Today’s article looks at the explosive growth of renewable energy, but also places it in the context of our overall energy demands.
Rapid Rise in Biofuels Production — U.S. Takes the Lead
The first graphic shows the rapid rise in global biofuel production that has occurred in the past decade — led by the United States.
While it is not indicated in the spreadsheet, these production numbers apparently represent barrels of oil equivalent (BOE). The reason I say that is that the BP data indicate U.S. biofuel production of 8.7 billion gallons, but actual production of ethanol alone in 2011 was reportedly 13.9 billion gallons. U.S. biodiesel also contributed over 1 billion gallons. But these biofuels have lower energy density than crude oil, which means that if converted to barrels of oil equivalent the BOE number would be lower than actual volumetric production.
Cumulatively, the U.S., Brazil, and the European Union account for 87% of global biofuel production. The U.S. produced 48% of the world’s 2011 biofuel total, mostly in the form of corn ethanol. Brazil produced 22.4%, primarily as sugarcane ethanol. However, ethanol production in Brazil has been flat to declining in recent years due to disappointing sugarcane harvests. The third major biofuel producing region is the EU, which is the leading biodiesel-producing region in the world. The EU was responsible for 16.5% of global biofuel production. Other than the U.S. and Brazil, the only other countries producing more than 3% of the global biofuel total were Germany (4.8%) and Argentina (3.8%).
Solar PV’s Explosive Growth
The next figure shows the explosive growth of solar photovoltaic (PV) capacity, dominated by Europe. (The data did not break down into capacity specific to the EU, and data were only available from 1996).
Global PV capacity has increased at a dramatic pace since 2007, driven largely by generous incentives in Europe. In 2011, Europe was responsible for 74% of the world’s total PV capacity, with Germany leading the way at 35.8% of the global total. Italy — not Spain as many might have suspected — was in 2nd place in Europe with 18.4% of global PV capacity. Spain was in 3rd place at 6.2% of global PV capacity.
Solar PV capacity for U.S. and China are far behind European capacity, but I broke them out separately in the next graphic to show that they — as well as Japan — have also shown explosive growth in adding PV capacity.
Wind Power — China Jumps Ahead of the U.S.
As the next graphic demonstrates, global wind power has also grown rapidly in recent years. At 239 gigawatts of installed capacity, global wind capacity is well above solar PV’s 69 gigawatts of capacity. Wind power is also more evenly distributed around the world.
Once again, Europe does have the most installed capacity of any region at 40% of the world’s total, but China recently surpassed the U.S. and now possesses 26% of the world’s installed wind capacity versus 19.7% for the U.S. Cumulatively, the three areas are responsible for 86% of global wind capacity.
Taking a Look at the Global Energy Mix
Of course as many would be quick to point out, despite the rapid growth the renewable portion of the world’s energy mix is still small. The next graphic shows the total renewable contribution toward the energy that was consumed in 2011.
The renewable portion — which included solar PV, wind power, geothermal power, and power from biomass — accounted for 1.6% of the world’s energy consumption, up slightly from 1.4% in 2010 and coming almost exclusively from developed countries. However, BP includes ethanol and biodiesel under the “Oil” category, and if we make that adjustment the renewable portion rises to 2.1% . If we include hydropower in the renewable category, the renewable share rises to 8% of total consumption. (Note that these numbers do not include conventional biomass burning, which I identified in my book as the “main energy source for cooking for most of the developing world, and the primary source of energy for over 2 billion people.”)
Oil was the largest contributor to our global energy needs at 33% of total consumption, followed by coal (30%), natural gas (24%), hydroelectricity (6%), and nuclear power (5%). Cumulatively, fossil fuels provided 87% of the world’s energy in 2011, which was actually a tiny fraction higher than in 2010 (86.9%). (If we add nuclear power, fossil fuels plus nuclear power provided 92.1% of all energy in 2010, and declined a tiny fraction to 92.0% in 2011 because of a slight decline in nuclear electricity).
Given the explosive increase in renewable capacity, why would the world have used a slightly higher fraction of fossil power in 2011? Intuition might indicate that this fraction should be falling, but not only did the fraction from fossil fuels grow slightly, overall consumption of fossil fuels grew by nearly 3%. So renewables aren’t growing fast enough to displace fossil fuels; they are merely supplementing them.
The main reason for this is that developing countries are gravitating toward the cheapest and most reliable energy sources they can find, and those tend to be fossil fuels. This was demonstrated earlier in this series by showing the growth of coal consumption in developing regions.
The reliability issue can be brought into focus by comparing the capacity of wind or solar power with the electricity that was actually produced. The ratio of the actual output over the potential output if the power source produced 100% of the time is called the capacity factor. In the U.S., the capacity factor for nuclear power plants in 2011 was 89%. The U.S. Energy Information Administration (EIA) estimates that the capacity factors for electricity derived from fossil fuels or nuclear power are in the range of 85% to 90%, 92% for geothermal, 52% for hydropower, 34% for wind, and 25% for solar PV.
We can cross-check this with the data from the BP report. Total consumption of solar power was reportedly 55.7 terawatt-hours (TW·h). (I have an enquiry into BP on exactly how they obtain consumption numbers; a colleague suggested that the numbers are probably readily available since production is generally subsidized — and thus the production must be measured). The 69 gigawatts of total installed solar PV capacity could produce 69*24*365 = 604 TW·h if solar produced 100% of the time. Thus, the capacity factor based on those numbers is only 9%.
But the real number is actually higher than that, because the capacity number is based on the end of the year, while actual production is measured throughout the year. We can get a better true capacity factor if we average the PV capacity of the end of 2010 and the end of 2011, which would be more indicative of average 2011 capacity. In this case, the capacity factor for solar PV rises to 11.6%, which is far below the EIA estimate.
For wind power, the average capacity between year end 2010 and year end 2011 was 219 gigawatts, which could potentially produce 1,918 TW·h. Actual consumption was 437 TW·h, implying a capacity factor of 23% — double the capacity factor for solar PV, but again far below the EIA’s estimate of 34%. If we look at just the data for the U.S., the solar capacity factor in 2011 comes to only 6% for some reason (3.5 gigawatts of average capacity for 2010 and 2011, but only 1.8 TW·h of consumption), but the capacity factor for wind was better than the global average at 31.6%.
These capacity factors help explain why developing countries are embracing fossil fuels. Developed countries with ample supplies of stable power can afford to increase the penetration of wind and solar power into their grids. Power-hungry developing countries are building up those supplies of stable power, which will enable them to increase the supplies of intermittent power. But given the current cost and intermittency of wind and solar power, no developing country is going to rely on them heavily.
Unless a cost-effective energy storage system is commercialized and widely adopted, wind and solar power will continue to depend on firm power, which is predominantly from fossil fuels or nuclear power (but sometimes from hydropower). In fact, we often say that wind and solar must be backed up by firm power, but in reality they are merely providing a small offset to our use of fossil fuels.
Nevertheless, the growth rate for almost every class of renewables over the past decade far surpasses the growth rate of fossil fuels and nuclear power. But because it is starting from a very low base — and because of the need to be backed by firm power — it is questionable whether renewables like solar power, wind power, and biofuels can make a major contribution (e.g., more than 10% of the world’s total consumption) in the foreseeable future.