As to the energy efficiency of EVA, here's a public disclosure report filed with the SEC by Aura Systems in El Segundo CA, who have a pretty impressive record for developing new tech applications. Note the bold type:

". Electromagnetic Valve Actuators (EVA)

Over the past several years, the Company has been applying its patented
electromagnetic technology to a variety of applications. One application
developed is its electromagnetic valve actuator (EVA), which is an
electromagnetic actuator capable of opening and closing internal combustion
engine valves, replacing the mechanical camshaft on an engine. EVA uses the
power of electromagnets to open and close engine valves, and is capable of
accomplishing this in less than 3/1000 of a second. The engine computer that is
used on virtually all modern automobile engines will send to the EVA electronics
module a valve position command in the same way it will send a fuel injector
command. The EVA electronic module will implement the command, and wait for the
next command from the computer.

Two major benefits arise from the EVA's ability to open and close the
valve electromagnetically: 1) the camshaft and associated mechanical hardware
can be eliminated, and 2) the opening and closing of the intake and exhaust
valves can be commanded by the engine computer. As an example, EVA has been
retrofitted on a 140 HP, 2.3L 4 cylinder Ford engine that is currently running
in the laboratory.

Computer control of the valve timing has potentially material benefits
to engine performance, fuel economy and emissions. With EVA, the computer can
precisely control the amount of air that is allowed into the engine in the same
way that modern fuel injectors control the amount of fuel. By optimizing this
"fuel-air mixture" dynamically as a function of engine RPM and load, optimum
engine performance can be achieved over the entire operating range of the
engine. With a standard camshaft, the engine can be optimized at only one range
of RPM and load conditions. That is why very high performance engines idle
"rough", as they are optimized for high RPM, thereby sacrificing smoothness at
low RPM.

By optimizing the fuel-air mixture dynamically, both performance
(horsepower) and fuel economy will increase, while emissions are expected to
decrease. The implementation of EVA also greatly simplifies the engine
mechanically. The entire camshaft assembly, with includes timing chain,
camshaft, rocker arms, etc. is replaced by very simple valve actuators. Other
emission systems currently on the vehicle, such as the EGR (exhaust gas
recirculation) and IMRC (intake manifold runner control) valves can be
eliminated. Even the throttle assembly can be eliminated by using EVA to
control the amount of air going into the engine. Overall engine cost may be
substantially reduced.

Due to the Company's patented design, EVA requires relative little
power to operate. Lab measurements have shown that the total power required to
operate EVA is typically well under 100 watts/valve. Because of friction and
mechanical losses, a typical camshaft requires 3 to 5 horsepower to operate
(1hp=750 watts).

The Company is currently under contract to retrofit EVA's on different
types of diesel, automobile and motorcycle engines."

Note that the claimed power use for these EVAs is 100w/valve x 10 valves/camshaft in an F1 engine = 1Kw per 10 valves vs. 3 to 5 x .75Kw per cam in a cammed valvetrain. It appears that EVA is potentially more efficient than a camshaft-operated valve train.