M URD OCH RESEARCH REPOSI TORY This is the author’s final version of the work, as accepted for publication following peer review but without the publisher’s layout or pagination. The definitive version is available at : http://dx.doi.org/10.1016/j.renene.2015.01.052 McHenry, M.P. and Doepel, D. (2015) The ‘low power’ revolution: Rural offgrid consumer technologies and portable micropower systems in nonindustrialised regions. Renewable Energy, 78 . pp. 679-684. http://researchrepository.murdoch.edu.a/25408/ Copy r ight : © 2015 Elsevier Lt d. I t is post ed here for your personal use. No fur t her dist ribution is per m it t ed. 1 Title: The ‘low power’ revolution: rural off-grid consumer technologies and portable 2 micropower systems in non-industrialised regions. 3 4 Authors: Mark. P. McHenrya*, David Doepelb. 5 6 Affiliations: aSchool of Engineering and Information Technology, Murdoch University, 7 Western Australia. bThe African Technology Policy Studies Network (ATPS) Chapter in 8 Australia, Murdoch University, Western Australia. 9 10 *Corresponding author details: mpmchenry@gmail.com, +61 (0) 430485306. 11 12 ABSTRACT 13 This review analyses the growth in small ‘low power’ renewable energy and consumer 14 product technologies and their potential utility in rural and remote economic development. 15 The historical legacy of increasingly industrial-scale and expensive centralised high voltage 16 alternating current (AC) systems contrasts starkly against the dynamic plethora of energy 17 efficient portable low power direct current (DC) devices and consumer goods that underpin a 18 modern economy. Advantages of portable DC devices are their inherent utility as a deferrable 19 load and imbedded storage, enabling the appliance to become the balance of system (BOS) 20 component and the power management system when coupled to portable renewable energy 21 system or a microgrid. These developments present the opportunity to revise broad 22 assumptions of appropriate energy system investment models for non-industrialised nations 23 without an expensive historical centralised high voltage AC industrialisation legacy. It also 24 presents the opportunity to revisit appropriate rural clean energy stand-alone or microgrid 25 system designs and configurations, and engage the information and communication 26 technology (ICT) sector as a major new investor in energy services and infrastructure. 27 28 Keywords: renewable energy; stand-alone; DC; low voltage; rural; economic development. 29 30 1. Introduction 31 Today billions of portable information and communication technology (ICT) devices, 32 including smartphones, tablets, lights, MP3 players, electric gardening equipment, PCs and 33 many accessories with rechargeable batteries are now in circulation worldwide, and are 34 increasingly associated with user energy autonomy and energy efficiency (Schuss and 35 Rahkonen 2012; Didier, Toshimitsu et al. 2013; Ruutu, Nurminen et al. 2013; Willems, Aerts 36 et al. 2013). This includes the most non-industrialised regions of the world. For example, 37 when around 63% of people in sub-Saharan Africa have access to improved drinking water 38 (United Nations 2013), and only around 30% have access to centralised electricity services 39 (Welsch, Bazilian et al. 2013); access to mobile phones have grown from practically zero to 40 around 50% in only a decade (GSMA Intelligence 2013; The World Bank 2013). Why is this 41 so? In contrast to the ‘hard won’ capital-intensive conventional electricity and water 42 infrastructure investments by governments and international agencies (The World Bank 2013; 43 United Nations 2013; Welsch, Bazilian et al. 2013), the swift adoption of ICT and the roll-out 44 of the associated infrastructure has occurred relatively autonomously on a largely commercial 45 basis in a very short timeframe. 46 The relatively low population-wide levels of access to water and electricity services is 47 much more extreme for those living in rural ‘off-grid’ areas in non-industrial areas. The vast 48 majority of rural poor populations in non-industrialised nations have no access to reliable, 49 safe, healthy, and affordable centralised electricity services (Karekezi 2001; Schultz, 50 Platonovaa et al. 2008; Welsch, Bazilian et al. 2013). Where access does exist, economic 51 barriers often predominate, as many rural poor households cannot afford to connect to a 52 centralised electricity network (Adkins, Eapen et al. 2010; Soto, Basinger et al. 2012; Adkins, 53 Oppelstrup et al. 2013). For these households to enjoy the benefits of modern utility services, 54 small-scale systems must become, and are becoming, a cost-effective alternative in remote 55 areas (Seeling-Hochmuth 1997; Vandenbergh, Beverungen et al. 2001; Edenhofer, Pichs- 56 Madruga et al. 2011; Soto, Basinger et al. 2012). Much of the global focus and effort has 57 been on simple cost-effective technologies like basic lighting, as there remains two billion 58 people without access to modern lighting globally (Schultz, Platonovaa et al. 2008). Sadly 59 households in rural developing areas using traditional biomass lighting pay a similar 60 proportion of their household income for lighting as the average American family, yet only 61 receive around 0.2% of the lumen-hours (Irvine-Halliday, Doluweera et al. 2008). Clearly, 62 the economic capacity of families using traditional biomass for lighting will likely find it a 63 challenge to afford the high costs of conventional centralised electricity services when ‘it 64 arrives’. 65 In industrialised and non-industrialised nations alike, conventional electricity 66 infrastructure and networks themselves are becoming viewed as a major limiting factor in the 67 provision of efficient and cost-effective electricity services (McHenry 2013). However, at the 68 small-scale, fundamentally new models of low cost and flexibility of 69 (re)configuration/expansion of small-scale ‘smart’ and microgrid power systems offer major 70 advantages in multi-user systems for rural areas at lower costs (Vandenbergh, Beverungen et 71 al. 2001; Welsch, Bazilian et al. 2013). This research focusses on the unique options of 72 including the storage capability and deferrable load options that enable demand side 73 management (DSM) from ‘low power’ consumer goods and ICT devices as a new form of the 74 continually evolving DC microgrid infrastructure and control system to foster creative 75 electricity system design rethinking (McHenry 2013; McHenry 2013; Willems, Aerts et al. 76 2013). This new ICT consumer good infrastructure includes the improved functionality, 77 connectivity, and portability of devices such as ‘plug and play’ balance of system (BOS) 78 components with distributed and portable appliances, effective DC bus regulation, imbedded 79 energy storage, all with major safety benefits and an attractive and user-friendly interface 80 unseen in the traditional energy sector. This enables small-scale renewable energy and smart 81 microgrid concepts to cost-effectively enter the home to enhance both personal and 82 economically productive uses, and reduce the past issues of poor user-friendliness, capacity 83 limitations, and high cost of the previous generations of renewable energy technology. 84 The historical inability of conventional renewable energy systems to be a cost- 85 effective means to supply traditionally inefficient tools and equipment in rural small-to- 86 medium enterprises (SMEs) has resulted in energy efficiency and low power systems 87 becoming a major unmet market need (Karekezi and Kithyoma 2002; Schultz, Platonovaa et 88 al. 2008; McHenry 2009; McHenry, Doepel et al. 2014). For example, with the development 89 of light emitting diodes (LEDs), using personal portable photovoltaic (PV) modules and 90 batteries in small lighting systems is a practical and more affordable ‘disruptive technology’ 91 (Mills 2010; McHenry, Doepel et al. 2014). Advancing improvements in ruggedness, low 92 voltage tolerance, small size, high optical efficiency, and low cost of LEDs have enabled 93 small-scale lighting and PV-battery combinations to flourish (Mills 2010). These advances 94 have sustained the belief that DC renewable energy will eventually become the preferred 95 generation technology for small stand-alone systems in non-industrialised regions (Schultz, 96 Platonovaa et al. 2008), particularly with low wattages and voltages (Karekezi and Kithyoma 97 2002; Willems, Aerts et al. 2013). However, LEDs may be simply the first example of a 98 disruptive low power and micropower technology, particularly in terms of facilitating 99 productive applications such as communication, reading, and night-time education. ‘Back lit’ 100 portable personal devices are largely replacing conventional books and desktop computers as 101 learning and communication mediums of choice. It is also common to use the brightness of 102 some screens and inbuilt LEDs for basic task lighting (making LEDs themselves out-dated in 103 many cases). 104 In addition to the social benefits of energy and ICT service integration, economically 105 productive rural applications arising from such services (commerce, communications, 106 electronics, agri-business, etc.) will assist further economic development and innovation to 107 capture the greater benefits of improved rural supply chain opportunities (Martinot, Chaurey 108 et al. 2002; McHenry, Doepel et al. 2014). At present, small-scale rural development, energy 109 infrastructure, production, communications, capacity building, extension services, and agri- 110 marketing activities remain disaggregated, and their integration is under-emphasised in current 111 approaches (Jayne, Govereh et al. 2002; Edenhofer, Pichs-Madruga et al. 2011; Lynd and 112 Woods 2011). Conventional models of rural energy infrastructure, mechanisation, education, 113 and extension investments have typically long lead time horizons, and are separated into 114 distinct and isolated fields of planning and funding. In contrast, modern rural development 115 activities requires an acceleration of new technology and knowledge adoption and must connect 116 the diverse rural supply chains and inputs (knowledge, energy, agricultural inputs, technology, 117 commodity prices, etc.) (Jayne, Mather et al. 2010). As rural subsistence regions traditionally 118 have poor access to new technologies and productive inputs, a greater focus on creating a 119 suitable environment to enable participation in economically productive applications with 120 appropriate energy and ICT technologies is key (Opara 2011; McHenry, Doepel et al. 2013; 121 McHenry, Doepel et al. 2014). 122 123 124 2. Innovative portable ICT networks, generation, and portability 125 Many portable personal devices are powered through a computer universal serial bus 126 (USB). Indeed the ICT sector has advanced the USB to already become a pervasive yet 127 largely unplanned DC microgrid rolled out in many global modern workplaces (Figure 1). 128 The continued development of low voltage DC and USB device coupling multiple small- 129 scale generation for personal ICT device charging is yielding higher efficiency and lower 130 power options suitable for rural and remote regions (Wong 2013). The most common USB 131 ports are USB 2.0 and 3.0, and in terms of power the nominal voltage of the USB is 5V, 132 (USB 2.0 maximum 5.25V and minimum 4.75V, with a nominal power of 2.5W), with a 133 maximum current of 0.50A. The more recent USB 3.0 is also 5V, (maximum 5.25V and 134 minimum 4.45V, with a nominal power of 2.5W), and exhibits current variants of 0.150A, 135 0.900A, and 1.5A. (The 1.5A port is limited to charging only with no data transfer capability, 136 and the USB charging ports are able to deliver up to around 5A). Recent developments in the 137 USB standards include the USB Power Delivery protocol, delivering a maximum 20V and 138 minimum 5V, (with variable voltage capability) and with a limited output of 5A, enabling a 139 maximum nominal power of 100W. The new protocol can provide power in both directions, 140 optimise power management between appliances, and several other advanced enabling 141 capabilities (usb.org 2014).. As such, the ICT sector is now a major new investor in and 142 producer of low voltage DC electricity network infrastructure as a byproduct of their business 143 model. 144 [Insert Fig 1 approximately here] 145 146 Many new portable ICT goods for the relatively wealthy ‘western’, ‘consumer’ or 147 ‘adventure’ market are becoming available and now leading the development of many new 148 renewable energy system configurations and designs. For example, the company Goal Zero 149 produces the ‘Nomad 27’, a 0.151m2 , 1.5kg monocrystalline PV array rated at 27W, VSC 150 ~19V, with dimensions of 113 x 57cm unfolded, and able to be folded into a portable 151 package with dimensions 26.7 x 18 x 5cm (and exhibits a buck regulated USB output of 5V, 152 0.5A, 2.5W maximum, or a 13-15V 1.6A, 24W maximum DC unregulated output). The 153 product is aimed at the adventure/camping market and has is designed for portability, 154 interconnectivity, and to power multiple ICT devices. The same company produces the 155 ‘Sherpa 50’ - a 0.50kg lithium-ion (nickel manganese cobalt oxide, NMC) 9-13V DC battery- 156 charger unit, with dimensions 11.4 x 3.8 x 12.7cm, and a capacity of around ~56Wh 157 comprising of six 3.6V, 2.6Ah cells. The battery-charger unit can utilise 15-25V DC (30W 158 maximum) charging, and has a USB port output (able to provide a regulated 5 V 0-1.5A (7W 159 maximum), and can be coupled to the ‘Nomad 27’, an AC wall adapter, or a 12V DC system. 160 These technologies enable owners to carry a DC microgrid literally on their back, and it 161 provides a new perspective of suitable energy infrastructure in rural regions. 162 Portable technology developments present a challenge to the renewable energy sector of how 163 to customise small-scale hybrid power supply system designs that consider creative 164 interdependent and operational strategies for non-linear characteristics of portable 165 components and site/load characteristics (Seeling-Hochmuth 1997). For example, portable 166 PV panels on vehicles and personal clothing are exposed to complex orientation, 167 illumination, and shading patterns (Gao, Dougal et al. 2009). Amorphous silicon modules are 168 impacted by partial module shading to a lesser degree than polycrystalline or monocrystaline 169 PV modules (Architectural Energy Corporation 1991), and direct technology substitution 170 may be a simple solution. Alternative conventions may also play a role in system design for 171 efficiency and robustness under conditions associated with being portable. PV arrays are 172 conventionally connected in series to produce a desired voltage, and any PV cell shading will 173 inhibit the collection of energy from the remaining array that may be under full illumination 174 conditions (Gao, Dougal et al. 2009). When one or more PV cells are damaged, or when 175 modules are partially shaded, the increased temperatures in the damaged/shaded cells act as 176 inefficient conductors and seriously reduces module output (Architectural Energy 177 Corporation 1991). Partial (cloud, tree, or moving objects/infrastructure) shading of PVs can 178 lead to rapid fluctuations in output, and series-connected wiring results in either impedes the 179 ability to collect the output from fully illuminated cells when one in the string is partially 180 shaded, or the partial output of the shaded cells (if diode bypassed) (Rohouma, Molokhia et 181 al. 2007; Gao, Dougal et al. 2009). Most available consumer PV products use series 182 configurations, and at present bypass diodes are used at PV module electrical terminals to 183 enhance power production and prevent the high levels of resistance from impacting the entire 184 string when series-connected modules are damaged or shaded (Architectural Energy 185 Corporation 1991; Gao, Dougal et al. 2009). In practice PV outputs act like extremely fast 186 ‘ramp-up’ and ‘ramp-down’ of traditional generation (Naoto, Satoh et al. 2006). Rapid 187 fluctuations in PV shading patterns makes maximum power point (MPP) tracking a challenge 188 with each system string MPP value dependent on upstream PV module characteristics, 189 making it difficult to identify the global MPP for diode bypass PV systems as multiple local 190 MPPs exist with each changing rapidly (Gao, Dougal et al. 2009; Manfredi and Pagano 191 2011). Many existing MPP algorithms use DC/DC converters that are insufficiently fast (a 192 few seconds) to cater for MPPs change rapidly (over a tenth of a second), particularly in 193 series-connected PVs (Patel and Agarwal 2008; Gao, Dougal et al. 2009). Non-conventional 194 configuration of a highly parallel PV array wiring configuration engenders a relatively 195 consistent MPP voltage of all cells largely independent of irradiance levels, and small 196 deviations from the MPP does not reduce power output to a great extent, with the system 197 voltage becoming weakly related to temperature changes (Rohouma, Molokhia et al. 2007; 198 Gao, Dougal et al. 2009). Nonetheless, advancements in MPP algorithms will required faster 199 response times to changes in PV responses when portable or for variable meteorological 200 conditions, in addition to increases stability, robustness, and efficiency (Manfredi and Pagano 201 2011). 202 203 204 3. A revolution of low power DC and energy systems and payment options 205 Much conventional large rural equipment such as variable speed drives, industrial 206 lighting, power electronics, batteries, flywheels, and other storage mechanisms are generally 207 DC systems that require conversion from AC (Anand and Fernandes 2010; Willems, Aerts et 208 al. 2013). Low voltage PV energy systems are by no means new, as 48V has long been used 209 by the ICT sector for remote systems, improving the general availability of low voltage BOS 210 components (Anand and Fernandes 2010; Boroyevich, Cvetkovic et al. 2013). Continued 211 developments in converter/inverter and step up converter technology have enabled numerous 212 non-conventional energy system designs (including parallel PV module configurations and 213 step up converters for grid-connect systems, and small single PV cell converter systems as 214 low as 0.3V) (Gao, Dougal et al. 2009). For low voltage system applications the combination 215 of a reduction in net load through higher appliance efficiency and the reduced DC/AC and 216 AC/DC conversion losses enables the selection of smaller and less costly generation and 217 storage components. Coupling of multiple low voltage generation and appliances on a 218 common DC bus controlled by DC/DC converters enable improved system regulation to 219 achieve more energy efficient conversion, and enables system components to be introduced 220 to allow a cost-effective evolution of the system to meet changing needs (Vandenbergh, 221 Beverungen et al. 2001; Brenna, Tironi et al. 2004; Ortjohann, Omari et al. 2007; Welsch, 222 Bazilian et al. 2013). The DC system bus voltage is important because the efficiency of 223 conversion between generation and loads increases with less conversion stages, and is also 224 fundamental safety parameter (Anand and Fernandes 2010; Willems, Aerts et al. 2013). In 225 general a 48V DC system is considered very safe for humans when grounded. Ensuring unity 226 power factor (UPF) is an important consideration for DC systems, as the energy potential of 227 DC bus terminal with respect to ground varies at high switching frequency, leading to the 228 voltage variation leaking current and causing equipment damage and user safety concerns 229 (Anand and Fernandes 2010). Notably the employment opportunities in the sector are a 230 massive potential new industry, particularly considering the skills and training required to 231 install/maintain low voltage equipment does not require a lengthy four-year electrical 232 apprenticeship. 233 Portable ICT device charging from small-scale renewable energy systems and 234 microgrids has the potential to introduce additional savings to households in off-grid rural 235 areas (Schuss and Rahkonen 2012; Didier, Toshimitsu et al. 2013). For example, local mobile 236 phone charging services in non-industrialised countries without quality energy service 237 provision generally costs around US$1-2 per week, and the travel time to reach charging 238 stations is often considerable (Irvine-Halliday, Doluweera et al. 2008; Adkins, Eapen et al. 239 2010). Yet, mobile phone battery capacities are commonly only between 1 and 2 Ah with 240 voltages of only a few volts. This associated cost per unit of energy is expensive for 241 individuals with no charging services at home. Furthermore, the conversion efficiency of 242 conventional AC voltages in the home to low power DC mobile devices is commonly very 243 low (~15%) (Ruutu, Nurminen et al. 2013). Therefore, in general distributed small-scale 244 stand-alone home system DC bus networks are recommended when higher user loading at 245 night is combined with renewable energy generation systems that have a high solar fraction. 246 Similarly, home system AC bus networks are preferable with high daytime loads and high 247 liquid fuel generation penetration (Vandenbergh, Beverungen et al. 2001). Research by 248 Anand (Anand and Fernandes 2010) found 48V DC with DC/DC converters to be an 249 optimum voltage when comparing between 400V, 325V, 230V 120V and 48V) to efficiently 250 meet energy needs in a residential home consuming 7.9kWh d-1, even with standard 251 appliances (ceiling fan, air conditioning in summer, refrigeration, LED lighting, computers, 252 washing machine, and TV). Anand (Anand and Fernandes 2010) found that meeting an 253 equivalent load demand using 48V and 120V DC systems will require less (~15%) electricity 254 than AC systems due to lower losses converting from DC to AC and vice versa for standard 255 residential loads in industrialised nations(Boroyevich, Cvetkovic et al. 2013). Without the 256 historical legacy and sunk capital of industrialised nations developing a centralised high 257 voltage AC generation and distribution model, it seems unlikely that that this model would be 258 the default choice for establishing electricity services today. It is a failure of imagination to 259 propose ‘traditional methods’ of using copper and fibre cables in rural developing areas, and 260 is wholly inappropriate when stand-alone, mobile, and satellite options are available. This 261 conventional lack of science and innovation is akin to being creatively stuck in the same ‘rut’ 262 as the historical legacy of the rail/tram/cart wheel gauges following the original imperial 263 roman war chariot gauge. A more recent example is the path dependency of the QWERTY 264 keyboard (Page 2006), yet as we also know with ICT devices there have been many 265 successful alternatives that co-exist with the QWERTY, including mobile phones. Thus, we 266 need not follow the same development path/rut, or have one successful model, and have 267 multiple opportunities in the relative ‘greenfields’ of development needing new solutions 268 using more flexible state-of-the-art technology. 269 Installing state-of-the-art technology in rural poor regions generally raises the hard 270 questions of technical limitations, who will pay, commercial arrangements, regulation, tariffs, 271 donors, and subsidies (Tenenbaum, Greacen et al. 2014). Yet there is growing interest in 272 fostering development pathways through commercial ‘trade’ rather than ‘aid’ globally, 273 particularly to sustain the investment momentum of initiatives once they commence 274 (McHenry, Doepel et al. 2014). For example, research at Stellenbosch University and with 275 Specialized Solar Systems in South Africa has focussed on low-cost appropriate options to 276 supply informal housing with domestic electricity services using low power DC systems and 277 appliances. In 2011 the first ‘iShack’ was constructed with effective passive thermal 278 management, solar hot water, and a ~20W PV module-battery-distribution system with 279 efficient LED lighting and mobile phone charging points to be affordable, modular, robust, 280 minimise conversion losses, and be upgradable for fridges, microwaves, stereos, TVs and 281 ICT devices. The iShack initiative is now incorporating alternative commercial financing, 282 asset ownership, and low power DC ‘Watt-hour’ metering options (as opposed to AC kWh 283 metering common globally) (Figure 2) (Keller 2012; Taverner-Smith 2012). Complimentary 284 research by Soto et al. (Soto, Basinger et al. 2012) on small-scale microgrid payment systems 285 in ~200 households (in Mali and Uganda) implemented a successful cost recovery model. 286 Known as ‘microutilities’, electricity supply (with customised control options) and associated 287 communication information automatically sent to consumers who purchase cards from local 288 vendors on a prepaid basis using a toll-free SMS account recharging comparable to mobile 289 phone payment systems (Soto, Basinger et al. 2012). These and many other comparable 290 advances demonstrate that it is technically feasible for conventional utilities to rethinking 291 their infrastructure approach towards a smarter customer interface in a very large and 292 distributed low power DC energy market in rural non-industrialised regions, and in parallel 293 recoup infrastructure investment costs while adhering to governmental commercialisation and 294 regulation impetuses (Soto, Basinger et al. 2012; Boroyevich, Cvetkovic et al. 2013; 295 McHenry 2013). 296 [Insert Fig 2 approximately here] 297 298 299 4. Novel low power DC storage and hybrid capabilities/applications 300 Conventional battery storage systems in stand-alone power supply systems are 301 generally less reliable than most other components and are oversized relative to the daily load 302 in the attempt to maximise battery lifespan to minimise replacement costs (McHenry 2009; 303 McHenry 2009). Lead-acid batteries remain the most common storage technology use in 304 stand-alone power supplies (Lambert, Holland et al. 2000; McHenry 2009; McHenry 2009), 305 and lead-acid battery replacement and disposal are serious economic and environmental 306 issues (Martinot, Chaurey et al. 2002). Energy storage technologies ideally should be reliable 307 over numerous cycles, have a low self-discharge rate, minimal maintenance requirements, a 308 high 309 environmental/storage/safety characteristics, and an ability to withstand periods of low 310 charge (Lambert, Holland et al. 2000; Lazarov, Zarkov et al. 2012; Boroyevich, Cvetkovic et 311 al. 2013). Indeed the portable LED lighting system component with the shortest life is often 312 the battery (Mills 2010). While most batteries are low voltage DC technologies, the concept 313 of a battery bank in a stand-alone power system as a separate useful component and an 314 integral ‘imbedded’ storage capacity with multiple utility in a system is now possible. For 315 example, rather than a passive component that stores generated energy and assists variable 316 generation, it is now incorporated within appliances themselves as a novel storage design 317 consideration for new low voltage DC microgrid systems. For an unusual example, the high 318 power production available from portable supercapacitors (a presently uncommon technology 319 in ICT devices and low power DC microgrids) can supply some storage and supply large 320 currents (as when motors start) (Seo, Kim et al. 2010; Glavin and Hurley 2012). 321 Supercapacitors have little or no maintenance requirements, high energy densities, high 322 power ratings, long lives (around 1 million charge cycles at rated temperatures), are 323 composed of environmentally benign materials, and can be totally discharged and charged 324 with practically zero memory effect (Robbins and Hawkins 1997; Karandikar, Rathod et al. 325 2009; Kim, Chang et al. 2010; Fahad, Soyata et al. 2012; Das, Das et al. 2013). 326 Supercapacitors can be totally discharged and charged at very large amperages at almost 327 100% cycle efficiency, and can be designed to meet daily load requirements without concern 328 for the supercapacitor lifespan, and only consideration of the maximum voltage and current, 329 the solar resource, the load, and the operating temperature (Kim, Chang et al. 2010). For 330 instance, Maxwell’s BCAP3000 has a rated capacity of 3,000F, maximum ESRDC of 0.29mΩ, 331 a rated voltage of 2.70V (2.85V maximum), with a large maximum continuous current of 332 210A at operating temperatures 40-65oC. The weight of a single BCAP3000 is 0.59kg, with a 333 length of 130mm, and a diameter of 61mm, with the ability to store 3.04Wh. Demonstrating 334 creative applications of such small DC supercapacitor components by enthusiasts is their 335 adoption in home electronic component spot welding, being a portable low cost and low 336 power (yet high amperage) capacitive discharge appliance (among other uses). charging efficiency, robust, low cost, high energy density, good 337 Supercapacitors have also been demonstrated to be an effective storage option and 338 also a compensatory component to PV output variability. As a rough indication, cycling a 339 supercapacitor through half of its voltage range provides or stores around 75% of its available 340 energy capacity, and can be charged/discharged at a rate of around 60% of fully 341 charged/discharged in one second, and 80% by two seconds, and be totally 342 charged/discharged (>99%) by around four-to-five seconds. Short interval storage enables 343 and expanded suite of options for more effectively using intermittent PV generation capacity 344 in stand-alone systems (Maranda and Piotrowicz 2010). PV-supercapacitor system 345 simulations by Lazarov et al. (Lazarov, Zarkov et al. 2012) included a 820Wp PV array, a 346 1000W single-phase inverter, two supercapacitors with a total capacity of 166F and a 347 nominal voltage of 48V connected to a 50V DC bus. The voltage of the supercapacitor bank 348 varied from 50V (at around 100% SOC) to approximately 10 V (around 0% SOC), and 349 effectively maintained the DC bus voltage to the nominal 50V, apart from a small reduction 350 to around 49V at the zero SOC point. The simulations by Lazarov et al. (Lazarov, Zarkov et 351 al. 2012) showed that the fully charged supercapacitor bank was able to fully compensate for 352 total loss of an assumed 800Wp PV generation output for 228 seconds, or 366 seconds for an 353 assumed 500Wp PV output (Lazarov, Zarkov et al. 2012). The use of actual electrical storage 354 as compensatory components and as appliances, and also in combination with conventional 355 notions of ‘virtual storage’ from deferrable loads (such as water pumping and refrigeration) 356 can be incorporated into system control scheduling and load hierarchies. The additional 357 flexibility in including storage capacity of all types is also bolstered by the advancing 358 appliance efficiencies such as new generations of low voltage pumps (also operating on USB) 359 and more efficient magnetic and hybrid-fuel thermal refrigeration options (McHenry, Doepel 360 et al. 2013). Even relatively inefficient small conventional compression fridges (~200L) often 361 consume less than 100W (including using low voltage DC versions) when the compressor is 362 on and usually only operate at 25% of the time depending on usage patterns. Yet, the 363 advancements of new low power and clean energy technology capabilities and applications 364 will certainly not be without their own teething issues, as we have seen in the past, some of 365 which are detailed below. 366 367 368 5. Ongoing issues with the traditional renewable energy development paradigm 369 It still remains common for relatively little long-term small appliance and renewable 370 energy product testing to occur prior to the introduction of new products (particularly in non- 371 industrialised nations and commonly inspired by various donor programme embodiments). 372 This is often because testing is deemed to be too time consuming and expensive (Adkins, 373 Eapen et al. 2010). Even when ‘bundling’ several existing commercial products into a new 374 energy systems that individually meet high standards and minimum performance 375 requirements, the new bundled system still requires appropriate technical validation of safety 376 and performance over time with ongoing technical support (Martinot, Chaurey et al. 2002). 377 As an example, it is commonly thought that LED lanterns have been successfully introduced 378 to several poor countries (Schultz, Platonovaa et al. 2008). However, LED technology can 379 vary considerably in terms of technical performance, as poor-quality LED products are 380 known to have reduced end-user trust in the technology (Mills 2010). LED lifetimes are 381 commonly falsely overgeneralised as consistently long-lasting, yet can vary markedly 382 between ‘low power’ (~0.2 W) LEDs lasting between 250 and 2,500 hrs and ‘high power’ 383 (~1-5 W) LEDs lasting up to 50,000 hrs (Mills 2010). Ensuring availability of replacement 384 component and appliances is notoriously difficult in many non-industralised regions, and 385 wider dissemination is limited by poor product support and high upfront capital costs (Apte, 386 Gopal et al. 2007; Adkins, Eapen et al. 2010). Without a sustained presence of an effective 387 technical support structure for new products and services, and a critical mass in technology 388 adoption in a location to support these commercial services, sustaining access to replacement 389 parts and maintenance services is a fundamental limitation. The variable voltage of 390 technologies is also an issue with the lack of standardisation for the suitable 391 application(Willems, Aerts et al. 2013). However, with the evolution of the USB capabilities 392 and the management of variable Low voltage DC energy and data delivery over one single 393 cable (usb.org 2014). When introducing commercial (unsubsidised) new technologies, it is 394 commonplace to hear discussions of microfinance, payment plans, rental options (etc.), all in 395 the aim to create a sustainable local industry and guide it through initial sensitisation, 396 capacity building, and barrier removal processes (Adkins, Eapen et al. 2010). The 397 international aid/donor sector agencies often have developed detailed, targeted, and 398 comprehensive stand-alone financial mechanisms to assist some technology dissemination in 399 non-industrialised regions. However, the ICT sector already incorporates a comparably 400 detailed and globally successful sales model in such regions, and it may be more appropriate 401 to also collaboratively partner with ICT companies to meet development aims. Just as mobile 402 phone networks are rapidly expanding in non-industrialised nations (Didier, Toshimitsu et al. 403 2013; GSMA Intelligence 2013; The World Bank 2013), partnering with ICT companies is 404 becoming a practical alternative to partnering with financial, donor, and government sectors 405 for developing microfinance for development projects, and may neatly fit into existing ICT 406 company corporate social responsibility (CSR) programmes. 407 408 409 6. Conclusions 410 Smart grids and microgrids have been likened to a merger of energy, ICT, and 411 telecommunications sectors which will necessitate numerous revisions of technical and 412 governmental assumptions regarding how this new major sector will advance economic 413 growth and global competition (McHenry 2013). In the context of the renewable energy and 414 ICT industrial expansion into the non-industrialised countries, it is important to view 415 developments within the existing paradigm of players and supply chains, including donor 416 agencies, 417 entrepreneurs, households, community organisations, conventional energy service providers 418 and the associated regional service availability and financial capacities in the regions. 419 (Martinot, Chaurey et al. 2002). Partnerships between ‘low power’ renewable energy, ICT, 420 and other sectors in rural and remote energy development has the potential to become a major 421 competitor and complement to the industrial-scale and centralised high voltage AC network 422 model of development (Boroyevich, Cvetkovic et al. 2013). The recent revolution in USB 423 standards to include data and increasing levels of useful bi-directional power flow with 424 variable voltage has the potential to become a major low voltage DC microgrid backbone. 425 With increasing availability of ‘personal power systems’, the portability of connecting 426 renewable energy generation with appliances that include imbedded battery storage and 427 advanced interfaces will require creative design that improves system performance under 428 variable conditions. This will require an unprecedented level of modularisation, robustness, 429 upgradability, energy efficiency with variable configuration, and also consideration of end- 430 of-life safety, storage, and disposal due to the growth and rapid turnover of personal ICT and 431 energy devices. Many of these advances are occurring at an rapid pace backed by the large 432 and growing global consumer device market in both industrialised and non-industrialised 433 nations. government policy, existing conventional product manufacturers, rural 434 Despite intentional and planned development activities, the increasingly dynamic 435 market in energy efficient and portable low power DC ICT devices is likely to support an 436 autonomous level of unplanned development in non-industrialised countries. Significant 437 revision of conventional thinking will be necessary, particularly when fast-paced ICT product 438 lifetimes and advances are juxtaposed with multi-decade relative stagnation in electricity 439 industry infrastructure models. Armed with the advantages of portable DC devices, imbedded 440 storage, and portable renewable energy systems, individuals have the opportunity to 441 customise their own systems to suit their unique needs and capacities for innovation. The 442 stand-alone power supply system and ICT sectors also a have a major economic opportunity 443 with literally billions of rural people seeking creative systems and designs that ‘revolutionise’ 444 their energy services and development paradigm, rather than simply ‘industrialise’ it. 445 446 References 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 Adkins, E., S. 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The PC 605 is the AC/DC interface (100-240VAC, 0.8A/19VDC 1.58A) with ‘island mode’ using only 606 DC utilising the battery to power the USB network (5VDC) to several consumptive 607 appliances, five of which have their own imbedded battery storage (tablet, phone, camera, 608 MP3 player, and speaker), and four powered only by the USB ports (flexible second 609 keyboard, thumb drive, external hard drive, and LED light). 610 611 Figure 2: An upgraded low power DC microgrid home with solar hot water, PV array 612 incorporating battery storage, LED lighting, small domestic appliances and ICT devices, 613 including Specialized Solar Systems unique DC Watt-hour metering suitable for small-scale 614 home DC microgrids. Courtesy of Professor Mark Swilling at Stellenbosch University, South 615 Africa. 616