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L’énergie dans le développement de la Nouvelle-Calédonie

 | 
Yves Le Bars
, 
Elsa Faugère
, 
Philippe Menanteau
, 
et al.

Energy management: a major challenge for New Caledonia’s sustainable development and its energy security

The potential energy efficiency of industrial systems and recycling waste

Texte intégral

1Increasing the energy efficiency of industrial systems is a major challenge for the future. The aim is to reduce emissions of greenhouse gases into the atmosphere and to preserve stocks of fossil fuels, by reducing the demand for energy. In order to do so, potential energy sources must be identified, evaluated and then developed using a suitable methodology and an approach to processes as a whole.

TO INCREASE ENERGY MANAGEMENT IN THE INDUSTRIAL SECTOR

The aims of the energy-climate package

2The International Energy Agency’s scenarios (IEA) demonstrate that, in terms of the major potential for reducing greenhouse gas emissions, between now and 2030, 29 % on average stems from actions to be undertaken in terms of energy efficiency in relation to the demand for electricity, and 36 % stems from savings made on burning fossil carbon. The energy-climate pack-age has incorporated these facts and set itself the primary aim of an energy efficiency gain of 20 % for industrial systems, in order to proportionally reduce CO2 emissions, by 2020, thanks to a reduction in energy consumption.

3It should be noted that improvements in energy efficiency in the indus-trial sector were of the order of 2 to 3 % per annum up until 1990, but that, since then, improvements have not risen above 1 % per annum. In other words, the leaders of industry have made constant and considerable efforts to improve efficiency, but now, without technological breakthroughs in the implementation of their processes, the targets set by the energy-climate plan will not be met.

There are numerous current and future research projects

4In order to meet Kyoto targets, numerous research projects are being undertaken around the world, in particular in France, where the National Research Agency (ANR) launched a thematic programme of research into “Energy efficiency and the reduction of CO2 emissions within industrial systems (EESI)” in the Spring of 2009. This reduction must be accompanied by a reduction in operating costs and the preservation of resources, ultimately resulting in savings for the client. The application of these targets will present a considerable technological challenge, which is likely to have a profound effect on modes of energy consumption.

Industry’s response

5Almost 70 % of the final energy consumed by the industrial sector is used to cover heat-related requirements (boilers, furnaces, drying, heating) while the remainder mainly comprises non-heat related electricity.

6There is considerable potential for saving energy, particularly by furnaces, boilers, driers, electric and thermal motors. The renewal rate for industrial equipment, which is approximately 5 to 6 % per annum, means that this sector has major potential for innovation and improvements in terms of energy efficiency. This should enable basic concepts to be reconsidered, by incorporating technological breakthroughs, and processes to be re-examined by conducting thorough analyses of the main systems. Innovative technologies and their transfer to industry represent a potential source of added value and new industrial activities.

7Three catalysts enabling CO2 emissions in industry to be reduced:

  • improving the energy efficiency of processes, recycling waste and identifying new sources of renewable energy will ultimately enable energy costs to be reduced,
  • developing and deploying new technologies to capture and store car-bon dioxide,
  • putting in place financial incentives and/or penalties by governments, as well as banks for exchanging CO2 emission permits.

8This technological revolution in the approach to processes may result in energy efficiency being re-invented, specifically in terms of complete industrial production systems (defining the minimum amount of energy needed to produce a product). In this way, energy will be better used, which will result in improvements in a company’s competitiveness, the quality of products, savings for the client and, ultimately, jobs.

CONTRIBUTING TO IMPROVING THE ENERGY EFFICIENCY OF INDUSTRIAL SYSTEMS IN NEW CALEDONIA

9The aim of this section of the report is not to interfere with the policy and strategic choices of the leaders of industry, but to offer them new approaches and processes that could be deployed in New Caledonia. In order to do so, we will be relying on the results of research or new processes already in use around the world or currently being evaluated.

10(During our trip to New Caledonia, we were not able to meet with management of the Goro Nickel plant or to visit the power station at Prony. For these two sites, our assessments are based on solely public, and not technical, data.)

11Almost 60 % of the total primary energy consumed in New Caledonia is used in the metal industry, to generate electricity and heat. This is therefore an industry with heavy energy requirements in terms of electricity and heat, with emission sources that are concentrated on a few sites, thereby offering the opportunity for future capture and storage of the CO2 emitted. Currently, the plan is to use CCS technology (Carbon Capture and Storage) only for units emitting at least 100,000 tonnes of CO2/year.

12In comparison with recent decisions by European governments, a target of reducing CO2 emissions by 20 % may serve as a guide for improving energy efficiency in industry, even before carbon capture.

13In order to achieve significant energy savings, leaders of industry need to explore new approaches by:

  • making the best choice of primary energy1;
  • identifying and quantifying their potential energy sources for development (an improvement in the conversion of primary energy will result in an increase in energy efficiency),
  • putting in place integrated technologies for recovering thermal energy, even in the case of low temperatures (transporting, storing and recycling heat),
  • renovating or replacing process components with more efficient equipment,
  • guaranteeing energy integration with intelligent computerised optimisation of control and command processes,
  • seeking new outlets for their waste (mainly heat).

WHICH PRIMARY FUEL SHOULD WE CHOOSE?

14Both SLN and Enercal have chosen coal for their new thermal power stations at Doniambo and Prony respectively. This choice is broadly question-able as coal is the fuel that has the most unfavourable CO2 emission factor (CO2 emissions per kWh), it therefore has the worst ecological footprint. On the other hand, the price of coal is currently very attractive, with considerable reserves spread evenly around the world (some being located in Australia).

15Hydrogen, the production of which requires a great deal of energy, burns without producing CO2, but no combustion process is satisfactory nowadays. Liquid hydrocarbons, such as heavy fuel oil or other petroleum products, are expensive and their price is linked to fluctuating oil prices.

16The most environmentally-friendly hydrocarbon would be natural gas with the optimum CO2 emissions per kWh. Unfortunately, supplying New Caledonia with natural gas does not appear conceivable as the construction of a methane tanker terminal is hard to envisage, given that the lagoon is not deep enough for a standard sized methane tanker (of the order of 70,000 to 150,000 m3) with a draught of 10 metres. Furthermore, these types of methane tankers have capacities that would be too large for local use; it would ultimately be necessary for all industrial consumers to choose this same fuel and for a decision to be made to construct a gas pipeline between the various sites…

ENERGY EFFICIENCY STRENGTHS ON THE SLN SITE

17Energy efficiency on the site at Doniambo will be improved (an improvement of approximately 7 % in energy efficiency) thanks to the short term replacement of the heavy fuel thermal power station with three coalpowered circulating fluidised bed boiler units (FBC). The choice of this process appears judicious in an island environment like that of New Caledonia because, despite a slightly lower thermal output and a slightly higher acquisition cost than a pulverised coal-fired power station (PC), this type of technology is seen as optimal and more efficient when demand for output is low (three 70 MW generating units at Doniambo). Unfortunately, this boiler cannot operate with water under supercritical (Tc=376 °C and Pc=221 bars) or hypercritical (Tc=700-720 °C and Pc=350 bars) conditions. It is the output of this unit (which is too low) that is prejudicial to the use of this process, as there are not technically any steam turbines with an output of less than 400 MWelectricity capable of operating in conditions where both the temperature and pressure are high, despite the use of nickel-based refractory alloys.

18FBCs are flexible in terms of fuel (poly-fuel), which is a considerable benefit, with the use of various types of coal, biomass or purification plant sludge. Energy recovery from incineration waste in Greater Nouméa should provide power of approximately 7,700 MWh/year, i.e. 2,600 MWhelectricity/ year. An identical calculation could be made for recycling the 15,000 tonnes of green waste from Nouméa and its suburbs (approximately 52,000 MWhheat/ year, i.e. 17,000 MWhelectricity/year). All the same, this is negligible in relation to net electricity generation in New Caledonia.

19In other respects, emissions of pollutants (nitrogen and sulphur oxides) from the future FBC power station will be lower than from a coal-fired power station, which is not equipped with denitrification or desulphurisation units (the acquisition cost is prohibitive for low outputs). In effect, in a circulating fluidised bed power station, where the combustion temperature is between 850 and 920 °C, the production of nitrogen oxide is low because the chemical processes that create these oxides are only triggered at temperatures above 1,500 °C. As for sulphur oxide emissions, these are neutralised by the addition of crushed limestone, creating calcium sulphate. The resulting waste therefore meets current European environmental standards.

20The time needed to establish a new operating or accessibility set point for maintenance is longer than for a direct flow boiler (PC). While a gas or fuel oil boiler only needs a few minutes and a PC boiler around ten or so minutes, an FBC may require several hours or days because of the thermal inertia of the refractories used to build its walls. The flexibility of use and availability of facilities will therefore not be optimal.

21Technologies are currently being developed to connect two FBC units in order to capture CO2 emissions at a cost that is far lower than that of more traditional techniques. In effect, by creating a chemical cycle, which will use a metal to transport the oxygen, the CO2 will be naturally concentrated in the waste, which can be immediately sent to the storage site.

22The close proximity of the electricity generation plant to the principal user, i.e. the plant, will guarantee a secure and reliable supply of energy and, above all, a minimisation of conveyance losses.

23N.B. More detailed information on the operation and optimisation of processes appears in “New energy production and storage technology” and “Emissions and the reduction of greenhouse gas emissions in New Caledonia” on the subject of CO2 capture.

THE WEAKNESSES OF NEW CALEDONIAN INDUSTRY IN TERMS OF ENERGY EFFICIENCY

The plant at Doniambo

24The SLN plant currently consumes 40 % of its energy in the form of electricity, with the remaining 60 % coming from heavy fuel oil or coal combustion for processing ore. Increased energy efficiency should therefore apply to both the power station and the plant.

25Over the past ten years, a combination of high demand for nickel and reasonable energy costs has not encouraged SLN to change its practices and to seek new ways of saving energy in terms of its processes. A visit to the plant at Doniambo reveals that personnel are extremely capable and aware of energy and environment related issues. However, a number of “hot spots” were noted: Doniambo would suffer from an increase in production costs, which could be blamed on a decline in nickel levels, maintenance and personnel costs, governmental obligations, an increase in the price of fuel oil and sea freight, etc. In other words, an increase in energy efficiency at the plant is a possibility.

26The pyrometallurgical process comprises a number of clearly defined stages, which correspond to changes in the physical and chemical state of the ore when subjected to heating and cooling operations. It should certainly be possible to identify opportunities for recovering energy from transfers of heat between electric and rotary calcining furnaces and drying, even though steam is already exchanged between the power station and the furnaces.

27Furthermore, it appears that, when designing the system, adequate consideration was not given to a new plant/factory “connected system” type approach. This stage requires the process to be re-examined as a whole, beginning, if possible, with the end product - nickel. The ability of new technologies, new materials and new high-performance components to optimise the process and its management in order to increase energy efficiency should be evaluated at every stage. By improving energy efficiency, the cost of fossil fuels as well as emissions that are harmful to the environment and the health of personnel and neighbouring populations will be reduced.

The thermal power station at Prony

28One of the advantages of this power station, with its pulverised coalfired boiler, was its minimal cost compared to coal-fired power stations or FBCs. Unfortunately, this type of system has an extremely unfavourable ecological footprint, because of its emissions, which are caused by the use of lignite. The low output of generating units means that the addition of flue gas decontamination units is not profitable. As a result, it will be impossible to equip it with a CO2 capture unit without major modifications.

29In order to limit emissions of pollutants into the atmosphere, Enercal will supply the furnace with brown coal from Australia. The relatively low sulphur content of this low grade coal will limit sulphur emissions, but the CO2 emission factor of the power station will be even worse (the low NCV of lignite).

The Goro Nickel plant

30By using a hydrometallurgical procedure to process the ore, this plant requires less energy, as some of it is provided by the in situ production of sulphuric acid thanks to the highly exothermic reaction of sulphur. The fact that this is a modern plant gives rise to the belief that its energy efficiency was considered at the design stage. But beware of chemical pollution of the environment!

The future power station at Koniambo

31The design of this future coal-fired power station and the pyrometallurgical plant should incorporate experience gained from Doniambo in terms of the FBC boiler.

WHAT RESULTS SHOULD BE EXPECTED FROM IMPROVED ENERGY EFFICIENCY?

32And, first of all, a little advice in order to know where to focus our efforts:

Conducting scientific monitoring

33Scientific monitoring of processes enables the cost of energy and emissions of pollutants to be reduced.

Optimising processes

34By beginning with the product, nickel or the generation of electricity, the process is re-examined using an energy audit, conducted at every stage, in order to identify the optimum energy model and to make use of efficient equipment. Energy systems can also be incorporated and connected. There should also be efforts to use systemic IT approaches and powerful tools to implement, monitor, regulate and manage processes in an optimised manner. Finally, the outcome should be favourable financially and environmentally, thanks to the minimisation of emissions of pollutants; and not failing to take account of the impact of pollution on the health of workers and the general population.

Preparing for CO2 capture and storage

35This begins with the choice of a combustion process that can be tailored to CO2 capture and storage (setting aside space close to the power station) and, if possible, planning the simultaneous capture of CO2 coming from the pyrometallurgical plant and the circulating fluidised bed power station. This is also requires the examination and planning of a CO2 network within the island, for possible transportat to storage areas in peridotite rock or to a sea port, from which the CO2 is shipped to an off shore sequestration location or to another country (Australia, for example).

Recycling urban and agricultural waste heat

36It is possible to recover and recycle energy from flue gas, using heat pumps, to air-condition all industrial and tertiary buildings; it is also possible to envisage the creation of a network to transport and distribute refrigeration over small and medium distances (less than 10 km) in and around Nouméa (a valid proposal for new housing developments).

37Small and medium sized companies and industries could set up close to a plant and benefit from the available free heat (food freezing companies, for example, with the creation of agricultural and fisheries systems). It is also possible to envisage the establishment of first generation biofuel production plants, which need low temperature heat (below 100 °C) for their ethanol distillation processes or the transesterification of raw vegetable oils. In all cases, every effort should be made to seek markets for the deployment of these systems.

WHAT POSSIBLE ENCOURAGEMENT/INCENTIVES COULD THERE BE TO PROMOTE INNOVATION?

38Tax incentives from the government and/or the state may be envisaged to encourage research into new ways of making savings by incorporating innovations into processes. On the other hand, the application of penalties could force the leaders of industry to make energy savings, provided that these measures are additional ones in relation to their usual business. This type of policy should be accompanied by the development of technologyrelated higher education systems, in partnership with international research centres, and the creation of a network of research/design offices that are able to incorporate the results of research into the local economy.

CONCLUSION

39New Caledonia has a mono-industry (metal), which is a large consumer of energy and a major polluter. Its remoteness adversely affects the search for energy efficient industrial systems (the impossibility of importing natural gas, for example). On the other hand, the introduction of modern and efficient technologies, optimisation of a system and control and command based approach should allow substantial energy savings to be made in terms of the consumption of primary fossil fuel energy by local industries. In order to achieve this, there is a need to recycle lost heat and, to a lesser extent, to gradually make use of renewable energies and waste. Penalties applied at source could be imposed in the event of a failure to comply with regulations.

40Techniques are being developed for the capture and storage of CO2 by the power station at Doniambo (cf. “Undertakings and the reduction of greenhouse gas emissions in New Caledonia”), which, even though they are still at the research stage, should form the subject of immediate monitoring.

41The mining and metal industry has advantages and exhibits the conditions needed to achieve improved energy management and a reduction in CO2 emissions by means of capture. There is a need to ensure that these developments do not proceed to the detriment of the quality and price of end products, employment and the health of personnel and the general population.

42The leaders of industry must continue their efforts to control their own energy demands by increasing the energy efficiency of their processes, which will enable them to reduce their production costs and, ultimately, to create savings for their clients. Over the coming decade, they must make provision for a significant reduction in the quantities of carbon emitted, using CO2 capture, and pollutants in their waste.

Notes

1 In “New energy production and storage technologies”, we will be making a comparison of the various primary energy resources available, whether they are traditional, such as natural gas, gaseous or liquid hydrocarbons and coal, or alternatives, such as hydrogen, biomass, biogas or algae.

© IRD Éditions, 2010

Conditions d’utilisation : http://www.openedition.org/6540