Jetting away from our wet, unsettled summer to sear under the extreme heat of the southern Europe, holidaymakers are inevitably bankrolling their resulting carbon emissions into an even hotter Mediterranean and more heavily drenched Ireland next summer.
Air conditioning has become critical across continental Europe, driving high energy usage at a time when hydroelectric generation is being throttled by low rivers. Some nuclear power stations along the Rhône and Garonne rivers have had to reduce their power output because the river waters are too warm to act as coolant.
Matching the hot summer demand for air conditioning, both the Spanish and Greek authorities have invested heavily in solar power. Earlier this month, Reuters reported 24 per cent of Spain’s energy in July had come from solar farms, from 16 per cent a year ago.
In Greece, 34 per cent of its electricity generation came from solar on July 24th, a national record. The Irish figure, reported in this newspaper on July 22nd is around 10 per cent of national output.
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Australia is also investing heavily in solar power, particularly using rooftop panels for domestic housing. On October 17th last, an astonishing 92 per cent of South Australia’s energy came from solar. But a study this month by the University of New South Wales cautioned against the medium-term stability of Australian solar power.
The Australian weather is becoming cloudier. Scattered fair-weather cumulus can lead to a temporary ramp down in solar energy output, and stratus clouds may diminish generation for hours. Equally, sudden clearing of the skies can lead to a rapid surge in output. As the Australian power grid becomes dominated by solar power ahead of other energy sources, abrupt reductions and surges from local weather conditions can adversely impact the system stability. In the light of climate change, the report recommends careful national planning to manage solar ramping effects.
Can we overcome the clouds?
As a young man growing up in Los Angeles in the 1940s, Donald Bren was fascinated by a Popular Science magazine article discussing the possibility of satellites capturing solar energy and beaming it back to Earth. Today, the 91-year-old is a retired real-estate developer, having become one of the richest philanthropists in the US. A decade ago, he and his wife Brigitte committed $100 million to the California Institute of Technology for a space-based solar project. This month the first prototype system demonstrated the transmission of harvested solar energy as microwave power in space, and beaming it back to Earth. The amounts of energy were small but the prototype shows it is feasible to use relatively low-cost components, and to concentrate the generated energy into a focused and steerable beam.
The research team believe that their system could be about eight times more efficient than any terrestrial solar farm, due to the intensity of solar energy in space. The lightweight satellite reduces the power required by the launch system, mitigating criticism that the carbon emissions from a launch would outweigh the carbon-free solar generation. However, critics also observe the long-term vulnerability of solar panels in space to micrometeroids and radiation, particularly since the panels might be several square kilometres in area to harvest commercially viable amounts of power.
Solar power, and perhaps in due course fusion, is superseding carbon-based fuels. And there can be other benefits
Can we instead create our own suns here on Earth?
Current nuclear reactors use fission to generate energy – disintegrating uranium atoms by bombarding them with neutron bullets, with each rupture leading to even more neutrons in a chain reaction. The process is challenging to control, and the resulting fragments remain radioactive for decades. By contrast, nuclear fusion, as occurs in the sun, merges small hydrogen atoms together to make larger atoms of helium. The result has minimal radioactive waste, and cannot form a chain reaction. Furthermore, if the pressure and temperatures required to achieve fusion are lost, the activity simply stops – unlike the possibility of runaway fission reactions. Finally, fusion produces more energy per kilogramme of fuel compared with fission.
Fusion is thus considerably safer than fission. However, fusion is difficult to engineer, recreating the sun in a miniature form. Nevertheless, last December a team at Lawrence Livermore Labs in California successfully achieved controlled nuclear fusion, yielding more energy than that required to attain fusion. This month they have had a second successful demonstration. Further experimentation and scaling are needed before a commercial system, but it is a very considerable breakthrough.
Solar power, and perhaps in due course fusion, is superseding carbon-based fuels. And there can be other benefits. AP News this month reported that a Bavarian farmer is using 32 acres of raised solar panels not only to generate power, but as a parasol to shield his crops of hop from the intense summer heat and to help retain ground moisture.
