Solar Power Alone Will Not Solve Energy or Climate Needs

Solar Energy / Economics

Date posted: 09/27/17

Jatin Nathwani opines that although he is paid to evaluate renewable energy, which means his funding may encourage a particular technology, he also investigates energy options, alternatives and their utility. He has found that people get confused with terminology. Capacity installed in kilowatts (kW) is not equal to energy produced in kilowatt hours (kWh), and the energy services we demand and pay for (such as cooking, cooling, lighting, entertainment) is measured in kilowatt hours. For large-scale, industrial purposes, output is measured in megawatt hours (MWh) or gigawatt hours (GWh). The technical capacity of any energy technology to deliver useful energy is measured as energy output. Because of the efficiency of energy conversion, solar energy output tends to be low. For example, the energy produced from a large number of solar arrays combined as 1,000 megawatts (MW) installed capacity will deliver, on average, an energy equivalent of 10 to 12% of its capacity. In contrast, a nuclear plant delivers energy at 80 to 90% of its rated capacity. The current global installed capacity of 224,684 MW provides energy output of 253,593 GWh, equivalent to an annual capacity factor of 11 per cent. Similarly, Germany’s installed capacity of 39,784 MW results in energy output of 36,056 GWh at a capacity factor of 10.3%, which currently includes a large contingent of nuclear power plants, and burning of brown coal, both of which they plan to replace with windmills and solar panels. So, for the same installed capacity, solar energy produced is eight to nine times less than nuclear. If you want the same amount of energy, then you would need to install an equivalent solar capacity that is higher by as large a margin , that is eight to nine times the number of additional solar arrays. The point here is not to diminish the value and positive contribution that solar can make towards reducing our dependence on fossil fuels to help achieve a global energy transition towards a low carbon energy future. The hype needs to be tempered by a realistic assessment of the emerging energy demand at the global level and the effective capability of meeting growth in energy demand on a very large scale. You don’t want to get conscripted to the view that one energy option, solar, is the sole answer, and it also happens to be an option that does not deliver large volumes of energy from the installed base. The scope and scale of change required to meet climate change targets is anything but trivial. This suggests a complementary and reinforcing role for many different energy technologies with low-carbon attributes such as wind, solar, hydro, geothermal, nuclear power, and natural gas as an interim substitute for coal. The world population is forecast to approach nine billion people in 2050, with many to shift in income from extreme poverty to low- and middle income levels, which means an inexorable upward pressure on need for energy. A warming climate is another driver of growth in energy demand for cooling.