Profitability of sparse district heating

The expansion of district heating into areas of low heat densities (heat sparse areas) constitutes a challenge due to the higher distribution costs. The profitability of sparse district heating has been analysed from actual investments in 74 areas with 3227 one-family houses connected to district heating between 2000 and 2004 in Göteborg, Sweden. The profitability was estimated from a probable price model, a typical marginal heat generation cost, and the investments from the actual connections made. The analysis identified factors as the linear heat density and heat sold per house explaining the main variations in profitability. The profitability analysis was concluded with a competition analysis. The main conclusion is that sparse district heating is possible when reaching low investment costs for the local distribution network and low marginal costs for the heat generation. In Sweden, the general competitiveness of sparse district heating is facilitated by the high consumption taxes for fuel oil, natural gas, and electricity. Hence, it should be more difficult to introduce sparse district heating in other countries with low energy taxes.     

Stockholm CHP potential—An opportunity for CO2 reductions?

The potential for combined heat and power (CHP) generation in Stockholm is large and a total heat demand of about 10 TWh/year can be met in a renewed large district heating system. This model of the Stockholm district heating system shows that CHP generation can increase from 8% in 2004 to 15.5% of the total electricity generation in Sweden. Increased electricity costs in recent years have awakened an interest to invest in new electricity generation. Since renewable alternatives are favoured by green certificates, bio-fuelled CHP is most profitable at low electricity prices. Since heat demand in the district heating network sets the limit for possible electricity generation, a CHP alternative with a high electricity to heat ratio will be more profitable at when electricity prices are high. The efficient energy use in CHP has the potential to contribute to reductions in carbon dioxide emissions in Europe, when they are required and the European electricity market is working perfectly. The potential in Stockholm exceeds Sweden's undertakings under the Kyoto protocol and national reduction goals.     

On the potential trade-offs between energy supply and end-use technologies for residential heating

In Sweden, where district heating accounts for a significant share of residential heating, it has been argued that improvements in end-use energy efficiency may be counter-productive since such measures reduce the potential of energy efficient combined heat and power production. In this paper we model how the potential trade-offs between energy supply and end-use technologies depend on climate policy and energy prices. The model optimizes a combination of energy efficiency measures, technologies and fuels for heat supply and district heating extensions over a 50 year period. We ask under what circumstances improved end-use efficiency may be cost-effective in buildings connected to district heating? The answer hinges on the available technologies for electricity production. In a scenario with no alternatives to basic condensing electricity production, high CO₂ prices result in very high electricity prices, high profitability of combined heat and power production, and little incentive to reduce heat demand in buildings with district heating. In contrast, in a scenario where electricity production alternatives with low CO₂ emissions are available, the electricity price will level out at high CO₂ prices. This gives heat prices that increase with the CO₂ price and make end-use efficiency cost-effective also in buildings with district heating.     

Regional energy system optimization – Potential for a regional heat market

Energy supply companies and industrial plants are likely to face new situations due to, for example, the introduction of new energy legislation, increased fuel prices and increased environmental awareness. These new prerequisites provide companies with new challenges but also new possibilities from which to benefit. Increased energy efficiency within companies and increased cooperation between different operators are two alternatives to meet the new conditions. A region characterized by a high density of energy-intensive processes is used in this study to find the economic potential of connecting three industrial plants and four energy companies, within three local district heating systems, to a regional heat market, in which different operators provide heat to a joint district heating grid. Also, different investment alternatives are studied. The results show that the economical potential for a heat market amounts to between 5 and 26 million EUR/year with payback times ranging from two to eleven years. However, the investment costs and the net benefit for the total system need to be allotted to the different operators, as they benefit economically to different extents from the introduction of a heat market. It is also shown that the emissions of CO₂ from the joint system would decrease compared to separate operation of the systems. However, the valuation of CO₂ emissions from electricity production is important as the difference of emitted CO₂ between the accounting methods exceeds 650 kton/year for some scenarios.     

Fossil fuels substitution by the solar energy utilization for the hot water production in the heating plant “Cerak” in Belgrade

The main objective of this paper is to evaluate energy and environmental benefits of the large-scale solar heating system connection with district heating system. The assessment of fossil fuels substitution by the solar energy for the hot water production for domestic use, during the summer period, is done. Hot water for district heating and domestic use is produced in heating plant “Cerak” placed in the suburb of Belgrade. The existing production and distribution system are based on fossil fuel energy, mainly on the natural gas. In the first phase of the project plan was to install about 10,000 m² of solar collectors to substitute nearly 25% of natural gas consumption. During the summer period, the saving of natural gas calculated for presented system is approximately 430,000 m³ and in this way 900 t of the CO₂ emissions would be reduced.     

Energy use of integral refrigerated containers in maritime transportation

The global trading of perishable goods is possible through the application of product refrigeration and atmospheric control during transportation. A mean energy consumption rate of 2.7 kW/TEU was assumed in this study, but was found to have potential variations of around ±60%. New Zealand’s maritime trade was considered as a case study for the year 2007 to place the effect of refrigerated transport in context. For individual refrigerated containers, approximately 19% of the energy use related to its journey is used for refrigeration purposes. In 2007, approximately 18% and 61% of New Zealand’s imported and exported food products by mass, respectively, required some form of refrigeration during transportation. Maintaining the refrigerated state of imports and exports to and from New Zealand during maritime transportation consumed approximately 280 GWh of electricity. Assuming all this electricity was generated onboard vessels using auxiliary engines, approximately 61 kt of fuel was consumed and 190 kt of CO₂ produced. Refrigeration is of particular importance to the many greenhouse gas or carbon footprinting studies conducted around the world. Implications are discussed in the context of greenhouse gas emissions from the transport of apples from NZ to the UK and long-term storage of UK apples.     

Wet and dry cooling systems optimization applied to a modern waste-to-energy cogeneration heat and power plant

In Brescia, Italy, heat is delivered to 70% of 200.000 city inhabitants by means of a district heating system, mainly supplied by a waste to energy plant, utilizing the non recyclable fraction of municipal and industrial solid waste (800,000 tons/year, otherwise landfilled), thus saving annually over 150,000 tons of oil equivalent and over 400,000 tons of CO₂ emissions.     

Coproduction of district heat and electricity or biomotor fuels

The operation of a district heating system depends on the heat load demand, which varies throughout the year. In this paper, we analyze the coproduction of district heat and electricity or biomotor fuels. We demonstrate how three different taxation scenarios and two crude oil price levels influence the selection of production units to minimize the district heat production cost and calculate the resulting primary energy use. Our analysis is based on the annual measured heat load of a district heating system. The minimum-cost district heat production system comprises different production units that meet the district heat demand and simultaneously minimize the district heat production cost. First, we optimize the cost of a district heat production system based on the cogeneration of electricity and heat with and without biomass integrated gasification combined-cycle technology. We considered cogenerated electricity as a byproduct with the value of that produced by a condensing power plant. Next, we integrate and optimize different biomotor fuel production units into the district heat production system by considering biomotor fuels as byproducts that can substitute for fossil motor fuels. We demonstrate that in district heating systems, the strengthening of environmental taxation reduces the dependence on fossil fuels. However, increases in environmental taxation and the crude oil price do not necessarily influence the production cost of district heat as long as biomass price is not driven by policy measures. Biomotor fuel production in a district heating system is typically not cost-efficient. The biomotor fuels produced from the district heating system have to compete with those from standalone biomotor fuel plants and also with its fossil-based counterparts. This is also true for high oil prices. A carbon tax on fossil CO₂ emissions based on social cost damage will increase the competitiveness of biomass-based combined heat and power plants, especially for BIGCC technology with its high electricity-to-heat ratio.     

Improvement of the cogeneration plant economy by using heat accumulator

The optimisation code ACOM (Advanced Cogeneration Optimisation Model) is used with purpose of assessing influence of the district heat accumulator on the Elektrana-Toplana (EL-TO) Zagreb cogeneration plant economic performance. The plant supplies hot water for district heating, steam for industry and electric power. It is possible to achieve economic benefits by charging the accumulator during the day time, when the electricity price is high, and by releasing district heat during cheap night hours, when other parts of equipment may be shut down. The consequences of this strategy are the decrease of total annual electricity production and fuel consumption, whereby the savings of some 1.8 mil Euro/a are achieved with the reduction of CO₂ emission by about 23,000 t/a or 6.4% and SO_x by about 200 t/a or 16.9%.     

Sustainability of a wind power plant: Application to different Moroccan sites

In this paper, three main steps allowing the definition of the sustainability of a wind power plant (WPP) are described in detail. The first step is to choose a site with a good wind potential. In this respect, two approaches have been introduced: traditional wind statistical estimations based on the identification of the Weibull probability density function on specific sites; and an innovative Kriging approach based on artificial neural networks to reconstruct the profile of the mean wind speed of the territory. In the second step, given technical details, the energetic sustainability of a WPP installation is assessed according to a model computing the wind energy production per year, as well as the details of its efficiency. Finally, as third step, a cost/benefit evaluation on the overall reduction in CO₂ emissions with respect to traditional fossil fuel energy plants is reported. From a wind speed characterisation viewpoint, the case study is referred to the overall Moroccan territory. From a WPP model viewpoint, the case study is referred to the installation of a specific WPP, which would allow the production of more than 2 GWh per year in the south Atlantic coast and of nearly 1 GWh per year in the Mediterranean coast in the neighbourhood of Tangier.     

Assessment of Thailand indoor set-point impact on energy consumption and environment

The paper presents an investigation of indoor set-point standard of air-conditioned spaces as a tool to control electrical energy consumption of air-conditioners in Thailand office buildings and to reduce air pollutants. One hundred and forty-seven air-conditioned rooms in 13 buildings nationwide were used as models to analyze the electricity consumption of air-conditioning systems according to their set indoor temperatures, which were below the standard set-point and were accounted into a large scale. Then, the electrical energy and environmental saving potentials in the country were assessed by the assumption that adaptation of indoor set-point temperature is increased up to the standard set-point of 26 °C. It was concluded that the impacts of indoor set-point of air-conditioned rooms, set at 26 °C, on energy saving and on environment are as follows: The overall electricity consumption saving would be 804.60 GWh/year, which would reduce the corresponding GHGs emissions (mainly CO₂) from power plant by 579.31×10³ tons/year.     

Pathways to a sustainable European kraft pulp industry: Trade-offs between economy and CO2 emissions for different technologies and system solutions

In this paper the trade-off, in terms of annual net profit for the mill and global emissions of CO₂, between different technology pathways for utilization of excess steam and heat at kraft pulp mills is investigated for a case depicting a typical Scandinavian mill of today. The trade-off is analysed for four future energy market scenarios having different levels of CO₂ charge. The technology pathways included in this study are increased electricity production in new turbines, production of district heating, increased sales of biomass in the form of bark and/or lignin, and carbon capture and storage (CCS). The results show that the proven pathways, increased electricity production, bark export and district heating production, are economically robust, i.e. they are profitable for all of the studied energy market scenarios. The new and emerging technology pathways, that are CCS and lignin extraction, hold a larger potential for reduction of global CO₂ emissions, but their economic profitability is more dependent on the development of the energy market. All in all, it can be concluded that to realize the larger potential of reduction of global CO₂ emissions a high carbon cost alone may not be sufficient. Other economic stimulations are required, e.g. technology-specific subsidies.     

Reduction of electricity use in Swedish industry and its impact on national power supply and European CO2 emissions

Decreased energy use is crucial for achieving sustainable energy solutions. This paper presents current and possible future electricity use in Swedish industry. Non-heavy lines of business (e.g. food, vehicles) that use one-third of the electricity in Swedish industry are analysed in detail. Most electricity is used in the support processes pumping and ventilation, and manufacturing by decomposition. Energy conservation can take place through e.g. more efficient light fittings and switching off ventilation during night and weekends. By energy-carrier switching, electricity used for heat production is replaced by e.g. fuel. Taking technically possible demand-side measures in the whole lines of business, according to energy audits in a set of factories, means a 35% demand reduction. A systems analysis of power production, trade, demand and conservation was made using the MODEST energy system optimisation model, which uses linear programming and considers the time-dependent impact on demand for days, weeks and seasons. Electricity that is replaced by district heating from a combined heat and power (CHP) plant has a dual impact on the electricity system through reduced demand and increased electricity generation. Reduced electricity consumption and enhanced cogeneration in Sweden enables increased electricity export, which displaces coal-fired condensing plants in the European electricity market and helps to reduce European CO₂ emissions. Within the European emission trading system, those electricity conservation measures should be taken that are more cost-efficient than other ways of reducing CO₂ emissions. The demand-side measures turn net electricity imports into net export and reduce annual operation costs and net CO₂ emissions due to covering Swedish electricity demand by 200 million euros and 6 Mtonne, respectively. With estimated electricity conservation in the whole of Swedish industry, net electricity exports would be larger and net CO₂ emissions would be even smaller.     

Biomass gasification in district heating systems – The effect of economic energy policies

Biomass gasification is considered a key technology in reaching targets for renewable energy and CO₂ emissions reduction. This study evaluates policy instruments affecting the profitability of biomass gasification applications integrated in a Swedish district heating (DH) system for the medium-term future (around year 2025). Two polygeneration applications based on gasification technology are considered in this paper: (1) a biorefinery plant co-producing synthetic natural gas (SNG) and district heat; (2) a combined heat and power (CHP) plant using integrated gasification combined cycle technology. Using an optimisation model we identify the levels of policy support, here assumed to be in the form of tradable certificates, required to make biofuel production competitive to biomass based electricity generation under various energy market conditions. Similarly, the tradable green electricity certificate levels necessary to make gasification based electricity generation competitive to conventional steam cycle technology, are identified. The results show that in order for investment in the SNG biorefinery to be competitive to investment in electricity production in the DH system, biofuel certificates in the range of 24–42 EUR/MWh are needed. Electricity certificates are not a prerequisite for investment in gasification based CHP to be competitive to investment in conventional steam cycle CHP, given sufficiently high electricity prices. While the required biofuel policy support is relatively insensitive to variations in capital cost, the required electricity certificates show high sensitivity to variations in investment costs. It is concluded that the large capital commitment and strong dependency on policy instruments makes it necessary that DH suppliers believe in the long-sightedness of future support policies, in order for investments in large-scale biomass gasification in DH systems to be realised.     

Estimating marginal CO2 emissions rates for national electricity systems

The carbon dioxide (CO₂) emissions reduction afforded by a demand-side intervention in the electricity system is typically assessed by means of an assumed grid emissions rate, which measures the CO₂ intensity of electricity not used as a result of the intervention. This emissions rate is called the “marginal emissions factor” (MEF). Accurate estimation of MEFs is crucial for performance assessment because their application leads to decisions regarding the relative merits of CO₂ reduction strategies. This article contributes to formulating the principles by which MEFs are estimated, highlighting the strengths and weaknesses in existing approaches, and presenting an alternative based on the observed behaviour of power stations. The case of Great Britain is considered, demonstrating an MEF of 0.69 kgCO₂/kW h for 2002–2009, with error bars at +/−10%. This value could reduce to 0.6 kgCO₂/kW h over the next decade under planned changes to the underlying generation mix, and could further reduce to approximately 0.51 kgCO₂/kW h before 2025 if all power stations commissioned pre-1970 are replaced by their modern counterparts. Given that these rates are higher than commonly applied system-average or assumed “long term marginal” emissions rates, it is concluded that maintenance of an improved understanding of MEFs is valuable to better inform policy decisions.     

Using biomass for climate change mitigation and oil use reduction

In this paper, we examine how an increased use of biomass could efficiently meet Swedish energy policy goals of reducing carbon dioxide (CO₂) emissions and oil use. In particular, we examine the trade-offs inherent when biomass use is intended to pursue multiple objectives. We set up four scenarios in which up to 400 PJ/year of additional biomass is prioritised to reduce CO₂ emissions, reduce oil use, simultaneously reduce both CO₂ emission and oil use, or to produce ethanol to replace gasoline. Technologies analysed for using the biomass include the production of electricity, heat, and transport fuels, and also as construction materials and other products. We find that optimising biomass use for a single objective (either CO₂ emission reduction or oil use reduction) results in high fulfilment of that single objective (17.4 Tg C/year and 350 PJ oil/year, respectively), at a monetary cost of 130–330 million €/year, but with low fulfilment of the other objective. A careful selection of biomass uses for combined benefits results in reductions of 12.6 Tg C/year and 230 PJ oil/year (72% and 67%, respectively, of the reductions achieved in the scenarios with single objectives), with a monetary benefit of 45 million €/year. Prioritising for ethanol production gives the lowest CO₂ emissions reduction, intermediate oil use reduction, and the highest monetary cost.     

The Bad Blumau geothermal project: a low temperature, sustainable and environmentally benign power plant

The 250 kW geothermal project at Bad Blumau is the first geothermal project developed in Austria by the private sector following the deregulation of the electricity industry in this country. What makes the project unique besides its private ownership structure is its ability to generate electrical power and district heating for the Rogner Bad Blumau Hotel & Spa by using a low temperature geothermal resource. Installed in the record time of less than a week, the air-cooled ORMAT ® Energy Converter (OEC) CHP module has been in commercial operation since July 2001. With an annual availability exceeding 99%, between October 2001 and December 2002 the plant delivered 1,560,000 kWh to the local grid. The geothermal CHP module utilizes brine at 110 °C, available from a 3000 m deep production well. Exiting the OEC unit at a temperature of 85 °C, the brine is then fed into the district heating system, providing heat for the Rogner Bad Blumau Hotel & Spa. The geothermal brine is returned from the district heating system and injected into a 3000 m depth reinjection well. The system is a pollution-free, unattended operating power generation module, which has avoided more than 1100 kg of CO₂ emissions over its first operating year.     

Direct application of geothermal energy: 2005 Worldwide review

This paper is a review of worldwide direct applications of geothermal energy. It attempts to update the surveys presented at and after the World Geothermal Congresses of 1995, 2000 and 2005. Seventy-two countries report direct utilization of geothermal energy. In May 2005, the direct-use projects had an estimated installed thermal capacity of 28,268 MWt. The thermal energy usage is 273,372 TJ/year (75,943 GWh/year), a 43% increase over 2000; the annual compound growth rate is 7.5%.The distribution of thermal energy used by category is approximately 32% for geothermal heat pumps, 30% for bathing and swimming (including balneology), 20% for space heating (of which 83% is for district heating), 7.5% for greenhouse and open-ground heating, 4% for industrial process heat, 4% for aquaculture pond and raceway heating, <1% for agricultural drying, <1% for snow melting and cooling, and <0.5% for other uses. The equivalent annual savings in fuel oil amounts to 170 million barrels (25.4 million tonnes) and 24 million tonnes in carbon emissions to the atmosphere.     

Feasibility of CHP-plants with thermal stores in the German spot market

The European Energy Exchange (EEX) day ahead spot market for electricity in Germany shows significant variations in prices between peak and off-peak hours. Being able to shift electricity production from off-peak hours to peak hours improves the profit from CHP-plant operation significantly. Installing a big thermal store at a CHP-plant makes it possible to shift production of electricity and heat to hours where electricity prices are highest especially on days with low heat demand. Consequently, these conditions will have to influence the design of new CHP-plants. In this paper, the optimal size of a CHP-plant with thermal store under German spot market conditions is analyzed. As an example the possibility to install small size CHP-plant instead of only boilers at a Stadtwerke delivering 30,000 MW h-heat for district heating per year is examined using the software energyPRO. It is shown that, given the economic and technical assumptions made, a CHP-plant of 4 MW-el with a thermal store participating in the spot market will be the most feasible plant to build. A sensitivity analysis shows to which extent the optimal solution will vary by changing the key economic assumptions.     

Miscanthus and willow heat production—An effective land-use strategy for greenhouse gas emission avoidance in Ireland?

Recent decoupling of EU direct payments from agricultural production, to land-area-based payments, has accelerated the national trend of declining livestock numbers, presenting opportunities for new agricultural products. This paper uses life-cycle analyses to quantify the national magnitude and area-based efficiency of greenhouse gas (GHG) emission reductions possible from utilising indigenously grown willow and Miscanthus as heating fuels in domestic/commercial premises. Willow and Miscanthus fuel-chain emissions were calculated at 0.045 and 0.062 kg CO₂ eq. kWh_th, compared with 0.248, 0.331 and 0.624 kg CO₂ eq. kWh_th for gas, oil and electric heat, respectively. Long-term soil C sequestration where willow and Miscanthus are grown on tillage land could exceed fuel-chain emissions, resulting in heat production better than C-neutral. Net GHG emission reductions ranged from 7671 kg CO₂ eq. ha⁻¹ a⁻¹ where willow displaced grassland and gas to 34,187 kg CO₂ eq. ha⁻¹ a⁻¹ where Miscanthus displaced set-aside and electric heat. A simple, indicative scenario assumed that energy-crops were grown on set-aside and destocked grassland in the ratio of 1:2, and displaced a total of 4728 GWh_th combined gas, oil and electric heat. Consequent net GHG emission reductions arising from sole utilisation of either willow or Miscanthus equated to 2.6% or 2.5% of 2004 national emissions, and required just 2.9% or 2.1% of Ireland's agricultural land area. Net total emission reductions were relatively insensitive to variation in yield and cultivation emissions, but large reductions associated with electric-heat displacement will decline as electricity production becomes less GHG-intensive, and may not be representative of other countries. Energy-crop heat production offers considerably greater GHG emission reduction potential compared with agricultural destocking alone, and appears to represent an efficient land-use option for this purpose.