Homes and businesses lead energy efficiency gains, cars lag behind

BUSINESSDESK: A swing away from heavy industry, more use of electricity for home heating and dramatically better use of aircraft contributed to an overall improvement in New Zealand's energy efficiency between 1990 and 2011. 

However, the mining sector has become much more energy intensive over the same period and the move to larger cars and less use of public transport has seen the overall energy efficiency performance of passenger vehicles worsen over those 21 years, new figures from the Ministry of Business Innovation and Employment show.

Total energy consumption grew in all categories because of population and economic growth, and the figures, developed with the Energy Efficiency and Conservation Authority, seek to isolate the impact of improved energy efficiency.

They divide New Zealand's energy use into three broad categories: residential, transport and a business sdection covering all industry, commercial activity and public sector consumption other than oil refining and chemical manufacturing such as methanol and agri-chemical production.

Energy intensity in the business category, accounting for 64% of total energy consumption, fell by 21% over the two decades, from an average of 2.9 Petajoules of energy per $1 billion of output in 1990 to 2.3 PJs per billion dollars in 2011.

Among reasons for this were a slump in energy use after the global financial crisis, with gross consumption falling from a peak for the period of about 260 PJs in 2007 to just under 250 in 2011.

But structural changes to the economy were also important contributors, as energy intensive activities grew more slowly than the commercial sector, reflecting a switch to wood waste from coal in wood product manufacturing, and a drop in highly energy-intensive wood processing from 2005 onwards.

"Consumption of both electricity and wood increased significantly between 1990 and 2011, whereas the consumption of gas, coal and liquid fuels all remained relatively flat during this time," MBIE says.

The overall impact was an energy efficiency dividend for the business category of 11 PJs between 1990 and 2011.

While household consumption grew by 29.8 PJs in the 21 years, that was mainly through population growth, a move to smaller numbers of people per household in the 1990s and a trend to larger homes in the 2000s.

Accounting for 12% of total national energy consumption, the residential sector was the biggest gainer in energy efficiency terms, with the switch away from fossil fuels to electricity for household energy driving an energy efficiency gain equivalent to 17 PJs during the period.

Passenger transport showed the most mixed trends, reflecting the shift from transporting goods by low energy-intensity shipping to higher energy-intensity trucking by road and a slight worsening in the energy intensity of both cars and buses.

"The potential exists to significantly decrease energy consumption by shifting mode share from cars to buses and rail due to their relatively low energy intensities," MBIE says.

Offsetting this worsening trend for land transport was a dramatic improvement in the energy efficiency of aircraft used in domestic travel, mainly reflecting fuller planes. They were around 60% full in 1990, compared to about 80% full by 2011, halving the energy intensity rating for domestic aviation.

Industry sub-categories showed substantial variation in energy intensity trends over the two decades.

Mining, including oil and gas activity, showed a 52% rise in energy intensity to 3.5 PJs per billion dollars of output from 2.3 PJs in 1990: the largest single increase of any industry, although mining is one of the smallest sectors by total energy use.

The biggest energy-using industry – wood, pulp, paper and printing – became 33% more energy-intensive, going from 14.3 PJs per billion dollars of output in 1990 to 19.

Non-industrial "commercial" activity showed a 25% energy efficiency gain over the period, while the non-metallic minerals sector – covering activity such as cement and lime making – showed a 40% improvement.