The Future of Renewal Energy

In a recent study (by Jacobson and Delucchi) it was concluded that renewable energy based on wind, water and sunlight (“WWS”) could provide all new energy globally by 2030 and replace current non-renewable energy sources by 2050.

Projected global energy demand by 2030 is 17 trillion watts. Table 1 shows estimates of the potential energy available from various renewal energy sources:

Table 1: Availability of Global Renewable Energy

Table 2 presents results based on assumption that 90% of global energy is supplied by wind and solar, and 10% by other renewable.

Table 2: Infrastructure Requirements for Supplying All Global Energy in 2030 from Renewable Sources

What are the current issues?

(i)         Net Energy

Renewal energy sources generally have low net energy ratio, compared to fossil fuels (oil and coal). Net energy is the ratio of energy available for final consumption divided by energy required to produce it (or energy return on energy invested, the “EROI”). Table 3 demonstrates the net energy ratio for various energy sources.

Table 3: Net Energy Ratios for Various Energy Sources

(ii)        Intermittency

            Most energy supplies cannot be matched to demand as easily as fossil fuels. Energy diversity is one approach to intermittency and the other is to have battery storage. The latter needs further development.

A complete transition to renewable energy will likely take several years. In the meantime, fossil fuels especially natural gas-fired plants are best suited for balancing energy supply-demand.

Reference:

The Economics of Renewal Energy, David Timmons, Jonathan M. Harris, and Brian Roach, Tufts University