We study the specific energy consumption for the production of nitrogen fertilizers and the various options that are available to reduce this consumption. The average energy consumption for ammonia production (by means of steam reforming of natural gas) in 1988 was 33.5 GJ/ton (LHV). The technical energy savings potential for the year 2000 is 16% [the specific energy consumption thus falls to 28.0 GJ/ton (LHV)]. The profitable energy savings potential is a potential saving of 6% with a payback period of less than three years. The thermodynamic minimum energy consumption using the steam reforming route is 19.1 GJ/ton (LHV). We calculate the effect that savings in ammonia production will have on the energy required for the production of several types of N-fertilizers (urea, nitric acid, ammonium nitrate, and CAN).@en

An accurate and fast method is presented for calculating the energy requirement of consumption items. The method combines process analysis and input-output analysis. The energy requirement of a particular consumption item is calculated in ten steps, each dealing with certain parts of the production network. Each step can be standardized to a large extent. The method is illustrated by applying it to one product: a domestic refrigerator.@en

The gross energy requirement (GER) for the major petrochemical products (ethylene, propylene, butadiene and benzene) and the major bulk polymers (low density polyethylene, polypropylene, polystyrene and polyvinylchloride) is determined. The GER-values for LDPE, PP, PS and PVC are 69.8, 61.6, 81.5 and 55.7 GJ/ton, respectively. The potential energy saving in the process chain for each product is assessed on the basis of commercially available technologies. The profitable potential, savings (i.e. with a payback period shorter than 3 yr) is about 8% of the GER-figure. The technical potential for savings varies from 12% for ethylene to 25% for PVC. In addition, the potential savings are investigated for the industrial sectors involved, namely oil refining (15% of total primary energy demand), inorganic chemicals (6%) and petrochemicals (9%).@en

The economic potential of industrial combined generation of heat and power (CHP) in The Netherlands and the associated reduction in CO2 emissions are estimated. A computer model is used in which a simulation and an economic optimization of possible CHP plants are carried out individually for each of the 300 largest energy-consuming industrial plants in The Netherlands. Starting from the present steam consumption, the economic potential is calculated to be about 2200 MW, using a discount rate of 5% and a depreciation time of 25 years. The reduced CO2 emissions would be equivalent to about 4% of the present CO2 emissions in The Netherlands. An expected increase in gas turbine efficiencies of 5% could increase the potential by more than 50%. The CHP potential which might be realized by industry autonomously is likely to be less than 400 MW. With an investment grant from the government of 40%, this capacity can, at best, be doubled. Putting a tax of Dfl 100 per tonne on the emission of CO2 will probably be more effective. In order to realize a large part of the CHP potential, stricter policy measures might be necessary. One measure could be legislation forbidding the use of large-scale steam generation in conventional boilers. Another option is for the utilities to invest in and operate CHP plants by themselves on the understanding that 1 tonne of CO2 avoided may cost 100 Dfl. The latter option is implemented at present.@en

Industrial energy consumption in the European Union has been studied, the focus being on specific energy consumption of various industrial sectors. An analysis is made of the main structural factors (e.g., primary or secondary production, product types) that affect energy efficiency. The industrial sub-sectors and production processes considered are those that are most important from an energy point of view, namely, oil refining, petrochemicals, ammonia, paper, cement, and steel production. These sectors consume 18% of the primary energy in the EU. There are considerable differences between the energy efficiencies of industries in EU member states. If each sector were to apply "best practice technology", then potential improvements in energy efficiency in the EU would be on average 15 ± 4% for oil refining, 21 ± 2% for ammonia, 25 ± 5% for paper, 13 ± 1% for cement, and 27 ± 3% for steel. No analysis can be made of possible improvements in the energy efficiency in the petrochemical industry because insufficient statistics are available. An improvement in the quality of international statistics is necessary to produce more reliable assessments.@en

One way to reduce carbon dioxide (CO2) emissions to the atmosphere is to recover it from an energy conversion process (e.g. from stack gases) and to store it in an aquifer (a permeable, mainly sandy, underground layer). The main goal of this study was a preliminary evaluation of this kind of storage. Allowing for a large uncertainty in the geological properties, we arrived at the following tentative results. The average cost of disposal is $1.4 per ton CO2 stored. The enclosing layer of most aquifers seems impermeable enough to prevent the CO2 from rising to the surface within at least 10 000 years. The main technical uncertainty is whether the water in the reservoir can be pushed aside fast enough to prevent an intolerable pressure build-up in the reservoir. The disposal of CO2 in aquifers seems to be a feasible option in the light of existing geological knowledge. If it is a practical possibility, the opportunities are large and the costs appear to be relatively low. However, uncertainties remain in the technical sphere. These uncertainties have to be studied and dispelled before the disposal of CO2 in aquifers can be said to be called technically feasible.@en

The development of industrial combined heat and power (CHP) in the Netherlands in the period 1968-1988 is studied in order to explore the factors that influenced this development, and particularly the effect of government measures designed to stimulate CHP. Between 1968 and 1988 1200 MW of CHP capacity was installed, mainly on the basis of gas turbines. Up to 1978 there was hardly any government policy directed towards the stimulation of industrial CHP. From 1978 onwards a number of stimulating measures have been introduced. From an analysis of the effects of government incentives on payback times we can conclude that some of the measures, among them the investment grants, had a considerable effect on the profitability of CHP investment.@en

The potential for improving energy efficiency in the Netherlands up to the year 2000 is discussed with the help of a database containing 300 energy conservation techniques. Investigations show that technically it is feasible to reduce emissions by 41% by applying all the energy conservation techniques. The policy of the Dutch government is directed to increase energy efficiency between 1990 and 2000 by about 20%. From our study we conclude that this figure is feasible and can be reached by applying energy conservation techniques with net negative CO2 emission reduction costs. However, we also conclude that stronger incentives for energy conservation are probably required than applied at present.@en

On the basis of information that can be extracted from existing databases, combined with information from literature and interviews, a database called BIN has been constructed containing data about the consumption of fuel, steam and electricity by approximately the 300 largest energy-consuming industrial plants in The Netherlands. Comparison with national statistics shows that the industrial plants incorporated in the database are responsible for 80% of the total industrial demand on primary energy carriers (excluding their use as feedstock). Thirteen industrial plants already cover 50% of this demand. The paper and board industry, the refineries, the chemical industry, and the basic metal industry are almost consumption over size classes has been derived. This article also gives the temperature distribution of the industrial steam consumption in The Netherlands. Of the 64 million tonnes of steam produced in boilers in the industrial plants included in the database the weighted average enthalpy is 3.17 MJ/kg and the average exergy is 1.29 MJ/kg, both with liquid water of 10°C as the reference. The plant-specific data included in the database can be used for research into industrial energy conservation measures, e.g. the combined generation of heat and power (CHP).@en

The feasibility of polymer membranes for the recovery of CO2 from flue gases of a power plant is examined. With a computer program based on the cross flow permeation model for membranes, several parameters are optimized to obtain the lowest specific CO2 mitigation costs. With gas separation membranes commercially available, the minimum attainable specific mitigation costs are calculated to be US$48 per tonne of CO2 avoided (at 50% CO2 purity, 75% CO2 recovery). When restrictions are posed to the purity of CO2 (95%) and the degree of CO2 recovery (90%), this figure is much higher: US$71 per tonne of CO2 avoided. Cost reduction possibilities and perspectives are discussed. Our analyses shows that membranes with a selectivity of at least 200 are required to make membranes a serious competitor of other separation techniques.@en

Gas turbine based combined heat and power generation (cogeneration) has developed strongly in the Netherlands in the past twenty years and has the potential to do so also in the future. In this paper the effect of government incentives, both in the past and in the future, is explored. In the years 1968 through 1988 1200 MW of industrial cogeneration capacity was installed, based primarily on gas turbines technology. This brought total cogeneration capacity to 1800 MW. The amount of electricity generated by private companies tripled in the period 1968 through 1988. In 1988 industrial power generation supplied 37 MJe, which is equal to nearly 15% of the total amount of electricity consumed in the Netherlands. In the period up to 1978 there was hardly any governmental policy directed towards stimulation of industrial cogeneration. From 1978 onwards a number of stimulating measures have been brought into operation. From an analysis of implementation and effects of government incentives we conclude that the investment grants provided by the government had a considerable effect on the profitability of cogeneration investments. To a lesser extent this was also valid for relatively cheap standby power contracts that were provided by the utilities. However, stimulation of cogeneration only occurred as far as it concerned electricity production for owner consumption. The production of electricity which had to be sold to the utility grid has never been profitable enough from the industrial viewpoint, notwithstanding the provided incentives, like improved buy-back tariffs. The future potential of industrial cogeneration has been calculated using a computer model in which a simulation and economic optimization is carried out individually for each of the 300 largest industrial plants in the Netherlands. Using this computer model it can be calculated that in principle the cogeneration capacity in the Netherlands can still be doubled. The cogeneration capacity that can be expected to be realized without any government incentive is estimated to be less than 400 MW. The application of investment grants up to 40% can at best double this figure. Carbon taxes of up to $150 per tonne C are somewhat more effective. In order to realize a large part of the ultimate potential stronger policy measures are necessary, which could be regulation which forbids the use of large-scale steam raising in conventional boilers. Without the application of such physical regulation not much may be expected of private industrial investments in cogeneration. However, utility initiatives presented recently hold the promise of realizing a large part of the potential of industrial cogeneration in the Netherlands.@en

A new scheme is described for electricity production based on coal gasificiation with recovery of CO2. Coal is gasified into a synthesis gas, mainly consisting of hydrogen and carbon monoxide. After clean-up, this synthesis gas is separated by a membrane into a carbon-rich gas and a hydrogen-rich gas. The hydrogen-rich gas is fed to a conventional gas turbine. The carbon-rich gas is fed to another gas turbine, where it is fired in a mixture of oxygen and CO2. The exhaust of the latter is almost pure CO2 and can be stored outside the atmosphere. The CO2 emissions of this plant are about 10% of the emissions of an IGCC plant without CO2 recovery, and the conversion efficiency is approx. 6% lower. A first estimate is that the electricity production costs are about one third higher. It is found that the specific emission reduction costs can be limited to about $16 per tonne of CO2 avoided. The main technical problem of this new scheme is the development of a new type of gas turbine with CO2 as working fluid.@en

A broad range of measures can be applied to reduce the net carbon dioxide emissions to the atmosphere and hence diminish the expected increase of the greenhouse effect. The method discussed here concerns the recovery of carbon dioxide from gases with a high carbon content. After recovery, the carbon dioxide is disposed of in exhausted natural gas (NG) fields. In an integrated-gasifier, combined-cycle (IGCC) power plant, coal is converted to an intermediate synthesis gas. The carbon can be recovered from this synthesis gas in three steps: 1. (i) conversion of the carbon monoxide to carbon dioxide, 2. (ii) extraction of the carbon dioxide by a physical absorption process and 3. (iii) compression and drying of the carbon dioxide. The method reduces the emission of carbon dioxide by about 88%. Application of this process might decrease the net energy-conversion efficiency from 43.6% in the original IGCC base configuration to 38.1% in the low-carbon-dioxide-emission integrated-gasifier, combined-cycle (LCE-IGCC) plant. Assuming a fuel price of 4 Dutch guilders (Dfl)/gigajoule (GJ) for coal, the recovery of the carbon dioxide costs 25 Dfl/metric tonne (t) of carbon dioxide avoided, while electricity-production costs increase from 7.0 to 8.7 Dutch cents (Dct)/kWeh for the disposal of carbon dioxide. Storage in exhausted NG fields is a suitable option in The Netherlands. Upon exhaustion, the Dutch gas fields could store 40 times the total current Dutch annual carbon dioxide production. This disposal is likely to cost about 3.5 Dfl/t CO2, which increases the electricity-production costs by 0.3 Dct/kWeh. It is estimated that the removal of about 88% of the carbon dioxide from an IGCC power plant will cost 28.5 Dfl/t carbon dioxide avoided and lead to an increase of <30% in the electricity-production costs.@en

A simple approximation model is proposed to estimate the output power of a PV (photovoltaic) module coupled directly to a battery, given the array plane irradiation and the battery voltage. Calculations were performed on a PV streetlight system in the Netherlands; the PV modules of the system were made up of 40 cells. The average overestimation of the array output for the investigated periods is 6%, due to systematic errors at irradiation levels below 300 W/m² and at high module temperatures. Comparisons are made to a more elaborate calculation method based on a one-diode model for a PV module. The latter model gave a better accuracy of 2%. However, when pyranometer irradiation data were used instead of reference cell data, an overestimation of up to 10% for both models was found. It is therefore concluded that the error introduced by the approximation model may be acceptable in comparison with the uncertainty introduced by using pyranometer data.

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The restructuring of the Netherlands power supply has resulted in break up into a production and a distribution sector. There has also been an amendment of the term "east saving" on which the distributor's back supply compensation is based: three tariffs are now announced, with confusing effect. This paper gives a new proposal for the compensation, based on the actual nett cost saving. This provides 8.4 cent/kWh compensation in the daylight hours in the months November to February, and 4.2 cent/kWh in the daylight hours of the remaining months. (R.H.)@en

As part of an overall analysis of future energy use and supply in the Netherlands, work has been carried out on the possible shape of the future public load pattern. To this end a study has been performed concerning the time dependence of the electricity demand of fifty user types. These demand patterns have been summed up to get a total demand which compared satisfactorily with the realized pattern for the year 1980. In order to construct a demand pattern for the year 2010, the demand patterns were summed up, taking into account a demand pattern with increased differences between high and low demand. However, this change has only a small effect on the performance of a diversified electricity production park.@en

A model for the simulation of autonomous energy systems using wind and solar power with Diesel back up is described. The model, known as SOMES, uses a statistical approach for the evaluation of wind energy fluctuations. The application of SOMES to an operating wind/Diesel system gave satisfactory results.@en

In electricity systems in which wind generators and photovoltaic cells play a large part in the production of electricity, a major problem is the matching of production and demand. This problem can be solved by means of storage facilities together with back-up generating capacity. To analyse the value of short-term as well as long-term storage facilities, a computer model has been developed which can simulate electricity systems that are fed largely by renewable energy sources. A brief description of the model is given. With this model calculations have been made for a possible situation where electricity in the Netherlands is supplied mainly by wind generators and PV cells, whereas and combined cycle units and gas turbines are used as back-up power.@en

In the analysis of industrial energy use, detailed information on the time patterns and simultaneity of demand for energy carriers provides a basis for studying various possibilities of improving the structure of industrial energy use. This article describes the results of an investigation of the energy use patterns in six branches of industry: paper and board, meat products, dairy products, beet sugar, starch and starch derivatives, beer and malt. The results have been used to estimate the potential for cogeneration of heat and electric power in these industry branches.@en

Potential of wind energy as a source of energy is considered. The main limitations to wind energy use in power supply are location, storage and raw materials requirements for the wind turbines. Environment factors complicate location, but photovoltaic excitation and energy storage in hydrogen form will improve matters considerably. The wind turbine manufacturing industry is however still in its infancy, which radically impairs the macro-economic aspect of the technology. (R.H.)@en