectors total fuel consumption. In the assessment this emission reduction potential estimated to be 40 % of whole energy production potential. (Karvosenoja et all. 2007)

Most used boiler-types in small scale energy production plants are burner, grate and bubbling fluidized bed boilers. Burner can be used in Grate boilers also, which allow an additional fuel use, like natural gar or heavy/light fuel oil.

Heat-only or vapor production stations does not produce electricity and their operation efficiency in these plants are high, even 85-93 %. Flue gas losses cause the biggest efficiency loss in these stations (Jalovaara et al. 2003). These are the most common plant type in small scale energy production plants.

Back pressure power plants are traditionally industry- and district heating plants, which produce heat and electricity. These power plants are adjusted so they produce needed thermal energy and electricity is produced on a side. Operation efficiency is typically 80-85 % in industry and 85-90 % in district heating plants. Ratio between produced thermal energy and electricity is about 0,2-0,3 for industry and 0,45-0,55 for district heating plants (Jalovaara et all. 2003)

Gas turbine-/gas motor-/ diesel motor power plant are also solutions for a small scale plant, which can be use when wood chip or peat is vaporised. These plants produce thermal energy, vapor for process or both in incineration plant. Ratio between produced thermal energy and electricity is 0,5-0,6 and total operation efficiency is 80-85 % for gas turbine linked with incineration plant. For similar motor plant the ratio is 0,9 and total operation efficiency is 90 % (Jalovaara et al. 2003).

• • • Fuels and emissions

Wood chip or peat most used main fuel in small scale energy production plants in Finland. Many plants use mineral coal, refined municipal waste, heavy fuel oil or different waste- and production gases. Boilers type defines fuels which can be used in the plant.

Solid fuels consist roughly three different part; water, flammable and inflammable inorganic material. Flammable material is most important part and the two others parts are weakening factors for combustion. Flammable materials components are carbon, hydrogen, nitrogen, sulphur and oxygen. Energy which is released in the combustion depends of fuels carbons and hydrogen’s quantities. Sulphur and nitrogen, which the fuel contains, are significant origin for greenhouse emissions. Fuel contain trace elements also, which portions are less than 0,1 % of the fuels mass (Raiko et all. 2002).

Plants, which use solid fuels, often use supplementary fuels, because the accessibility or/and price of the supplementary fuel. Most common used supplementary fuels are mineral coal, recycling fuels and heavy fuel oil.

Mineral coal is not used as a main fuel in small scale energy production plants, but it can be used as supplementary fuel. Mineral coals sulphur content varies for its origin. In Finland is prescribed that mineral coals sulphur content cap is 1 % (96/61/EY). Because of high ash content, about 10 % of the mass, burning mineral coal creates high particle emissions. Because ash contains heavy metals too, heavy metal emissions are also high (Lahtinen & Kompula 1995).

Recycling fuels can be used as supplementary fuel too. Main recycling fuels are Recovered Fuel (REF) and Refused-derived Fuel (RDF). Use of recycling fuels sets restrictions to flue gas cleaning. Incineration directive came into effect end of year 2005, which restricts every energy production plant emission caps to same low level. This has restricted concisely use of recycling fuels in small scale energy production plants, where flue gas measurement commitments would bring expenses too high.

Heavy fuel oil is most suitable for solid fuel boilers as backup or supplementary fuel, because it got good accessibility and high thermal value. Oil burn in grate boiler plant requires separate burner. Oil has quite low ash content, so emissions are mainly from unburned carbon hydrogen compounds and coke. Emissions are mainly fine particles (Lahtinen & Kompula 1995).

In tables one and two are listed fuel characteristic and typical emission factors for less than 50 MW plants in Finland. Some of the factors have emission reduction technique like Electro-static precipitator (ESP), cyclones or Low-NOx-burners. Table 1. Typical carbon dioxide factors for fuels (Kivihiilitoimikunta 2004)

Fuel	Carbon dioxide factor
.	[g CO2/MJfuel]
Mineral coal	94
Natural gas	45
Heavy fuel oil	77
Light fuel oil	74
Shred peat	106
Woodchip	114

Table 2. Typical emission factors for small scale energy production plants in Finland (Jalovaara et all. 2003)

Boiler type / Fuel	Fuels thermal energy output in the plant	NOx	SO2	Dust
.	[MW]	[mg/MJ]	[mg/MJ]	[mg/MJ]
Burner
Heavy fuel oil	<5	150-250	350-500	20-90
(some of the plants have Low-Nox burners	5-15	150-250	350-500	10-70
.	15-50	120-200	350-500	5-40
Light fuel Oil	<5	100-150	50-70	<10
(some of the plants have Low-Nox burners	5-15	100-150	50-70	<10
.	15-50	60-120	50-70	<10
Natural gas	<5	60-100	0	0
(some of the plants have Low-Nox burners	5-15	60-100	0	0
15-50	40-80	0	0
Fluidized bed boiler (ESP)
Peat	5-10	150-200	150-250	10-50
.	10-50	130-200	150-250	5-20
Wood	5-0	80-150	<30	10-70
.	10-50	80-150	<30	5-30
Circulation fluidized bed boiler (ESP)
Peat	20-50	80-150	150-250	5-20
Wood	20-40	70-120	<30	5-30
Grate (ESP + Cyclone)
Peat	<5	150-250	150-250	20-150
.	5-10	150-250	150-250	5-120
.	10-50	140-220	150-250	5-100
Wood	<5	80-200	<30	20-150
.	5-10	80-200	<30	20-150
.	10-50	70-150	<30	10-150
Coal	5-10	70-150	400-600	400-600
.	25-40	80-200	5-50	5-50

Small scale district heating plants In Helsinki metropolitan area are mainly burner type boiler heat-only stations, which mainly use heavy fuel oil or natural gas. Some of them have cyclones and emulators, but some does not have flue gas cleaning system, because particle emissions are low in natural gas burn.

• • Over 50 MW district heating plants

District heating is produced mainly in large plants, which use combined heat and power (CHP) production. CHP-plants produced 2007 74 % and separate district heating plants 26 % of the district heating total thermal energy in Finland.

Needed thermal energy is produced addition of power production in district heating CHP-plants. If thermal energy is not needed, it is directed to sea. Need of electricity is increasing and there for new CHP-plants are usually built near population centers. Thus community need of thermal energy would be satisfied by economically and less environmental burdening way. Heat-only or vapor producing district heating plants are usually used only in cold weather to compensate peaks in need of thermal energy.

Often cities CHP-plants are measured to produce heat, which satisfies about half of needed heat in coldest weather. Other district heating production plants compensates then what is needed, usually this is about 20 % of the total thermal energy. These so called peak plants are started when temperature decreases under -5 or -10 °C.

• • Heat storing

District heating consumption is not steady during a year, there’s not only short term but also long term variation. Long term variations mean monthly variations and are caused changes in outdoor temperatures. Short term varieties are hourly changes and are affected by outdoor temperature and other weather conditions, like wind, clouds and rain and of course change in need of warm tap water. These variations make timing of district heating production harder, because most of the thermal energy is produced in co generation plants, also called heat and power plant. CHP- plant is adjusted to match need of thermal energy and produced power depends from that. In other words produced power depends from plants ratio of produced heat and power. Heat-only boiler plants thermal energy load can be reduced by storing the thermal energy in the district heating network or separate heat storage. Heat storing in co generated of heat and power district heating network has many benefits: - Power production increase when recharging heat storage. - Adjustable power production. - Lower district heating energy production costs by storing heat when production costs are lower and discharged when costs are higher. - Replaces energy, which is lost in back pressure plant or heat-only boiler plant planned or unplanned shutdown. - Reduces need of thermal energy peak plants. - It is more cleaner way to produce thermal energy heat-only boiler plants. Water filled tank is most suitable for short time heat storing, where water acts as mass which binds thermal energy and heat transferring fluid. Water has heat storing capability of 1,16 kWh/m3,°C. Warm water will settle top of cold water in the tank, because of density differences.

Heat storages can be connected to district heating network by two ways; directly, when district heating networks water will flow trough the storage and indirectly, when water in the storage and in district heating network doesn’t mix (Sipilä, Kari. 1985).