$40B organics market - http://www.ers.usda.gov/topics/natural-resources-environment/organic-agriculture/organic-market-overview.aspx. That makes it
Annual sustainable forest yield of 12.5B cubic meters or 105 exajoules - [2], p. 615

Total USA energy use - 25 PWhr - [4] - (petawatt hours (See Metric Prefixes))
Equivalent to 90 exajoules, consistent with Renewable Energy "Blue Bible" above.

250GW of PV is installable on existing rooftops - Cosservative estimate (50% of residential rooftops) - [5]

Per year, let's take average insolation as 6 hours per day * 365 days - or 550 TWhr per year. That is 2% of USA's energy use, or 5% of USA's electric use. This is JUST RESIDENTIAL ROOFTOPS. Needs to add commercial rooftops, parking lots, roadway medians.

USA road density - 67 km/ 100 sq km of area - [6]
USA area - 10 million sq km
USA roads - 6.7 million km. Assume an average road is 2 lane with shoulder - each lane has 12 foot (3.7m) standard in the USA - [7] - or an area of about 100,000 sq km. This could power 1/4 of the world's energy needs (oil, nukes, solar)
Area required to power all of the world with PV is 400,000 sq km - [8]
Total forest area of the world - 4 billion hectares - [9] - 30% of land area of world.
Total farmland area worldwide -
Total land area - 150M sq km - google
Total agriculture land - 33% of world land according to FAO - [10]
Energy per capita US vs Switzerland - As an indicator, the average energy use per person is 12,000 watts in the USA but only 3,000 in the Switzerland - [11]
Percentage of USA energy by source. Coal electricity is 40% - [12]
Half of USA rooftops could replace all coal electricity in the USA - [13]
World electricity production 2009 - 20PWh - [14]
Area of all cities compared to world land area - 0.5% - [15] - or 750,000 sq km.

Other

Given $1200/year battery costs of Tesla Model S, cost of fuel or electricity is $1700 - no savings - between the electric and regular fuel option approximately at the 15,000 mile per year mark - according to cost calculator at [20]
Lithium Ion batteries - predicted to go down to under $200/kWh -[21]
Nickel-Iron battery energy density - 50Wh/kg - [22]

EVs could replace 75% of petroleum fuel - [26]
Materials cost for a 18650 cell (Lithium Ion) is $1.25 (about 4W) - [27]
Lithium is $40/lb - [28]
According to this source - [29] - we have 100 years of nickel reserves, nad 200 years of iron and aluminum.
Nickel - $6/lb
Iron - 20 cents/lb

Resources