Holistic design for synergies across sectors: Léogâne as model for rural utilities
Plans for Léogâne’s redevelopment include environmental remediation and optimization of material and resource flows across the energy, water, agricultural and transportation sectors. Investment in one sector, per the plan, creates the stability needed to initialize another; this is integral to the final outcome and can’t be undertaken successfully unless the supporting sectors are in place. The new paradigms for the plan rely upon the cascading of energy, water or residual resources extracted from nature across these sectors. Through colocation and coupling of complementary components, the program will capitalize on designed-in exchanges among multiple system elements. For instance, floodwater control may also be used to generate energy, irrigate crops and improve water quality. Agricultural and municipal solid waste can provide energy and heat for industrial processes while returning beneficial soil amendments. The vision entails closing loops to create a self-sufficient, holistic system, one that captures synergies, creates economic efficiencies, and eliminates waste. Promoting synergies between economic gains and social infrastructure helps to amplify benefits, ensuring that real gains are made in all sectors for the poorest and most vulnerable people (OECD 2006b). The design also promotes colocation of complementary entities such as industry, hospitals, clinics and schools, allowing these entities to take advantage of infrastructural outputs and/or contribute inputs. Overall, the plan reduces reliance upon most ‘first world’ carbon-intensive systems, substituting for the most part technologies that can, after training, be constructed and managed by local labor. In addition to new jobs, the scheme also entails alternative employment opportunities for agriculture, agroforestry, and aquaculture industries envisioned for the commune, along with other forms of local enterprise.
Léogâne is an ideal locus for reconstruction as its landscape mirrors that of much of Haiti, with its steep rural mountains, rivers and streams, and its populous alluvial plains. Successes in Léogâne could be used as templates for integrated development across rural Haiti where conditions are similar. Interventions in Léogâne were therefore designed along just such a typical corridor running from the mountainous uplands in the South, through the more populous alluvial plain and down to the coast on the North. The area is bounded on either side by the Momance River and the Rouyonne River, both of which have large seasonal variations.
Local efforts to guide reconstruction along this mountain-to-coast transect will help to inform placement of the system’s modular elements. Working components will be sited at locations with specific relationships to both natural resources and existing settlements (Figure 2). For example, the upland placement of wind turbines captures higher wind speeds. Photovoltaic arrays, interspersed with agriculture, occupy the middle range and power the pumping of water from a nearby receiving reservoir to a holding reservoir above for the pumped-hydro-storage generation system. Within this region too, biomass salvaged from agriculture will be used to supplement energy generation. All along this corridor, riparian resources will be stabilized for flood control, infrastructure protection, and for improved water quality for farming and aquaculture.
A base load generated by a pumped-hydro storage system (PHS) will power the industrial, civic and commercial sector. Explained below, the PHS is a generation system networked for reliability and redundancy. The distribution of electrical services also relies on an integrated delivery mechanism: a set of service points or ‘‘nodes’’ (Figure 3). This approach standardizes and maximizes the reach of new services. In the town center, for example, nodes serve neighborhoods, public plazas, the markets and other civic functions. Nodal locations will be linked by a newly paved road network. These stations will also serve as outlets for clean drinking water and as drop-off locales for waste collection. Here, cellphones may be recharged, as well as auxiliary LED lamps. Organic and solid waste dropped off at these service points (incentivized through rebates) will be carted to a nearby waste processing (biodigestion) plant site for augmentation of the power-supply. Economies obtained from colocation and simultaneous construction of these services will make the best use of limited resources until more are at-hand to finally extend services to individual dwellings. The nodal service points create an integrated web of services linking new and existing infrastructure. A few are designed to incorporate auxiliary community services such as ‘‘electronic cafes.’’ A number of ‘‘nodes as community-hubs’’ are also planned for the town square, on school campuses, clinics and at the hospital.
Proposal components
Generation of renewable energy
Léogâne’s renewable power system (with diesel back-up) will have its base load generated by PHS, powered by distributed wind and solar PV farms of 10 MW and 8.6 MW respectively. Electricity produced by these renewables will pump a quantity of water from the lower to the upper reservoir, where it is stored until released on demand (Figure 4). Passed through turbines, it generates the base-load for the microgrid. The PHS effectively acts as the storage battery and load-leveling device for the overall system (one of GEMi co-founder Daniel C. Gregory’s many primary organizing concepts). Léogâne’s PHS system is sized at a 10 MW, with a 180-meter head. The upper and lower reservoirs each have a water storage volume of 157,000 m3. The closed-loop flow of PHS water through surface-mounted pipes will not interfere with local riverine ecology; however, these must be placed in stabilized areas. For 8–10 hours during the day, electricity will reliably feed local micro-grids serving key industrial, commercial and residential locations, as well as some outlying areas. This type of system, which minimizes transmission losses, could serve much of Haiti where mountainous regions and streams are adjacent to urbanized areas.
For system resiliency, the PHS system is reliant on multiple, complementary sources with intermittent energy supply. While Haiti’s North and West Departments enjoy dependable wind velocities, Léogâne’s flatlands do not reliably produce sufficient wind speeds. Placement of wind farms at higher inland elevations in the commune will better take advantage of seasonal and diurnal on- and off-shore breeze. One or more solar farms comprised of commercially available PV panels will provide electricity to the PHS during the 11–13 hours of daylight. Excess power, not needed for water pumping, will augment the microgrid. Floating PV arrays are placed spanning across each of the PHS water reservoirs, comprising part of the generation system. Floating on pontoons, these arrays shade the water, reducing evaporation. The water in turn lowers the arrays’ temperatures, improving their efficiency. The arrangement also avoids unnecessary displacement of agricultural land.
Placed on opposite hilltops at elevations of 600+ meters, a total of eighty-six 100 kW wind turbines will complement the solar farm as primary feed for the pumped-storage system. These medium size turbines, selected in part for easier transport on primitive roads, are supported by lattice towers that provide greater stability in this earthquake- and hurricane-prone region.
The GEM model assumes a long-term phased approach to 24/7 power. The electrical consumption planned per household is calculated initially as quite minimal; it covers basic energy services, allowing for night illumination, and the operation of small pumps for drinking water, radio and other small appliances including cell phone charging. Community nodes and hubs are more energy intense and require power sufficient for small refrigerators, laptop computers, basic medical equipment, and some income producing productive uses. In all, it is estimated that basic household services, along with commercial, community activities (schools and clinics) could be provided for on average just 50 kilowatt-hours per person per year, (Dilip Ahuja et al. 2008) for an annual project total of 5,000 MW hours.
Telecommunications upgrades
Even before the 2010 earthquake, Haiti’s telecommunications infrastructure was generally underdeveloped (fixed line penetration at the lowest in Latin America and the Caribbean). However, the country’s internet connectivity is comparatively robust as most Haitian internet service providers connect to the internet via satellite and are not reliant on undersea fiber optic cables. Also, despite the national poverty level, mobile phone coverage has grown rapidly. For that reason, the community nodes will provide capacity for cell-phone recharging and servicing as well as internet cafes.
Ecological restoration and enhancement
That valuable natural resources lie within its boundaries is a condition hardly unique to Léogâne. Just as elsewhere across Haiti, these ecosystem services represent one of its greatest assets. These, unfortunately, have been subject to degradation. Therefore, environmental stabilization and resource regeneration are necessary preconditions to the development of energy systems, agricultural improvements, industry and economic development. Stormwater management, flood control, soil stabilization and reforestation are critical prerequisites to the installation of the energy corridor. A program of river stabilization (repair of eroding banks and other flood control measures constructed with local materials) will alleviate hazardous deluges that occur during tropical downpours. New reservoirs located upland will store stormwater for irrigation. Riparian buffering, described below, will help reinvigorate damaged marginal areas, while the introduction of new agriculture, agroforestry, aquaculture practices, and the new rural settlements supporting them, will stabilize the topography and restore hydrological systems.
The delta
Restoration of the imperiled coral reefs and mangroves, along with flood mitigation and bank restoration, is imperative to re-provisioning ecosystem services. Mangrove restoration must take place first so as to protect fragile corals implants that act as filtering systems, trapping debris and silt, balancing nutrient loads. Mangroves protect coastal zones from the impacts of major weather events. Reforestation and riverbank reconstruction will further reduce outflows of sediments and must be advanced with the delta restoration. Secondly, coral reefs, which take decades to build, have a vital interconnected role and must be quickly cultivated to also serve as storm surge barriers, while they rebuild local biodiversity. A promising artificial platform system called the “Reef Ball”™ is recommended for reef regeneration (The Reef Ball Foundation-Designed Artificial Reefs). It consists of a perforated concrete form with plugs of healthy new coral fragment inserts placed on the ocean floor in suitable habitat which can be economically utilized to speed the repopulation process. Mangroves can be planted in biodegradable baskets using a range of salt-tolerant and saline resistant species based on local conditions.
Riparian buffers
The riparian corridors along the Momance and Rouyonne were former oases of ecological diversity. Stripped of native vegetation, the eroded riverbank must be rebuilt to confine river flow. The middle zone, bordering the mountainous highlands and the alluvial plain, is ill-equipped to manage flooding, resulting in soil loss from agricultural lands and damage to human settlements. Riparian restoration within a demarcated corridor between 50 to 300 feet wide will recreate vegetated and forest buffer strips and patches that armor the riverbank to absorb floodwaters and slow erosion. Through pollutant removal and temperature moderation downstream, marine biodiversity and water quality will be restored. These new riverine habitat corridors will also aid in species migration across adjacent developed landscapes. During initial restoration, land holdings must be restructured along these rivers, including no-trespassing conservation zones and a less stringent long-term management system developed with local input.
Reforestation and agroforestry
In addition to the soil retention and ecosystem services returned through restored riparian buffers, trees and plantings are reintegrated using ‘agro-forestry’ models. Proposed intercropping of trees with food plants will foster stewardship while increasing land productivity through crop-shading and nutrient exchanges. Fruit production, timber from jatropha trees, vertiver grasses and coir industries can be integrated with adjacent irrigation channels to boost agricultural productivity and local enterprise. The integration of agroforestry is both economically and ecologically vital for regeneration (Collier 2009). Local inhabitants must be able to benefit while enabling ecological services to flourish.
Upland reservoirs
New reservoirs will be constructed at higher elevations in the energy corridor for flood mitigation and water storage. Independent of the pumped-hydro storage system, these reservoirs (875 m3 and 220 m3 capacity for the Momance and Rouyonne Rivers respectively), will divert floodwaters. Freshwater drawn from this impounded source will be also used for local crop irrigation. Micro-turbines placed within these channels will provide power to local farmers in rural areas not serviced by the micro-grid. New 100-foot riparian buffers within this upland zone, containing an estimated 380,000 trees, shrubs and grasses combined with riprap from concrete debris, will stabilize the soil.
Other integrated services
Transportation
As part of the integrated services development, improvements to roadbeds and associated stormwater drainage are vital to support the installation and upkeep of new infrastructure and spur economic development. Concrete pavers such as ones currently used in Léogâne are recommended for surfacing main and side street roads and plazas in the city center, as these are pervious to water and easy to repair. For resurfacing peripheral roads, application of lime-based soil stabilizers renders a more reliable pavement with low environmental impact at low cost. Such improvements can serve heavier traffic, including small vehicles moving collected waste to a new ‘eco-industrial park’ (defined below).
One of the major service points also serves as a multi-modal transportation center: a dedicated hub located on one of Haiti’s main highways just a short walk from the civic center. The station will accommodate buses, motorcycles, personal motor vehicles, and bicycles and has a small, attached market. It will be linked by new sidewalks, with pick-up and drop-off areas to improve pedestrian safety. Attached to the waiting area and public restrooms is a biodigester (see below) stationed to also receive large deposits of agro-waste delivered along the main road from outlying areas for transfer to the eco-industrial park.
Waste management
Waste is an unrealized resource, its management central to local economic revitalization. It creates employment, fosters community involvement and promotes environmental stewardship. Proper refuse management reduces water supply contamination as well. A comprehensive proposal for Léogâne’s waste diversion was developed that separates plastics, organics, metal and wood for recycling. It includes a new on-site processing facility, along with storage, transport, and connections to the large scaled biodigester and related generation facility (see An Eco-Industrial Park for Léogâne below). A mechanism to incentivize citizens to deliver sorted materials to the collection and pick-up points will be overseen by a new collection administration system. An educational campaign inculcating the benefits of resource conservation will also be vital for implementation.
Waste-to-biogas
Seventy-five percent of Haiti’s total waste stream is organic, comprised of crop residuals and other biomass, along with food and other domestic waste (Booth et al. 2010). It constitutes a largely untapped resource. The plan calls for a distributed biogas production system made up of strategically placed and variously scaled biodigesters (small for a cluster of dwellings, to larger community-scaled units). These biodigesters rely on slow anaerobic digestion that yields methane from organic human and animal waste mixed with agro-residuals. This is converted into useful biogas and a residual soil amendment byproduct. Benefits include production of a new fuel source for cooking or for additional electricity generation; improved sanitation and public health; greenhouse gas reduction, and increased farm yields, along with job creation.
An eco-industrial park for Léogâne
Léogâne sits in an agricultural region long renowned for sugarcane production, Haiti’s second largest cash crop after coffee. Yet in recent years, production and profits have faltered and Haiti has become a net importer of sugar from South America (Nienaber 2010). Léogâne now has one of the lowest yields for sugar cane in the Western hemisphere, with a range of 8 to 40 MT per hectare, compared to 85 MT in other parts of Haiti or Latin America (Barjon 2011b). Revival of the sugarcane industry (along with restoration of local food production) is essential for Haiti’s overall recovery. Better management of existing resources and development of new markets would restore production to historic levels. A resurgent cane industry will restore much-needed jobs, as two-thirds of the Haitian work force and 25% of GDP production has remained in agriculture (Eberhard et al. 2010).
Léogâne’s sugarcane production can be increased through more efficient management of existing resources as well as repair and expansion to the local processing facility, the Darbonne Sugar Mill. Additional resource efficiency can be gained through biodigestion of bagasse, the fibrous by-product of cane processing. The biogas extraction method has a higher energy capacity than simple bagasse combustion, which is a source of pollution. The process also co-produces a high quality fertilizer. Such an integrated resource management approach makes use of unrecognized assets, while reducing reliance on expensive fossil fuel fertilizers and potentially boosting agricultural yields (Piasecki 2013). Extensions to the Darbonne Mill property would effectively turn it into an eco-industrial park. Colocation of an industrial-scaled biodigester at the sugar mill would provide secondary or stand-by biogas cogeneration in Léogâne. The bagasse/biodigester upgrade can be coupled with Léogâne’s collected organic waste, delivered and stored on-site. This new co-generation system would have a capacity of 31.1 MW (Brown & Ward 2012). Plastic waste would also be processed as a complementary use in this eco-industrial park, recycled into lightweight compressed bricks for local use.