The editorial "The Next Energy Plan" {Aug. 14} correctly discussed oil conservation but only briefly mentioned alternative oil sources. They deserve more attention. Some history:

I spent a mercifully short part of my youth in Nazi Germany and recall that the Nazis managed to synthesize petroleum from coal. Even the Nazis admitted that it was more expensive than natural petroleum, but it did seem to burn, and it enabled them to fight a long war despite little access to natural petroleum.

Like Germany, Japan had few oil sources at home during World War II. Access to foreign sources was cut off by U.S. submarines and aircraft. But Japan had no synthetic petroleum. The result: American aircraft were finally able to fly back and forth over Japan without fighter opposition. The Japanese fighters had no fuel.

Government policy should now, during our third Mideastern oil crisis in 17 years, urgently focus on research and development to reduce the cost of synthetic petroleum to the point at which it would make Mideastern petroleum irrelevant. We will then have become independent from the chronically unstable Middle East and its strongmen, compared to whom George III was a saint.

RUDOLPH E. HIRSCH Washington

Most conservative economists would agree that the price of gasoline (and other petroleum products) should at a minimum reflect its full cost. Clearly that cost includes a sizable share -- perhaps at least a third -- of the defense budget. That share, for reasons of economic efficiency, should therefore determine the minimum federal tax on gasoline. Any lower tax would amount to a de facto federal subsidy. Conservation would flow automatically from the price increases such a tax would cause, as would reduced dependence on imported oil and those who might control its supply.

Because the burden of such a large tax would be regressive, some offsetting benefit would need to be provided to the lowest income groups -- perhaps increased personal tax exemptions, welfare payments and food stamps.

A much larger oil import tax is superficially an attractive alternative, since it is imported oil which requires the defense expenditures. However, that approach would simply increase domestic oil company profits and, beside being blatantly protectionist, would hasten the day when domestic reserves are exhausted and the country is at the mercy of the oil exporting countries.

The deflationary impact of such a large gasoline tax -- and the major (and badly needed) deficit reduction it would permit -- would also go a long way toward offsetting the inflationary impact of higher international oil prices. It would enable the Federal Reserve to reduce interest rates.

In short, many problems -- energy conservation, inflation, the deficit and growing dependence on OPEC -- would be alleviated by removing the federal subsidy on gasoline and charging the consumer what it really costs. J. C. PETER RICHARDSON Washington

Whatever happened to renewable energy sources? Photovoltaic? Hydroelectric? Alcohol distilled from corn? Oil extracted from plants? Wind power? Wave power? Improving properties of the electric storage battery? Renewable energy sources could provide jobs for our citizens, make the United States an independent energy-producing nation and rid of us of our present insatiable thirst for capriciously priced and capriciously supplied foreign oil.

The writing was on the wall when we waited in long lines to fill our gasoline tanks in 1973. And still today our leaders, blinded by a destructive craving for foreign oil, fail to recognize viable alternatives. And I shake at my very core to think that the youth of our great nation may -- once against -- die in another senseless, barbaric war. NORMAN H. FORSTER Washington