Published: 19 September 2011

Switch from coal to natural gas may not slow climate change

Although the burning of natural gas emits far less carbon dioxide than coal, a new study concludes that a greater reliance on natural gas would fail to significantly slow down climate change.

While coal combustion emits large amounts of carbon dioxide, it also releases sulfates and other particles that may help cool the planet by blocking heat from the sun.

Credit: Robert Kerton/ScienceImage

The study by Tom Wigley – Adjunct Professor at the University of Adelaide and a senior research associate at the National Center for Atmospheric Research (NCAR) in the US – underscores the complex and sometimes conflicting ways in which fossil fuel burning affects Earth's climate.

While coal use causes warming through emission of heat-trapping carbon dioxide, it also releases comparatively large amounts of sulfates and other particles that, although detrimental to the environment, cool the planet by blocking incoming sunlight.

The situation is further complicated by uncertainty over the amount of methane that leaks from natural gas operations. Methane is an especially potent greenhouse gas.

Adj. Prof. Wigley's computer simulations indicate that a worldwide, partial shift from coal to natural gas would slightly accelerate climate change through to at least 2050, even if no methane leaked from natural gas operations, and through to as late as 2140 if there were substantial leaks.

After that, the greater reliance on natural gas would begin to slow down the increase in global average temperature, but only by a few tenths of a degree.

‘Relying more on natural gas would reduce emissions of carbon dioxide, but it would do little to help solve the climate problem,’ concludes Adj. Prof. Wigley.

‘It would be many decades before it would slow down global warming at all, and even then it would just be making a difference around the edges.’

The study will be published in the peer-reviewed journal Climatic Change Letters in October.

Source: NCAR

Published: 26 September 2011

Renewable energy sector to benefit from wind-speed research

Craig Macaulay

While some recent international studies have shown a decrease in wind speeds in several parts of the globe, including Australia, more recent results from CSIRO show that Australia’s average wind speed is actually increasing.

The ability to accurately quantify long-term variations in wind speeds is essential to the viability of Australia’s wind power sector.

Credit: Gregory Heath

CSIRO scientists have analysed wind speed observations to understand the causes of variations in near-ground-level wind and explore long-term wind speed trends.

Accurate estimates of long-term trends provide a useful indicator for circulation changes in the atmosphere and are invaluable for the planning and financing of sectors such as wind energy, which need to map risk management under a changing climate.

‘We have a good picture of wind energy availability across Australia from previous CSIRO wind mapping and, with the growth of wind farms, there is an emerging need to understand how climate change can affect the wind resource,’ says Dr Alberto Troccoli, lead author of a recent paper published in Journal of Climate. ¹

‘Wind power production is expected to increase greatly over the coming years and the associated electricity system will be subject to variations of several hundred megawatts – depending on wind availability.

‘The ability to quantify with accuracy these long-term variations is essential to the sector from an economic point of view.’

Dr Troccoli said that, averaged across Australia over 1989–2006, wind speeds measured at a height of 10 metres had increased by 0.69 per cent per annum, compared to a decline of 0.36 per cent per annum for wind speeds measured at 2m height.

‘The potential for increasing the efficiency of energy operations by using quality weather and climate information is therefore apparent and one of the first steps is the standardisation of wind recording stations.

‘Wind observations, like other meteorological variables, are sensitive to the conditions in which they are observed – for example, where the instrumentation sits relative to topographical features, vegetation and urban developments.’

The team found that the wind speed trends over Australia are sensitive to the height of the station, with winds measured at 10m displaying an opposite and positive trend to those reported by a previous study, which analysed only winds measured at 2m.

Light winds measured at 10m, a height that represents better the free atmospheric flow, tend to increase more rapidly than the average, whereas strong winds increase less rapidly than the average winds. Light and strong wind measured at a height of 2m tend to vary in line with the average winds.

‘Our work shows a number of challenges with the consistency of the observations during their period of operation and between sites across Australia,’ adds Dr Troccoli.

‘The quality of future wind observational datasets will depend on having consistency between sites, particularly with respect to measurement procedure, maintenance of instrumentation, and detailed records of the site history.’

He said the work has implications for a variety of sectors beyond wind energy including building construction, coastal erosion, and evaporation rates.

The conjunction of energy and meteorology is the central theme of the International Conference Energy & Meteorology on the Gold Coast in November.

Read Dr Troccoli’s thoughts on What’s the energy forecast? Bringing meteorology and generation together in the online forum, The Conversation.

¹ A. Troccoli, K. Muller, P. Coppin, R. Davy, C. Russell and A. Hirsch (2011) Long-term wind speed trends over Australia. Journal of Climate, doi: 10.1175/2011JCLI4198.1

Welcome to the ECOS Archive site which brings together 40 years of sustainability articles from 1974-2014.

For more recent ECOS articles visit the blog. You can also sign up to the email alert or RSS feed