Presentation on theme: "Yangon, Myanmar Dr. Chris Greacen September 5, 2013"— Presentation transcript:
1Technologies that Empower Distributed Generation for Rural Electrification: Options for Myanmar Yangon, MyanmarDr. Chris GreacenSeptember 5, 2013Good morning everyone. It is an honor to be invited to speak at this workshop.In this workshop you have already had presentations on micro-hydropower and biogassification. I work in East Africa and in countries in Asia on renewable energy and rural electrification. In my work I have seen some innovative and practical technologies that complement micro-hydropower or biogassification mini-grids. They also complement conventional rural electrification through grid expansion.They do this by helping communities of electricity users to manage peak loads, by internet-based remote monitoring of mini-grids; by lowering the cost of extending wires; and by using pre-electrification technologies to quickly roll out basic electricity services for lighting and cell-phones at low cost...1
2Outline Mini-grids and conventional grid extension What happens when the grid arrives?Low cost pre-electrification (solar micro-grid)Lowering distribution cost for low-density rural electrification (SWER)Technologies to help spread out peak loads on mini-grids (MCBs, Gridshare)
3Electricity for whom?This is a photograph from Laos, but it illustrates a point that I believe applies here in Myanmar as well. When we are thinking about rural electrification it is useful to ask, “electricity for whom?” Do the transmission lines just pass overhead, bypassing people like this woman carrying fuel wood? Or does electrical service reach everyone?
4Extending the grid and rural mini-grids CustomersCustomersMini-GridNationalGridOne way to help ensure that rural electrification reaches people quickly is to develop policies that encourage a coordinated process that includes distributed isolated renewable energy mini-grids, in concert with grid extension.This holds promise in expanding overall expansion of electrical service more quickly than grid extension alone.Small Power ProducerLarge Plants
5Electrification: 26%I understand that currently Myanmar has an electrification rate of about 26%. If electrification is only accomplished through extending the grid, it will take many years for parts of the country to be electrified.
6Electrification: 50%Encouraging rural mini-grids means expands where the main grid has not yet reached.
8Myanmar – Kayuklot Township electricity to 500 households Rice husk gasifierMyanmar – Kayuklot Township electricity to 500 householdsAlready this is happening – small entrepreneurs and community groups are building biomass gassifier projects, like this one in Kayuklot Township, or micro-hydropower mini-grids.
9What to do when the “big grid” expands to reach the “little grid”? Option 1: formerly off-grid generators connect to the grid to sell electricityDC sources (e.g. solar)Grid-connect inverter requiredAC generators (e.g. hydro)Digital relay requiredOne big question that is arising in other countries were mini-grids are being built is what to do when the main grid expands? There are well-developed technologies and regulatory rules that allow these formerly isolated generators to connect to the main grid and sell electricity back.Chris Greacen, Richard Engel, and Thomas Quetchenbach, A Guidebook on Grid Interconnection and Island Operation of Mini-Grid Power Systems Up to 200 kW (Schatz Energy Research Center and Palang Thai, LBNL--‐6224E).
10What to do when the “big grid” expands to reach the “little grid”? Option 2: purchase electricity from national grid for distribution on mini-grid.Mini-grid must be built to acceptable standardsA second, and equally important option, is that the mini-grid operator purchases electricity at wholesale prices from the main grid and distributes it to its customers. This requires that the mini-grid distribution system is build to sufficient standard to accept grid power.
11What to do when the “big grid” expands to reach the “little grid”? Option 1 + 2: both!Of course, both are possible. For example, many mini-grids find that after several years they have inadequate electricity to meet evening loads. A renewable energy mini-grid connected to the main grid can purchase supplemental electricity when needed, and sell electricity back at other times of day when its own loads are not high.
12Here are a couple examples Here are a couple examples. This 40 kW micro-hydro in Thailand used to be an isolated mini-grid, and is making arrangements to sell electricity to the main grid.Mae Kam Pong, Chiang Mai, ThailandBuilt by government & community40 kWUsed to be off-grid;Making arrangements to sell electricity to grid
134 MW hydro - Tanzania electricity to 4000 households in >15 villages & sells to the grid This private 4 MW hydropower project in Tanzania, Africa, sells electricity to 4000 households in 15 villages along its own distribution lines, and also exports electricity to the main grid.
14Affordable pre-electrification Pre-electrification is:safe lightingcell phone chargingsmall appliancesPre-electrification is generally not:Agricultural millingPower tools (electric saws, etc.)Water pumpingIn many cases, instead of waiting for the grid to arrive or a full-scale mini-grid, it makes sense to do pre-electrifcation. These systems supply small amounts of very useful power for lighting, cell phones, and small appliances like efficient TVs or radios.
15Pre-electrification solar micro-grid Devergy in Tanzania I’ve been particular impressed by the pre-electrification technology of a solar micro-grid company, called Devergy, in Tanzania.
16DevergyEvery household that wants electricity gets an electronic pre-paid meterElectricity paid with cell phoneAbout $7 per month
17Devergy pre-electrification technology Every 5-6 households served by an “Enbox”60 watts of PV24 volt, 20 Amp-hr batteryZigBee wireless electronics, networked to metered households and other EnboxesThe micro-grid sends update on status of all meters, voltage & current of all Enboxes via cell-phone (GPRS) carrier to internet every 5 minutes.Devergy also runs a small kiosk in the village that sells super-efficient applieances like LED lights, LED TVs, and well as top-up minutes in the pre-pay meter.
18Single Wire Earth Return (SWER) Single wire system using ground as return conductorIt is used for low cost rural electrificationwhen expanding the grid, one technology to consider is Single Wire Earth Return (SWER).Source: Tulloch & Davies, SWER: New Zealand & Australian Experience.
19How it all started Lloyd Mandeno invented SWER in New Zealand in 1925. Seen in 1940’s as preferred solution for remote, sparsely populated areas.200,000 km of SWER now in NZ and Australia.Successfully used in NZ, Australia, Canada, India, Brazil, Africa and Asia for sparsely populated areasSWER has been around now for nearly 90 years,Source: Tulloch & Davies, SWER: New Zealand & Australian Experience.
20How does it work?Resistance R1 = R (conductor) + R (earth return path)Allow 0.05 ohms/km at 50 Hz for earth return path.Source: Armstrong. Single Wire Earth Return
21Source: Armstrong 2002. Single Wire Earth Return Advantages of SWERCost ReductionOne conductor, less pole top equipmentLong, hilltop to hilltop spansFewer switching and protection devicesIn Australia & NZ:Capital cost 50% less than 2-wire, single-phase70% less than 3-wire, 3 phaseDesign SimplicityReduced maintenance costsEstimated 50% maintenance cost savingReduced bushfire hazard – avoid conductor clashingSource: Armstrong Single Wire Earth Return
22Limitations of SWER Restricted load capacity Requirement for reliable low resistance earthing at isolating and distribution transformersPossible interference with metallic communications systemsHigher losses due to charging currentsSources I’ve found indicate that several transformers, each 200 kVA in capacity are generally possible.Source: Tulloch & Davies, SWER: New Zealand & Australian Experience.
23Technologies to help reduce peak loads on micro-hydro mini-grids Voltage drops
24Miniature Circuit Breakers (MCBs) or PTCs to limit peak loads kWh meterMini-circuit breakerMini-circuit breaker can encourage peak load reduction
25Case Study - Load management A 35 kW micro-hydro plant in Rukubji, BhutanLighting, TVs, rice cookers and water boilers are the common loadsVoltage dropsNote that all mini-grids are power limited and therefore subject to brownouts; this particular graph comes from a mini-grid where residents commonly use rice cookers and water boilers to cook their morning and evening meals and have no limits on the amount of power they can draw. As you can see, the spike in current at meal times results in a corresponding drop in voltage.As on many mini-grids, when load exceededgeneration capacity,brownouts occurredSource: Schatz Energy Research Center
26GridShare Load Management Technology Humboldt State University team, in partnership with Bhutan Power Corporation and Bhutan DOE developed the GridShare.The GridShare, installed in each household, limits household load only during a brownout or voltage drop.The device is intelligent enough to detect rice cookers, and keeps them turned on for people to finish cooking their rice.A more sophisticated approach is a device called GridShare, developed by the Humboldt State University team and deployed in a 35 kW micro-hydro project in Bhutan. The consumers of this mini-grid were experiencing brownouts and some times blackouts when demand exceed supply. The GridShare device that was installed in each of the households senses the mini-grid voltage. Whenever the voltage drops below a certain threshold, it limits the load to the house to 400W. That’s when the LED turns red. But the GridShare is also intelligent enough to detect rice cookers, the most common large load in a Bhutanese house, and using a timer, keeps the rice cooker on for people to finish cooking their rice. It then limits the load for that household if the voltage is still low. If the load is already limited, the GridShare will not let a consumer connect a rice cooker.
27GridShare Load Management Technology Electrical data indicated a reduction of over 90% in severe brownoutsReduced spoiled riceandResidents stated:“the grid is more predictable”The GridShare pilot project data indicates that user-interactive demand-side management strategies are effective at reducing brownouts on mini-grids;This is a comparison of approximately 1 year of data, where severe brownouts are defined as times where the voltage drops below 190 V for at least 10 minutes. Before: July 22nd, June 9th, After: July 22nd, 2011 – June 9th, 2012Such load management systems increase the reliability of mini-grids and thus ensure reliable access to electricity.
28Conclusions Technology Application Impact Interconnection relays mini-grid connect to main-gridLowers risk to developers of isolated mini-gridsSolar pico-gridAffordable pre-electrificationdeliver small amounts of electricity, deploy quickly, inexpensivelyZigBee & GPRS internet connecctivitymonitoring of remote mini-gridsLowers repair costs by catching problems early on.SWERLow cost grid extensionReduced hardware costMCBs and GridShareManagement of peak loadsFewer brownouts