Genesis Energy emitted more carbon dioxide in generating electricity last year than any year in the last decade, as it used more coal to make up for a lack of hydropower and gas.
Genesis Energy's Huntly Power Station. Photo: Genesis Energy
Low rainfall and lake levels have hampered hydropower generation, and unforeseen gas outages have led to lower fossil gas supply able to be used in generation. As a result, more coal has been used.
The energy generator and retailer put out 4029 kilotonnes of carbon dioxide emissions in the last financial year, 82.5 percent more than the average of 2207 kilotonnes between 2016 and 2020, and more than any year dating back to at least 2010, as far as Genesis' publicly available statistics go.
This is about 5 percent of the country's total emissions.
The recently released 2021 financial year figures show Genesis generated 2955 gigawatt hours (GWh) of electricity from coal in the 2021 financial year, more than doubling FY20 (1339 GWh) and FY19 (1404 GWh) and quadrupling FY18 (657 GWh). The smallest amount generated by coal in recent years was 186 GWh in 2017.
The number of tonnes of carbon dioxide gas emitted per gigawatt hour of energy produced in the June 2021 quarter was 596, the most in any quarter since at least the September 2009 quarter.
The Huntly Power Station - where this coal is burnt - emitted more carbon dioxide per energy output in April, May and June this year than any quarter dating back to at least 2009, when Genesis Energy's publicly available usage statistics go back to.
A fossil gas shortage has meant the company's dual fuel (able to be powered by both gas and coal) rankines have been powered by coal 96 percent of the time over the last year.
The amount of coal Genesis holds in stock was also lower than in any quarter, at 189,000 tonnes.
South Island lake levels are back at normal levels after significant rain over the last six weeks, but North Island lakes are still below average.
In 2015, Genesis Energy announced a plan to stop using its coal fired Rankine units at Huntly Power Station by December 2018. In 2016, the company pushed that back to the end of 2022. Then in 2018, Genesis pushed that back again to 2030, or 2025 under normal market conditions.
The company is aiming to reduce generation emissions by more than 36 percent by 2025, removing 1.2 million tonnes of annual carbon emissions. To do this it has a strategy to have access to 2650 GWh of clean energy by 2030. Part of this is a recently-opened Waipipi wind-farm which will produce 433 GWh annually.