Economic crisis accelerates renewable possibilities

Fraunhofer Institute for Solar Energy

Evidence for irreversible and ultimately catastrophic climate change is getting more obvious. An acceleration of related phenomena including the reduction of the Arctic ice shield and the melting of Antarctic glaciers exceed the most pessimistic scenarios of the calculations in the Intergovernmental Panel on Climate Change Report 2007.

Concentrix Solar power plant in Puertollano, Spain. © Concentrix Solar GmbH

Exceeding certain irreversible, poorly defined tipping points in the world climate system runs the risk of destroying the extraordinary climate stability of the Holocene period of the last 12,000 years, giving rise to the age of the anthropocene, where man influences the climate in unpredictable and perilous ways.

Using and producing

We need a rapid change in how we use and produce energy. Limitations of fossil fuels, especially oil and gas, provide urgency as we approach a possible peak in production at 90 million barrels a day. After the end of the current economic crisis, we could return to ever-increasing prices for oil and gas, driven by the widening gap between global production and demand. There are two goals: increased energy efficiency and production of renewable energy.

A large proportion of energy is used for heating and cooling buildings. Technologies are already available to drastically tackle this, with interest in green cities promoting them increasing worldwide. Masdar City in Abu Dhabi is the first city (50-100,000 inhabitants) to be designed and constructed, entirely powered by efficient use of renewable, mainly solar, energy.

Production technologies and transport are areas where energy could be used more efficiently. Hybrid cars are developing into plug-in hybrids. Fully electric automobiles could get standardised battery systems allowing fast exchange at charging stations. A smart power distribution grid will optimise electric energy use and release from storage systems that might include battery-charging stations connected to huge numbers of batteries.

Globally we need about 15-20 TW of power generated from sustainable, better renewable sources. Nuclear fission will not be available for at least 50 years, but this will, at best, make a small contribution. It is highly doubtful whether Carbon Capture and Storage will ever be viable as the technology requires increased energy use. Long-time carbon sequestration in large volumes might follow the example for the failed sequestration of nuclear waste up to now as the safe long-distance transportation and long-term storage of CO₂ is technologically problematic and the not-in-my-backyard problem arises, just as for nuclear storage.

Focusing on solar

This leaves renewable energies. Water, geothermal and energy production based on biological waste provide complementary energy to fluctuating wind and solar sources. Long term, however, there is no alternative to the direct use of solar energy on a TW scale. With about 120,000 TW delivered by the sun, harvesting up to 20TW is entirely possible with current technologies. These will get more efficient and cheaper with higher production volumes and intensive research. Currently, solar thermal energy conversion by concentrated power plants is more cost efficient than direct photovoltaic (PV) harvesting. As PV technology is a semiconductor production technology, we can expect drastic cost reductions with increased production volume, similar to the last 50 years in semiconductors and last 20 years in PV.

Around 80% of the PV market, producing more than 8GW of new systems annually, uses crystalline silicon, the second most abundant element on earth. Replacing the preferred ultrapure semiconductor-grade silicon with dirtier material, such as purified or upgraded metallurgical silicon (umg-Si), would lead to greater cost reductions and volume growth. Thin film technologies based on amorphous Si, CdTe or CuInGaS are experiencing rapid growth as they provide PV power at the lowest cost per watt, but the low efficiencies compared to silicon modules are a serious barrier to increasing market shares. For areas with intensive direct sunshine, concentrated PV based on high-efficiency multiple junction cells from thin-film epitaxial III/V materials are a very attractive alternative as they are mounted on posts with two-axis trackers following the sun. This allows for agricultural use of the land below.

Germany has less than perfect sunshine conditions, but has developed a world-leading position with 5.3 GW (end of 2008) of PV capacity. Electricity suppliers have to buy PV-generated power at a feed-in rate financially attractive for investors. This rate is guaranteed for 20 years, but the rate offered to new investors next year is decreased by 8%. In a few years, it will dip below the household electricity price (‘grid parity’), so this mechanism will only be used for excess power above consumption. The impact on household rates is hard to notice – about 1 ct /kWh – but the rapidly expanding PV industry, including tens of thousands of local installers, provides valuable employment.

High-voltage direct current transmission lines need global investments on a huge scale. If we could transmit energy over long distances with little loss, this could mean an ultimately worldwide energy grid. At any time the sun is shining somewhere, the grid could bring energy where it is needed.
We should not wait for further crises, disasters or incidents to force us to re-think our objectives; we must act today, and fast. Government-supported research and development and effective market incentives programmes are the most important and the most efficient first step.

Fraunhofer Institute for Solar Energy Systems ISE
W: www.ise.fraunhofer.de