Helen Mulligan

University of California, Berkeley

Institute of Urban and Regional Development, 316 Wurster Hall

Berkeley, California 94720-1870 USA

tel:+1 (510) 642 1628 e-mail: hmullig@berkeley. edu

The built environment has an essential role to play in the transition to a low — carbon future envisaged in the Kyoto Protocol: buildings account for one-third to half of all energy consumption in developed countries. As yet, however, market — based policy tools have had little bearing on the construction professions. This paper examines the relevant issues and suggests a role for market-based mechanisms in overcoming some deep-seated barriers to the uptake of energy — efficiency measures in buildings. Finally, it uses case study examples of low — energy building projects in California to illustrate the potential for innovative use of market-based mechanisms in this field.

Background

Successive reports of the Intergovernmental Panel on Climate Change (IPCC) have expressed the scientific consensus that increasing concentrations of greenhouse gases in the Earth’s atmosphere are likely to bring about changes in the global climate. The extent and nature of these changes is still unclear; however, there is international concern about potentially severe consequences. This has led to the pursuit of mitigating policies, in particular to those which will lead to downward pressure on the level of greenhouse gases. Per capita emission of greenhouse gases — the most important of which is carbon dioxide — varies greatly by country (fig. 1). This points up the potential for substantial impacts to be made by action on the part of countries in the developed world, and by international linkage.

Many of the developed countries, including member states of the European Union, are following the route of co-ordinated action under the Kyoto Protocol. Target for greenhouse gas emission under the Protocol, are accompanied by “flexible mechanisms” to increase the efficiency with which a global target could be met. These are:

• trading of permits, within and between developed countries

• Joint Implementation (JI): trading with transition economies, i. e. Eastern Europe and

the CIS

• Clean Development Mechanism (CDM): trading with developing countries.

The USA is currently pursuing policy options outside the Kyoto process. However, there is parallel interest in mechanisms similar to those described in the Protocol.

The overall goal for the operation of UESP systems is to ensure continuous power supply to the loads while minimizing the total operation cost, including fuel, maintenance and replacement. Therefore each component transmits periodically cost functions of its production (offer) or consumption (demand) (i. e. price per Wh). Optionally forecasts for the production from fluctuating sources will be generated. One major mechanism within the energy management system is a stock exchange model for economic optimization where from all these functions a market price is determined. The current price then leads to the actual share of power between components which is given back to them as set point.

Wind Generator Diesel Generator

Fig. 2: Extended UESP System with additional generators to supply increased energy demand

2. Main advantages of UESP and their technical background

• Flexibility and Extendibility

Plug-and-Play principle, adaptation to demand, no programming nor parameter set-up necessary, supports all kinds of (future-) components

• Reliability

Mount-and-Forget principle, detailed system’s health determination, remote monitoring capabilities

• Operation and Maintenance (Lifetime cost)

Least cost operation, fuel saving, extending lifetime, maintenance planning

• Investment Cost (Components and Installation)

Competitive to conventional systems

A particular example of the application of the technique is the provision of a uniformly illuminated receiver surface for a paraboloidal solar dish concentrator. In Fig. 3, successive surfaces of different illumination levels in front and behind the focal point may be produced according to the concentration factor desired. Fig. 4 shows a particular case in the range of 500 suns and the distribution of concentration over the receiver surface; variation from the mean is less than 1%. The variation can be even lower if the tolerance of the optimisation process is set lower.

where C-1eceiver is the radiation flux concentration factor and Eleceiver the density of radiation °ver A^r.

Fig. 5 shows three possible receiver surfaces, a hemispherical surface, a paraboloidal surface and a surface in between these two extremes. For the paraboloidal receiver the relation of dDish and dRecever in Eq. 2 is constant for all a.

But since the area AR, eceiver is not tangential to the paraboloidal this equation does not describe the radiation flux concentration on the paraboloidal receiver. Therefore the illumination on a paraboloidal receiver is not constant. If /3(a) is defined as the angle between the normal at a specific point on the dish given by a and the normal of Aoish, Y(a) is the angle between the normal on the receiver and the normal of AR, eceiver. Therefore the concentration on the receiver is:

d 2

CRecever (a) = cos(Y(a)) (Eq. 3)

Receiver

It can be seen that d1D)ih /dReceiver = const. for a paraboloid while cos(/(a)) is decreasing for the outer regions, while cos(/(a)) = const. for a hemisphere while d2sh /dReceiver is increasing for the outer regions. The desired surface must be therefore somewhere between a paraboloid and a hemisphere, which is the third surface in Fig. 3. In a future paper, we will show how Eq. 3 can be used to derive the function of the surface for even illumination by solving a corresponding differential equation.

Menno Veefkind, Delft University of Technology, Faculty of Industrial Design Engineering, Landbergstraat 15, 2628CE, Delft, phone: +31 15 2783772, fax: +31 15 2781839 Bas Flipsen, Delft University of Technology, Faculty of Industrial Design Engineering Herman Broekhuizen, Delft University of Technology, Faculty of Industrial Design Engineering

In order to increase the diffusion of PV-technology in portable consumer products figures on the amount of energy that can be harvested during the use of such products is needed. This paper presents two experiments that are carried out in order to gain data on the energy that can be harvested by the application of PV-cells on portable products. Although the experiments are not sufficiently extensive for the deduction of clear figures, their results are presented as a first exploration in this field. The discussion is based on a comparison of both experiments and focuses on the equipment that was used and the samples taken.

Introduction

A special group within consumer electronics can be characterised as "personal products," portable products that offer the user a "nomadic lifestyle" due to the absence of data — or power cords. Examples that illustrate the advance of these personal products are the Walkman, the laptop computer and the mobile telephone. When "powered as usual” these products include primary — or rechargeable batteries, which are a source of discomfort due to their weight, necessary replacement or need for recharge. Moreover, from an economic as well as from an environmental point of view, batteries are a costly energy source. The PES (Personal Energy Systems) group does research on the application of alternative energy sources for personal products. At the moment of writing the energy sources under investigation are PV-power, human power and fuel cells. The PES group itself is part of the faculty of Industrial Design Engineering, which mission statement is "Products for people.”

When industrial designers think of alternative energy sources for portable products, they often bring up PV-power as one of the options. The optimism, with which industrial designers approach the use of PV-technology in consumer products, in the first place, often turns into scepticism when the energy that can be harvested under "real" operating conditions is determined. For this reason the expectations for the use of PV-technology as the power source for consumer products seem to have tempered the last years. A framework that provides a rational view on the use of PV-technology in consumer products is needed in order to come out of this impasse. An important part of such a framework is the assessment of product ideas that include a PV energy source in an early stage of product development. A fundamental part of this assessment is the simulation of the product’s energy balance. An earlier study that was presented at the ISES 2003 conference (Veefkind, 2003) shows that the simulation of the energy balance of portable consumer products is difficult, due to the inexistence of data on the amount of energy that can be harvested on portable consumer products.

Method

From a methodological point of view sizing solar power systems for consumer products is not different from sizing any other solar power system. Sizing procedures based on the energy balance of the whole system, such as described in "Solar electricity” (Markvart,
2000) are in theory equally applicable for consumer products. In practice differences occur in the input to the sizing procedure. This is due to the fact that sizing procedures are designed for stationary stand-alone systems to be used outdoors. Typical input parameters that are used in order to determine the available solar irradiation for such systems are meteorological data and the inclination of the solar module. Consumer products will often be used in more complicated environments, for example because they are placed behind a window. Iowa Thin Film (Iowa Thin Film) provides figures for the irradiance in different situations as a percentage of the full sun. Those figures can be used as input for a sizing procedure for stationary consumer products. However, there is no figure available for the irradiance that will be caught by a portable product that is going to be carried around.

If it comes to information on the energy that can be harvested by portable products, three levels can be distinguished: PV-module level, PV-system level and product level (see figure 1). On each level data on the performance of the product exist, as well as data on the conditions that enables this performance. Data gathering on the first two levels takes place under laboratory conditions. Data gathering on product level takes place in the field and includes many variables, amongst others the influence of human behaviour.

This study focuses on the performance of PV-cells on portable products on product level. Over the past few years different experiments in this field have been carried out at the Faculty of Industrial Design Engineering. These experiments have been carried out independently, and therefore differ in terms of the equipment used, the parameters that were under investigation and the conditions under which the experiments have been carried out. None of the experiments is carried out sufficiently extensive to allow the deduction of clear figures for the energy that can be harvested on portable products. In this exploratory study two different experiments are compared. This leads to a discussion concerning the gathering of data on the performance of PV-powered products on product level.

There is a wide range of plant biomass derived energy products, many of which could be exported from Russia to the EU, see figure 1 and table 1. The problem of their production has been in general solved, and different manufacturing methods have been developed, some of them being currently commercialised. Certainly, existing technologies are far from perfection and there is still much to be done to find more efficient technical solutions. However it is not the matter of prime importance, as far as the subject discussed in this paper concerned. The key point and the main barrier on the way of Russian energy bio­products to the EU consumers are evidently high costs of long-distance transportation. Therefore the main principle should be the choice of the products which have undergone deepest possible refining and which can be transported in cheapest and easiest way. Electric power produced from biofuels, best of all, responds to these requirements and is obviously the most preferable product from plant biomass for export to the EU. Electric power transmission and distribution techniques have long-term common traditions world­wide, though electric parameters standards, such as for mains frequency and voltage differ from those in Russia. Dedicated power transmission systems in compliance with EU electric power standards should be constructed. Since there is no methods for distinguishing "green” electricity produced on the basis of renewable biomass from "polluted” one that has been generated from fossil fuels, permanent inspection of bio­power suppliers will be necessary.

Gaseous biofuels such as pyrolysis gas have chemical composition more or less close to those of natural gas because their main combustible constituent is methane. Relatively high content of carbon oxides make their calorific value, lower compared with natural gas.

Pyrolysis gas can be either used locally for heat and power generation or exported using existing or dedicated pipelines (including blends with natural gas). Bio-gas has still lower calorific value and contains corrosive substances such as sulphur and nitrogen oxides. Existing Figure 1 Energy products from plant biomass.

transcontinental pipelines

made mainly of mild steel are therefore inapplicable for transportation of bio-gas. Synthesis-gas is an advanced refinery product obtained by catalysis of hydrocarbons or carbohydrates at high temperatures in presence of water vapours to achieve high contents of methane or/and hydrogen, which is extremely explosive. For above reasons, bio-gas and synthesis-gas are not recommended for long-distance transportation and have to be used locally for heat and power generation.

Liquid biofuels have essentially different physicochemical properties and their optimal transportation methods should differ, as well. Light bio-fuels (ethanol, MTBE, etc.) have the same properties as those manufactured from a hydrocarbon feedstock and can be blended into gasoline. All conventional methods of transportation can be applied to these products. Bio-diesel is a product of catalysis of fatty acids present in some plants (sunflower, soybeans, rape seed, peanut, etc.) that can be used in the form of blends with conventional diesel fuels. Traditional petroleum products transportation practice (pipelines, see or railway transport) can be applied.

Pyrolysis oils (bio-oils) are relatively new fuels manufactured by fast thermochemical treatment of plant biomass at medium temperatures. Since these products are corrosive substances, their transportation by existing mild steel pipelines is problematic. Blending with petroleum products is also a serious technical problem because of bio-oil’s hydrophilic nature, while petroleum derived liquids are hydrophobic. Till this problem is not efficiently solved, local combustion for heat and power generation seems the best way to use bio-oils today.

Solid energy bio-products. Wood pellets is one of the simplest bio-products manufactured from wastes of timber-cutting and woodworking industry. They have substantial advantages over conventional firewood (particularly, higher specific heat of combustion). Standardised performance properties such as moisture content, density and size makes the firing process controllable and therefore efficient. Wood pellets can be also a feedstock for further conversion aimed at manufacturing products briefly discussed above. Though the cost of pellets produced in Russia would be obviously much lower than in any of EU countries, it is still unclear whether their total price for the EU, of which essential part is transportation costs, complies with merchantability requirements. Profitability of their long­distance transportation is more dependent on the price of a raw-stock and energy
efficiency of the preparation technology, particularly moisture extraction operation, than that of advanced refinery products.

Charcoal has the highest calorific value of all bio-fuels. It is produced during thermochemical conversion of a plant biomass in quantities from 10% to 35%, depending on heating rate, final temperature and duration of the process. Unlike anthracites and other fossil coals used in metallurgy, charcoal does not practically contain sulphur and is therefore an effective reducing agent that can be applied for production high-grade steel and other metals. Its extraordinary high absorption capacity has been long employed in chemistry and medicine. Non-energy applications of this bio-product make its market price much higher than just a fuel and may raise the profitability of the entire production cycle of fuels from plant biomass.

Heat and hot water are normally not intended for long-distance transportation. They have to be used at a site or relatively close to it for domestic, municipal or industrial purposes thus reducing the overall cost of produced biofuels and their transportation.

The construction of a large hydroelectric plant at an extremely favourable location in the Democratic Republic of Congo near Inga was also investigated for one proposed scenario (s. also [Kan 99]) The construction of a hydropower plant with a capacity of 38 GW was the decision resulting from computational optimisation. This would lower the costs of electricity by 5.3% compared to the base-case scenario due to more economic generation and incidental system benefits. A primary reason for the low costs of the electricity produced at Inga is the high average load of the hydropower plant of about 6900 FLH and the relatively low anticipated investment costs at this very advantageous site. Two-thirds of the electricity produced at Inga is transmitted over a HvDc system with 26GW capacity, connecting the generating station with Region 17, with the remainder conducted in equal amounts over two HVDC systems with a combined capacity of 12 GW, joining Inga with Regions 16 and 18.

• 6.5 Electricity Transmission within the Scenarios

In all scenarios — with the exception of restrictive and expensive insular configurations — electricity transmission is of significant importance. The necessary conversion capacity for the HVDC grid exceeds values of over 750 GW in some cases. (This level corresponds to about one-half of the installed generation capacity of all production facilities in the scenario regions.) The grid is used to achieve smoothing effects among different resource — dependent generation capacities using renewable energies, and to provide access to hydroelectric plants and to distributed biomass power plants with associated storage media for wide-area backup applications. In the base case scenario, for instance, about 42% of the electricity generated is transmitted over the HVDC system between the regions within the supply area. Measured against the total electricity costs the cost of the transmission system amounts to 7% of which the main part of 5% is contributed by the transmission lines and cables. HVDC transmission has a higher intrinsic system stability than AC lines. Furthermore the transmission system of the base case scenario is highly redundant due to the fact that the thermal limit of the transmission lines is about twice the
rated power and due to the fact that between almost al regions two or more systems are designed to be built parallel. But nevertheless if further redundancy was seen as desirable this could be relatively inexpensively achieved. A somewhat extreme idea would be to erect two whole systems of transmission lines in parallel. This would mean that the costs of transmission lines and cables would double but at the same time the losses would decrease and thus the overall cost increase would only be about 3% ensuring a degree of immunity against faults, which is by far higher than stipulated for today’s systems.

• 7 Conclusions Drawn from the Scenarios

The fundamental technical prerequisites for an electricity system realized entirely with renewable energies have already been fulfilled. Even at today’s prices, the price of electricity need not to be higher than from a newly erected combined-cycle gas power plant when all costs are included. The annual difference in cost compared with the current national bill for electricity, which accounts for roughly 2.2% of gross national product, would impose less than a 3%o additional burden e. g. in the case of Germany, thereby constituting a highly rational alternative to the predictable consequences of climate change and declining fossil fuel resources. Foreseeable cost reductions — particularly for renewable energy technologies — make a comprehensive renewable energy system both conceivable and potentially more economical than all current means of providing electrical energy. The problem of converting our electricity system to one that is both globally competitive and environmentally benign is therefore hardly a financial or technical issue, being instead almost entirely dependent on political attitudes and governmental priorities. Responsible political decisions are now imperative for allocating the necessary technical, scientific and economic resources to achieve this goal.

New principles of building integration will be demonstrated. The demonstration projects are varied, as some promote PV placing them on the facades in highly visible ways, while others try to blend the modules with the decor making them almost invisible. There is also the use of double functions of the PV modules, which makes the PV installation add more value to the building.

New and so far untried financing schemes are evaluated, balancing financial risk with long­term investment payoff and partnerships
between the real-estate owner, the tenants and the local utility company.

Several of the buildings hold high

environmental profiles in general, e. g. through low energy designs. To give an example, in building Holmen/Grynnan the total energy consumption per sqm residential floor area and year has been limited to 60 kWh (40 kWh heat and 20 kWh electricity). It is half the consumption compared to the best-applied technology in contemporary building designs.

Eight high-profile building projects in the Nordic countries and in the Netherlands are participating in PV-NORD:

3.2

Holmen/Grynnan, Sweden 40 kWp will be installed on two multi-family houses, located in a new residential area in the southern part of the city centre of Stockholm. PV modules will be integrated in the fagade, in the balcony balustrades and as part of windows of the top floor. The innovative challenge is to find solutions where the PV modules will harmonise with the building design and if possible also serve with a double function as in the case of the balconies and the windows. A construction company develops the building, and the apartments are sold to the tenants.

The RE market is still nascent and needs to be proactively developed if the huge potential it offers is to be realised. The barriers to RE have been discussed in detail in RE literature. In the initial stages of development, technical barriers predominate. In order for a technology to become cost-effective, market barriers such as inconsistent pricing structures typically have to be overcome. Then there are institutional, political and legislative barriers, which hinder the market penetration of technologies. These tend to arise from a lack of awareness of, and experience with, new technologies, and the absence of a suitable institutional and regulatory structure. Finally, there are social and environmental barriers, which result mainly from a lack of experience with planning regulations that hinder the public acceptance of a technology. A sound strategy to increase market penetration of renewables will need to address all these barriers.

However, the biggest barrier to greater renewable energy use is cost, despite the reductions achieved over recent years. Other obstacles, particularly for the increased use of renewable electricity, include subsidies and other support mechanisms for competing conventional fuels (especially coal and nuclear power). Lack of full cost pricing when determining the cost of competing energy supplies also hinders the development of renewable energy since the cost of environmental impacts are usually not included in energy prices. High discount rates and competition on short-term electricity prices, as seen in electricity markets undergoing a change in regulatory framework, may disadvantage projects with high capital costs but low running costs, such as renewable electricity systems — unless governments set up schemes designed to replace estimated deficiencies in the market place. The high cost of renewables and perceptions about the technology make it difficult for RETs to access finance. As a result, financial barriers

appear to be most prominent for developing renewables. Several financial support programs have been taken up by international agencies and public as well as private funds have been created to provide access to finance (Wohlgemuth and Painuly, 1999).

1.2 Single cell geometry

Passive cooling is found to work well for single-cell geometries, even for flux levels as high as 1000 suns, because of the large area available for heat sinking. Edenburn [5] found a heat sink with longitudinal fins to be a cost-effective cooling arrangement for concentration levels up to 170 suns. He also suggested using a finless housing box as a heat sink for concentration levels below 90 suns, although this would result in very high cell temperatures on extreme days, and a defocusing mechanism might be necessary for "worst-case scenarios". Minano [6] found the cell size to be the determining factor when designing passively cooled single-cell concentrators. His model suggests that a concentration of 1000 suns would be possible for cells of less than 5 mm diameter. Heat sinks for these cells would be similar to those used for power semiconductor devices. Outdoor experiments by Araki et al. [7] on an array of Fresnel lenses which focus the light onto single cells mounted on a heat-spreading aluminum plate show a temperature rise of
cells over ambient of only 18°C, without conventional heat sinks, for a concentration level of about 500 suns. Good thermal contact between the cell and the heat spreading plate is shown to be crucial to keep the cell temperature low. A single cell lens array which employs a heat sink with longitudinal fins is patented by Graven et al. [8].

Edenburn [5] also considered using active cooling on his point focus arrays, but found that the parasitic power losses involved in pumping and in dissipating the waste heat make active cooling more expensive than passive cooling for single cells. The only exemption would be for very large lenses (more than 300 mm in diameter). However, to enable a cost comparison between the different cooling regimes, the possible advantage of using the extracted heat for thermal energy supply purposes is not taken into consideration. Edenburn concludes that if this were done, active cooling would be the most cost-efficient solution.

Strebkov D. S., Zadde V. V., Kharchenko V. V.

The All-Russia Institute of the Electrification of an Agriculture.

Silicon, obtained as raw material is a subject to the subsequent processing by directional crystallization, by Cz-growth or casting method. These processes require significient energy expenses. Earlier [1,2] the opportunity of obtaining of silicon ingots in solar furnace with the structure and crystal perfection suitable for manufacturing solar cells with 10% efficiency was shown.

Parameters of obtained silicon.

Ingots of silicon in diameter of 40-50 mm were fabricated in focus of the solar furnace by a method of a floating zone without the special reactionary chamber directly in open air. Energy necessary for fusion of initial silicon energy was applied to a melted zone, formed on a butt — end face of seed rod in the form of the concentrated sunlight.

Ingots of silicon with SOG-Si parameters were obtained. They had a columnar structure with big graines extended along the growth axis and high values of diffusion length of minor carriers. In some cases up to 70 % of the brought up ingots had monocrystalline area. In monocrystal sites of ingots the density of the dislocations determined with etching pit technic use, made value from 10 up to 105cm-2 . The contents of oxygen determined by IR-absorption method despite of constant contact of a melting-pot bath of melt with atmospheric air, did not exceed value of 2.10 16 cm-3. Contents of impurities in the made samples of n and p-type correlated with their contents in initial raw material, however always had lower values.

And this fact concerned not only to the impurity having low segregation factor, but also to impurities which at solidification could be removed with difficulties (phosphorus), or practically could not be removed at all (boron).

In [3] it is shown, that at growing of silicon by the mentioned above method so intensive purification processes take place, that, in opinion of authors, the opportunity of SOG-Si production from metallurgical silicon as initial raw material becomes realistic.