Robust Extra Low Cost Nano-grids (RELCON)

Lead Research Organisation: University of Oxford
Department Name: Engineering Science

Abstract

RELCON is targeting Sustainable Development Goal 7- to ensure access to affordable, reliable, sustainable and modern energy for all. At present the World Bank estimates there to be about 1.3 billion people without access to electricity. This goal is seen as an enabler to improving the plight of people as determined by the Millennium Development Indices. There is a clear correlation between per capita electrical energy consumption, energy access and the Human Development Index. ODA list countries are the front and centre target of this research. This proposal meets the challenge to provide good Tier 3 electricity provision for homes and Tier 4 levels of electricity for community productive services and will be commercially viable at a cost of $4 per month per household (typical low end spend for kerosene). Furthermore, it has been designed so as to be grid ready.

This ambitious challenge is met by delivering a downwards step-change in the costs of distribution infrastructure by recognising that PV is becoming much cheaper and that widespread decentralised storage enables a significant decrease in distribution cabling costs. The system comprises of a nano-hub, serving 15 to 25 dwellings, each with a separate touch-safe ultra low voltage line. By having smart, low cost power electronic converters at each end of the line, mitigates many of the issues of volt drop. Furthermore, the local storage provides additional power at peak time, enabling the end user to have access to power in excess of the line rating. The batteries also allow for reduced peak powers on the lines that reduce the net losses, as well as providing additional resiliency to the system. The nano-hub can also accept a grid connection, thus greatly reducing the costs of delivering power to the already connected end users.

RELCON has five work streams: 1) Understanding the needs of the community, 2) System design and operation, 3) Low cost, robust power converters 4) Protection systems and 5) In field prototype trial.
This project will develop the underlying technology, analysis tools and datasets to enable the robust design and operation of this novel network architecture that is fit for providing for the electricity needs of off-grid communities. It brings together exceptional expertise from three Universities, Oxford, Cardiff and the Co-operative University of Kenya, as well as three complimentary partner companies: Kenya Power (the main distribution and customer facing utility), African Power Storage (a UK based startup developing nano-hub) and Tropical Power (an implementation partner with an impeccable record). These partner companies already start to provide clear pathways to enabling significant impact.

Planned Impact

It is the vision of RELCON that the research developed by this project will make a significant impact on the number of people without electricity access. RELCON specifically identifies a route to develop a novel electricity system that can be commercially viable, and that provides a sustainable route to substantial energy consumption via a grid connection. RELCON will meet the energy trilemma directly by providing a system that is affordable (<$4/ month), clean (PV) and secure (local generation and storage).

Rural communities will benefit from access to DC electricity in the home to power lights, phone charging, entertainment, and low power (<300W) appliances such as power tools, shavers, fans, refrigeration and egg incubators. The nano-hub allows for (AC or DC) power up to a total 5kW, enabling a wide range of productive services including health care, education, water pumping, welding and commercial businesses. There is therefore a route to not only improving their social well-being, but also their wealth creation ability.

Electricity utilities/ Rural Electrification Authorities (e.g. Kenya Power) will benefit by having a clear route to significantly increase electricity access that is financially sustainable. Additionally new tariff structures can be developed and trialed. This approach removes significant risk to an electrification programme, as actual consumption and commensurate financial data will be available. As the grid is connected, most of the expensive components (PV and central storage) can be reused in other locations, or can be used to provide additional resilience from notorious line outages.

NGO's/ project implementers can benefit from the opportunity to develop a market that provides improved services compared to Solar Home Systems but at a capital expenditure much less than mini-grids.

UK companies can benefit from the development of new products that fulfil a very large gap in a very large market.

The planet will benefit in that the substantial improvement of the social and human capital of LMICs will come at a significantly reduced impact on the environment.
 
Description The design of the electronics was improved to include a more comprehensive data communications capability. It is shown that Lorawan can be used, but that using the cable for communications is also possible.
A new technique was developed that modulated the DC-DC converters to provide low bandwidth communications, at no extra cost. It was also shown that high bandwidth communications over the cable is possible.
The use of a single cable to each home was adapted to use multi-core cables, which then branch to each home. This enabled a more cost effective and robust trenching regime.
A very low cost soil resistance meter was developed to allow infield testing for the impact of lightning strikes.
Exploitation Route This has initiated interest by some commercial firms, but impacts are too early to quantify.
Sectors Energy

URL https://epg.eng.ox.ac.uk/our-research/relcon/
 
Description The impact of optimising both the spatial and the temporal operation of a constrained grid has impacted the thinking of Project LEO. This has helped the development of local flexible markets.
First Year Of Impact 2021
Sector Energy
Impact Types Economic