The closure of incentives for renewable electricity generation, and limited availability for grid connections to export electricity to the national grid, has meant the appetite for developing new renewable projects in NI has virtually disappeared.

However, Co Derry businessman John Henderson believes that renewable electricity generation can still deliver a significant return on investment, and subsequent savings, in the absence of funding.

The Northern Ireland Renewables Obligation (NIRO) incentivised renewable electricity generation and closed for new onshore wind installations in April 2016. It closed for all other technologies a year later, and there remains no replacement policy in the pipeline.

Although the NIRO did not go over budget, unlike NI’s other renewable energy scheme, the Renewable Heat Incentive, John Henderson points out that both schemes were similar, in that they encouraged generation of energy, and not utilisation.

“The issue for many grassland farmers is not growing grass but getting their livestock to utilise it. Renewable energy generators face the same problem,” he said.

John has a coffee bean roasting business and a small farm in Upperlands. A 5kW wind turbine was installed six years ago and at the time he calculated that 68% of the electricity generated was exported to the electricity grid.

Export

He points out that it is renewable generators selling electricity into the grid that has brought significant issues with congestion on that grid.

John also questions the economics of selling electricity in times of surplus generation and then buying electricity back at an increased price in times of deficit. Typical tariff rates involve electricity being sold at 4p per kilowatt- hour (kWh) and imported for 15p/kWh.

“We realised we needed to find a way to store surplus energy so we purchased two 28kWh sodium ion batteries from the US in November 2015,” John said.

The business also increased renewable generation to 13kW by adding 4kW of solar panels to the roof of the dwelling house, and another 4kW to a shed roof.

John now utilises 90% of electricity generated and has displaced heating oil, gas and diesel costs for his home and business with renewables. He has also not used electricity from the grid since April and estimates electricity will not need to be imported until mid-August. Overall, he has budgeted for an eight-year payback on the renewable system.

The solar panels and wind turbine are accredited with NIRO and receive payment through the scheme, but John maintains that farm businesses can avail of potential financial benefits by focusing on storing and utilising renewable energy generated.

Costs

He believes the cost of renewable generators and electricity storage will continue to decrease as the technologies develop. “At present, 20kW of solar panels would cost around £24,000 and 50kW of storage would be around £20,000. Installation costs then vary in each scenario depending on how buildings are wired,” John said.

Key to making financial savings from renewables is being able to displace existing costs. In John’s case, a key cost was transport which was reduced by switching from a diesel van to an electric van. “We have covered 42,000 miles in the van and had no problems with it. Our transport costs from our annual accounts have reduced from £4,500 to £1,300 due to having no fuel costs and less servicing,” he said.

For farm businesses, he said that savings could simply be made by reducing electric bills, as long as renewable energy is able to be stored in batteries and then used to power milking parlours or heat water.

Some energy is inevitably lost in the storage process, with John’s system currently operating at 86% efficiency. An unknown is how long the battery storage system will last, but John is fairly confident, given that the manufacturers estimate sodium ion batteries should last around 3,000 cycles (empty to full charge) and his system hasn’t completed a full cycle since April.

The total cost and payback of John’s system was increased due to a second control system, which manages the charging and discharging of the batteries, having to be installed.

The first control system that John installed in November 2015 was not effective in managing the changing flow of electricity into and out of the batteries.

“Electricity is generated in DC (direct current) and is also stored in DC but used in AC (alternating current). You need an efficient invertor to change it.

‘‘Variations in generation constantly occur due to a cloud moving away from the sun or a gust of wind and some control systems cannot handle that,” he said.

If the control system cannot manage fluctuations in generation, it causes the installation to stop generating for a period. “It is again similar to grassland management, utilisation drives further production,” John said.

The new system was installed in April and it has worked well allowing no electricity to be imported from the grid since then, with John predicting his business and dwelling house will be self-sufficient until mid-August.

Batteries

Searching for adequate batteries was an ongoing process for nearly five years due to changes in technology and regulations.

Saltwater batteries were bought because purchasing large-scale lithium batteries proved difficult due to regulations surrounding their disposal. Retailers of lithium batteries are required to provide services for disposal at the end of their life. John said that this was difficult to agree with battery importers and it was also going to be an unknown cost for the lifetime of the battery.

Another issue that can be common with lithium-based batteries is the potential for thermal run away, where batteries overheat and become unusable.

John said that lead-based batteries were also an option and are generally cheaper, but they can only be discharged to 50% capacity. “This would have meant we would have needed double the storage, and lead batteries also have a shorter lifetime from manufacturers,” he said.

Electric van

He uses the electricity to power an electric van which has a 100-mile range on a fully charged battery.

Charging from flat at home takes six hours on the 3kW fast charge or eight hours at 2kW. Rapid charge points located across NI to top up during long journeys allow an 80% charge from flat in 20 minutes.

The system is set up so that if there is surplus electricity and the batteries are full, the electricity is used to heat water and it is only exported to grid when this is at capacity.